氧化镁/聚醚砜复合膜吸附材料的制备与除氟性能研究

以活性氧化镁和聚醚砜(PES)为原料,采用共混法制备了氧化镁/聚醚砜复合膜吸附材料;用扫描式电子显微镜(SEM)和ASAP2020型比表面及孔径分析仪进行了表征,并研究了复合膜对氟离子的吸附性能。SEM结果表明,氧化镁颗粒在聚合物膜中均匀镶嵌分布,提高了膜的孔隙率。比表面积与孔径分析表明复合膜的比表面积约为颗粒氧化镁的1/3。复合膜对水中氟离子的吸附在60min后基本达到平衡;30cm2的复合膜(厚度为200μm)可以处理50mL氟离子溶液(质量浓度为5mg/L),使其符合饮用水含氟标准(<1mg/L);吸附量随初始浓度的增加而增加,吸附符合Freundlich等温式,无最大饱和吸附量;吸附氟离子的复合膜可以脱附再生,且再生后仍具有较高的吸附容量。     

聚吡咯/壳聚糖复合膜的制备及其对Cu(Ⅱ)和Cr(Ⅵ)吸附机制

以聚吡咯(PPy)和壳聚糖(CS)为原料,制备PPy/CS复合膜,通过红外、孔径分析、热分析和SEM等手段对其结构进行表征,并研究了PPy/CS复合膜对Cu(Ⅱ)和Cr(Ⅵ)吸附性能的影响及吸附机制,考察了pH值、吸附时间、溶液起始浓度等因素对吸附率的影响.结果表明,初始浓度对吸附率影响最大;在pH=3.5、温度为33...     

羟乙基纤维素/海藻酸钠复合膜对六价铀的吸附性能及吸附机制

将羟乙基纤维素(HEC)与海藻酸钠(SA)进行混合,利用戊二醛交联处理后制备了HEC/SA高分子复合多孔薄膜,并探讨了其对模拟含铀废水中的六价铀(U(Ⅵ))的吸附特性。通过静态实验,探讨了初始pH值、U(Ⅵ)初始浓度、温度和吸附时间等对HEC/SA复合膜吸附U(Ⅵ)效果的影响;对吸附过程进行了热力学与动力学分析,利用FTIR、SEM和X射线能谱等手段分析了其吸附机制。实验结果表明,U(Ⅵ)的吸附量与温度正相关,吸附平衡时间约为90min,最佳吸附效果的初始pH值为5.0;吸附过程符合准二级动力学模型,主要表现为颗粒内部扩散;等温吸附过程符合Langmuir等温吸附线模型,在45℃时,HEC/SA复合膜对U(Ⅵ)的最大吸附容量达357.1mg·g-1,HEC/SA复合膜对U(Ⅵ)的吸附存在离子交换作用,与U(Ⅵ)的相互作用基团为羧基。     

树脂/聚醚砜复合膜的制备及其对碘离子的吸附性能

以聚醚砜(PES)为膜的基质材料,以粉末状阴离子交换树脂(201×7)为功能颗粒,采用相转化的方法制备了阴离子交换树脂/聚醚砜复合膜。用扫描电子显微镜(SEM)对膜形貌进行表征,采用电子拉伸试验机测定了复合膜的力学性能,采用傅里叶红外光谱(FTIR)对膜吸附机理进行了研究。SEM结果表明,树脂颗粒在聚合物膜中均匀镶嵌分布,树脂的添加提高了膜的孔隙率,且树脂含量越大孔径越大,复合膜的机械拉伸强度随树脂含量的增加而略有降低。选用树脂含量为60%(w/w)的复合膜进行吸附性能研究,结果表明,吸附可在120min内达到平衡,该吸附膜在pH值为3~9范围内对碘离子有很好的吸附去除效果;吸附量随初始浓度增加而增加,吸附符合Freundlich模型,无饱和吸附量,说明多层吸附在吸附过程中发挥重要作用。共存阴离子如硫酸根、氯离子、硝酸根离子的存在会降低碘离子吸附量。FTIR结果表明,复合膜对碘离子的吸附主要是物理吸附。吸附碘离子的复合膜可以脱附再生,且多次再生后,吸附量未见降低。     

