Characterization of Cassava Root Husk Powder: Equilibrium, Kinetic and Modeling Studies as Bioadsorbent for Copper(II) and Lead(II)

This study was aimed to investigate Pb(II) and Cu(II) ions removal ability from aqueous solution by cassava root husks (CRH) as a cheap, sustainable and eco-friendly bioadsorbent. The CRH was characterized by Fourier Transform Infrared (FTIR) spectroscopy which indicated the availability of various functional groups for metal coordination and the result was supported by elemental analysis studies. UV-Visible spectral studies indicated the presence of oxalate () and it could possibly interact with metal ions to give rise to a stable chelated coordination complex which affects metal ions removal efficiency. Bioadsorption process was carried out as a function of metal concentration, contact time, pH of the solution, particle size, and dosage of the adsorbent. Experimental results indicated the optimal adsorption condition of pH 4 for both Pb(II) and Cu(II) ions, dosage of 0.1 g/0.1L and 1 g/0.1L for Pb(II) and Cu(II) ions respectively, adsorption equilibrium time of 2 and 25 minutes for Pb(II) and Cu(II) respectively, and concentration of 0.5 mg/L for both metal ions. Kinetic data best fitted pseudo-second-order model and not the pseudo-first-order model. Equilibrium data best fitted the Freundlich model than the Langmuir model. Specific surface area and pore volume studies indicated that CRH is non-porous and hence rapid adsorption kinetics is expected. Supporting the experimental results, molecular modeling studies performed using Schrödinger software predicted several sites in the structure capable of docking with metal ions.

Kinetics and Thermodynamic Studies: Adsorption of Pb, Cr and Ni Ions from Spent Lubrication Oil (SLO) Using Acid Modified Clay

Adsorption of Pb, Cr, and Ni ions from spent lubrication oil (SLO) by sulphuric acid modified clay (SAMC) was investigated considering the effect of contact time and temperature of the adsorption system. The removal percentage of the heavy metals was found to be temperature and contact time-dependent. Adsorption of the heavy metals increases with an increase in temperature and contact time with 95.0% - 100% adsorption recorded at the temperature of 331 K with the equilibration time of 12 hours. The thermodynamic and kinetics investigation of the adsorption process showed that the adsorption of these metals by the modified adsorbent is a spontaneous and endothermic physical adsorption process that followed the pseudo-second-order kinetic model.

Interpretation of Adsorption Thermodynamics and Kinetics

A complete study of adsorption processes will be less complete if the structure and dynamics of its different elements and how they interact is not well captured. Therefore, the extensive study of adsorption thermodynamics in conjunction with adsorption kinetics is inevitable. Measurable thermodynamic properties such as temperature equilibrium constant and their non-measurable counterparts such as Gibbs free energy change, enthalpy, entropy etc. are very important design variables usually deployed for the evaluation and prediction of the mechanism of adsorption processes.

粉煤灰提铝残渣制备4A分子筛及Cu(Ⅱ)吸附研究

4A分子筛由于其优异的阳离子交换能力,成为处理重金属废水优良的吸附材料。为了达到以废治废的目的,以粉煤灰酸法提铝残渣为原料制备地质聚合物,再经水热原位转化合成体型化4A分子筛。采用XRD、FT-IR、SEM、BET、TGA等手段对4A沸石进行表征,探讨吸附时间、Cu(Ⅱ)初始浓度、吸附剂用量及溶液p H对其吸附性能的影响,并结合动力学方程和吸附等温线模型对其吸附过程进行研究。结果表明,所合成的4A分子筛孔隙发达且微孔含量较多,总比表面积为71.85 m^(2)/g,其中微孔比表面积为53.91 m^(2)/g,微孔孔径主要集中在1.3 nm左右。体型化4A分子筛吸附Cu(Ⅱ)的最佳条件为吸附时间为240 min、Cu(Ⅱ)初始质量浓度为100 mg/L、吸附剂用量为2.0 g/L、溶液p H为6~9,此时吸附量为32.97 mg/g,Cu(Ⅱ)的去除率可达65.93%。吸附过程符合准二级动力学模型,以化学吸附为主。Langmuir模型拟合效果较好,表明Cu(Ⅱ)在合成4A沸石上的吸附过程为单分子层吸附,且拟合得到的Cu(Ⅱ)的最大吸附量为37.05 mg/g。

Electrocoagulation process for the treatment of metal-plating wastewater:Kinetic modeling and energy consumption

