SN Applied Sciences

, 1:1379 | Cite as

Modified tapioca starch for iron nanoparticle dispersion in aqueous media: potential uses for environmental remediation

  • Umma S. Rashid
  • Senay Simsek
  • Sushil R. Kanel
  • Achintya N. BezbaruahEmail author
Research Article
Part of the following topical collections:
  1. 2. Earth and Environmental Sciences (general)


Synthesis of cost-effective surface-modified nanoscale zero-valent iron (NZVI) for use in environmental remediation is a challenge. Herein, we report the synthesis of modified tapioca starch-coated NZVI (CNZVI) particles and their application for effective aqueous nitrate remediation. We used 2-octen-1-ylsuccinic anhydride (OSA) to modify the native starch and, thus introduced carboxyl and ester groups for effective binding of the starch to the NZVI surface. Coating NZVI (3 g L−1) with 35% OSA-modified tapioca starch (10 g L−1) significantly improved colloidal stability of CNZVI in deionized (DI) water compared to bare (unmodified) NZVI (p = 0.000). Approximately 66% of CNZVI remained suspended till 2 h as compared to 4% of bare NZVI. Nitrate removal studies (20, 40, and 60 mg \({\text{NO}}_{3}^{ - }\)–N L−1 and 1 g L−1 of nanoparticles) showed CNZVI removed nitrate effectively (54–71% removal). The nitrate removal by CNZVI followed second-order reactions with surface normalized reaction rate constants ranging from 0.003 to 0.007 L m−2 h−1. Shelf life of the coated nanoparticles was found to be 3 months. High biochemical oxygen demand was expressed during respirometric biodegradation studies indicating ease of biodegradation of the CNZVI particles. Coating NZVI particles with OSA-modified tapioca starch is expected to have widespread scientific and industrial application potentials for ex situ as well as in situ contaminant remediation. The authors opine that the use of tapioca starch as the raw material for coated nanoparticle synthesis will be a value addition for the crop, and thus, nanotechnology will contribute to agricultural economy.

Graphic abstract


Iron nanoparticle Dispersion Agglomeration Tapioca starch Nitrate removal 2-Octen-1-ylsuccinic anhydride (OSA) In situ remediation Agricultural economy 

1 Introduction

The use of nanoscale zero-valent iron (NZVI) for contaminant remediation and management has gained popularity over the years, and the recent efforts are targeted at improving treatment efficiency [38, 59, 67]. NZVI particles can treat contaminants effectively because of their high specific surface area-to-volume ratio, rapid kinetics, and high reactivity [5, 26, 55]. Researchers have used NZVI to treat different contaminants [38] including chlorinated compounds [10, 29], dichromate [66], pesticides [8, 11, 14], arsenic [9, 27], heavy metals [21, 30, 31, 34, 64], nitrate and ammonia [12, 56, 67], and phosphate [1, 49, 50, 62, 63]. Additionally, NZVI has been explored for possible use in algal (energy) production [2].

However, bare (unmodified) NZVI particles agglomerate easily in aqueous environment and that reduce the available reactive surface area of the particles [29, 55]. Agglomeration occurs because repulsive electrostatic forces are overpowered by attractive van der Waals and magnetic forces [41]. The agglomerated particles are to be removed from the aqueous phase as they settle down in the treatment reactors or pore spaces in the aquifer. To improve the colloidal stability of NZVI particles, surface modification has been done [25, 27, 29, 42, 58]. Surface modification can provide both electrostatic and steric repulsion to prevent particle agglomeration [27, 29, 58]. To prepare physically more stable and chemically more reactive NZVI, different stabilizers like polymers have been used for coating. These polymers include poly(acrylic acid) (PAA) and poly(vinyl alcohol-co-vinyl acetate-co-itaconic acid) (PV3A) [23], poly(styrene sulfonate) (PSS) [40], amphiphilic polysiloxane graft copolymers (APGC) [29], guar gum [58], carboxymethyl cellulose (CMC) [36, 42, 53], and chitosan and polyaniline [68]. The polymer used needs to contain an anchoring group (e.g., hydroxyl, carboxyl, or ester) to bind to the surface of NZVI. These polymer-coated NZVIs not only have shown improved colloidal stability but also improved contaminants removal [18, 25, 29]. However, high cost [57], limited biodegradability, and complex synthesis process have limited the use of these polymers.

Among different candidates, polysaccharides are potential biopolymers for coating NZVI particles which will be easy to prepare and apply [57]. Starch is one of the relatively cheap and green polysaccharides which is easily available across the globe. Starch is a mixture of polymers: linear amylose and branched amylopectin (SI, Fig. S1). The hydrophilic nature of starch can improve NZVI’s colloidal stability [15]. Native (i.e., unmodified) starch-stabilized bimetallic iron nanoparticles significantly increased the degradation of trichloroethylene (TCE) in water [18]; an unnamed water-soluble analytical grade starch was used in that study, and starch chemistry was not elucidated.

Starch is commonly used in food industry for dispersion (stabilization) of additives in foods such as salad dressings, custards, and puddings. Starch is made up of repeating glucose units bound together by glycosidic bonds [(C6H10O5)n-(H2O), SI, Fig. S1a]. Native starches can be modified through chemical, physical, and enzymatic routes [48] to make them effective in nanoparticle dispersion. Attaching hydrophobic groups to the repeating glucose units, we can create amphiphilic starch molecules that can function as effective emulsion stabilizers [5]. Further, introducing carboxyl and ester groups to the polymer may help in binding the starch to the surface of NZVI [19, 29, 44].

This work extensively explored the starch chemistry and used octenyl succinic anhydride (OSA) to modify starch for coating NZVI particles. OSA-modified starch is amphiphilic in nature and known to function as emulsion stabilizer [6]. An OSA-modified starch contains carboxyl and ester groups [7], and these two groups would bind strongly to the NZVI surface [19, 29, 44] and would be ideal for coating the NZVI particles. Importantly, NZVI particles have a protective oxide coating, and OSA with carboxyl and ester anchoring groups has affinities to bind with iron oxides. The hydrophilic blocks help NZVI particles disperse better and, thus, prevent them from agglomeration [29, 40, 42]. Additionally, starches have high molecular weights (a starch’s molecular weight varies depending on its plant origin) which would improve colloidal stability by increasing steric repulsions [40]. We investigated the performance of coated NZVI (CNZVI) particles for their colloidal stability and ability to remediate aqueous nitrate in batch experiments.

2 Materials and method

2.1 Materials

Iron (II) sulfate heptahydrate (FeSO4·7H2O, Aldrich Chemical), sodium borohydride (NaBH4, ACS grade, Alfa Aesar), methanol (95 + %, BDH), sodium hydroxide (NaOH) (ACS grade, BDH), 2-octen-1-ylsuccinic anhydride (OSA) (Dixie Chemical Company), commercially available modified tapioca starch (Ingredion, Inc, USA), hydrochloric acid (HCl, EMD Millipore), deuterium oxide (D2O, Sigma-Aldrich), sodium sulfate (Na2SO4, Sigma-Aldrich), potassium hydroxide (KOH, Sigma-Aldrich), urea (Sigma-Aldrich), potassium nitrate (KNO3, Mallinckrodt Chemicals), ammonium sulfate ((NH4)2SO4, J.T. Baker), BOD Nutrient Pillows (Hach, USA), lithium hydroxide pillows (LiOH, Hach, USA), and nitrogen gas (N2, Praxair) were used as received unless otherwise specified. Ingredion Incorporated (Illinois, USA) supplied native tapioca starches.