高疏水氟化SiO2/聚醚砜复合膜的制备与表征

以正硅酸乙酯（TEOS）和全氟癸基三乙氧基硅烷（PFDTES）为混合Si源,以聚醚砜（PES）为基膜材料,通过真空过滤和热处理工艺制备单侧高疏水氟化SiO₂/PES（fSiO₂/PES）复合膜。通过ATR-FTIR、XPS、TEM和FESEM等对单侧高疏水fSiO₂/PES复合膜进行表征,考察PFDTES修饰量和热处理条件对膜疏水性能的影响,并评价fSiO₂/PES复合膜的疏水稳定性能。结果表明,当PFDTES:TEOS的质量比为3时,高疏水fSiO₂/PES复合膜的疏水性能较好（接触角为131.5°）;当热处理温度为100℃,热处理时间为4 h时,高疏水fSiO₂/PES复合膜表面的接触角为138.9°,且其对不同pH值的溶液都有良好的疏水性能。      

聚乙二醇对明胶/壳聚糖复合膜性能的影响

采用流延成型法制备了不同用量聚乙二醇200(PEG200)和聚乙二醇800(PEG800)增塑的明胶/壳聚糖复合膜,研究了PEG对明胶/壳聚糖复合膜吸湿性能、透水汽性和拉伸性能的影响,用X射线衍射(XRD)法分析了复合膜的结晶行为。结果表明,PEG的种类和用量会影响明胶/壳聚糖复合膜的结构和性能。在水活度较低时,PEG会降低复合膜的初始吸湿速率和吸湿能力;水活度较高时,PEG会提高复合膜的初始吸湿速率和吸湿能力。PEG能降低明胶/壳聚糖复合膜的单分子层吸附值和拉伸强度,增大复合膜的透水汽性、断裂伸长率及结晶度。     

氧化石墨烯/海藻酸钙水凝胶复合膜对水中Cd(II)的吸附

将氧化石墨烯(GO)、致孔剂与海藻酸钠共混后与CaCl₂交联制备的GO/海藻酸钙（CA）水凝胶复合膜作为含重金属废水的吸附材料。采用SEM和TEM表征了复合膜的表面形貌及透射性能,且分析了GO的加入对复合膜的力学性能、平均孔径、水通量及表面官能团的影响。为探究GO/CA水凝胶复合膜的吸附性能,考察了其吸附Cd(II)的影响因素:pH（6~7）值、初始离子浓度、接触时间、温度（三者均正相关）。用FTIR、XPS在吸附前后对复合膜进行了表征;引入了吸附动力学和等温线模型分析其吸附机制。探究结果表明GO的加入提高了复合膜的力学性能、平均孔径及水通量;吸附过程遵循Langmuir等温线,属于单层吸附,拟合得到的最大吸附量为173.61 mg/g;伪一级和伪二级吸附动力学分别在低浓度和高浓度时能较好地描述吸附过程的动力学行为;吸附机制主要为物理作用力吸附和离子交换。经过5个连续的吸附-解吸循环证明了GO/CA水凝胶复合膜的可重复利用性。      

氧化石墨烯/海藻酸钠复合膜对Pb(Ⅱ)的吸附性能和机制

海藻酸钠（SA）基的过滤膜是处理含Pb（Ⅱ）废水的理想膜分离材料,将氧化石墨烯（GO）和尿素添加进SA中,以CaCl₂溶液交联,制备出GO/SA复合膜,并考察了其对水溶液中Pb（Ⅱ）的吸附性能。通过静态吸附实验,探讨了Pb（Ⅱ）初始浓度、GO质量分数、初始pH值和吸附时间、吸附-解吸次数等对GO/SA复合膜吸附Pb（Ⅱ）效果的影响;对吸附过程进行了吸附动力学和吸附热力学分析,利用FTIR-ATR、XPS等对GO/SA复合膜吸附Pb（Ⅱ）的机制进行了解析。结果表明,GO/SA复合膜对Pb（Ⅱ）的吸附量与Pb（Ⅱ）初始浓度正相关,在pH=5时吸附效果最优,GO质量分数为0.3wt%时为最优配比;吸附过程符合伪二级动力学模型;热力学等温吸附过程符合Langmuir等温吸附模型,温度为318 K时,Langmuir模型拟合得到的GO/SA复合膜吸附量达到320.51 mg·g-1。GO/SA复合膜对Pb（Ⅱ）的吸附机制主要为物理吸附。      

高交联温度下聚二甲基硅氧烷/聚醚砜渗透汽化复合膜的制备及性能研究

以聚醚砜(PES)平板多孔膜为支撑层,聚二甲基硅氧烷(PDMS)膜为分离层,在高温交联条件下制备了PDMS/PES渗透汽化复合膜。用扫描电镜对复合膜形貌进行了表征,复合膜表面平整、致密,分离层与支撑层外表面结合紧密。研究了PDMS质量分数对膜产生最高衍射峰时对应的2θ值、水与乙醇的接触角以及以10%(质量分数)乙醇水溶液为料液,30℃下复合膜渗透汽化分离性能的影响。结果表明:随着PDMS含量的增加,产生最高衍射峰时对应的2θ值先增大后减小。当PDMS含量为15%(wt,质量分数,下同)时,PDMS/PES复合膜有良好的疏水性和亲醇性,PDMS/PES复合膜的分离因子最大,最大值为4.60,对应的渗透通量为10325.54g/(m~2·h),分离指数出现最大值为47483.02。因此,15%PDMS条件下制备的PDMS/PES复合膜综合性能最好。     