It is known that wastewater produced by the metal-plating industry contains several heavy metals, which are acidic in nature and therefore toxic for the environment and for living creatures. In particular, heavy metals enter the food chain and accumulate in vital organs and cause serious illness. The precipitation of these metals is mostly achieved by pH adjustment, but as an alternative to this method, the electrocoagulation process has investigated in this study using iron and aluminum electrodes. The effects of the pH adjustment on removal before and after the electrocoagulation process were investigated, and cost analyses were also compared. It was observed that a high proportion of removal was obtained during the first minutes of the electrocoagulation process;thus, the current density did not have a great effect. In addition, the pH adjustment after the electrocoagulation process using iron electrodes, which are 10% more effective than aluminum electrodes, was found to be much more efficient than before the electrocoagulation process. In the process where kinetic modeling was applied, it was observed that the heavy metal removal mechanism was not solely due to the collapse of heavy metals at high pH values, and with this modeling, it was seen that this mechanism involved adsorption by iron and aluminum hydroxides formed during the electrocoagulation process. When comparing the ability of heavy metals to be adsorbed, the sequence was observed to be Cr>Cu>Ni>Zn, respectively.

Removal of Dye Using Lignin-Based Biochar/Poly(ester amide urethane)Nanocomposites from Contaminated Wastewater

The pursuit of incorporating eco-friendly reinforcing agents in polymer composites has accentuated the exploration of various natural biomass-derived materials.The burgeoning environmental crisis spurred by the discharge of synthetic dyes into wastewater has catalyzed the search for effective and sustainable treatment technologies.Among the various sorbent materials explored,biochar,being renewable,has gained prominence due to its excellent adsorption properties and environmental sustainability.It has also emerged as a focal point for its potential to replace other conventional reinforcing agents,viz.,fumed silica,aluminum oxide,treated clays,etc.This study introduces a novel class of polymer nanocomposites comprising of lignin-based biochar particles and poly(ester amide urethane)matrix via a feasible method.The structural evaluation of these nanocomposites was accomplished using Fourier-transform infrared spectroscopy,X-ray photoelectron spectroscopy,and powder X-ray diffraction.The polymer nanocomposites exhibited superior mechanical properties with an increment in tensile strength factor by 45%in comparison to its pristine matrix,along with an excellent toughness value of 90.22 MJm^(−3)at a low loading amount of only 1 wt%.The composites showed excellent improvement in thermal properties with a sharp rise in the glass transition temperature(Tg)value from−28.15℃to 84℃,while also championing sustainability through inherent biodegradability attributes.Beyond their structural prowess,these polymer nanocomposites demonstrated excellent potential as adsorbents,displaying efficient removal of malachite green and tartrazine dyes from aqueous systems with a removal efficiency of 87.25%and 73.98%,respectively.The kinetics study revealed the pseudo second order model to be the precision tool to assess the dye removal study.Complementing this,the Langmuir adsorption isotherm provided a framework to assess the sorption features of the polymer nanocomposites.Overall,these renewable biochar integrated polymer matrices boast remarkable recovery capabilities up to seven cycles of usage with an excellent dye recovery percentage of 95.21%for the last cycle,thereby defining sustainability as well as economic feasibility.

酯交换合成碳酸二甲酯反应动力学研究

研究了离子交换树脂催化碳酸乙烯酯(EC)和甲醇(MeOH)酯交换合成碳酸二甲酯(DMC)的反应动力学。在间歇搅拌釜式反应器中研究了催化剂的种类、搅拌速率、醇酯摩尔比、催化剂用量和反应温度对酯交换过程的影响;采用拟均相动力学模型对实验数据进行关联。结果表明,估算的动力学参数使计算结果和实验数据吻合较好,建立了离子交换树脂催化酯交换反应的动力学模型,为反应精馏过程中的模拟计算以及工业化生产提供了一定的理论支持。

改性玉米秸秆对水中磷酸根的吸附动力学研究

将化学改性后的玉米秸秆制备阴离子交换剂,重点研究了改性玉米秸秆对磷酸根的吸附动力学特性.通过静态实验,考察了在不同pH、温度、磷酸根初始浓度条件下,改性玉米秸秆对磷酸根吸附效果的影响,并分别用伪一级动力学方程、伪二级动力学方程、修正伪一级动力学方程和颗粒内扩散方程进行拟合,计算出相应的速率常数.结果表明,Langmuir等温模式能更好地描述改性玉米秸秆对磷酸根的吸附效果,并且随着温度的升高,改性玉米秸秆对磷酸根的最大吸附量逐渐减小.改性玉米秸秆对磷酸根的吸附是一个快速吸附过程,30 min内即可达到吸附平衡,该吸附过程符合伪二级动力学方程和颗粒内扩散方程,吸附速率主要受颗粒内扩散控制.随着初始浓度的增大,伪二级吸附速率常数逐渐减小,颗粒内扩散速率常数逐渐增大.通过改性玉米秸秆对磷酸根的吸附动力学研究,可以为反应器的设计和污水处理装置的运行提供基础信息,对于去除水溶液中磷酸根的技术应用具有重要实际意义.