2.2 NZVI synthesis

NZVI was synthesized by borohydride reduction in ferrous iron in FeSO4·7H2O according to previously published method [10, 32]. After reduction, the black NZVI clusters were washed with ethanol to remove unreacted NaBH4. The NZVI was dried overnight in a vacuum oven under nitrogen environment. The dried NZVI was ground using a ceramic mortar and pestle to produce NZVI particles. Powdered NZVI particles were stored in amber glass vials in nitrogen environment for later use.

2.3 Preparation of OSA-modified tapioca starch

Native tapioca starch was modified with octenyl succinic anhydride (OSA) to create an amphiphilic starch. OSA modification was performed as described in published reports [6, 17]. Briefly, starch (100 g) was dispersed in 225 mL DI (deionized water) water by constantly stirring in a 500-mL beaker, and the pH of the slurry (at ~ 25 °C) was adjusted to 8.5–9.0 by dropwise addition of 1 M NaOH. While maintaining the pH of the solution, OSA (3, 15, 35, and 50% w/w starch) was slowly added to the solution using a burette. Following the addition of OSA, the mixture was stirred for 6 h (pH 8.5). For high OSA concentrations (≥ 15%), Na2SO4 was added (5% w Na2SO4/w starch for 15% OSA, 13.6% for 35% OSA, and 20% for 50% OSA) to prevent the starch granules from swelling. Once the reaction was complete, the slurry was neutralized to pH 7 with 1 M HCL. The modified starch was washed three times with DI water by centrifuging at 2500 rpm for 15 min and once with acetone. Once washed, the modified starch was dried at 40 °C in nitrogen environment for 24 h and stored in glass bottles.

2.4 OSA-modified tapioca starch-coated NZVI (CNZVI) preparation

To coat NZVI, various concentrations of native and OSA-modified starch (1, 5, and 10 g L−1) were prepared in deoxygenated deionized (DI) water. Native starch or OSA-modified starch suspensions were brought to boil, cooled to 50 °C, and stirred overnight (with the heating on) to produce a gelatinous solutions. Following starch preparation, NZVI particles (60 mg) were combined with 20 mL of starch solution (nitrogen purges) in clear glass vials. Each vial’s head space was flushed with nitrogen gas, and the NZVI–starch mixture was sonicated for 30 min to prevent agglomeration of NZVI particles using previously published method [29]. Immediately following sonication, the reactors were placed in a custom-made end-over-end shaker (28 rpm) and rotated for 72 h (optimized as a part of preliminary work) for the starch to coat the NZVI particles. After 72 h, the coated NZVI (CNZVI) particles were centrifuged and washed with copious amount of deoxygenated DI water to remove excess starch. Fresh deoxygenated DI water (20 mL) was added to each vial, and the washed CNZVI particles were stored in the glass vials for future use.

2.5 Characterization of OSA-modified tapioca starch

FTIR spectrometer (FTIR, Nicolet 8700, Thermo Scientific) was used to confirm the substitution of carbonyl groups of OSA on the starch molecule in 15% and 50% OSA-modified tapioca starch and compared with FTIR data obtained for native starch. ~ 1.5 grams of sample was ground with potassium bromide (KBr) and pressed into a pellet disk. The samples were scanned over the wavelength of 400–4000 cm−1. Background spectra were subtracted from the sample spectra.

Nuclear magnetic resonance (NMR) was used to confirm the presence of OSA methyl protons and to determine the degree of substitution (DS). The starch samples were purged with D2O three times; samples were lyophilized between each purge. Next, the samples were dissolved in D2O (0.6 mL) a final time at 80 °C for 1 h and placed in NMR tubes (8 inch, 5 mm, thick wall). 1H spectra were obtained using a Bruker (Billerica, MA, USA) Ascend 400 MHz NMR. The analysis was conducted at 25 °C for 64 scans with a delay time of 1 s. DS was calculated according to the methods of Shih et al. [46]. The internal standard was the equatorial proton of the anhydroglucose unit (AGU) of starch (5.2–5.4 ppm). Extent of OSA substitution was determined by the integration of the methyl protons of the OSA (0.8–0.9 ppm). DS was calculated using the equation DS = (A0.8–09)/(3*A5.2–5.4) where A0.8–0.9 = methyl protons of OSA and A5.2–5.4 = equatorial protons of the AGU of starch [46]. DS is the average number of hydroxyl groups substituted per glucose unit comprising a starch molecule [51]. The decreased number of hydroxyl groups indicates that more OSA molecules (containing esters and carbonyls) have reacted with starch molecule to form ester derivatives during the modification [51].

2.6 Colloidal stability studies

Colloidal stability of bare NZVI and CNZVI was monitored using UV–Vis spectrophotometry. CNZVI particles stored in vials (see CNZVI preparation) were used. The content in a vial was sonicated for 15 min, and 2 mL suspension of CNZVI was pipetted into a glass cuvette (UV–Vis spectrophotometer, DR5000, Hach, USA) immediately; the sedimentation behavior (i.e., change of light intensity) was observed over 2 h at the wavelength of 508 nm [29]. A concentration of 3 gL−1 of bare NZVI (same iron concentration as in CNZVI) in deoxygenated DI water was evaluated as a control after 15 min of sonication.

2.7 Characterization of nanoparticles

NZVI particles were coated with 35% OSA-modified tapioca starch and were dried in a nitrogen environment for 24 h. Dried CNZVI samples were sprinkled onto carbon tabs attached to aluminum mounts. Images were obtained with scanning electron microscopy (SEM) (JEOL JSM-7600F, JEOL USA, Inc., Peabody, Massachusetts). Energy-dispersive spectroscopy (EDS) was done using an Ultra Dry silicon drift X-ray detector and NSS-212e NORAN System 7 X-ray Microanalysis System (Thermo Fisher Scientific, Madison, Wisconsin). Spent CNZVI particles were also characterized to compare with fresh CNZVI.