PDMS-AMEO膜用于渗透汽化分离乙酸/水体系的性能研究

采用原位聚合法制备了氨丙基三甲氧基硅氧烷交联聚二甲基硅氧烷( PDMS- AMEO)/有机蒙脱土(OM-MT)/聚醚砜(PES)复合膜,采用SEM和TGA对PDMS-AMEO/OMMT/PES的形貌、热学性能进行了研究.考察了复合膜在乙酸-水溶液中的溶胀性,以及OMMT含量、料液温度和浓度对膜渗透汽化性能的影响.     

Fluoride removal on Fe–Al-impregnated granular ceramic adsorbent from aqueous solution

A novel Fe–Al-impregnated granular ceramic adsorbent has been developed for fluoride removal from aqueous solution. Batch experiments were performed to investigate the effect of contact time, initial pH, adsorbent dose, and the presence of competing anions on the adsorption of fluoride. More than 96 % removal of fluoride was achieved within 48 h from 10 mg/L initial fluoride solution at neutral pH. The adsorption process was well explained with pseudo-second-order and pore diffusion models. The maximum adsorption capacity of adsorbent for fluoride removal was 3.56 mg/g according to the Langmuir isotherm model. The optimum fluoride removal efficiency was observed between pH ranged of 4.0–9.0. The fluoride removal efficiency was significantly decreased in the presence of carbonate and phosphate anions. Results from this study demonstrated potential utility of Fe–Al-impregnated granular ceramic adsorbent that could be developed into a viable method for fluoride removal from aqueous solution.     

Removal of excess fluoride from water using waste residue from alum manufacturing process

The ability of waste residue, generated from alum manufacturing process, to remove fluoride ion from water has been investigated. Series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The factors investigated include the effect of contact time, adsorbent dose, thermal pretreatment of the adsorbent, neutralization of the adsorbent, initial fluoride concentration, pH of the solution and effect of co-existing anions. Results showed that Adsorption of fluoride is fairly rapid in first 5min and thereafter increases slowly to reach the equilibrium in about 1h. The removal efficiency of fluoride was increased with adsorbent dosage. About 85% removal efficiency was obtained within 1h at an optimum adsorbent dose of 16g/L for initial fluoride concentration of 10mg/L. Heat treatment and surface neutralization of the adsorbent did not improve the fluoride removal capacity and efficiency. The amount of fluoride adsorbed increased with increasing initial fluoride concentration. The percentage of fluoride removal remains nearly constant within the pH range of 3-8. The adsorption data at ambient pH were well fitted to the Dubinin-Radushkevick (D-R) isotherm model with a capacity of 332.5mg/g of the adsorbent. The adsorption kinetic was found to follow a pseudo-second-order rate equation with an average rate constant of 2.25gmin(-1)mg(-1). The presence of bicarbonate at higher concentrations (100-500mg/L) decreased the fluoride removal efficiency while other anions (chloride, sulfate, phosphate and nitrate) have no significant effect within the concentration range tested. The overall result shows that the waste residue is efficient defluoridating material.     

Preparation and characterization of porous granular ceramic containing dispersed aluminum and iron oxides as adsorbents for fluoride removal from aqueous solution

Porous granular ceramic adsorbents containing dispersed aluminum and iron oxides were synthesized by impregnating with salt solutions followed by precipitation at 600°C. In the present work detailed studies were carried out to investigate the effect of contact time, adsorbent dose, initial solution pH and co-existing anions. Characterization studies on the adsorbent by SEM, XRD, EDS, and BET analysis were carried out to clarify the adsorption mechanism. The adsorbents were sphere in shape, 2-3mm in particle size, highly porous and showed specific surface area of 50.69 sq m/g. The fluoride adsorption capacity of prepared adsorbent was 1.79 mg/g, and the maximum fluoride removal was obtained at pH 6. Both the Langmuir and Freundlich isotherm models were found to represent the measured adsorption data well. The experimental data were well explained with pseudo-second-order kinetic model. Results from this study demonstrated potential utility of Al/Fe dispersed in porous granular ceramics that could be developed into a viable technology for fluoride removal from aqueous solution.     

