改性炭化谷壳负载纳米Fe3O4对含As(V)废水的吸附性能

以谷壳为原料，通过600℃缺氧高温热解制备一种炭化谷壳（CRH-I），并利用CRH-I通过改性负载方法获得另一种新型的负载纳米Fe3O4的碱改性炭化谷壳（CRH-II）。经过对比表面积进行表征分析发现，CRH-II相较CRH-I的BET比表面积增大约30%，达到182 m2·g-1，微比表面积和微孔体积都扩大了6倍左右。FTIR分析结果表明，相比CRH-I，CRH-II分子间的羧基和酚羟基官能团有所增加，产生了芳构化反应和脂肪醚类物质。吸附实验表明，相对CRH-I而言，CRH-II对As（V）的吸附率明显提高。pH=2时，CRH-II对溶液中As（V）的吸附率达到98.3%；但是As的吸附率随着溶液pH值升高而逐渐降低，pH=11时下降最为明显，吸附率只有63.4%。CRH-II吸附反应满足准动力学二级方程，其相关系数为R2=0.999；在不同温度下，将CRH-II对As（V）的吸附验数据进行Langmuir方程和Freundlich等温方程拟合，结果更符合Langmuir方程；在25℃时，相关系数R2=0.985。解吸吸附实验证明，CRH-II依然具备良好的吸附性能，且再生吸附性能稳定。

Adsorption characteristics of As(V) on modified carbonized rice husk loading nano Fe3O4 in wastewater

Carbonized rice husk (CRH-I) was first prepared from the anoxic pyrolysis of rice husk at 600℃, and then modified with an alkali to form CRH-II and loaded onto Fe3O4 nanoparticles. The BET analysis of CRH-II compared to CRH-I revealed about 30% increase in the specific surface area to 182.03 m2·g-1 and a 6-fold expansion of the micro-surface area and microspore volume. FTIR analysis indicated that compared to CRH-I, the intermolecular carboxyl and phenolic hydroxyl groups were more numerous inside CRH-II, and that the aromatization effects were concurrently observed with the production of aliphatic ether substances. Adsorption experiments demonstrated enhanced adsorption ability for CRH-II over CRH-I, with 98.3% adsorption rate of As(V) on CRH-II in pH 2 wastewater. The adsorption rate of As(V) on CRH-II gradually decreased with increasing the solution pH; the minimum adsorption rate of 63.4% was observed at pH 11. The adsorption of As(V) onto CRH-II was modeled by using the dynamics equation of a quasi two-level system and correlation coefficient (R2) of 0.999. The experimental data of As(V) adsorption on CRH-II better conformed to the Langmuir isotherm equation (R2=0.985 at 25℃) than the Freundlich isotherm equation at different temperatures. Adsorption and desorption experiments indicated that CRH-II had good adsorption properties and a stable regenerative adsorption.