Chromium Removal and Sorption Mechanism from Aqueous Solutions by Wine Processing Waste Sludge

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• 作者：Cheng-Chung Liu ; Ming-Kuang Wang ; Chyow-San Chiou ; Yuan-Shen Li ; Yu-An Lin ; Shu-Shan Huang
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2006
• 出版时间：December 20, 2006
• 年：2006
• 卷：45
• 期：26
• 页码：8891 - 8899
• 全文大小：180K
• 年卷期：v.45,no.26(December 20, 2006)
• ISSN：1520-5045

文摘

Wine processing waste sludge (WPWS) has been shown to be an effective sorbent for the sorption of heavymetals (i.e., chromium and nickel), but the mechanism of removal of hexavalent chromium [Cr(VI)] by WPWSremains obscure. The aims of this study were to determine the effects of temperature, initial concentration ofCr(VI), and particle size on the removal Cr(VI) using WPWS. The characteristics of WPWS were determined,and sorption mechanism studies were also performed. The WPWS used was a deposit mixture containingconsiderable quantities of chemical coagulation as well as activated sludge precipitation from the settlingbasins of a wastewater treatment plant. Differential scanning calorimetry (DSC) analysis revealed that theWPWS comprised abundant labile carbohydrates and few aromatic structures. According to the IR spectrum,carboxylic groups were the most important functional group in WPWS, interacting with chromium speciesby protonation and redox reaction. All kinetic experiments were conducted at an initial pH of 2.0, and all ofthem had reached steady state within 240 min. The final pH values of the suspensions were approximately4.2, and the increase of the pH caused low Cr removal. In addition, about 2-18% of the Cr(III) remained inthe liquid phase. The Cr removal percentage increased with increasing temperature (i.e., 14-25%), but itwas less affected by particle size (17-22%). All kinetic data obtained from different conditions showedgood compliance with a pseudo-second-order model, and the rate constant k₂ was found to range from 0.032to 0.074 g mg^-1 min^-1. Some of the Cr(VI) ions were reduced to Cr(III) ions as a result of oxidation oforganic components in WPWS, as indicated by monitoring using the X-ray absorption near-edge spectroscopic(XANES) technique.