UV modification of biochar for enhanced hexavalent chromium removal from aqueous solution
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This study was conducted to understand the effects of ultraviolet (UV) irradiation on the physicochemical properties and the hexavalent chromium (Cr(VI)) removal ability of biochar. Structural and morphological analysis showed that UV irradiation increased the specific surface area of biochar and added a large amount of oxygen-containing functional groups (e.g., carboxyl, lactonic, and hydroxyl) to biochar’s surface. Batch sorption experimental results showed that UV-modified biochar (UVBC) produced at the pyrolysis temperature of 300 °C, the irradiated time of 24 h, and the irradiation distance of 40 mm exhibited excellent Cr(VI) removal ability (from 1.11 mg/g for BC to 20.04 mg/g for UVBC, a 18.1-fold increase). The adsorption kinetics and adsorption isotherm data agreed well with the pseudo-second-order model and Freundlich model, respectively. Experimental and modeling results suggest that the oxygen-containing functional groups and specific surface areas of biochars were notably increased by UV irradiation, which enhanced Cr(VI) adsorption by surface complexation. X-ray photoelectron spectroscopy (XPS) analysis of UVBC before and after reaction with Cr(VI) showed that reduction occurred during Cr(VI) adsorption. The energy consumption of UV modification is 2.7 MJ per gram of UVBC produced, which is comparable to that in activated carbon. The results showed that the method of UV modification of biochar is a very novel and effective method for the adsorption of Cr(VI) in solution.
KeywordsUV irradiation Biochar Hexavalent chromium Adsorption Specific surface area Oxygen-containing functional groups
The research was supported by (1) Tianjin Science and Technology Program (16JCTPJC51100), (2) National Natural Science Foundation of China (41473070), and (3) The National Water Pollution Control and Treatment Science and Technology Major Project (2015ZX07203-011-06).
- Dong X, Ma LQ, Zhu Y, Li Y, Gu B (2013) Mechanistic investigation of mercury sorption by Brazilian pepper biochars of different pyrolytic temperatures based on X-ray photoelectron spectroscopy and flow calorimetry. Environ Sci Technol 47(21):12156–12164. https://doi.org/10.1021/es4017816 CrossRefGoogle Scholar
- Kim WK, Shim T, Kim YS, Hyun S, Ryu C, Park YK, Jung J (2013) Characterization of cadmium removal from aqueous solution by biochar produced from a giant Miscanthus at different pyrolytic temperatures. Bioresour Technol 138:266–270. https://doi.org/10.1016/j.biortech.2013.03.186 CrossRefGoogle Scholar
- Li Q, Jin BS, Huang YJ, Zhong ZP, Li B, Sun Y (2009) Preparation of biomass activated carbon by steam activation. J Southeast Univ 39(5):1008–1011Google Scholar
- Li Z, Katsumi T, Inui T, Imaizumi S (2011) Woods charred at low temperatures and their modification for the adsorption of Cr(VI) ions from aqueous solution. Adsorpt Sci Technol 28(5):99–108Google Scholar
- Lyu H, Gong Y, Gurav R, Tang J (2016a) Biochar application: essential soil microbial ecology. In: Ralebitso-Senior TK, Orr CH (eds) Potential application of biochar for bioremediation of contaminated systems. Elsevier Inc., Netherlands, pp 221–246Google Scholar
- Qiu M, Luo D, Ding X, Liu Y (2012) Comparison of the cost of chemical precipitation in the treatment of chromium containing wastewater. Environ Protect Circ Econ 3:61–62Google Scholar
- Rajapaksha AU, Chen SS, Tsang DCW, Zhang M, Vithanage M, Mandal S, Gao B, Bolan NS, Ok YS (2016) Engineered/designer biochar for contaminant removal/immobilization from soil and water: potential and implication of biochar modification. Chemosphere 148:276–291. https://doi.org/10.1016/j.chemosphere.2016.01.043 CrossRefGoogle Scholar
- Yan J, Han L, Gao W, Xue S, Chen M (2014) Biochar supported nanoscale zerovalent iron composite used as persulfate activator for removing trichloroethylene. Bioresour Technol 175C:269–274Google Scholar
- Yin QQ, Wang SR (2013) Analysis and activation of biomass rapid pyrolysis carbon. J Basic Sci Eng 21(1):45–53Google Scholar
- Zhou L, Liu Y, Liu S, Yin Y, Zeng G, Tan X, Hu X, Hu X, Jiang L, Ding Y, Liu S, Huang X (2016) Investigation of the adsorption-reduction mechanisms of hexavalent chromium by ramie biochars of different pyrolytic temperatures. Bioresour Technol 218:351–359. https://doi.org/10.1016/j.biortech.2016.06.102 CrossRefGoogle Scholar