Lead Adsorption on Rice Husk as a Function of pH Control
The use of agro-based waste materials in treatment zones for removal of heavy metals from the aqueous phase by adsorption represents a low-cost and possibly effective remediation alternative. In this study, the adsorption of lead (Pb2+) on a rice-husk residue was tested in different experiments with initial 100 mg Pb2+/L, initial pH values of 3, 5, or 7, and solid:liquid ratio (mass basis) of 1:20. In some experiments pH was allowed to vary, whereas in other experiments pH was kept approximately fixed. For the experiments with variable pH, Pb2+ was most adsorbed (93%) in the test where pH increased from 3 to 5.1, and least adsorbed in the test where pH decreased from 7 to 6.4. The point of zero charge of the rice husk was determined to be pH 4.5. For the experiments with fixed pH, the optimum pH for Pb2+ adsorption (95%) was found to be pH 5, and the test at pH 3 removed 67% of the initial Pb2+. The results allowed to grasp the significant effect pH control plays on Pb2+ adsorption, and the relevance of studying the factors that control pH during Pb2+ adsorption in a field application (in-situ treatment zone).
KeywordsAdsorption Agro-based residues Lead Permeable reactive barriers Rice husk
This research was based on equipment purchased with grant # 2012/08797-2, Sao Paulo Research Foundation (FAPESP).
- Drever JI (1997) The Geochemistry of Natural Waters: Surface and Groundwater Environments, 3rd edn. Prentice Hall, Upper Saddle RiverGoogle Scholar
- ITRC, Interstate Technology & Regulatory Council (2005) Permeable Reactive Barriers: Lessons Learned/New Directions. Permeable Reactive Barriers Team. Washington, D.C. http://www.itrcweb.org/Documents/PRB-4.pdf
- U.S. Environmental Protection Agency (1998), Permeable Reactive Barrier Technologies for Contaminant Remediation, EPA/600/R-98/125, Washington, D. CGoogle Scholar