颗粒化坡缕石表征及对Pb~(2+)的吸附特性

坡缕石黏土进行简单提纯后,和海藻酸钠、纯水充分混合(物料比为坡缕石∶海藻酸钠∶水=100 g∶9 g∶77 m L),并在潮湿密闭环境下浸润24 h,制成粒径5 mm颗粒。(105±2)℃干燥后,焙烧2 h,制备颗粒状坡缕石吸附剂,采用XRD、BET进行表征,通过静态吸附实验探讨了pH值、Pb⁽²⁺⁾初始浓度、反应时间和反应温度对吸附的影响,确立了颗粒化吸附剂对Pb(2+)初始浓度、反应时间和反应温度对吸附的影响,确立了颗粒化吸附剂对Pb⁽²⁺⁾的吸附动力学和吸附等温线。结果表明,在颗粒化后,坡缕石黏土主要XRD衍射峰得以保留;600℃下烧结,使比表面积降低,而孔容积增大。随着pH值增大,坡缕石颗粒吸附剂对Pb(2+)的吸附动力学和吸附等温线。结果表明,在颗粒化后,坡缕石黏土主要XRD衍射峰得以保留;600℃下烧结,使比表面积降低,而孔容积增大。随着pH值增大,坡缕石颗粒吸附剂对Pb⁽²⁺⁾的吸附量增加;随着初始浓度的增加,颗粒吸附剂对Pb(2+)的吸附量增加;随着初始浓度的增加,颗粒吸附剂对Pb⁽²⁺⁾的吸附去除率逐渐降低,平衡吸附量则逐渐上升。当pH值为5.0,Pb(2+)的吸附去除率逐渐降低,平衡吸附量则逐渐上升。当pH值为5.0,Pb⁽²⁺⁾初始浓度2 500 mg/L时,平衡吸附量达59.85 mg/g。吸附动力学符合颗粒内扩散模型。颗粒化坡缕石吸附剂对Pb(2+)初始浓度2 500 mg/L时,平衡吸附量达59.85 mg/g。吸附动力学符合颗粒内扩散模型。颗粒化坡缕石吸附剂对Pb⁽²⁺⁾的吸附符合Langmuir吸附等温式,属于吸热反应。     

蛇纹石-粘土复合颗粒吸附地下水中氟离子实验研究

为高效解决含氟地下水污染问题,采用室内静态实验方法,利用粘结挤压法制备的新型吸附剂蛇纹石-粘土复合颗粒对含氟地下水进行吸附实验研究,分析了在不同投加量、反应时间、振荡速度、pH值、温度、初始氟离子浓度条件下蛇纹石-粘土复合颗粒的除氟性能,并探究了除氟机理.实验结果表明,处理200 mL、5 mg/L的含氟地下水,蛇纹石-粘土复合颗粒投加量500 mg、反应时间120 min、振荡速度120 r/min、pH值6.5～7.0、温度30℃时效果最佳,氟离子去除率达94.32％;去除率随原水氟离子浓度的增大而逐渐减小.吸附动力学拟合结果表明,蛇纹石-粘土复合颗粒吸附剂对氟离子的吸附作用符合准二级动力学方程,吸附等温线符合Freundlich等温吸附模型;应用2.0 mol/L的明矾对蛇纹石-粘土复合颗粒浸渍12 h进行再生效果较好,再生率为78.93％.     

颗粒化坡缕石表征及对Pb~(2+)的吸附特性

坡缕石黏土进行简单提纯后,和海藻酸钠、纯水充分混合(物料比为坡缕石∶海藻酸钠∶水=100 g∶9 g∶77 m L),并在潮湿密闭环境下浸润24 h,制成粒径5 mm颗粒。(105±2)℃干燥后,焙烧2 h,制备颗粒状坡缕石吸附剂,采用XRD、BET进行表征,通过静态吸附实验探讨了pH值、Pb~(2+)初始浓度、反应时间和反应温度对吸附的影响,确立了颗粒化吸附剂对Pb~(2+)的吸附动力学和吸附等温线。结果表明,在颗粒化后,坡缕石黏土主要XRD衍射峰得以保留;600℃下烧结,使比表面积降低,而孔容积增大。随着pH值增大,坡缕石颗粒吸附剂对Pb~(2+)的吸附量增加;随着初始浓度的增加,颗粒吸附剂对Pb~(2+)的吸附去除率逐渐降低,平衡吸附量则逐渐上升。当pH值为5.0,Pb~(2+)初始浓度2 500 mg/L时,平衡吸附量达59.85 mg/g。吸附动力学符合颗粒内扩散模型。颗粒化坡缕石吸附剂对Pb~(2+)的吸附符合Langmuir吸附等温式,属于吸热反应。     

