Affiliation:
1. Department of Chemistry and Life Science, Hubei University of Education, Wuhan 430205, China
2. Hubei Environmental Purification Material Science and Engineering Technology Research Center, Hubei University of Education, Wuhan 430205, China
3. Hubei Key Laboratory of Purification and Application of Plant Anti-Cancer Active Ingredients, Hubei University of Education, Wuhan 430205, China
4. Hubei Engineering Technology Center of Environmental Purification Materials, Hubei University of Education, Wuhan 430205, China
Abstract
The possibility of using three types of NaOH-treated tea residues (green tea, pu-erh, and tieguanyin) as low-cost adsorbents for Cr(VI) treatment was investigated. The surface charge, composition, morphology, structure, and functional groups in the obtained biosorbents were characterized by pHzpc, cellulose content, SEM, BET, XRD, and FTIR spectroscopy. The nonlinear pseudo-first-order, pseudo-second-order, and Elovich models were used to investigate adsorption kinetics at various initial concentrations. The adsorption processes were more consistent with the pseudo-second-order kinetic model in the range of 5-50 mg L-1. The adsorption isotherm at 298 K was described using the nonlinear Langmuir, Freundlich, Temkin-Pyzhev, and Dubinin-Radushkevich models, indicating that the process was favorable and complex with maximum adsorption amounts of 6.15, 19.50, and 12.31 mg g-1 for green tea, pu-erh, and tieguanyin residues, respectively. Thermodynamic analysis revealed that the adsorption was a spontaneous, endothermic process. The results demonstrated that all materials had the potential to successfully remove Cr(VI) from the aqueous solution.
Funder
Hubei Provincial Department of Education
Subject
Surfaces and Interfaces,General Chemical Engineering,General Chemistry