Removal of cadmium and nickel from wastewater using bagasse fly ash--a sugar industry waste

The bagasse fly ash, an industrial solid waste of sugar industry, was used for the removal of cadmium and nickel from wastewater. As much as 90% removal of cadmium and nickel is possible in about 60 and 80 min, respectively, under the batch test conditions. Effect of various operating variables, viz., solution pH, adsorbent dose, adsorbate concentration, temperature, particle size, etc., on the removal of cadmium and nickel has been studied. Maximum adsorption of cadmium and nickel occurred at a concentration of 14 and 12 mg x l(-1) and at a pH value of 6.0 and 6.5, respectively. A dose of 10 g x l(-1) of adsorbent was sufficient for the optimum removal of both the metal ions. The material exhibits good adsorption capacity and the adsorption data follow the Langmuir model better then the Freundlich model. The adsorption of both the metal ions increased with increasing temperature indicating endothermic nature of the adsorption process. Isotherms have been used to determine thermodynamic parameters of the process, viz., free energy change, enthalpy change and entropy change.     

赤泥-粉煤灰加气混凝土制备研究

赤泥是铝土矿提取氧化铝过程中产生的废弃物.赤泥建材化利用具有使用量大、产品附加值高等特点,是赤泥无害化、资源化利用的优选途径.以强度级别A3.5、密度级别B06的加气混凝土为设计目标,研究了组成材料、养护制度对赤泥-粉煤灰加气混凝土强度、密度的影响.结果表明,采用赤泥、粉煤灰等固体工业废料制备的加气混凝土,强度和密度满足加气混凝土砌块质量要求,满足建筑材料放射性核素限量要求.     

Adsorption of mercury(II) by coal fly ash

Coal fly ash, an industrial solid waste, was found to have a good adsorption capacity for mercury(II). Adsorption of mercury(II) on coal fly ash conforms to Freundlich's adsorption model. Several parameters such as time of equilibration, effect of pH, effect of initial concentration of solute, effect of fly ash dose etc. were studied. The maximum adsorption was observed after shaking for 3 h. Solution pH was the most important parameter affecting the adsorption. The optimum pH range was 3.5–4.5. There was total adsorption of mercury below 10 mg l⁻¹. The performance of coal fly ash as an adsorbent was found to be significant when compared with activated powdered charcoal.     

蛭石微细粉的特性及其吸附亚甲基蓝的研究

为了探明天然蛭石对于有机阳离子染料的吸附特性,本文系统表征了气流粉粹得到的蛭石微细粉的物相组成、粒度分布、孔径分布、比表面积、Zeta电位;研究了在不同pH值、固液比、时间、亚甲基蓝浓度条件下蛭石微细粉对亚甲基蓝的吸附量和去除率.结果表明,该蛭石微细粉的主要矿物相为蛭石,含有少量的云母,平均粒径为21.65μm,比表面积为12.63m^2/g,表面呈负电荷.在pH值呈中碱性时蛭石对亚甲基蓝的吸附量最大.在固液比为3g/L、浓度为50mg/L、吸附时间为8h的条件下,蛭石对亚甲基蓝浓度的吸附量为16.42mg/g,去除率达到98.54％.     

SDS-硅藻土吸附亚甲基蓝和孔雀石绿染料的动力学和热力学

文章主要研究了SDS-硅藻土对亚甲基蓝和孔雀石绿两种染料的吸附动力学和热力学。研究结果表明,SDS-硅藻土对亚甲基蓝和孔雀石绿的平衡吸附量分别为16.3mg/g和20.1mg/g。亚甲基蓝和孔雀石绿在SDS-硅藻土上的吸附行为均可用Langmuir等温方程来描述,20℃时的相关系数分别为0.939 1和0.963 6,升温有利于吸附的进行。准二级吸附速率方程能更好的描述亚甲基蓝和孔雀石绿在SDS-硅藻土上的吸附动力学,20℃时的相关系数分别为0.991 0和0.990 8。通过计算不同温度各热力学参数ΔG、ΔH和ΔS,理论上证实该吸附为一自发的吸热过程,且以物理吸附为主。     