2.8 Nitrate removal studies

Nitrate (20, 40, and 60 mg \({\text{NO}}_{3}^{ - }\)–N L−1) removal batch experiments were conducted in commercial grade polyethylene terephthalate bottles (225 mL nitrate solution in deoxygenated DI water) used as sacrificial reactors. The nitrate stock solution (100 mg \({\text{NO}}_{3}^{ - }\)–N L−1) was prepared with 0.7218 g of KNO3 (dried for 24 h at 105 °C) in 1 L of deoxygenated DI water. Deoxygenation was done by bubbling the DI water with pure N2 gas for 2 h. The specific test solutions (20, 40, and 60 mg \({\text{NO}}_{3}^{ - }\)–N L−1) were prepared from the stock solution for removal experiments via dilutions with deoxygenated DI water. CNZVI (1 g L−1 of NZVI) particles were added into the \({\text{NO}}_{3}^{ - }\)-N solution, the reactors were sealed with a rubber stopper, and air was flushed out from the headspace with N2 gas. Controls with only 35% OSA-modified tapioca starch (10 g L−1, no CNZVI) in the \({\text{NO}}_{3}^{ - }\)-N solution and blanks (only \({\text{NO}}_{3}^{ - }\)-N solution with no starch and CNZVI) were used. The reactors were rotated in the end-over-end shaker at 28 rpm. Batches of sacrificial reactors were taken out at predetermined intervals (0, 30, 60, 120, 240, 360, and 720 min), and aliquots were withdrawn. NZVI particles were filtered from the aliquots using 0.2-μm syringe filters [29, 55], and the samples were tested for \({\text{NO}}_{3}^{ - }\)-N using a double-junction nitrate electrode (VWR, USA) as per Standard Method 4500 [3]. The nitrate removal data were fitted into zero-, first-, and second-order reaction models to understand the reaction kinetics.

Since ammonium and nitrite were expected to be generated when iron reduces nitrate [22], samples were also analyzed for all nitrogen species. Nitrogen mass balances were done for samples used in the 20 mg \({\text{NO}}_{3}^{ - }\)–N L−1 removal studies. These samples were collected at 0, 1, 2, 6, and 12 h and tested for nitrite (\({\text{NO}}_{2}^{ - }\)-N), ammonium (\({\text{NH}}_{4}^{ + }\)-N), and nitrate (\({\text{NO}}_{3}^{ - }\)-N) using an Auto Analyzer 3 (AA3, High Resolution Digital Colorimeter, Seal Analytical, USA) and Auto Analyzer Method G-139-95, Rev. 5. The nitrates in the sample were converted to nitrite when passed through the cadmium reduction column and analyzed as nitrite, whereas the nitrite samples were analyzed directly as nitrite. The difference between the combined nitrogen (nitrate plus nitrite) and the nitrite concentration in the sample was the nitrate concentration. Ammonium samples were analyzed as \({\text{NH}}_{4}^{ + }\)-N using the Berthelot reaction [45] and Auto Analyzer Method 145-95, Rev. 4.

2.9 Shelf-life study

Many batches of CNZVI (1 g NZVI/L) were prepared and stored in a laboratory cabinet at room temperature (22 ± 2 °C). \({\text{NO}}_{3}^{ - }\)-N removal studies were conducted at predetermined time interval over a 4-month period.

2.10 Starch biodegradation

The biodegradation behavior of OSA-modified starch and CNZVI particles was studied using respirometric experiments following the OECD 301 C Modified MITI test (I) [39]. Biochemical oxygen demand (BOD) was monitored using an automated closed-system respirometer (BODTrak Apparatus, Hach, USA). BODTrak measures the quantity of oxygen consumed in the system by monitoring changes in headspace pressure (Hach. BODTrak II User Manual, 2013). Headspace pressure decreases as the bacteria use the oxygen present while they consume the organic matters in the sample [16]. BOD data were collected continuously using a data logger and stored in a computer connected to the instrument during the 28-day test period. Mixed liquor suspended solids (MLSS) were collected from the City of Moorhead Wastewater Treatment Plant (Moorhead, MN) and used immediately as seeds (i.e., the microorganisms to start the degradation study).

2.11 Quality control and statistical analysis

All experiments were conducted in triplicates, and the average values are reported along with the standard deviations. One-way ANOVA was done to compare the sedimentation data to determine statistically significant differences in datasets. Tukey’s pairwise comparison was used after the one-way ANOVA to identify which groups among the samples were significantly different.

3 Results and discussion

3.1 Synthesis of octenyl succinic anhydride (OSA)-modified tapioca starch

OSA-modified tapioca starch was successfully produced. A number of characterization techniques were used to ensure that modification was done to the extent expected.

FTIR analyses: FTIR was used as an initial screening tool to confirm the esterification reaction between starch hydroxyl groups and OSA. FTIR spectra of native and OSA-modified tapioca starch (Fig. 1a) show different types of C–O bond stretching between 800 and 1200 cm−1. The band near 860 cm−1 represents the C–H and CH2 deformation [35, 47]; the band near to 1081 and 1160 cm− 1 is attributed to the anhydroglucose ring C–O stretch; the peak close to 1015 cm− 1 is assigned to the C–O of the C–O–C in the polysaccharide [35, 47, 61]. Band at 2931 cm−1 represents the C–H stretching vibration, and the one at 1650 cm−1 is for bound water present in the starch [35, 47]. OSA modification is confirmed by the presence of adsorption bands around 1720 and 1570 cm−1. The band around 1720 cm−1 corresponds to C=O stretching vibration caused by the formation of an ester group and that at 1570 cm−1 represents the asymmetric stretching vibration of carboxyl groups [7, 47, 51, 54]. These results confirm the substitution of hydroxyl groups in starch by carbonyl and carboxyl groups of OSA.
Fig. 1

a FTIR spectra of native and OSA-modified tapioca starch; b1HNMR spectra of OSA-modified tapioca starch samples. (i) Native; (ii) commercially available modified tapioca starch; (iii) 3% OSA; (iv) 15% OSA; (v) 35% OSA; (vi) 50% OSA. Inserts: spectra expansion of 0.5–2.7 ppm; c1HNMR of 50% OSA-modified tapioca starch

1H-NMR analyses: 1H-NMR was used to quantify the chemical modification of the OSA starches and to determine the degree of substitution (DS) [5, 54]. Since OSA starches are amphiphilic, they tend to form aggregates in aqueous media [54] and that inhibits water solubility. Poor solubility can significantly reduce NMR signals, which can result in an error in estimated DS [54]. To overcome solubility issues, the samples were prepared and scanned in D2O [46, 54] which partially dissolves starch samples. 1H-NMR spectra were analyzed for native tapioca starch, commercially available modified (OSA) tapioca starch, and 3, 15, 35, and 50% OSA-modified starches (Fig. 1b). The peaks at 4.10–3.18, 4.64, 4.96, and 5.38 ppm represent the hydrogen of glucose units at different positions [5, 6, 46, 47]. OSA modification is confirmed by the addition of signals between 0.8 and 2.7 ppm [5] and changes in signals around 5.50 ppm [6, 54]. The peaks between 0.8 and 2.7 ppm (Fig. 1b, c) match with the results reported by others for OSA substitution [5, 6, 46, 54]. The peak assignments and molecular structure of OSA-modified starch are shown separately (Fig. 1c). The peak (Fig. 1b, c) observed at 0.8 ppm are from the methyl protons of the octenyl succinate (OS) group. The intensity of this peak varied with the amount of modification reflecting different DS of each modification. OSA modification also introduced a low-intensity peak at 0.9 ppm. This peak indicates the shift of terminal methyl protons in some substituted octenyl succinate group [6]. The octenyl succinate groups are hydrophobic, and this hydrophobicity might cause aggregation in aqueous media and shifting of methylene proton [6]. The peaks located around 1.2–2.7 ppm in OSA-modified starches were from the protons of the methylene groups of OSA [13]. These peaks were integrated using Bruker Topspin v3.2 software, and the DS for each starch was determined (Table 1) as described in the Materials and Method section.
Table 1