Removal of fluoride from aqueous solution by polypyrrole/Fe3O4 magnetic nanocomposite

Polypyrrole (PPy)/Fe₃O₄ magnetic nanocomposite as a novel adsorbent was prepared via in-situ polymerization of pyrrole (Py) monomer using FeCl₃ oxidant in aqueous medium in which Fe₃O₄ nanoparticles were suspended. The adsorbent was characterized by Attenuated Total Reflectance Fourier transform infrared spectroscope (ATR-FTIR), Brunauer–Emmet–Teller (BET) method, field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscope (HR-TEM), X-ray photoelectron spectroscope (XPS) and X-ray diffraction (XRD). Magnetic property of the adsorbent was measured by electron spin resonance (ESR). Subsequently, the ability of the adsorbent to remove fluoride ions from aqueous solution was demonstrated in a batch sorption mode. Results reveal that the adsorption is rapid and that the adsorbent has high affinity for fluoride, which depends on temperature, solution pH and adsorbent dose. From equilibrium modelling, the equilibrium data is well described by Freundlich and Langmuir–Freundlich isotherms while the adsorption kinetics is described by the pseudo-second-order model. Thermodynamic parameters confirm the spontaneity and endothermic nature of the fluoride adsorption. Meanwhile, the fluoride adsorption proceeds by an ion exchange mechanism.     

Study the adsorption of phenol from aqueous solution on hydroxyapatite nanopowders

In this study, the hydroxyapatite (HAp) nanopowders prepared by chemical precipitation method were used as the adsorbent, and the potential of HAp nanopowders for phenol adsorption from aqueous solution was studied. The effect of contact time, initial phenol concentration, pH, adsorbent dosage, solution temperature and adsorbent calcining temperature on the phenol adsorption, and the adsorption kinetic, equilibrium and thermodynamic parameters were investigated. The results showed that the HAp nanopowders possessed good adsorption ability to phenol. The adsorption process was fast, and it reached equilibrium in 2h of contact. The initial phenol concentration, pH and the adsorbent calcining temperature played obvious effects on the phenol adsorption capacity onto HAp nanopowders. Increase in the initial phenol concentration could effectively increase the phenol adsorption capacity. At the same time, increase in the pH to high-acidity or to high-alkalinity also resulted in the increase in the phenol adsorption capacity. Increase in the HAp dosage could effectively increase the phenol adsorption percent. However, the higher calcining temperature of HAp nanopowders could obviously decrease the adsorption capacity. The maximum phenol adsorption capacity was obtained as 10.33mg/g for 400mg/L initial phenol concentrations at pH 6.4 and 60 degrees C. The adsorption kinetic and the isotherm studies showed that the pseudo-second-order model and the Freundlich isotherm were the best choices to describe the adsorption behaviors. The thermodynamic parameters suggested that the adsorption of phenol onto HAp was physisorption, spontaneous and endothermic in nature.     

Removal of fluoride ions from aqueous solution at low pH using schwertmannite

Wastewater containing fluoride requires polishing after precipitation/coagulation treatment in order to meet stringent environmental legislation. Accordingly, adsorption characteristics of fluoride onto schwertmannite adsorbent were studied in a batch system with respect to changes in initial concentration of fluoride, equilibrium pH of sample solution, adsorbent dosage and co-existing ions. Equilibrium adsorption data were obtained at 295.6, 303 and 313 K, and are interpreted in terms of two-site Langmuir, Freundlich, Langmuir-Freundlich, Redlich-Peterson, Tóth and Dubinin-Radushkevitch isotherm models. The experimental and equilibrium modeling results revealed that the capacity of schwertmannite for fluoride is high but insensitive to changes in solution temperature. An increase in equilibrium pH of sample solution reduced significantly the fluoride removal efficiency. In binary component systems, inner-sphere complex forming species had negative effects on fluoride adsorption while outer-sphere complex forming species improved slightly the fluoride removal efficiency. The schwertmannite adsorbent was regenerable and had the ability to lower the fluoride concentration to acceptable levels.     