水化氯铝酸钙去除水中氟及其动力学研究

采用聚合氯化铝和电石渣合成水化氯铝酸钙,用于处理低浓度的含氟水。探讨了吸附时间、溶液初始pH值、吸附剂加入量、初始氟离子浓度及竞争阴离子等因素对氟离子吸附效果的影响。研究表明,100 mL初始氟离子浓度为27.25 mg/L的溶液中加入水化氯铝酸钙1.5 g/L、pH=3,在常温条件下水浴振荡(160 r/min)吸附90 min,其处理后浓度可满足国家《无机化学工业污染物排放标准》(GB 31573—2015)6 mg/L的直接排放标准。水化氯铝酸钙对氟的吸附过程符合准二级动力学模型,并且颗粒内扩散模型表明,水化氯铝酸钙吸附氟离子是一个以化学吸附为主的复杂过程。     

静电纺壳聚糖/PVA纳米纤维膜对甲基橙的吸附特性

以静电纺丝制备的壳聚糖(CS)/聚乙烯醇(PVA)纳米纤维膜为吸附剂,研究了反应时间、甲基橙初始质量浓度、膜吸附剂用量和pH值对吸附甲基橙染料的影响,并通过吸附动力学行为和吸附等温线研究了其吸附机制。结果表明:当pH值在5～9之间、甲基橙初始质量浓度为100 mg/L、吸附剂用量为30 mg、反应时间为60～120 min之间时,吸附效果最佳且吸附平衡时间为3 h;CS/PVA膜对甲基橙的吸附既有物理吸附也有化学吸附,化学吸附占主导作用,CS/PVA膜对甲基橙的吸附符合Langmuir等温线和拟二级动力学模型。     

蟹壳生物吸附剂对水中镍离子的吸附研究

采用颗粒状蟹壳(0.25～0.80mm)对水中Ni2 的去除进行了静态吸附试验.考察了搅拌强度、吸附剂投加量、溶液初始pH值以及Zn2 或Cu2 的存在对Ni2 吸附效果的影响.试验结果表明,为保证Ni2 的去除率,搅拌强度应不小于350r/min,溶液初始pH值宜控制在4～7;Cu2 的存在对Ni2 的吸附有较大影响.经过5级静态吸附后,Ni"的吸附量达到43.4mg/g.蟹壳对Ni2 的吸附符合Freundtich吸附等温模型.     

柠檬酸改性白酒糟对Cu、Cd、Cr和Pb的吸附特性研究

以柠檬酸改性白酒糟为吸附剂,考察了pH值、吸附剂投加量、反应时间、吸附质初始浓度等对水中Cu、Cd、Cr和Pb吸附性能的影响,探究了改性白酒糟的等温吸附及吸附动力学特性。结果表明,相对最优的实验条件为pH=4,吸附剂投加量4 g/L,反应时间3 h,吸附质初始浓度60 mg/L;改性白酒糟对Cu、Pb、Cd、Cr的吸附过程更符合准二级动力学方程和Langmuir等温线方程,计算得到理论最大吸附量为Cu 11.19 mg/g, Cd 7.49 mg/g, Cr 5.63 mg/g, Pb 9.36 mg/g。     

羧甲基化壳聚糖修饰磁性硅粒子去除Cr(Ⅵ)离子

先通过硅酸钠水解在磁性Fe3O4纳米粒子表面包覆二氧化硅,制得磁性硅粒子(Fe3O4@SiO2);然后再通过碳二亚胺活化接枝法在Fe3O4@SiO2纳米粒子表面接枝高脱乙酰度羧甲基化壳聚糖(CMC),制备了一种新型磁性纳米吸附剂(Fe3O4@SiO2@CMC)。通过透射电镜(TEM)、红外光谱(IR)、X射线衍射(XRD)以及振动样品磁强计(VSM)对其进行了表征,着重研究了其对水中Cr(Ⅵ)离子的吸附性能。结果表明:溶液的pH值能显著影响吸附剂对Cr(Ⅵ)离子的吸附效果,pH值为2时效果最佳。结合相应pH值下Cr(Ⅵ)的形态分布,探讨了这种新型材料对Cr(Ⅵ)的吸附机理。结果表明:其吸附机理及吸附容量与Cr(Ⅵ)的离子形式有关,吸附过程以离子交换与静电引力为主。吸附平衡数据分别采用了Langmuir和Freundlich方程进行拟合。结果表明,等温吸附数据更符合Langmuir模型,T=298 K、pH=2、V=5 mL时,吸附剂的饱和吸附容量qm=86.96 mg/g,吸附常数为0.0174 L/mg。     