Degree of substitution (DS) in OSA-modified tapioca starch

Tapioca starch

Degree of substitution

Reported DS values

Commercially available modified (OSA) tapioca starch



3% OSA


0.016–0.017 [46, 51, 52]

15% OSA


0.045–0.051 [5, 51]

35% OSA



50% OSA


0.088 [5]

aNA not available

The DS for 15% OSA starch in this research is twice the reported values (Table 1), which could be attributed to differences in the addition rate of OSA, solution pH, and reaction time. Bai et al. [5] reported that the solution’s pH dropped rapidly and was difficult to maintain at OSA concentrations ≥ 15%. As DS decreases when the solution pH drops below 8.5 [51], it is possible that the reduced amount of OS substituted in Bai et al.’s study was because of the rapid pH drop during OSA addition. Song et al. [51] used a reaction time of 4 h, while the current study allowed the reaction to continue for 6 h and the authors think that the extended contact time between OSA and starch molecules helped in achieving higher DS.

Higher DS values on starches modified with increased OSA concentrations match literature reports [6]. Others reported DS = 0.11 for 25% [7] and 0.088 for 50% [5] OSA starch, and the current study mirrors those results (Table 1). The DS likely decreased at 50% OSA because the solution’s pH was difficult to maintain, and the starch granules swelled despite the addition of Na2SO4. Swelling starch granules made the solution difficult to stir and that might have limited the number of starch molecules contacting OSA. The results presented here and by Bai et al. [5] suggest that there is a critical OSA concentration for optimizing the DS. The authors have decided to designate that OSA-modified starch which showed best dispersibility of CNZVI to be the optimal for this research.

3.2 Colloidal stability studies

NZVI particles (3 g L−1) were coated with three different concentrations (1, 5, and 10 g L−1) of OSA-modified tapioca starch, and their sedimentation behavior was monitored using UV–Vis spectrophotometry. Bare NZVI was used as the control in the sedimentation studies. The sedimentation data indicate that OSA-modified tapioca significantly improved sediment behavior of CNZVI compared to the control (Fig. 2; detailed data with standard deviations are shown in SI, Fig. S2). However, over the 2-h sedimentation study, some of the NZVI particles apparently got oxidized and changed the color of the solution to light red. This color has increased the value of absorbance and might have shown a higher dispersion value for CNZVI (Fig. 2). The NZVI coated with 10 g L−1 35% OSA-modified tapioca starch formed the most stable suspension as compared to the lower concentrations of OSA-modified tapioca starch (Fig. 2). Approximately 66% of CNZVI remained suspended till 2 h as compared to only 4% of bare NZVI (Fig. 2d). The remaining studies presented in this work used CNZVI obtained with 35% OSA-modified tapioca starch (concentration = 10 g L−1). The 35% OSA-modified tapioca starch had the highest DS as well (Table 1).
Fig. 2

Sedimentation behavior of NZVI coated with OSA-modified tapioca starch concentration of a 1 g L−1; b 5 g L−1; c 10 g L−1. NZVI concentration = 3 g L−1 (Fig. 2d is a select presentation from this plot at time points 60 and 90 min); d comparison of aqueous dispersion of bare NZVI and CNZVI (10 mg L−1 35% OSA-modified tapioca starch was used for CNZVI)—the vertical error bars represent ± standard deviations ( Open image in new window bare NZVI; Open image in new window native tapioca starch-coated NZVI; Open image in new window 3% OSA tapioca starch-coated NZVI; Open image in new window 15% OSA tapioca starch-coated NZVI; Open image in new window 35% OSA tapioca starch-coated NZVI; Open image in new window 50% OSA tapioca starch-coated NZVI) (A = measured light absorbance, Ao = initial light absorbance)

3.3 Characterization CNZVI particles

SEM images of CNZVI (Fig. 3a, b) show discrete particles surrounded by a starch coating (the layer around the particles). CNZVI particle size ranges from 47.5 to 325 nm (Fig. 3d) with an average particle size of 118.6 nm (n = 200) while bare NZVI particles had a particle size of 10–90 nm (average ~ 35 nm). Some of the coated particles have formed chains (Fig. 3a, b), but individual particles are visible in the chains. The individual particles in each chain are well coated with the OSA-modified starch. Others [65] also observed chain formation with potato starch-coated NZVI particles. A magnified image (Fig. 3b) shows mostly small chains with occasional large clusters. The CNZVI/starch matrix also appears to be relatively porous (Fig. 3b).
Fig. 3

a Scanning electron micrograph of CNZVI; b scanning electron micrograph of CNZVI (magnified); c EDS spectra of freshly prepared CNZVI; d CNZVI particle size distribution

SEM/EDS spectra (Fig. 3a–c) of freshly prepared CNZVI show the presence of sodium (0.9%), carbon (7.7%), and oxygen (25.1%) in addition to iron (65.9%). CNZVI particles show higher oxygen content than bare NZVI particles (16% oxygen and 84% iron) that can be attributed to the ester and carbonyl groups from the OSA-modified starch. Sodium is likely present because of side reactions that occurred during starch modification from NaOH used for pH control [5, 51, 54] as well from NaBH4 used in NZVI synthesis. The percentage of sodium is very low indicating that the side reactions probably were not dominant.

3.4 Kinetics of nitrate removal studies

Kinetic studies were conducted to investigate how the nitrate is removed by CNZVI particles. During the 12-h study, CNZVI reduced \({\text{NO}}_{3}^{ - }\)-N concentrations from 20 to 5.81 mg L−1 (71% removal), 40 to 11.68 mg L−1 (69%), and 60 to 28.4 mg L−1 (54%) in 12 h while there was no removal in the control (only OSA-modified starch in nitrate solution) and the blank (only nitrate solution with no CNZVI or starch) (Fig. 4). The maximum nitrate removal capacity by CNZVI has been compared with other nanomaterials reported in the literature (Table 2), and it can be seen that CNZVI could achieve the way higher efficiency in nitrate removal compared to other modified NZVI but lower than the two hybrid nanomaterials (viz., Pd-Cu-NZVI and graphene oxide–NZVI).
Fig. 4

Nitrate reduction by CNZVI with initial \({\text{NO}}_{3}^{ - }\)-N concentration of a 20 mg L−1; b 40 mg L−1; c 60 mg L−1. NZVI concentration = 1 g NZVI/L, 35% OSA starch concentration = 10 g L−1. The data points are connected with straight lines for ease of reading only, and they do not represent trendlines. The vertical error bars indicate ± standard deviations ( Open image in new window CNZVI; Open image in new window OSA starch; Open image in new window blank)

