Adsorptive removal of heavy metal ions from industrial effluents using activated carbon derived from waste coconut buttons

Removal of heavy metal ions from industrial effluents by the activated carbon prepared by steam activation of waste coconut buttons through batch adsorption process.     

氨基修饰氧化石墨烯-羧甲基纤维素复合吸附剂的制备及其对Cr (VI)的吸附性能研究

为获得价格低廉、吸附性能优良的石墨烯基吸附剂,以氧化石墨烯（GO）、羧甲基纤维素（CMC）为基材,以聚乙烯亚胺（PEI）为改性试剂,通过化学修饰的方法制备了氨基修饰氧化石墨烯-羧甲基纤维素复合吸附剂（GO-PEI-CMC）.采用扫描电镜（SEM）、傅里叶红外光谱（FT-IR）及X射线光电子能谱（XPS）等表征手段证实了CMC、氧化石墨烯与PEI已成功复合.静态吸附实验表明GO-PEI-CMC对Cr （VI）表现出良好的吸附性能,由Langmuir等温吸附模型所得最大吸附量值为243.92 mg·g^-1.吸附动力学、吸附等温线研究表明GO-PEI-CMC对Cr （VI）的吸附为单分子层、化学吸附过程.GO-PEI-CMC对Cr （VI）吸附性能优良,且具有绿色环保、可生物降解的优点,是一种极具潜力的Cr （VI）吸附剂.     

醋酸纤维素吸附剂的制备及其性能表征

研究开发了1种球形醋酸纤维素吸附剂,对其制备方法、形态结构及其对水中4种有机氯农药的吸附性能进行了研究.扫描电镜结果表明,所制备醋酸纤维素吸附剂的外表面是一层致密的醋酸纤维素膜,内部为网状结构;对水中狄氏剂、艾氏剂、异狄氏剂、七氯4种有机氯农药有较强的吸附能力,12h后去除率均达到85%以上;并且对正辛醇-水分配系数(lgK_ow)较大的有机物具有更快的吸附速度,对七氯、艾氏剂的去除率在0·5h后可达99%.说明该吸附剂对水中亲脂性的有机物具有较高的吸附效能.     

Removal of heavy metal ions from aqueous solution using red loess as an adsorbent

The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25°C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HC1 solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.     

Selective adsorption of silver ions from aqueous solution using polystyrene-supported trimercaptotriazine resin

Trimercaptotriazine-functionalized polystyrene chelating resin was prepared and employed for the adsorption of Ag(I) from aqueous solution. The adsorbent was characterized according to the following techniques: Fourier transform infrared spectroscopy, elemental analysis, scanning electron microscopy and the Brunauer-Emmet-Teller method. The effects of initial Ag(I) concentration, contact time, solution pH and coexisting ions on the adsorption capacity of Ag(I) were systematically investigated. The maximum adsorption capacity of Ag(I) was up to 187.1 mg/g resin at pH 0.0 and room temperature. The kinetic experiments indicated that the adsorption rate of Ag(I) onto the chelating resin was quite fast in the first 60 min and reached adsorption equilibrium after 360 min. The adsorption process can be well described by the pseudo second-order kinetic model and the equilibrium adsorption isotherm was closely fitted by the Langmuir model. Moreover, the chelating resin could selectively adsorb more Ag(I) ions than other heavy metal ions including: Cu(II), Zn(II), Ni(II), Pb(II) and Cr(III) during competitive adsorption in the binary metal species systems, which indicated that it was a highly selective adsorbent of Ag(I) from aqueous solution.     