固载化纳米MnO2对砷的吸附性能研究

解决纳米MnO2在水处理后难分离回收的问题,以交联壳聚糖(CCTS)固载纳米MnO2,制备了纳米复合材料膜,考察其对水中砷的吸附性能,研究了溶液初始pH、吸附剂的用量、温度、初始质量浓度对砷吸附效果的影响。结果表明,在最优条件下,该膜对初始质量浓度小于4 mg/L的砷去除率达到98.88%以上。吸附等温线符合Freundlich模型,吸附动力学符合准二级动力学方程,考虑吸附过程为多分子层的吸附,既有物理吸附也有化学吸附。     

改性介孔微孔分子筛去除水中亚甲基蓝的研究

以壳聚糖包覆介孔-微孔复合分子筛(CS/MCM-41-A)为吸附剂去除水中的亚甲基蓝,研究了反应时间、溶液pH、溶液亚甲基蓝初始浓度、CS/MCM-41-A投加量、竞争离子对吸附的影响,分析了CS/MCM-41-A的吸附动力学和热力学特征。结果表明,25℃下,当CS/MCM-41-A投加量为0.3 g/L,溶液亚甲基蓝初始浓度100 mg/L,pH为6,吸附时间为40 min时,溶液中亚甲基蓝的去除率达到92.57%。CS/MCM-41-A吸附亚甲基蓝符合拟二级动力学方程,吸附等温线更好地符合Langmuir方程,CS/MCM-41-A对亚甲基蓝的有良好的吸附性能。     

Granulation of Fe-Al-Ce nano-adsorbent for fluoride removal from drinking water by spray coating on sand in a fluidized bed

A technology for the granulation of Fe-Al-Ce nano-adsorbent (Fe-Al-Ce) in a fluidized bed was developed. The coating reagent, a mixture of Fe-Al-Ce and a polymer latex, was sprayed onto sand in a fluidized bed. The granule morphology, coating layer thickness, granule stability in water and adsorption capacity for fluoride was investigated by analyzing samples for different coating time. The coating amount was from 3% to 36%. With increasing coating amount, granule stability decreased and adsorption capacity increased. FTIR analysis showed that the latex can react with active hydroxyl on the Fe-Al-Ce adsorbent, which led to a decrease of the adsorption capacity. Coated granules with a coating amount of 27.5% had a fluoride adsorption capacity of 2.22 mg/g (coated granules) at pH 7 and initial fluoride concentration of 0.001 M. A column test showed that 300 bed volumes can be treated with the effluent under 1.0 mg/L at an initial fluoride concentration of 5.5 mg/L, space velocity of 5 h^− 1 and pH of 5.8. The coating granulation of the Fe-Al-Ce adsorbent can produce granules that can be used in a packed bed for the removal of fluoride from drinking water.     

Nano Calcium-Aluminum Mixed Oxide: A Novel and Effective Material for Defluoridation of Drinking Water

In the present study nano calcium-aluminum mixed oxide material (NCAMO) was synthesized by solution combustion method in 1:1, 1:2, 4:1, 3:2 molar ratios of calcium and aluminum nitrates as oxidizers and urea as fuel for an efficient adsorption of fluoride from drinking water. Molar composition of 1:1 ratio was found to exhibit better adsorption properties and the same was characterized by XRD, FESEM, and FTIR. The optimized conditions for maximum adsorption capacity were achieved at pH4 with contact time of 4 hours by adding 1 g/L of NCAMO to initial fluoride concentration of 8 mg/L. The sorption of fluoride on NCAMO followed Langmuir isotherm model strongly suggested monolayer adsorption. The calculated equilibrium adsorption capacity 23.7 mg/g of NCAMO strongly suggests the dominance of monolayer adsorption process. The adsorption kinetics was well described by pseudo-second order equation confirming chemisorption.     