改性沸石对猪场沼液氮磷吸附特性与机理分析

针对猪场沼液氮磷含量高、有机污染严重、难以处理的问题,采用经氯化钠溶液改性沸石为载体对沼液中氮磷吸附特性和去除机理进行分析研究,考察了沸石投加量、吸附时间、沼液初始浓度等影响因素。结果表明:当沸石投加量为每100mL10g、吸附时间48 h时,最大氨氮去除率可达90.66%,氨氮饱和吸附量可达1.43 mg·g-1,最大总磷去除率可达85.97%,磷饱和吸附量可达0.16 mg·g-1。吸附后的沸石污泥含有大量氮磷元素,是一种优质缓释肥料。Freundlich、Langmuir方程均能较好地解析改性沸石的等温吸附过程,其吸附动力学符合准二级动力学模型,R2均达0.98以上。沸石对猪场沼液中有机态氮磷去除主要基于物理性吸附和沸石中的活性基团与有机官能团所产生的配位络合,无机态氮磷则主要以离子交换及吸附沉淀方式得以去除。

喹啉的O_3及O_3/UV降解规律

研究了O3单独作用及O3/UV联合作用时喹啉的降解规律,并对结果进行了比较.研究表明,空气吹脱和UV本身对喹啉的去除贡献率都不大.O3单独作用时,提高体系的初始pH值有利于喹啉的降解.O3/UV联合作用时,在某个临界pH值上,无论是提高还是降低体系的初始pH值都有可能提高喹啉的去除速率.初始pH值较低时,O3单独作用时喹啉的去除速率明显低于O3/UV联合作用时喹啉的去除速率,但在初始pH值较高的情况下,UV的介入可能会降低喹啉的降解速率.无论是O3单独作用还是O3/UV联合作用,喹啉的降解基本上满足伪一级反应动力学规律,如果体系的pH值基本保持恒定,这种规律就更为明显.

海绵铁处理Cr(Ⅵ)动力学

海绵铁是由精矿粉和氧化铁磷加工而成的铁质多孔性颗粒状物质,是一种新型水处理材料。本文应用海绵铁处理Cr(Ⅵ),研究了Cr(Ⅵ)的初始浓度、pH值、温度以及海绵铁粒径对动力学反应的影响,从lnC0/C-t曲线推断出海绵铁处理六价铬的反应属于准一级反应,考虑海绵铁活性表面随时间延长而衰减这一因素,提出了海绵铁处理Cr(Ⅵ)的动力学模型。

基于基准假组分模型的催化裂化反应-再生系统动态模拟

为实现催化裂化装置反应-再生系统动态模型的原料油切换操作模拟,建立了基准假组分动力学模型。该动力学模型根据原料的实沸点蒸馏曲线数据计算各原料基准假组分的质量分数,并模拟原料油性质的变化。以工业生产数据为基础,确定了8个动力学参数,并对模型计算结果进行了验证。在动力学模型基础上,结合所建立的沉降器汽提段和再生器动态模型,对催化裂化反应-再生系统进行了原料切换开环动态模拟。结果表明,模型具有较高的精确度,对不同性质的原料具有较好的适应性;所建模型可以实现原料切换操作;几个主要变量的变化趋势符合反应-再生过程规律。

乙烯氧化固定床反应器温度场模拟研究

针对乙烯氧化制环氧乙烷固定床反应器,利用YS-7型银催化剂的宏观反应动力学模型和固定床反应器拟均相二维数学模型方法,建立了催化剂床层的质量、热量平衡方程组,并采用Crank-Nicholson差分法对该偏微分方程组进行了数值计算。在模拟计算中,通过改变反应器汽包温度、反应器入口原料气温度、空速以及反应器入口原料气中乙烯、氧气、1,2-二氯乙烷的摩尔分数等工艺条件,系统地研究了以上各工艺条件单因素变化时对整个银催化剂床层温度场的影响。结果表明:随着固定床反应器汽包温度、入口原料气中乙烯、氧气摩尔分数的升高,以及固定床反应器中空速、入口原料气的温度及1,2-二氯乙烷摩尔分数的降低,银催化剂床层温度均有所升高,特别是床层"热点"区域的温度升高较明显。

纳米羟基磷灰石的镉离子吸附性能

以硝酸钙、磷酸、氨水为原料,采用共沉淀法合成了纳米羟基磷灰石粉体.以硝酸镉水溶液作为模拟废水,用Visual MINTEQ软件对模拟废水的溶液化学特征进行了计算,主要研究了溶液的初始pH值、反应时间以及镉离子(Cd2+)初始浓度等因素对纳米羟基磷灰石的镉离子吸附量的影响.实验结果表明,纳米羟基磷灰石的镉离子吸附性能在溶液初始pH为4～9的范围内比较稳定,其去除水溶液中镉离子的过程符合准二级动力学模型,并且与朗缪尔等温吸附和弗伦德里希等温吸附均表现出了较高的相关性,反映了纳米羟基磷灰石吸附水溶液中镉离子的反应以离子交换作用为主的特点.纳米羟基磷灰石不仅镉离子吸附容量大,而且初期吸附速率很快,是一种性能良好的环境矿物吸附材料.