磁性吸附材料CuFe2O4吸附砷的性能

根据Cu(Ⅱ)和Fe(Ⅲ)都对砷有较强的亲和性,制备了同时含有Cu(Ⅱ)和Fe(Ⅲ)的、可用磁分离方法进行分离回收的磁性吸附材料CuFe₂O₄,并对其进行了表征及吸附砷的性能研究.结果表明,该吸附剂对砷的吸附能力与溶液pH有关,在弱酸性及中性条件下,吸附砷的能力最强,而对As(V)的吸附能力比对As(Ⅲ)更强些,在平衡浓度为10μg/L时,其吸附容量可达10mg/g左右,可以很容易地将水中浓度为1～20mg/L的As(V)降到10μg/L以下.实验考察了几种无机阴离子对吸附砷的影响,表明较高浓度(砷浓度的20倍)的硫酸盐对As(Ⅲ)和As(V)的吸附均有一定影响,盐酸盐及磷酸盐则影响不明显;负载的As(V)可较容易地用0.1mol/L NaOH洗脱下来,使吸附剂再生,而As(Ⅲ)则难以洗脱,这与2种价态砷的吸附机理不同有关.     

Dyes adsorption using a synthetic carboxymethyl cellulose-acrylic acid adsorbent

Removal of noxious dyes is gaining public and technological attention. Herein grafting polymerization was employed to produce a novel adsorbent using acrylic acid and carboxymethyl cellulose for dye removal. Scanning electron microscopy and Fourier-transform infrared spectroscopy verified the adsorbent formed under optimized reaction conditions. The removal ratio of adsorbent to Methyl Orange, Disperse Blue 2BLN and malachite green chloride reached to 84.2%, 79.6% and 99.9%, respectively. The greater agreement between the calculated and experimental results suggested that pseudo second-order kinetic model better represents the kinetic adsorption data. Equilibrium adsorptions of dyes were better explained by the Temkin isotherm. The results implied that this new cellulose-based absorbent had the universaiity for removal of dyes through the chemical adsorption mechanism.     

Pb(II) removal from water using Fe-coated bamboo charcoal with the assistance of microwaves

Bamboo charcoal(BC) was used as starting material to prepare iron-modified bamboo charcoal(Fe-MBC) by its impregnation in FeCl 3 and HNO 3 solutions simultaneously,followed by microwave heating.The material can be used as an adsorbent for Pb(Ⅱ) contaminants removal in water.The composites were prepared with Fe molar concentration of 0.5,1.0 and 2.0 mol/L and characterized by means of N 2 adsorption-desorption isotherms,X-ray diffraction spectroscopy(XRD),scanning electron microscopy coupled with energy dispersive X-ray spectrometry(SEM-EDS),Fourier transform infrared(FT-IR) and point of zero charge(pH pzc) measurements.Nitrogen adsorption analyses showed that the BET specific surface area and total pore volume increased with iron impregnation.The adsorbent with Fe molar concentration of 2 mol/L(2Fe-MBC) exhibited the highest surface area and produced the best pore structure.The Pb(Ⅱ) adsorption process of 2Fe-MBC and BC were evaluated in batch experiments and 2Fe-MBC showed an excellent adsorption capability for removal Pb(Ⅱ).The adsorption of Pb(Ⅱ) strongly depended on solution pH,with maximum values at pH 5.0.The ionic strength had a significant effect on the adsorption at pH < 6.0.The adsorption isotherms followed the Langmuir isotherm model well,and the maximum adsorption capacity for Pb(Ⅱ) was 200.38 mg/g for 2Fe-MBC.The adsorption processes were well fitted by a pseudo second-order kinetic model.Thermodynamic parameters showed that the adsorption of Pb(Ⅱ) onto Fe-MBC was feasible,spontaneous,and exothermic under the studied conditions,and the ion exchange mechanism played an significant role.These results have important implications for the design of low-cost and effective adsorbents in the removal of Pb(Ⅱ) from wastewater.     

Synthesis of linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(Ⅱ) from aqueous solutions

The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy (FTIR), Solid carbon nuclear magnetic resonance spectroscopy (CNMR)), silicon^-29 nuclear magnetic resonance spectroscopy (Si NMR)), and X-ray diffraction spectroscope ((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy (FTIR)), scanning electron microscopy (SEM)), and X-ray photoelectron spectroscopy ((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II) followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430 mg/g. Thus, the waste linear low-density polyethylene-g-poly (acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent.     