Optimization of a Fe-Al-Ce nano-adsorbent granulation process that used spray coating in a fluidized bed for fluoride removal from drinking water

A coating granulation technology comprising the spraying of a Fe-Al-Ce nano-adsorbent suspension onto glass beads in a fluidized bed was developed. An acrylic-styrene copolymer latex was used as a binder. The granulated adsorbent was used in a packed bed for fluoride removal from drinking water. The effects of coating temperature, latex/Fe-Al-Ce ratio, and coating amount on granule compressive strength and adsorption capacity were investigated. With increased coating temperature, cross linking in the polymer in the coated layer increased, which resulted in increased granule strength but decreased adsorption capacity. With increased latex/Fe-Al-Ce ratio, more active sites were covered by the polymer, which also resulted in increased granule strength but decreased adsorption capacity. The optimal parameters for making high performance adsorbent granules were for the granules to be coated at 65 °C using a latex/Fe-Al-Ce ratio of 0.5:1 and a coating amount of 27.8%. These granules had a fluoride adsorption capacity of 2.77 mg/g (coated granules) for water with an initial fluoride concentration of 0.001 M that was treated at pH 7.     

Equilibrium and Kinetic Studies for Fluoride Adsorption from Water on Zirconium Impregnated Coconut Shell Carbon

Abstract

The batch adsorptive fluoride removal from water by Zirconium ion impregnated coconut shell carbon (ZICSC) was investigated. ZICSC was found to have fluoride adsorption capacity, 25 to 30 times that of plain activated carbon. The effect of various parameters such as pH, agitation time, and adsorbent dosage on fluoride removal were studied. The fluoride adsorption by ZICSC was above 90% for the entire pH range of 2–9 and the adsorption rate was extremely rapid, with 91% of the adsorption being achieved within 10 min of ZICSC contact for an initial fluoride concentration of 10 mg/L. The experimental data have been analyzed by Langmuir, Freundlich, Redlich‐Peterson, and Temkin sorption isotherm models and the adsorption data for fluoride onto ZICSC were better correlated to the Langmuir isotherm. The batch adsorption kinetics have been tested by first order, pseudo‐first order, and pseudo‐second order kinetic models with the subsequent determination of the rate constants of adsorption. The comparison of ZICSC with other adsorbents suggests that ZICSC provides a cost‐effective working solution to the defluoridation problem in the developing countries by its great potential application in fluoride removal from water.     

磁性氧化石墨烯对水溶液中铀（VI）的吸附性能研究

采用FeCl3作为磁流体制备磁性氧化石墨烯.考察了溶液pH值、溶液初始浓度、吸附温度和吸附时间对磁性氧化石墨烯吸附铀（Ⅵ）性能的影响,并探讨了吸附热力学、等温吸附性能和动力学.结果表明：磁性氧化石墨烯吸附铀（Ⅵ）的最佳pH值为7.0,吸附平衡时间为180min,298K时饱和吸附容量为113.27 mg/g.吸附行为符合Langmuir等温吸附模型和准二级吸附动力学模型,即表明吸附主要是受化学作用控制.     

Adsorption of fluoride from aqueous solution by magnesia‐amended silicon dioxide granules

BACKGROUND: A new kind of adsorbent, magnesia‐amended silicon dioxide granules (MAS), has been prepared by wet impregnation of silicon dioxide with magnesium chloride solution. The physicochemical properties were characterized using X‐ray diffraction (XRD), Fourier transform infrared (FT‐IR) and Brunauer, Emmett, Teller (BET) studies. The porous structure and high surface area of these granules make them suitable for sorption. The aim of this study was to show the possibility of defluoridation of water using MAS and to demonstrate the advantage of its use compared with silicon dioxide. RESULTS: XRD and FT‐IR analysis showed that amorphous magnesia was loaded on silicon dioxide after treating with magnesium chloride solution and calcining at 500 °C. Batch sorption experiments indicated that MAS is more effective than silicon dioxide for fluoride adsorption. The sorption capacities of MAS decreased as the solution pH rose. At pH 3, the maximum defluoridation capacity of MAS was 12.6 mg g^?1. The adsorption process fitted the Dubinin–Radushkevich isotherm and kinetic studies revealed that the adsorption followed second‐order rate kinetics. CONCLUSION: The results indicate that it is feasible to modify both the physical and chemical properties of silicon dioxide with magnesia so that it can be used as a potential adsorbent to adsorb fluoride from aqueous solution. Copyright © 2009 Society of Chemical Industry     