Table 2

Comparison of nitrate removal by different modified NZVI

Nanomaterial Type


Initial concentration (mg \({\text{NO}}_{3}^{ - }\)–N L−1)

Nanomaterial dose (g L−1)

Contact time (h)

Removal efficiency (%)



Integrated with

A. eutrophus cells







Capped with polyphenol







Entrapped in calcium alginate beads





[8, 11]


OSA starch





Current study


Pd-Cu deposited on NZVI







Coated with graphene oxide (GO)






NA not available

aReported as mg \({\text{NO}}_{3}^{ - }\) L−1. Here, it is converted to mg \({\text{NO}}_{3}^{ - }\)–N L−1, and the values have been rounded off

CNZVI was found to reduce nitrate following second-order kinetics [dC/dt = − kSA*ρA*C, where kSA = surface normalized reaction rate constant (L m−2 h−1), ρA = iron surface area concentration in the solution (m2 L−1), t = time (h), and C = nitrate concentration (mg \({\text{NO}}_{3}^{ - }\)–N L−1)]. Surface normalized reaction rate constants for nitrate removal ranged from 0.003 to 0.007 L m−2 h−1 for CNZVI (SI, Table S1). It is important to point out that a second-order reaction, instead of a commonly reported first-order/pseudo first-order reaction, was observed in our experiment. Johnson et al. [24] postulated that if contaminant removal by iron metal follows a second-order reaction kinetics, then change in specific reactivity of the metal surface significantly affects the reaction kinetics [24]. They presented the following surface area normalized equation (Eq. 1) to incorporate the effect of reactive surface sites in a contaminant removal/degradation reaction.
$${\text{d}}C/{\text{d}}t = - k_{2}* \varGamma* \rho_{A}* C$$
where k2 is the second-order rate constant for removal/degradation at a particular reactive surface area (Lh−1mol−1) and Γ is the surface concentration of reactive sites (mol m−2). Through this equation, they proposed that the contaminant removal/degradation occurs favorably in distinct sites such as kinks, impurities, pits, steps, other crystal faces, or surface defects. However, data are not typically available to quantify Γ, but according to Johnson et al. [24] it is prudent to use kSA (surface normalized reaction rate constant) to incorporate k2 and Γ (kSA = k2*Γ) in order to elucidate the factors that affect the reaction rate. In this study, iron in CNZVI particles was oxidized during nitrate removal and due to water-mediated corrosion. Here, nitrate was reduced and we detected ammonium (\({\text{NH}}_{4}^{ + }\)) and nitrite (\({\text{NO}}_{2}^{ - }\)) as the two dominant degradation products (Fig. 5). The iron oxides did not participate in nitrate reduction, but only Fe0 did. The particle size of zero-valent iron (core of the CNZVI) and consequently reactive iron surface area concentration (ρA) decreased over time. The decrease in both \({\text{NO}}_{3}^{ - }\) and surface area concentrations affected overall nitrate reduction, and it followed a second-order kinetics.
Fig. 5

Nitrogen mass balance when nitrate solution (Co = 20 mg L−1) was treated with CNZVI. CNZVI concentration = 1 g NZVI/L ( Open image in new window ammonium; Open image in new window nitrite; Open image in new window nitrate; Open image in new window total nitrogen species (aqueous phase); the solid line is for pH in the secondary axis)

The mass balance for nitrate reduction by CNZVI (Fig. 5) shows low ammonium production with very low nitrite generation. The samples contained 60% ammonium when nitrate was reduced by CNZVI for 12 h. The mass balance of nitrogen species in the reactor changed throughout the experiment. This balance line declined during the first hour and then increased between hours 1 and 2 (Fig. 5). The initial decline is related to the increase in pH to 9.46 and partial stripping of ammonium at this pH. Hwang et al. [22] reported the similar nitrogen mass balance scenario while reducing nitrate with NZVI. The value of pH increased from 7.52 to 9.92 in the first hour possibly due to proton consumption during the nitrate reduction [22], and the pH remained at ~ 10.00 for the rest of the experiment (Fig. 5).

3.5 Spent CNZVI characterization

The surface morphology of spent CZNVI and fresh CNZVI was examined in this study (SI, Fig. S3). Spent CNZVI particles appear to be irregularly shaped and have rougher surfaces (compared to fresh CNZVI). The average particle size of spent CNZVI (75.89 nm, n = 200, SI, Fig. S3a) is lower than fresh CNZVI (118.6 nm), indicating the starch layer might have degraded or sloughed off. Since the particles were still larger than bare NZVI (average diameter of bare NZVI ~ 35 nm), it can be assumed a starch layer was still present on the particles, which prevented the particles from aggregating. SEM images of spent CNZVI particles have flake like structures, which could be free/detached starch or iron oxide plates. Ryu et al. [43] also reported the formation of iron oxide plates when nitrate reacted with NZVI. EDS analyses of spent CNZVI indicated oxidation of iron (during nitrate reduction) as indicated by the 7% increase in oxygen [25.06% oxygen and 65.89% iron in fresh CNZVI (Fig. 3c), and 31.93% oxygen and 35.56% iron in spent CNZVI (SI, Fig. S3b)].

3.6 Shelf-life study

The CNZVI particles need to have long shelf life to be commercially viable (storage and transportability requirements). The results showed that there is no significant difference in \({\text{NO}}_{3}^{ - }\)-N removal by CNZVI up to 120 days after production (p = 0.079–0.999) with exceptions on Day 30 (p = 0.043) and Day 50 (p = 0.013). The CNZVI particles maintained their shelf life till 120 days (~ 63% nitrate removal, Fig. 6). There is no logical explanation for the exceptions for Day 30 and Day 50 data, but Data from Day 30 (67% removal) and Day 50 (66%) also indicate that removal efficiency did not decrease below the 0-day value (56%, Fig. 6). The 3-month shelf life is significant because that make it feasible transport the CNZVI particles to remote remediation sites from the production units and increases their storability in the production unit and on-site.
Fig. 6

Shelf-life evaluation of OSA-modified starch-coated NZVI was done over a 4-month period. There was no change in the ability of the coated NZVI to degrade nitrate over a period of 4 months. C0 = initial nitrate concentration (60 mg L−1 as \({\text{NO}}_{3}^{ - }\)-N) and C is nitrate (mg L−1 as \({\text{NO}}_{3}^{ - }\)-N) remaining at the end of the time interval

3.7 Starch biodegradation

Respirometric experiments were conducted for 28 days to monitor BOD expression (Fig. 7). There was a significant increase (p = 0.000) in BOD with the addition of either OSA starch or CNZVI particles (Fig. 7). The increase in BOD production suggests that OSA starch is easily biodegradable. It was observed that the CNZVI particles produced significantly more (p = 0.000) BOD than just OSA starch, suggesting that the iron in CNZVI possibly promotes microbial activity. There was a significant difference (p = 0.000) between the biodegradability of just OSA starch and CNZVI (~ 67% for OSA starch and 97% for CNZVI, SI, Fig. S4). Increased microbial populations in the presence of modified NZVI have been reported by others [20, 28]. As per OECD standard, a polymer is considered biodegradable if the percent biodegradation is greater than 60% within the first 10 days [39], and both OSA starch and CNZVI met this requirement (SI, Fig. S4).
Fig. 7

