Synthesis and characterization of a new adsorbent for capture of metal from aqueous solutions
A new material containing a potential ligand for transition metals was prepared through the reaction of 3-aminopropyltrimethoxysilane and thioglycolic acid. The new adsorbent was characterized by elemental analyses, infrared spectroscopy, solid-state 13C nuclear magnetic resonance, thermogravimetric analysis, transmission electron microscopy, and specific surface area calculations. The formulated material was used in the removal of cobalt, copper, and nickel cations from aqueous solutions. Calorimetric titration was applied to study the interaction of these cations with the new adsorbent; the latter displayed a chelating moiety with basic centers containing nitrogen, oxygen, and several sulfur atoms, capable of capturing cations from aqueous solutions. This process of extraction was carried out by a batch method to yield the following order of maximum retention capacity: Ni > Co > Cu. The process of cation interactions showed exothermic enthalpies. The calculated ΔG values are in agreement with the spontaneity of the proposed reactions and conformed to the values found by applying the Langmuir model to these systems. The positive entropy and negative enthalpy values indicated that the reactions are favorable.
KeywordsThioglycolic acid Adsorption Calorimetric titration Thermodynamic data
The authors are indebted to Coordenação de Aperfeiçoamento de Pessoal de Nível Superior—CAPES and Conselho Nacional de Desenvolvimento Científico e Tecnológico—CNPq for fellowships and financial support.
- 6.Airoldi C, Farias RF. O uso de silica gel organofuncionalizada como agente sequestrante para metais. Quim Nova. 2000;23(4):496–503.Google Scholar
- 9.Arakaki LNH, Espílola JGP, Oliveira SF. Calorimetric study of silica gel modified with thioglycolic acid with divalent cations from aqueous solution. Curr Top Colloid Interface Sci. 2002;4:210–25.Google Scholar
- 10.Arakaki LNH, Espínola JGP, Fonseca MG, Oliveira SF, Sousa AN, Arakaki T, Airoldi C. Thioglycolic acid grafted onto silica gel and its properties in relation to extracting cations from ethanolic solution determined by calorimetric technique. J Colloid Interface Sci. 2004;273:211–7.CrossRefGoogle Scholar
- 11.Sousa KS, Augusto Filha VLS, Pinto VHA, Fonseca MG, Espínola JGP, Arakaki LNH. Quimissorção de cátions divalentes em sílica gel modificada com ácido tioglicólico—A influência do pH e força iônica. Quim Nova. 2007;30:528–34.Google Scholar
- 13.Silva ALP, Sousa KS, Germano AFS, Oliveira VV, Espínola JGP, Fonseca MG, Airoldi C, Arakaki T, Arakaki LNH. A new organofunctionalized sílica containning thioglycolic acid incorporated for divalent cátions removal—A thermodynamic cátion/basic center interaction. Colloids Surf A Physicochem Eng Aspects. 2009;332:144–9.CrossRefGoogle Scholar
- 17.Lin-Vien D, Colthup NB, Fateley WG, Grasselli JG. The handbook of infrared and Raman characteristic frequencies of organic molecules. London: Academic Press; 1991. p. 160.Google Scholar
- 20.Arakaki LNH, Diniz JS, Silva ALP, Augusto Filha VLS, Fonseca MG, Espínola JGP, Arakaki T. Thermal study of chelates of Co(II), Cu(II), Ni(II), Cr(III), Mo(III), and Fe(III) with bis(acetylacetone) ethylenediimine on activated silica gel surface. J Therm Anal Calorim. 2009;97:377–82.CrossRefGoogle Scholar
- 23.Smith JM. Chemical engineering kinetics. 3rd ed. New York: McGraw-Hill; 1981. p. 310–22.Google Scholar