【作者】 付桂珍；

【导师】 龚文琪；

【作者基本信息】 武汉理工大学 ， 矿物加工工程， 2009， 博士

【摘要】 本课题研究利用蒙脱石、凹凸棒石粘土矿物与工业废料粉煤灰制备复合颗粒吸附材料用于处理电镀工业废水,开发出环境友好型矿物吸附材料,旨在解决电镀工业废水引起的重金属污染,同时为粘土矿物与工业废料粉煤灰的综合利用开辟一条有效途径,课题研究具有重要的理论意义和实际应用价值。论文对蒙脱石／粉煤灰颗粒吸附材料的制备条件及其处理含Cu、Zn、Ni、Cr等多种重金属离子电镀工业废水的吸附条件进行了系统的研究；运用XRD、SEM、DTA/TG、BET等测试分析手段对其进行了表征；研究了复合颗粒吸附材料对电镀工业废水中多种不同浓度重金属离子的吸附／解吸规律；并探讨了复合颗粒吸附材料去除废水中重金属离子的吸附动力学方程、吸附热力学参数及等温吸附作用机理。主要研究成果如下：1复合颗粒吸附剂的制备研究(1)蒙脱石／粉煤灰复合颗粒吸附剂制备适宜工艺条件为：蒙脱石与粉煤灰的比例为6：4,焙烧温度450℃,焙烧时间为0.5h,添加剂(工业淀粉)比例为蒙脱石／粉煤灰总质量的10%,颗粒直径为1～2mm。在上述工艺条件下制备的复合颗粒用于吸附处理初始浓度为200mg／L的含Cu2+废水,吸附率可达96.34%,且散失率小于1%。(2)凹凸棒石／粉煤灰复合颗粒吸附剂制备适宜工艺条件为：凹凸棒石／粉煤灰混合比6：4,焙烧温度400。C,硅酸钠和淀粉添加比例分别为凹凸棒石／粉煤灰总质量的15%和10%。在上述工艺条件下制备的复合颗粒对初始浓度为50mg／L含Zn2+溶液的吸附率达94.23%,其散失率为4.33%。2颗粒吸附材料的表征(1)在适宜造粒条件下制得的蒙脱石／粉煤灰颗粒吸附材料的XRD图谱分析表明蒙脱石／粉煤灰颗粒吸附材料焙烧前后其物相组成基本未发生变化；DTA／TG分析表明颗粒吸附材料焙烧前后其蒙脱石结构变化不大,主要是失去蒙脱石中的吸附水和层间水；SEM图像分析显示未焙烧的蒙脱石／粉煤灰颗粒吸附材料几乎未见有显气孔,有极少量的空洞,而焙烧后的蒙脱石／粉煤灰颗粒微孔结构十分明显,形状规则,孔径大小约20～5μm。该材料的物理性能测试表明：吸水率为31.80%,显气孔率为46.82%,体积密度为1.47 kg／m3,抗压强度为5.28MPa,比表面积为10.28m2／g。(2)在适宜造粒条件下制得的凹凸棒石／粉煤灰颗粒吸附材料的XRD图谱分析表明焙烧前后物相组成基本未发生变化,说明颗粒焙烧并未改变其物相组成。DTA／TG分析表明凹凸棒石／粉煤灰颗粒吸附材料焙烧前后其凹凸棒石结构变化不大,主要是失去凹凸棒石中的吸附水和层间水；SEM图像分析显示未焙烧的凹凸棒石／粉煤灰颗粒吸附材料有极少量的空洞,而焙烧后的凹凸棒石／粉煤灰颗粒微孔结构较为明显,形状规则,孔径大小约10-30μm。该材料的物理性能测试表明：吸水率为32.89%,显气孔率为54.77%,体积密度为1.11 kg／m3,抗压强度为2.15 MPa,比表面积为17.01m2／g。3复合颗粒吸附剂处理含单一重金属离子废水研究正交试验确定蒙脱石／粉煤灰颗粒吸附材料去除重金属离子的优化条件为：Cu2+、Zn2+、Ni2+、Cr6+初始浓度分别为100mg·L-1、25mg·L-1、20mg·L-1和10mg·L-1；吸附剂投加量分别为12g·L-1、20g·L-1、24g·L-1和20g·L-1；溶液pH值分别为6、7、7和3；反应时间均为80min。在优化试验条件下,吸附剂对Cu2+、Zn2+、Ni2+、Cr6+去除率分别为99.00%；、99.10%、98.90%和99.36%。4复合颗粒材料处理电镀工业废水的研究(1)蒙脱石／粉煤灰颗粒吸附材料去除电镀工业废水中重金属的优化条件为：颗粒吸附材料用量为50g／L,pH值为6.5,反应时间为80min。在优化试验条件下,Cu2+、Zn2+、Ni2+、Cr6+去除率分别为98.19%、98.07%、98.81%、99.06%,处理后的废水中这些重金属的残留浓度均低于国家污水综合排放标准(GB8978—1996)一级标准。(2)凹凸棒石／粉煤灰颗粒吸附材料去除电镀工业废水中重金属的优化条件为：颗粒吸附剂投加量为70g／L,pH值为6.5,反应时间为80min。在优化试验条件下,Cu2+、Zn2+、Ni2+、Cr6+去除率分别为98.14%、87.79%、97.52%、97.58%,处理后的废水中这些重金属的残留浓度均低于国家污水综合排放标准(GB8978—1996)一级标准。5颗粒吸附材料的再生与重复使用研究在几种不同解吸剂中,以1mol·L-1NaCl溶液对两种颗粒吸附材料的解吸再生效果最好。颗粒吸附材料经过六次再生和重复使用后,对废水中重金属离子的去除效果略有下降,且经过六次再生和重复使用后的散失率均在10%左右,说明两种颗粒吸附剂解吸再生后,重复使用效果均较好。6颗粒吸附剂对重金属离子的吸附作用机理探讨(1)蒙脱石／粉煤灰颗粒吸附材料对重金属离子的吸附过程基本符合一级反应动力学方程Ct=C0·e-kt,说明液膜扩散为吸附过程的主控步骤。吸附热力学研究表明,由吸附热力学参数ΔH<0,ΔS<0可知,温度升高不利于反应正向进行。ΔG<0,表明Gibbs自由能的减少是颗粒吸附剂材料吸附的主要动力。蒙脱石／粉煤灰颗粒吸附剂的吸附等温曲线符合Freundlich和Langmuir型两种吸附等温模型,其中与Langmuir型吸附等温式相关性更好。(2)蒙脱石与水中重金属离子的吸附机理主要是离子交换吸附；凹凸棒石吸附重金属离子主要以3种形式：表面氧合、微孔通道、凹凸棒石晶体结构中。粉煤灰对废水中金属离子的吸附作用可分为物理吸附、化学吸附和吸附-絮凝沉淀协同作用三种形式。(3)颗粒材料吸附速度机理研究表明：吸附剂在流体中吸附物质的速度,可以分为外部扩散过程、孔隙扩散过程和吸附反应过程三种,其中以最慢的孔隙扩散阶段起控制作用。更多还原

【Abstract】 Preparation of granulated composite materials using clay minerals and industrial wastes for treatment of electroplating industrial wastewater was studied in this paper.lt was the development of environment-friendly mineral adsorption materials. The issue aimed at solving heavy metal pollution caused by electroplating industrial waste water, and at the same time, it opened an effective way for the comprehensive utilization of clay minerals and fly ash of industrial wastes. The research topic was of important theoretical significance and practical application value.The preparation conditions for montmorillonite/fly ash granulated adsorption materials and the treatment of electroplating industrial wastewater containing Cu2+, Zn2+, Ni2+ and Cr6+ heavy metal ions were studied systematically in this paper. The materials were characterized by using XRD, SEM, DTA/TG, BET etc. The adsorption/desorption rules were studied with the