市政污泥陶粒对Cd2+吸附特性的影响

Effect of Municipal Sludge Ceramsiteon Cd2+ Adsorption Characteristics

关键词:  市政污泥陶粒  含镉废水  吸附动力学  吸附等温线  吸附机理

Key words:  municipal sludge ceramsite  cadmium-containing wastewater  adsorption kinetics  adsorption isotherm  adsorption mechanism

摘要:

为拓展市政污泥资源化利用和无害化处理途径，本研究以市政污泥、黏土和膨润土为原料，采用高温烧结技术制备市政污泥陶粒，以含Cd²⁺废水为污染物，考察市政污泥陶粒添加量、溶液初始pH值、吸附时长及Cd²⁺初始浓度对陶粒吸附性能的影响,研究其吸附动力学与等温吸附特性，并借助X射线衍射(XRD)、扫描电子显微镜(SEM)等表征手段，揭示其吸附机理。结果表明：①烧结后，市政污泥陶粒表面粗糙、孔隙结构及官能团丰富；②石英(SiO₂)、莫来石(Al₆Si₂O₁₃)、钙长石(CaAl₂Si₂O₈)和赤铁矿(Fe₂O₃)是市政污泥陶粒的主要晶相，吸附Cd²⁺后矿物成分不变；③在特定条件(陶粒添加量50 g、Cd²⁺初始浓度300 mg/L、吸附时间120 min、pH值6)下,Cd²⁺去除率高，表明陶粒具备高效吸附Cd²⁺的能力；④市政污泥陶粒对Cd²⁺的吸附包含物理吸附和化学吸附两种吸附方式,相较于准二级动力学模型，更符合准一级动力学模型，市政污泥陶粒对Cd²⁺的吸附既存在单层吸附，又存在多层吸附，吸附机制较复杂。研究结果可为市政污泥的资源化利用以及对Cd²⁺污染物的处理提供科学依据和技术支持。

Abstract:

In order to expand the means for the resource utilization and innocent treatment of municipal sludge,this study employed high temperature sintering to prepapre municipal sludge ceramsite with municipal sludge,clay,and bentonite as raw materials.Taking the wastewater containing Cd²⁺as a pollutant,this study examined the influences of the addition of municipal sludge ceramsite,the initial pH value of solution,the adsorption time,and the initial concentration of Cd²⁺ on the adsorption property of ceramsite.At the same time,the adsorption kinetics and isothermal adsorption characteristics were studied,and the unique adsorption mechanism was revealed by X-Ray Diffraction (XRD),Scanning Electron Microscopy (SEM) and other characterization methods.The results showed that:① After sintering,the municipal sludge ceramsite presented a rough surface,a pore structure,and abundant functional groups;② Quartz (SiO₂),mullite (Al₆Si₂O₁₃),calcium feldspar (CaAl₂Si₂O₈),and hematite (Fe₂O₃) were the main crystalline phases of municipal sludge ceramsite,and the mineral composition was unchanged after adsorption of Cd²⁺;③ Under certain conditions (addition of 50 g ceramsite,the initial Cd²⁺ concentration of 300 mg/L,the adsorption time of 120 min,and pH value of 6),the removal rate of Cd²⁺ was high,indicating the high ability of ceramsite to adsorb Cd²⁺;④ The municipal sludge ceramsite adsorbed Cd²⁺ in two manners: physical adsorption and chemisorption.The adsorption conformed more to the quasi-first-order kinetic model than to the quasi-second-order kinetic model.The municipal sludge ceramsite adsorbed Cd²⁺ via a complex mechanism involving both single-layer and multi-layer adsorption.The results can provide a scientific basis and technical support for the resource utilization of municipal sludge and the treatment of Cd²⁺ and pollutants.