铁改性生物炭对几种染料的吸附机理研究

Study on the adsorption mechanism of several dyes by iron-modified biochar

本文以生物炭为原料,经氧化亚铁硫杆菌生物沥滤,将离子态的铁负载到生物炭上再进行二次热解,制备出铁改性生物炭材料(FeBC).开展该材料对三苯基甲烷、偶氮和噻嗪类染料等典型染料进行吸附试验,考察材料投加量、染料浓度以及温度因素对染料去除的影响,利用XRD、FT-IR、XPS和BET等分析方法对FeBC进行表征并做吸附动力学模型和等温吸附模型拟合.结果表明,FeBC负载了Fe_(3)O_(4)后表面官能团和孔隙结构更加丰富.FeBC对几种染料的吸附结果符合一阶动力学方程和Langmuir等温吸附模型,证明FeBC对染料的去除是以物理吸附为主的单分子层吸附过程;染料去除率与初始浓度呈极显著负相关(P<0.01),与温度呈极显著正相关(P<0.01).本文初步揭示了该材料对几种染料的去除机理,是以孔隙吸附、氢键、π—π电子共轭吸附以及静电吸附等方式去除,改性后对不同染料吸附量提高达302.2%-409.5%.该研究为新型炭改性材料在染料废水中的处理提供了新思路.

In this paper,iron-modified biochar material(FeBC)was prepared by biolestrating by thiobacter ferrooxidans and loading ionic iron onto biochar for secondary pyrolysis.The adsorption tests on several typical dyes,such as triphenylmethane,azo and thiazine dyes,were carried out to investigate the effects of material dosage,dye concentration and temperature on dye removal.FeBC was characterized by XRD,FT-IR,XPS and BET,and the adsorption kinetics model and isothermal adsorption model were fitted.The results show that FeBC loaded with Fe_(3)O_(4) has more functional groups and pore structures.The adsorption results of FeBC on several dyes conform to the first-order kinetic equation and Langmuir isothermal adsorption model,which proves that the removal of dyes by FeBC is a single-molecule layer adsorption process based on physical adsorption.The dye removal rate was negatively correlated with initial concentration(P<0.01),and positively correlated with temperature(P<0.01).In this paper,the removal mechanism of several dyes by the material was preliminically revealed,including pore adsorption,hydrogen bond,π—πelectron conjugated adsorption and electrostatic adsorption.After modification,the adsorption capacity of different dyes was increased to 302.2%—409.5%.This study provides a new idea for the treatment of new carbon modified materials in dye wastewater.