5A分子筛载CuO对甲基橙的催化湿式过氧化氢氧化

以三水硝酸铜和5A分子筛为原料,采用湿法浸渍法制备了CuO-5A催化剂,采用扫描电镜、X射线衍射仪和红外光谱仪对其进行分析表征,并将其用于处理甲基橙模拟废水。考察材料种类(5A+H2O_2,20%CuO-5A+H2O_2,H2O_2)、铜负载量、pH值、催化剂投加量、温度等因素对催化效果的影响,并测定催化剂的稳定性,同时采用准一级动力学模型进行拟合分析。结果表明,CuO已成功负载在5A分子筛表面,采用20%的CuO-5A对甲基橙的催化湿式氧化效果最好。在甲基橙初始浓度为50mg/L、材料投加量为0.6g、pH值为2、温度为70℃条件下,第一次、第二次和第三次使用的CuO-5A在60min时对甲基橙的转化率分别为97.9%、92.3%和90.5%。不同温度下CuO-5A对甲基橙的催化湿式氧化行为可用准一级动力学方程来描述,拟合曲线展示了两个线性阶段,其中第二阶段活化能为50.35kJ/mol。

活性炭吸附处理黄磷化工渗滤液研究

研究了颗粒活性炭对黄磷化工渗滤液中有机物的吸附容量、吸附热力学和动力学。结果表明:颗粒活性炭对渗滤液中有机物的吸附容量几乎不受渗滤液pH值的影响,吸附45min后基本达到平衡。吸附等温线更符合修正的Freundlich模型,表明实验中的吸附主要是多分子层的吸附。拟二级动力学模型能更好的定量描述有机物在颗粒活性炭上的吸附过程,速率常数k2=0.12128g/(mg·min),平衡吸附量qe=5.78748mg/g。

循环流化床上升管内颗粒团聚行为的动态模拟

本文利用改进的颗粒流体动力学封闭的拟流体模型对循环流化床上升管内的颗粒团聚现象进行了模拟。模拟发现上升管内颗粒团聚物存在动态的产生、发展和消散的过程。颗粒团聚物的形成使其内部的相间滑移速度减小，从而使部分颗粒随气流上升，部分颗粒沿壁画下降。这两种运动形式的动态平衡造成了上升管内轴向浓度分布的Ｓ型曲线。

锯末对Pb^(2+)的吸附性能研究

采用廉价工业废弃物——锯末为吸附剂,研究其对水溶液中Pb2+的吸附特性。结果表明锯末对Pb2+的吸附速度较快,2 h内基本达到平衡。模拟二级速率方程很好地拟合了吸附反应的动力学方程(R2>0.99)。锯末对铅吸附的主要机制是离子交换,吸附量随pH升高而升高。离子强度对吸附反应有一定影响。Langmuir模型对锯末的吸附等温线拟合最好。热力学分析显示吸附反应具有自发,放热和熵增特性。

酸化凹凸棒石的制备及其对苯胺的吸附性能

以天然凹凸棒石为原料,利用不同浓度的盐酸对其进行酸活化改性。对改性后的酸化凹凸棒石进行XRD,SEM,BET,FTIR以及ZATA电位的表征,并以苯胺为模拟污染物,考察不同浓度的盐酸,以及吸附工艺条件对其吸附性能的影响。研究表明,当盐酸的活化浓度为6mol·L^(-1),苯胺溶液的pH为6,苯胺初始质量浓度为50mg·L^(-1),吸附剂投料量为0.5g,温度为30℃,吸附时间为240min时,酸化凹凸棒石具有较高的吸附活性,可吸附脱除75.2%以上的苯胺。此外,苯胺在酸化凹凸棒石上的吸附行为符合假二级动力学模型。

用海绵铁处理某矿山弱碱性含铀废水的试验研究

以海绵铁为水处理材料对含铀废水中的铀进行去除研究。考察了接触反应时间、废水pH、废水中铀初始浓度、海绵铁粒径、反应温度等因素对溶液中铀去除率的影响。结果表明:在pH为3~5时,海绵铁的粒径越小,对铀的去除率越高;铀和海绵铁的反应较迅速,随着反应时间的延长,溶液铀浓度逐渐降低,60 min基本反应完全;不同温度下的海绵铁除铀反应基本遵循准一级反应动力学规律。