particulate composite adsorbing materials to treat electroplating industrial wastewater containing a variety of heavy metal ions. The adsorption dynamic equation, thermodynamic parameters, and mechanism were discussed for the removal of heavy metal ions by using granulated adsorption materials.The main research achievements were as follows:1 Study on preparation of granulated adsorption materials(1) The optimum preparation process conditions for preparation of granulated adsorption materials of montmorillonite/fly ash were a ratio of montmorillonite to fly ash of 6:4, a calcination temperature of 450℃, a calcination time of 0.5h, additive industrial starch of 10% and the particle diameter of 1～2mm. When the granulated adsorption materials prepared under the above mentioned conditions were used to treat waste water of 200mg/L initial concentration containing Cu2+, its adsorption ratio was up to 96.34% and the loss ratio was less than 1%.(2) The optimum preparation process conditions for the preparation of granulated adsorption materials of attapulgite/fly ash were a ratio of attapulgite to fly ash of 6:4, a calcination temperature of 400℃, the additive ratio of sodium silicate and starch of 15% and 10% respectively. When the granulated adsorption materials prepared under the above mentioned conditions were used to treat waste water of 50mg/L initial concentration containing Zn2+, the adsorption ratio was up to 94.23%, and the loss ratio was 4.33%.2 Characterization of granulated adsorption materials(1) XRD pattern of the montmorillonite/fly ash granulated adsorption materials prepared under the optimum process conditions showed that the mineral phases were not changed before and later calcination. Montmorillonite mainly lost its adsorption water and interlayer water, which was observed from the DAG/TG pattern. SEM images analysis showed that there was hardly porous structure in granulated materials before calcination, but there were obviously porous structure and pore sizes of 20 to 50μm in granulated materials after calcination. The physical tests and analysis of granulated adsorption materials showed that the density was 1.47 kg/m3, water absorption capacity was 31.80%, apparent porosity was 46.82%, compressive strength was 5.28 MPa, and the surface area was 10.28m2/g.(2) XRD pattern of the attapulgite/fly ash particles adsorbed materials obtained under the appropriate conditions showed that the mineral phases were not changed before and after calcination. Attapulgite mainly lost its adsorption water and interlayer water, which was observed from the DAG/TG pattern. SEM images analysis showed that the granulated material had good porous structure, and pore sizes were from 10 to 30μm. The physical tests and analysis of granulated adsorption materials showed that the density of the granulated adsorption materials was 1.11 kg/m3, water absorption capacity was 32.89%, apparent porosity was 54.77%, compressive strength was 2.15 MPa, and the surface area was 17.01m2/g.3 Treatment of wastewater containing a single heavy metal ion with granulated adsorption materialsThe optimum conditions for granulated adsorption materials of montmorillonite/fly ash to remove heavy metal ions under orthogonal experiment were the amount of adsorbent dosage was 12g·L-1,20g·L-1,24g·L-1 and 20g·L-1 respectively; pH was 6,7,7 and 3 respectively; reaction time was 80min.When the initial concentration of Cu2+, Zn2+,Ni2+,Cr6+ was 100 mg·L-1,25 mg·L-1,20 mg·L-1 and 10 mg·L-1 respectively,the adsorbent ratio of removal of Cu2+,Zn2+,Ni2+,Cr6+ was 99.00%,99.10%,98.90% and 99.36% respectively under the optimal experimental conditions.4 Treatment of electroplating industrial wastewater with granulated adsorption materials(1) The optimum conditions for granulated adsorption materials of montmorillonite/fly ash to remove heavy metal in electroplating industial wastewater were the amount of granulated adsorption materials dosage was 0.05/cm3, pH was 6.5, and reaction time was 80min. The adsorbent removal rate of Cu2+、Zn2+、Ni2+、Cr6+ was 98.19%、98.07%、98.81%、and 99.06% respectively under the optimal experimental conditions. These residual concentrations of heavy metals waste water treated were lower than the first standard of the national waste water discharge (GB8978-1996).(2) The optimum conditions of using attapulgite/fly ash particles adsorbing material to remove heavy metal in electroplating industrial wastewater were granular adsorbent dosage was 0.07 g/cm-3, pH was 6.5, and reaction time was 80min. The removal ratio of Cu2+、Zn2+、Ni2+、Cr6+ was 98.14%,87.79%,97.52% and 97.58% respectively under the optimal experimental conditions. These residual concentrations of heavy metal wastewater were lower than the first standard of national wastewater discharge (GB8978-1996).5 Study on regeneration and reuse of granulated adsorption materialsThe effect of desorption and regeneration of two kinds of granulated adsorption materials was the best when using 1mol·L-1NaCl among several different desorption agents. The adsorptive ratio of granulated adsorption materials to remove heavy metal ions decreased slightly and the loss ratio was about 10% after six regeneration and reuse, which showed that the effects of two kinds of granulated adsorption materials were better after desorption and regeneration.6 Discussion of mechanism of adsorption of heavy metal ions on granulated adsorption materials(1) The reaction of adsorption with granulated adsorption materials of montmorillonite/fly generally was a first order reaction kinetics equation C1= C0·e-kt, which showed that the adsorption was mainly controlled by liquid membrane diffusion. As the adsorption thermodynamic parametersΔH<0,ΔS <0 andΔG<0 showed that rising temperature was not conducive to a positive reaction, which showed that the decrease ofΔG was the main driving force for the removal of the heavy metal ions.The adsorption data of granulated adsorption materials of montmorillonite/ fly fit with Freundlich and Langmuir adsorption isotherm models, and the correlation of Langmuir adsorption isotherm model was better.(2) The mechanism that heavy metal ions were adsorbed by montmorillonite was mainly ion-exchange adsorption. There were mainly three kinds of forms that the heavy metal ions were adsorbed by attapulgite, which were surface oxygenation, micro-pore channel and attapulgite crystal structure. Fly ash adsorbed metal ions could be divided into three forms:physical adsorption, chemical absorption and adsorption-flocculation sedimentation synergy.(3) Study on mechanism of adsorbent velocity of granulated adsorption materials showed that the adsorption velocity of adsorbent material in fluid could be divided into three stages, which were external diffusion, pore diffusion and adsorption reaction, and the slowest stage of pore diffusion process was the main control stage.更多还原