Organics degradation (BOD expression) during biodegradation studies ( Open image in new window CNZVI, Open image in new window OSA starch, and Open image in new window seed)

4 Conclusion

This study reports the first use of OSA-modified tapioca starch as a surface modifier for NZVI and the use of coated NZVI (CNZV) for aqueous contaminant (nitrate) removal. Modified tapioca starch can be used as an effective surface modifier for NZVI particles. Coating NZVI particles with 10 g L−1 35% OSA-modified tapioca starch had significantly improved the colloidal stability of the nanoparticles; ~ 66% of CNZVI remained suspended till 2 h as compared to only 4% of bare NZVI. The CNZVI also showed good nitrate reduction efficiency (54–71%). The coated nanoparticles were found to have shelf life of at least 3 months that makes their long-distance transport and long-term storage post-production feasible. Biodegradation studies indicated that CNZVI stimulates microbial growth which results in improved biodegradation of OSA starch and that makes the current CNZVI a good candidate for in situ application. Additionally, the use of tapioca starch is expected to add value to the crop.

5 Supplementary material

Second-order rate constants for nitrate reduction by CNZVI (Table S1); chemical structure of (a) starch (amylose); (b) octenyl succinic anhydride (OSA); and (c) OSA-modified starch (Fig. S1); Sedimentation behavior of NZVI coated with OSA-modified tapioca starch concentration of (a) 1 g L−1; (b) 5 g L−1; (c) 10 g L−1. NZVI concentration = 3 g L−1 (Fig. S2); spent CNZVI Characterization. (a) Particle size distribution; (b) EDS spectra of spent CNZVI; (c) scanning electron micrograph of fresh CNZVI; (d) scanning electron micrograph of spent CNZVI (Fig. S3); and percent biodegradation of starch on CNZVI and OSA-modified starch (Fig. S4).



This work was funded by National Science Foundation (NSF Grant# CMMI-1125674, PI: Bezbaruah). Mary F. Pate worked as a master’s student in this project and contributed to the work. Umma Rashid received fellowships from North Dakota Water Resources Research Institute. The authors acknowledge the North Dakota State University’s Electron Microscopy Core Laboratory (NSF Grant# CMMI-0821655) for the microscopy work done within this research. Any opinions expressed in this paper are those of the author(s) and do not, necessarily, reflect the official positions and policies of NSF, the United States Air Force, the U.S. Department of Defense, or the U.S. Government.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Human and animal rights statement

This article does not contain any studies with human participants or animals.

Supplementary material

42452_2019_1364_MOESM1_ESM.docx (1.1 mb)
Supplementary material 1 (DOCX 1109 kb)


