【作者】 龚兵丽；

【导师】 赵雅萍； 邱宇平；

【作者基本信息】 华东师范大学 ， 环境科学， 2009， 硕士

【摘要】 在工业废水处理当中,染料废水中因含有大量的有机染料,以其色度高、成分复杂、毒性大、难降解等特点,成为排放量大而又难以治理的有害工业废水之一。本文以典型染料亚甲基蓝（MB）为对象,研究了黑碳（BC）和TiO₂耦合工艺对其去除的效果及去除机理。黑碳是环境中化石燃料和生物质不完全燃烧产生的含碳高聚物,广泛存在于环境（大气圈、水圈、生物圈、土壤和岩石）中。黑碳具有高比表面积和丰富的表面官能团,对有机污染物有较强的吸附作用,与活性炭相比其简单的制备方式决定了黑碳广泛的应用前景。首先,本文研究了黑碳对亚甲基蓝的吸附,及吸附过程的动力学和热力学特性。结果表明:影响吸附的主要因素是温度、初始浓度、溶液pH值及转速等。吸附等温线能较好地吻合Langmuir和Freundlich吸附等温方程,Freundlich方程的拟合效果更好,说明其吸附更倾向于发生多层吸附,且在不同温度下,n都大于1,表明在所研究的范围内为优惠吸附过程。吸附热力学研究表明:△H>0,说明吸附为吸热过程;△G<0,说明吸附质倾向于从溶液中吸附到吸附剂表面,反应过程是自发进行的;△S>0,说明固/液相界面上分子运动更为混乱。吸附过程符合二级动力吸附方程,颗粒内扩散过程是影响吸附速率的主要控制步骤。其次,本文通过黑碳吸附——TiO₂光催化降解实验多因素分析,得出黑碳和二氧化钛耦合处理亚甲基蓝染料废水的降解效果最好。实验探讨了二氧化钛添加量、黑碳添加量、光照强度、初始浓度和初始pH值等因素对光催化降解过程的影响。对于5050mg/L亚甲基蓝溶液,最佳处理条件为TiO₂为0.5g/L,BC为0.2g/L,光照强度为3.3.7mW/cm²,且在碱性条件下比在酸性条件下的吸附光催化对MB的降解效率最高。溶液中不同电解质溶液对亚甲基蓝溶液的吸附光催化降解的去除都有影响。实验对比研究了四种电解质离子对降解过程的影响,得出影响效果为PO₄^3->NO₃^->SO₄^2->Cl^-。最后,阐明MB去除效率的提高,主要是BC吸附剂与TiO₂光催化剂协同作用的结果。即利用黑碳的吸附作用,将低浓度污染物富集到催化剂表面,为光催化降解提供有利的高污染物浓度的微环境。吸附剂同时可以吸附降解过程产生的中间产物,使其进一步被催化降解。经过充分的光催化降解,将有机物完全矿化为CO₂,H₂O等小分子,并离开吸附剂,吸附剂得到了原位再生,BC-TiO₂催化剂的协同作用是吸附、富集、光催化、再生过程的有机结合。更多还原

【Abstract】 With the development of the social economic,industries discharged large amount of dyes wastewater that were difficult to be degraded because of the high chroma,high toxicity.The aim of this study is to remove methylene blue（MB） by coupling Black carbon（BC） adsorption with TiO₂ photodegradation.BC is defined as the highly carbonaceous polymeric materials produced from incomplete combustion of fossil fuel and biomass.It exists in all the environmental media including atmosphere,hydrosphere,biosphere,soil and rock.With abundant surface functional groups and high surface area to be similar with that of the active carbon,BC is determined to have an extensive applicable adsorption prospect for organic pollutants.Firstly,adsorption kinetics and thermodynamics of Methylene Blue by black carbon was studied by batch experiments.The main influential factors included temperature, initial concentration,pH Values,and Oscillation.The adsorption isotherms fitted well to Langmuir and Freundich equation and the latter one is better suited.This indicated that the adsorption was multilayer adsorption.The parameters n＞1 show that the reactions are preferential process under different temperature.The thermodynamics study indicates that the positive value of△H shows an endothermic process,and the negative value of△G shows the spontaneous nature of the adsorption process,and the positive value of△S indicates the increased randomness at the solid/solution interface during the adsorption processes.The results showed that the adsorption rate for the solute appeared to be the second order kinetics and the intraparticle diffusion was the main rate-controlling step.Secondly,it is the best treatment efficiency for methylene blue removal by coupling BC adsorption with TiO₂ photodegradation resulting from the analysis of multiple-factor experiments.The effects of various factors such as the amount of TiO₂,the amount of BC, illumination intensity,initial concentration and pH Values on the photocatalytic behavior for MB were discussed.The opt condition for 50 mg/L dye solution degradation was TiO₂ 0.5 g/L,BC 0.2 g/L,illumination intensity 3.7 mW/cm².In the alkaline condition,the more efficient degradation occurs than that in the acidic environment.Different electrolyte solutions hinder the experimental process.Compared with four electrolyte ions,the degradation effect is PO₄³＞NO₃＞SO₄²＞Cl^-. Finally,this study explained clearly the synergy effect of BC adsorption and TiO₂ photocatalysis,i.e.low concentration pollutants are enriched in the catalyst’s surface by BC adsorption.It provides the micro-environment of the high concentration pollutants for TiO₂ degradation.Meanwhile,BC can adsorb the intermediate products simultaneously in the course of photodegradation,then in favor of the further photocatalytic degradation. After complete degradation,the dye is mineralized as CO₂,H₂O,and departure from the sorbent surface then the sorbents are regenerated.The synergy effect is the combination processes of adsorption,enrichment,photocatalysis and regeneration.更多还原