一步还原焙烧法制备炭载零价铁及其对水中Cr(Ⅵ)的去除

One-step reductive roasting synthesis of activated carbon supported zero valent iron for the removal of Cr(Ⅵ) from aqueous solution

以活性炭为还原剂和载体,通过一步还原焙烧法制备出炭载零价铁(AC-ZVI)材料。电镜扫描和X射线衍射分析结果表明,零价铁以平均粒径为2μm的颗粒均匀分布在活性炭表面和孔道中。采用间歇实验考察了炭载零价铁去除水中Cr(Ⅵ)的效果,结果显示炭载零价铁对水中的Cr(Ⅵ)具有很好的去除效果,在初始pH值为5、Cr(Ⅵ)浓度为50 mg·L^(-1)、AC-ZVI投加量(铁用量)为0.6 g·L^(-1)和反应温度为25℃的条件下,反应5 h后Cr(Ⅵ)的去除率达到86.8%;降低溶液pH、增加炭载零价铁投加量和提高反应温度均有利于Cr(Ⅵ)的去除,反应过程符合准一级动力学,表观反应速率常数k为0.655 h^(-1)(30℃),反应活化能为67.6 k J·mol^(-1)。研究结果表明,通过一步还原焙烧法制得的炭载零价铁可作为一种高效吸附还原材料用于Cr(Ⅵ)污染水体的治理。

An activated carbon-supported zero-valent iron（ AC-ZVI） material was prepared through a onestep reductive roasting method with activated carbon（ AC） as a reductant and supporting matrix. Scanning electron microscopy（ SEM） and X-ray diffraction（ XRD） analysis revealed that iron particles with an average diameter of 2 μm were dispersed uniformly on the surface and pores of the AC. Batch experiments were conducted to investigate the removal of Cr（ Ⅵ） from aqueous solutions by the AC-ZVI. The AC-ZVI showed efficient Cr（ Ⅵ）removal performance of 86. 8% within 5 h at an initial pH of 5,Cr（ Ⅵ） concentration of 50 mg·L-1,and ACZVI concentration of 0. 6 g·L-1at 25 ℃. The removal efficiency of Cr（ Ⅵ） increased with AC-ZVI dosage,temperature,and lower pH values. The removal of Cr（ Ⅵ） by the AC-ZVI followed pseudo-first-order kinetics,and the pseudo-first-order rate constant k was determined to be 0. 655 h-1（ 30 ℃）. The activation energy was found to be 67. 6 k J·mol-1. This indicated that AC-ZVI prepared through the reductive roasting method can be used as an efficient adsorptive and reductive material for the removal of Cr（ Ⅵ） from water.