Cr(Ⅵ)和Cr(Ⅲ)在改性秸秆吸附剂上的同步快速解吸方法及应用  

Synchronous rapid desorption of Cr(Ⅵ) and Cr(Ⅲ) on modified stalk adsorbent

作　　者：王镇乾[1] 曹威[1] 刘淑坡[1] 

机构地区：[1]华侨大学土木工程学院,福建厦门361021

出　　处：《农业环境科学学报》2017年第6期1218-1224,共7页Journal of Agro-Environment Science

基　　金：国家自然科学基金青年科学基金项目(51408239);华侨大学研究生科研创新能力培育计划资助项目~~

摘　　要：新型低成本吸附剂(改性玉米秸秆)去除重金属阴离子Cr(Ⅵ)的机理复杂,涉及吸附和还原转化两部分。本文通过建立铬在改性玉米秸秆上的解吸方法,将吸附的Cr(Ⅵ)与Cr(Ⅲ)同时转移至液相进行定量分析,从而应用于Cr(Ⅵ)去除过程中吸附与形态变化机理的定量描述。通过考察不同解吸液(HCl、H_3PO_4、NaCl)以及解吸液浓度、解吸时间、解吸温度等因素对总铬解吸效果的影响,确定了对Cr(Ⅵ)和Cr(Ⅲ)均具有良好解吸效果的解吸方法,即:采用2mol·L^(-1)H_3PO_4为解吸液,在解吸液体积20mL、25℃条件下,振荡10min,总铬回收率达95%。并以此为基础,通过系列Cr(Ⅵ)吸附-解吸实验,对吸附平衡后固-液两相中铬的形态分布进行定量分析并探讨Cr(Ⅵ)的吸附和形态变化机理。结果表明,改性秸秆吸附Cr(Ⅵ)符合Langmuir等温方程,最大吸附去除容量达35.9mg·g^(-1);吸附过程中Cr(Ⅲ)生成量随Cr(Ⅵ)吸附去除量的增加而增加,两者呈正相关(R^2=0.986);当达到饱和吸附后Cr(Ⅲ)的生成量趋于稳定,约3.7mg·g^(-1)。The removal mechanism of Cr（Ⅵ）by a novel low-cost adsorbent（modified corn stalk）is a complicated process that includes adsorption and reduction. In this study, a method for desorption of Cr on corn stalk was developed. The method can quantitatively describe the adsorption and speciation transformation during the absorption of Cr（Ⅵ）by transferring Cr（Ⅵ）and Cr（Ⅲ）from the solid-phase to the liquid-phase. The experimental factors, such as different desorption solutions（HCl, H3PO4, NaCl）, concentrations, contact time,and temperature were investigated and the optimal desorption condition was determined. The results showed that Cr（Ⅵ）and Cr（Ⅲ）could be desorbed sufficiently and 95% of Cr was recovered by adding 20 m L 2 mol·L-1 H3PO4 solution at 25 ℃ for a 10-min contact time. Based on the desorption method, the distribution of Cr（Ⅵ）and Cr（Ⅲ）in solid and liquid phases was quantitatively analyzed to explore the mechanisms of adsorption and speciation transformation of Cr（Ⅵ）. The adsorption process on stalk followed Langmuir isotherm adsorption model and the adsorption capacity of Cr（Ⅵ）was 35.9 mg·g-1. The amount of Cr（Ⅲ）increased with the growth of absorbed Cr（Ⅵ）and there was a positive correlation between them（R2=0.986）. The amount of Cr（Ⅲ） tended to stabilize after the adsorption reached equilibrium at 3.7 mg·g-1.

关 键 词：玉米秸秆 铬 吸附 解吸 形态转化 定量分析 

分 类 号：X712[环境科学与工程—环境工程]