  1. 1.
    Almeelbi T, Bezbaruah A (2012) Aqueous phosphate removal using nanoscale zero-valent iron. J Nanopart Res 14:14. CrossRefGoogle Scholar
  2. 2.
    Almeelbi T, Bezbaruah A (2014) Nanoparticle-Sorbed Phosphate: Iron and Phosphate Bioavailability Studies with Spinacia oleracea and Selenastrum capricornutum. Acs Sustain Chem Eng 2:1625–1632. CrossRefGoogle Scholar
  3. 3.
    American Public Health A, Eaton AD, American Water Works A, Water Environment F (2005) Standard methods for the examination of water and wastewater. 21st ed. edn. APHA-AWWA-WEF, Washington, D.CGoogle Scholar
  4. 4.
    An Y, Li T, Jin Z, Dong M, Li Q (2010) Nitrate degradation and kinetic analysis of the denitrification system composed of iron nanoparticles and hydrogenotrophic bacteria. Desalination 252:71–74. CrossRefGoogle Scholar
  5. 5.
    Bai Y, Shi YC (2011) Structure and preparation of octenyl succinic esters of granular starch, microporous starch and soluble maltodextrin. Carbohydr Polym 83:520–527. CrossRefGoogle Scholar
  6. 6.
    Bai YJ, Shi YC, Herrera A, Prakash O (2011) Study of octenyl succinic anhydride-modified waxy maize starch by nuclear magnetic resonance spectroscopy. Carbohydr Polym 83:407–413. CrossRefGoogle Scholar
  7. 7.
    Bai YJ, Shi YC, Wetzel DL (2009) Fourier transform infrared (FT-IR) microspectroscopic census of single starch granules for octenyl succinate ester modification. J Agric Food Chem 57:6443–6448. CrossRefGoogle Scholar
  8. 8.
    Bezbaruah AN, Krajangpan S, Chisholm BJ, Khan E, Bermudez JJE (2009) Entrapment of iron nanoparticles in calcium alginate beads for groundwater remediation applications. J Hazard Mater 166:1339–1343. CrossRefGoogle Scholar
  9. 9.
    Bezbaruah AN, Kalita H, Almeelbi T, Capecchi CL, Jacob DL, Ugrinov AG, Payne SA (2013) Ca-alginate-entrapped nanoscale iron: arsenic treatability and mechanism studies. J Nanopart Res. CrossRefGoogle Scholar
  10. 10.
    Bezbaruah AN, Shanbhogue SS, Simsek S, Khan E (2011) Encapsulation of iron nanoparticles in alginate biopolymer for trichloroethylene remediation. J Nanopart Res 13:6673–6681. CrossRefGoogle Scholar
  11. 11.
    Bezbaruah AN, Thompson JM, Chisholm BJ (2009) Remediation of alachlor and atrazine contaminated water with zero-valent iron nanoparticles. J Environ Sci Health Part B-Pestic Food Contam Agric Wastes 44:518–524. CrossRefGoogle Scholar
  12. 12.
    Cheng R et al (2017) Removal of waterborne phage and NO3- in the nZVI/phage/NO3- system: competition effect. Rsc Adv 7:25369–25377. CrossRefGoogle Scholar
  13. 13.
    Cizova A, Koschella A, Heinze T, Ebringerova A, Srokova I (2007) Octenylsuccinate derivatives of carboxymethyl starch—synthesis and properties. Starch-Starke 59:482–492. CrossRefGoogle Scholar
  14. 14.
    Cong X, Xue ND, Wang SJ, Li KJ, Li FS (2010) Reductive dechlorination of organochlorine pesticides in soils from an abandoned manufacturing facility by zero-valent iron. Sci Total Environ 408:3418–3423. CrossRefGoogle Scholar
  15. 15.
    Dong HR, Lo IMC (2013) Influence of calcium ions on the colloidal stability of surface-modified nano zero-valent iron in the absence or presence of humic acid. Water Res 47:2489–2496. CrossRefGoogle Scholar
  16. 16.
    Gu B et al (1999) Biogeochemical dynamics in zero-valent iron columns: implications for permeable reactive barriers. Environ Sci Technol 33:2170–2177. CrossRefGoogle Scholar
  17. 17.
    Han JA, BeMiller JN (2007) Preparation and physical characteristics of slowly digesting modified food starches. Carbohydr Polym 67:366–374. CrossRefGoogle Scholar
  18. 18.
    He F, Zhao DY (2005) Preparation and characterization of a new class of starch-stabilized bimetallic nanoparticles for degradation of chlorinated hydrocarbons in water. Environ Sci Technol 39:3314–3320. CrossRefGoogle Scholar
  19. 19.
    He F, Zhao DY, Liu JC, Roberts CB (2007) Stabilization of Fe-Pd nanoparticles with sodium carboxymethyl cellulose for enhanced transport and dechlorination of trichloroethylene in soil and groundwater. Ind Eng Chem Res 46:29–34. CrossRefGoogle Scholar
  20. 20.
    He F, Zhao DY, Paul C (2010) Field assessment of carboxymethyl cellulose stabilized iron nanoparticles for in situ destruction of chlorinated solvents in source zones. Water Res 44:2360–2370. CrossRefGoogle Scholar
  21. 21.
    Huang DL et al (2015) Synthesis and application of modified zero-valent iron nanoparticles for removal of hexavalent chromium from wastewater. Water Air Soil Pollut 226:14. CrossRefGoogle Scholar
  22. 22.
    Hwang YH, Kim DG, Shin HS (2011) Mechanism study of nitrate reduction by nano zero valent iron. J Hazard Mater 185:1513–1521. CrossRefGoogle Scholar
  23. 23.
    Jiemvarangkul P, Zhang WX, Lien HL (2011) Enhanced transport of polyelectrolyte stabilized nanoscale zero-valent iron (nZVI) in porous media. Chem Eng J 170:482–491. CrossRefGoogle Scholar
  24. 24.
    Johnson TL, Scherer MM, Tratnyek PG (1996) Kinetics of halogenated organic compound degradation by iron metal. Environ Sci Technol 30:2634–2640. CrossRefGoogle Scholar
  25. 25.
    Kanel SR, Goswami RR, Clement TP, Barnett MO, Zhao D (2008) Two dimensional transport characteristics of surface stabilized zero-valent iron nanoparticles in porous media. Environ Sci Technol 42:896–900. CrossRefGoogle Scholar
  26. 26.
    Kanel SR, Greneche JM, Choi H (2006) Arsenic(V) removal from groundwater using nano scale zero-valent iron as a colloidal reactive barrier material. Environ Sci Technol 40:2045–2050. CrossRefGoogle Scholar
  27. 27.
    Kanel SR, Nepal D, Manning B, Choi H (2007) Transport of surface-modified iron nanoparticle in porous media and application to arsenic(III) remediation. J Nanopart Res 9:725–735. CrossRefGoogle Scholar
  28. 28.
    Kirschling TL, Golas PL, Unrine JM, Matyjaszewski K, Gregory KB, Lowry GV, Tilton RD (2011) Microbial bioavailability of covalently bound polymer coatings on model engineered nanomaterials. Environ Sci Technol 45:5253–5259. CrossRefGoogle Scholar
  29. 29.
    Krajangpan S, Kalita H, Chisholm BJ, Bezbaruah AN (2012) Iron nanoparticles coated with amphiphilic polysiloxane graft copolymers: dispersibility and contaminant treatability. Environ Sci Technol 46:10130–10136. CrossRefGoogle Scholar
  30. 30.
    Li SL, Wang W, Liang FP, Zhang WX (2017) Heavy metal removal using nanoscale zero-valent iron (nZVI): theory and application. J Hazardous Mater 322:163–171. CrossRefGoogle Scholar
  31. 31.
    Li XQ, Zhang WX (2006) Iron nanoparticles: the core-shell structure and unique properties for Ni(II) sequestration. Langmuir 22:4638–4642. CrossRefGoogle Scholar
  32. 32.
    Liu YQ, Majetich SA, Tilton RD, Sholl DS, Lowry GV (2005) TCE dechlorination rates, pathways, and efficiency of nanoscale iron particles with different properties. Environ Sci Technol 39:1338–1345. CrossRefGoogle Scholar
  33. 33.
    Lubphoo Y, Chyan J-M, Grisdanurak N, Liao C-H (2016) Influence of Pd-Cu on nanoscale zero-valent iron supported for selective reduction of nitrate. J Taiwan Inst Chem Eng 59:285–294. CrossRefGoogle Scholar
  34. 34.
    Manning BA, Kiser JR, Kwon H, Kanel SR (2007) Spectroscopic investigation of Cr(III)- and Cr(VI)-treated nanoscale zerovalent iron. Environ Sci Technol 41:586–592. CrossRefGoogle Scholar
  35. 35.
    Miao M, Li R, Jiang B, Cui SW, Zhang T, Jin ZY (2014) Structure and physicochemical properties of octenyl succinic esters of sugary maize soluble starch and waxy maize starch. Food Chem 151:154–160. CrossRefGoogle Scholar
  36. 36.
    Mondal PK, Furbacher PD, Cui ZT, Krol MM, Sleep BE (2018) Transport of polymer stabilized nano-scale zero-valent iron in porous media. J Contam Hydrol 212:65–77. CrossRefGoogle Scholar