Removal of Reactive Red 195 from aqueous solutions by adsorption on the surface of TiO2 nanoparticles

Nanoparticles of TiO₂ were synthesized and characterized by XRD, BET, TG/DTA and TEM measurements. The commercial azo dye Reactive Red 195 (RR195) was selected as a model dye in order to examine the adsorption capacity of TiO₂ at room temperature, under dark conditions. It was demonstrated that RR195 could be efficiently adsorbed in aqueous suspension of TiO₂. A study on the effects of various parameters like initial pH, concentration of dye and concentration of adsorbent has been carried out in order to find optimum adsorption conditions. The optimum pH of sorption was 3. Substantial reduction of COD, besides removal of colour, was also achieved. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Equilibrium data fitted very well with the Langmuir model signifying the energetic homogeneity of TiO₂ surface adsorption sites. At the temperature of 30 °C, the maximum monolayer adsorption capacity obtained from the Langmuir model is 87 mg/g (pH 3.0). Kinetic studies were carried out and showed a rapid sorption of dye in the first 30 min while equilibrium was reached at 1 h. Three kinetic adsorption models were used to describe the kinetics data, the pseudo-first-order model, the pseudo-second-order model and the intraparticle diffusion model. The sorption kinetics of dye was best described by the pseudo-second-order kinetic model.     

Defluoridation behavior of nanostructured hydroxyapatite synthesized through an ultrasonic and microwave combined technique

The absorption performance of a nano-structured hydroxyapatite produced from a combined ultrasonic and microwave technique was examined for the removal of fluoride from contaminated water. The effect of physical and chemical parameters such as initial pH, contact time, initial fluoride concentration and temperature were investigated. The results indicated that the equilibrium adsorption data followed both the Langmuir and Freundlich isotherms, with a maximum monolayer adsorption capacity of 5.5mg/g at 298K. In addition, the kinetic studies have shown that the fluoride adsorption data followed a pseudo-second order model and that the intra-particle diffusion process played a significant role in determining the rate. The thermodynamic analysis also established that the adsorption process was endothermic and spontaneous. The initial and final fluoride loaded nano-hydroxyapatite samples were characterized using FESEM, TEM, XRD, FTIR and XPS methods. The analysis revealed that structural changes to the adsorbent had taken place.     

Removal of fluoride from aqueous media by Fe3O4@Al(OH)3 magnetic nanoparticles

A novel magnetic nanosized adsorbent using hydrous aluminum oxide embedded with Fe₃O₄ nanoparticle (Fe₃O₄@Al(OH)₃ NPs), was prepared and applied to remove excessive fluoride from aqueous solution. This adsorbent combines the advantages of magnetic nanoparticle and hydrous aluminum oxide floc with magnetic separability and high affinity toward fluoride, which provides distinctive merits including easy preparation, high adsorption capacity, easy isolation from sample solutions by the application of an external magnetic field. The adsorption capacity calculated by Langmuir equation was 88.48 mg g^?1 at pH 6.5. Main factors affecting the removal of fluoride, such as solution pH, temperature, adsorption time, initial fluoride concentration and co-existing anions were investigated. The adsorption capacity increased with temperature and the kinetics followed a pseudo-second-order rate equation. The enthalpy change (ΔH⁰) and entropy change (ΔS⁰) was 6.836 kJ mol^?1 and 41.65 J mol^?1 K^?1, which substantiates the endothermic and spontaneous nature of the fluoride adsorption process. Furthermore, the residual concentration of fluoride using Fe₃O₄@Al(OH)₃ NPs as adsorbent could reach 0.3 mg L^?1 with an initial concentration of 20 mg L^?1, which met the standard of World Health Organization (WHO) norms for drinking water quality. All of the results suggested that the Fe₃O₄@Al(OH)₃ NPs with strong and specific affinity to fluoride could be excellent adsorbents for fluoride contaminated water treatment.     

Adsorptive removal of methylene blue by tea waste

The potentiality of tea waste for the adsorptive removal of methylene blue, a cationic dye, from aqueous solution was studied. Batch kinetics and isotherm studies were carried out under varying experimental conditions of contact time, initial methylene blue concentration, adsorbent dosage and pH. The nature of the possible adsorbent and methylene blue interactions was examined by the FTIR technique. The pH(pzc) of the adsorbent was estimated by titration method and a value of 4.3+/-0.2 was obtained. An adsorption-desorption study was carried out resulting the mechanism of adsorption was reversible and ion-exchange. Adsorption equilibrium of tea waste reached within 5h for methylene blue concentrations of 20-50mg/L. The sorption was analyzed using pseudo-first-order and pseudo-second order kinetic models and the sorption kinetics was found to follow a pseudo-second order kinetic model. The extent of the dye removal increased with increasing initial dye concentration. The equilibrium data in aqueous solutions were well represented by the Langmuir isotherm model. The adsorption capacity of methylene blue onto tea waste was found to be as high as 85.16mg/g, which is several folds higher than the adsorption capacity of a number of recently studied in the literature potential adsorbents. Tea waste appears as a very prospective adsorbent for the removal of methylene blue from aqueous solution.