Research Article Biosorption of Zinc from Aqueous Solution Using Chemically

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. In this study, adsorption of zinc onto the adsorbent (untreated rice husk and NaOH-treated rice husk) was examined. During the removal process, batch techniquewas used, and the effects of pHand contact timewere investigated. Langmuir isothermwas applied in order to determine the efficiency of NaOH-treated rice husk used as an adsorbent.The zinc adsorption was fast, and equilibrium was attained within 30min. The maximum removal ratios of zinc for untreated rice husk and NaOH-treated rice husk after 1.5 h were 52.3 % and 95.2%, respectively, with initial zinc concentration of 25mg/L and optimum pH of 4.0. Data obtained from batch adsorption experiments fitted well with the Langmuir isotherm model. Maximum adsorption capacity of zinc onto untreated rice husk and NaOH-treated rice husk was 12.41mg/g, and 20.08mg/g respectively, at adsorbent dosage of 1 g/L at 25∘C. The nature of functional groups (i.e., amino, carboxyl, and hydroxyl) and metal ion interactions was examined by the FT-IR technique. It was concluded that the NaOH-treated rice husk had stronger adsorption capacity for Zn2+ compared with the untreated rice husk. The NaOH-treated rice husk is an inexpensive and environmentally friendly adsorbent for Zn2+ removal from aqueous solutions. 1