发泡剂对赤泥轻质免烧砖性能的影响

以赤泥、粉煤灰、水泥为主要原料,掺加一定量的激发剂和发泡剂,制备了赤泥轻质免烧砖。研究了发泡剂掺量对赤泥轻质免烧砖性能的影响。利用扫描电子显微镜对赤泥轻质免烧砖破坏断口进行了微观形貌分析。结果表明,当发泡剂掺量为10ml时,制得的试样性能较好,其密度、抗折强度、抗压强度分别为423kg／m3．049MPa和1.87MPa。     

Experimental design methodology applied to adsorption of metallic ions onto fly ash

The objective of this study was to define operating conditions which would conciliate a high removal of the five metallic cations (Cu2+, Ni2+, Zn2+, Cd2+, Pb2+) and a low desorption of these metal ions from the contaminated sorbents. To achieve this goal the strategy relied on the use of experimental design methodology. The influence of four parameters (fly ash/lime mass ratio, type of fly ash/lime sorbent, solution temperature, and sorbent concentration) on the removal at pH = 5 and the stabilization of the five metallic ions was studied. In the first step, the influence of three parameters on the removal of Cu2+ ions was studied (R2 = fly ash/lime mass ratio, type of sorbent, temperature). It was found that the same set of parameter values would produce both the highest removal and the lowest desorption for this cation: R2 = 9 g g(-1), sorbent B (made by mixing fly ash and lime in water, then drying this paste at 105 degrees C for 24 h), temperature of suspension equal to 60 degrees C. The formation of calcium silicate hydrate (CSH), resulting from the pozzolanic activity of fly ash, is assumed to be partially responsible for these mechanisms. In the second step, simplex methodology and Doehlert matrix were used to find the conditions in a 2D space (sorbent concentration, temperature of solution) that would give the highest removal from a solution containing five metallic cations and the lowest desorption of these five cations adsorbed on the contaminated sorbents. Then, the system response that had to be optimized was the total metallic ions concentration (TMIC, mol L(-1)). A TMIC was measured both for adsorption and leaching experiments. These responses were modelized using a second-order polynomial and the surface responses were plotted for adsorption and desorption results. A difference was observed between operating conditions reaching the highest adsorption from those that gave the lowest desorption. However, an adsorbent concentration around 122 g L(-1) and a solution temperature of 66 degrees C would lead simultaneously to a high adsorption and a low desorption.     

赤泥吸附去除淀粉废水中高浓度磷的研究

以铝矿工业废渣--赤泥为吸附剂去除高浓度淀粉废水中的磷,比较了三种原状赤泥的除磷效果,考察了反应时间、初始pH、NaOH投加顺序和赤泥投加量对除磷效果的影响.结果表明,赤泥具有很好的除磷能力,在投量为2 g/L、反应时间为2 h、反应结束前0.5 h投加2 mol/L的NaOH(25 mL/L)的条件下,除磷率可达98.2%.该研究在赤泥的资源化利用和淀粉废水中磷的去除方面有重要的意义.     

粉煤灰与其他废渣生产复合砖

阐述了粉煤灰与其他废渣生产复合砖,对粉煤灰、赤泥、钢渣等原料的性能进行了分析,并且给出了粉煤灰与废渣生产复合砖的生产工艺流程以及试验结果.     

粉煤灰粘土粉质粘土膨润土对镍离子吸附试验研究

研究了粉煤灰 、粘土、粉质粘土和膨润土从溶液中去除有毒金属镍离子的吸附过程。动态试验显示吸附过程是快速的。吸附试验结果表明,粉煤灰、膨润土对镍离子的吸附能力远大于粘土和粉质粘土,且粉煤灰大于膨润土。平衡吸附模型充分说明在高浓度下,镍离子在粉煤灰 、粘土、粉质粘土及膨润土上的吸附最符合 Langmuir 等温线, 在粘土和粉质粘土上的吸附也可用线性和 Freundlich 等温线来表示。试验结果还表明:随着吸附剂中镍离子含量的增加,粉煤灰等吸附剂对镍离子吸附的百分数均呈减小的趋势。