Removal of Fluoride from Aqueous Solution by CaO Nanoparticles

Abstract

Colloidal particles of CaO were synthesized by the sol-gel method. The particle morphology was characterized by FT-IR, TGA, DTA, and TEM analysis. The ability of the CaO nanoparticles for removal of fluoride from aqueous solution through adsorption has been investigated. All the experiments were carried out by batch mode. The effect of various parameters viz. contact time, pH effect (pH 2–10), adsorbent dose (0.01–0.1 g/100 ml), initial fluoride concentration (10–100 mg/l) and competitive ions has been investigated to determine the adsorption capacity of CaO nanoparticles. Almost complete removal (98%) of fluoride was obtained within 30 minutes at an optimum adsorbent dose of 0.6 g/L for initial fluoride concentration of 100 mg/L. The adsorption isotherm was also studied to find the nature of adsorbate-adsorbent interaction.     

铁-镧复合氧化物颗粒吸附剂除氟性能研究

对制备的铁-镧复合氧化物颗粒吸附剂进行了除氟性能评价,结果显示该吸附剂最大吸附量为12.1 mg/g,24 h内达到吸附平衡,吸附速率遵从拟一级反应,其吸附等温线符合Langmuir吸附模型,最佳吸附pH是5～7.主要干扰离子影响顺序为HCO_3~->HPO_4~(2-)>SO_4~(2-)>NO_3~->Cl~-.该吸附剂与颗粒活性氧化铝进行了连续吸附对比实验,结果显示前者的穿透时间大大高于后者,前者动态吸附量为后者的3倍.     

柠檬皮渣对亚甲基蓝吸附性能研究

采用柠檬皮渣作为吸附剂对水溶液中亚甲基蓝进行吸附研究,考察了柠檬皮渣用量、溶液pH值、吸附时间、亚甲基蓝浓度、温度对吸附量的影响。结果表明:当柠檬皮渣用量为1 g/L,亚甲基蓝的初始质量浓度为100 mg/L,pH值为7,温度为30℃时,柠檬皮渣对亚甲基蓝吸附效果最好,吸附量为36.2 mg/g,吸附过程符合Langmuir等温吸附模型,吸附动力学遵从准二级动力学方程,热力学参数计算结果表明此吸附过程为自发的放热过程。     

Adsorption behavior of fluoride ions using a titanium hydroxide-derived adsorbent

The removal behavior of fluoride ions was examined in aqueous sodium fluoride solutions using a titanium hydroxide-derived adsorbent. The adsorbent was prepared from titanium oxysulfate (TiOSO₄·xH₂O) solution, and was characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry-differential thermal analysis, Fourier transform infrared spectrum and specific surface area. Batchwise adsorption test of prepared adsorbent was carried out in aqueous sodium fluoride solutions and real wastewater containing fluoride ion. The absorbent was the amorphous material, which had different morphology to the raw material, titanium oxysulfate, and the specific surface area of the adsorbent (96.8 m²/g) was 200 times higher than that of raw material (0.5 m²/g). Adsorption of fluoride on the adsorbent was saturated within 30 min in the solution with 200 mg/L of fluoride ions, together with increasing pH of the solution, due to ion exchange between fluoride ions in the solution and hydroxide ions in the adsorbent. Fluoride ions were adsorbed even in at a low fluoride concentration of 5 mg/L; and were selectively adsorbed in the solution containing a high concentration of chloride, nitrate and sulfate ions. The adsorbent can remove fluoride below permitted level (< 0.8 mg/L) from real wastewaters containing various substances. The maximum adsorption of fluoride on the adsorbent could be obtained in the solution at about pH 3. After fluoride adsorption, fluoride ions were easily desorbed using a high pH solution, completely regenerating for further removal process at acidic pH. The capacity for fluoride ion adsorption was almost unchanged three times after repeat adsorption and desorption. The equilibrium adsorption capacity of the adsorbent used for fluoride ion at pH 3 was measured, extrapolated using Langmuir and Freundlich isotherm models, and experimental data are found to fit Freundlich than Langmuir. The prepared adsorbent is expected to be a new inorganic ion exchanger for the removal and recovery of fluoride ions from wastewater.