  37. 37.
    Motamedi E, Atouei MT, Kassaee MZ (2014) Comparison of nitrate removal from water via graphene oxide coated Fe, Ni and Co nanoparticles. Mater Res Bull 54:34–40. CrossRefGoogle Scholar
  38. 38.
    Mukherjee R, Kumar R, Sinha A, Lama Y, Saha AK (2016) A review on synthesis, characterization, and applications of nano zero valent iron (nZVI) for environmental remediation. Crit Rev Environ Sci Technol 46:443–466. CrossRefGoogle Scholar
  39. 39.
    OCED (1992) OECD (Organisation for Economic Co-operation and Development) guideline for testing of chemicals. Organisation for Economic Co-operation and Development, ParisGoogle Scholar
  40. 40.
    Phenrat T, Saleh N, Sirk K, Kim HJ, Tilton RD, Lowry GV (2008) Stabilization of aqueous nanoscale zerovalent iron dispersions by anionic polyelectrolytes: adsorbed anionic polyelectrolyte layer properties and their effect on aggregation and sedimentation. J Nanopart Res 10:795–814. CrossRefGoogle Scholar
  41. 41.
    Phenrat T, Saleh N, Sirk K, Tilton RD, Lowry GV (2007) Aggregation and sedimentation of aqueous nanoscale zerovalent iron dispersions. Environ Sci Technol 41:284–290. CrossRefGoogle Scholar
  42. 42.
    Raychoudhury T, Naja G, Ghoshal S (2010) Assessment of transport of two polyelectrolyte-stabilized zero-valent iron nanoparticles in porous media. J Contam Hydrol 118:143–151. CrossRefGoogle Scholar
  43. 43.
    Ryu A, Jeong SW, Jang A, Choi H (2011) Reduction of highly concentrated nitrate using nanoscale zero-valent iron: effects of aggregation and catalyst on reactivity. Appl Catal B-Environ 105:128–135. CrossRefGoogle Scholar
  44. 44.
    Saleh N et al (2005) Adsorbed triblock copolymers deliver reactive iron nanoparticles to the oil/water interface. Nano Lett 5:2489–2494. CrossRefGoogle Scholar
  45. 45.
    Searle PL (1984) The Berthelot or Indophenol reaction and its use in the analytical-chemistry of nitrogen—a review. Analyst 109:549–568. CrossRefGoogle Scholar
  46. 46.
    Shih FF, Daigle KW (2003) Gelatinization and pasting properties of rice starch modified with 2-octen-1-ylsuccinic anhydride. Nahrung-Food 47:64–67. CrossRefGoogle Scholar
  47. 47.
    Simsek S, Ovando-Martinez M, Marefati A, Sjoo M, Rayner M (2015) Chemical composition, digestibility and emulsification properties of octenyl succinic esters of various starches. Food Res Int 75:41–49. CrossRefGoogle Scholar
  48. 48.
    Simsek S, Ovando-Martinez M, Whitney K, Bello-Perez LA (2012) Effect of acetylation, oxidation and annealing on physicochemical properties of bean starch. Food Chem 134:1796–1803. CrossRefGoogle Scholar
  49. 49.
    Sleiman N, Deluchat V, Wazne M, Mallet M, Courtin-Nomade A, Kazpard V, Baudu M (2016) Phosphate removal from aqueous solution using ZVI/sand bed reactor: behavior and mechanism. Water Res 99:56–65. CrossRefGoogle Scholar
  50. 50.
    Sleiman N, Deluchat V, Wazne M, Mallet M, Courtin-Nomade A, Kazpard V, Baudu M (2017) Phosphate removal from aqueous solutions using zero valent iron (ZVI): influence of solution composition and ZVI aging. Colloids Surfaces a-Physicochem Eng Aspects 514:1–10. CrossRefGoogle Scholar
  51. 51.
    Song XY, He GQ, Ruan H, Chen QH (2006) Preparation and properties of octenyl succinic anhydride modified early indica rice starch. Starch-Starke 58:109–117. CrossRefGoogle Scholar
  52. 52.
    Song XY, Zhu W, Li Z, Zhu JJ (2010) Characteristics and application of octenyl succinic anhydride modified waxy corn starch in sausage. Starch-Starke 62:629–636. CrossRefGoogle Scholar
  53. 53.
    Su JF, Guo DX, Huang TL, Lu JS, Bai XC, Hu XF (2018) Sodium carboxymethyl cellulose-modified zero-valent iron used for redunction of nitrate in autotrophic denitrification systems. Environ Eng Sci 35:1228–1234. CrossRefGoogle Scholar
  54. 54.
    Sweedman MC, Tizzotti MJ, Schafer C, Gilbert RG (2013) Structure and physicochemical properties of octenyl succinic anhydride modified starches: a review. Carbohydr Polym 92:905–920. CrossRefGoogle Scholar
  55. 55.
    Tang SCN, Lo IMC (2013) Magnetic nanoparticles: essential factors for sustainable environmental applications. Water Res 47:2613–2632. CrossRefGoogle Scholar
  56. 56.
    Teng W, Bai N, Liu Y, Liu YP, Fan JW, Zhang WX (2018) Selective nitrate reduction to dinitrogen by electrocatalysis on nanoscale iron encapsulated in mesoporous carbon. Environ Sci Technol 52:230–236. CrossRefGoogle Scholar
  57. 57.
    Tiraferri A, Chen KL, Sethi R, Elimelech M (2008) Reduced aggregation and sedimentation of zero-valent iron nanoparticles in the presence of guar gum. J Colloid Interface Sci 324:71–79. CrossRefGoogle Scholar
  58. 58.
    Tiraferri A, Sethi R (2009) Enhanced transport of zerovalent iron nanoparticles in saturated porous media by guar gum. J Nanopart Res 11:635–645. CrossRefGoogle Scholar
  59. 59.
    Tosco T, Papini MP, Viggi CC, Sethi R (2014) Nanoscale zerovalent iron particles for groundwater remediation: a review. J Clean Prod 77:10–21. CrossRefGoogle Scholar
  60. 60.
    Wang T, Lin J, Chen Z, Megharaj M, Naidu R (2014) Green synthesized iron nanoparticles by green tea and eucalyptus leaves extracts used for removal of nitrate in aqueous solution. J Clean Prod 83:413–419. CrossRefGoogle Scholar
  61. 61.
    Wang W, Zhou MH, Jin ZH, Li TL (2010) Reactivity characteristics of poly(methyl methacrylate) coated nanoscale iron particles for trichloroethylene remediation. J Hazardous Mater 173:724–730. CrossRefGoogle Scholar
  62. 62.
    Wu DL, Shen YH, Ding AQ, Mahmood Q, Liu S, Tu QP (2013) Effects of nanoscale zero-valent iron particles on biological nitrogen and phosphorus removal and microorganisms in activated sludge. J Hazard Mater 262:649–655. CrossRefGoogle Scholar
  63. 63.
    Wu DL, Shen YH, Ding AQ, Qiu MY, Yang Q, Zheng SS (2013) Phosphate removal from aqueous solutions by nanoscale zero-valent iron. Environ Technol 34:2663–2669. CrossRefGoogle Scholar
  64. 64.
    Xi YF, Mallavarapu M, Naidu R (2010) Reduction and adsorption of Pb2 + in aqueous solution by nano-zero-valent iron-A SEM, TEM and XPS study. Mater Res Bull 45:1361–1367. CrossRefGoogle Scholar
  65. 65.
    Xiao R, Wazne M (2013) Assessment of aged biodegradable polymer-coated nano-zero-valent iron for degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). J Chem Technol Biotechnol 88:711–718. CrossRefGoogle Scholar
  66. 66.
    Xu CH, Zhu LJ, Wang XH, Lin S, Chen YM (2014) Fast and highly efficient removal of chromate from aqueous solution using nanoscale zero-valent iron/activated carbon (NZVI/AC). Water Air Soil Pollut 225:13. CrossRefGoogle Scholar
  67. 67.
    Xu SN, Hu ZQ (2015) Kinetics of nutrient removal by nano zero-valent iron under different biochemical environments. Water Environ Res 87:483–490. CrossRefGoogle Scholar
  68. 68.
    Yu ZG, Hu LM, Lo IMC (2019) Transport of the arsenic (As)-loaded nano zero-valent iron in groundwater-saturated sand columns: roles of surface modification and as loading. Chemosphere 216:428–436. CrossRefGoogle Scholar

Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  • Umma S. Rashid
    • 1
  • Senay Simsek
    • 2
  • Sushil R. Kanel
    • 3
  • Achintya N. Bezbaruah
    • 1
    Email author
  1. 1.Nanoenvirology Research Group, Department of Civil and Environmental EngineeringNorth Dakota State UniversityFargoUSA
  2. 2.Wheat Quality and Carbohydrate Research Group, Department of Plant SciencesNorth Dakota State UniversityFargoUSA
  3. 3.Office of Research and Sponsored ProgramsAir Force Institute of TechnologyDaytonUSA

Personalised recommendations