Synthesis of linear low-density polyethylene-g-poly(acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(Ⅱ) from aqueous solutions

The purpose of this work is to remove Pb(II) from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy(FTIR), Solid carbon nuclear magnetic resonance spectroscopy(CNMR)), silicon-29 nuclear magnetic resonance spectroscopy(Si NMR)), and X-ray diffraction spectroscope((XRD) were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb(II) from the aqueous solution. The Pb(II)-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy(FTIR)),scanning electron microscopy(SEM)), and X-ray photoelectron spectroscopy((XPS)). From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb(II). Kinetic studies indicated that the adsorption of Pb(II)followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb(II) ions was 430 mg/g. Thus, the waste linear low-density polyethylene-g-poly(acrylic acid)-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb(II) adsorbent.     

Decoupling the adsorption mechanisms of arsenate at molecular level on modified cube-shaped sponge loaded superparamagnetic iron oxide nanoparticles

In this study, a commercial cube-shaped open-celled cellulose sponge adsorbent was modified by in-situ co-precipitation of superparamagnetic iron oxide nanoparticles (SPION) and used to remove As(V) from aqueous solutions. Fe K-edge X-ray absorption spectroscopy (XAS) and TEM identified maghemite as the main iron phase of the SPION nanoparticles with an average size 13 nm. Batch adsorption experiments at 800 mg/L showed a 63% increase of adsorption capacity when loading 2.6 wt.% mass fraction of SPION in the cube-sponge. Experimental determination of the adsorption thermodynamic parameters indicated that the As(V) adsorption on the composite material is a spontaneous and exothermic process. As K-edge XAS results confirmed that the adsorption enhancement on the composite can be attributed to the nanoparticles loaded. In addition, adsorbed As(V) did not get reduced to more toxic As(III) and formed a binuclear corner-sharing complex with SPION. The advantageous cube-shape of the sponge-loaded SPION composite together with its high affinity and good adsorption capacity for As(V), good regeneration capability and the enhanced-diffusion attributed to its open-celled structure make this adsorbent a good candidate for industrial applications.     

Adsorption of Co(Ⅱ) from aqueous solutions by water treatment residuals

A study on the removal of Co(Ⅱ) from aqueous solutions by water treatment residuals(WTR)was conducted in batch conditions. The sorption process of Co(Ⅱ) followed pseudosecondorder kinetics, with 30 hr required to reach equilibrium. Using the Langmuir adsorption isotherm model, a relatively high maximum sorption capacity of 17.31 mg/g Co(Ⅱ) was determined. The adsorption of Co(Ⅱ) was dependent on pH values and was affected by the ionic strength. Results show that Co(Ⅱ) adsorption was a spontaneous endothermic process and was favorable at high temperature. Most of the adsorbed Co(Ⅱ) stayed on the WTR permanently, whereas only small amounts of adsorbed Co(Ⅱ) were desorbed. The shifting of peaks in FT-IR spectra indicated that Co(Ⅱ) interacted with the WTR surface through strong covalent bond formation with Fe(Al)–O functional groups. It was concluded that WTR can be a suitable material from which to develop an efficient adsorbent for the removal of Co(Ⅱ) from wastewater.     

利用新型稀土铈铁复合吸附剂去除水体腐殖质的研究

研究了稀土铈铁复合材料(CFA)对水体中黄腐酸(FA)的去除效能和作用机制.结果表明:CFA在平衡pH3.0～6.5的范围内对FA的去除效果较好,吸附速度快,120min即达到平衡.水体中FA与砷酸根在CFA上有很强的竞争作用,当FA加入量为5mg/L～10mg/L时,砷的饱和吸附量Q_o即丧失40%～50%,表明两者作用于材料相同的活性位点.吸附前后的红外谱图(FTIR)揭示了CFA表面羟基在FA去除中起着重要作用.通过Zeta电位的测定得出材料的等电点为5.6,因而pH偏酸性的条件有利于FA的去除.     

载铁(β-FeOOH)球形棉纤维素吸附剂去除地下水As(Ⅴ)的研究

制备了一种载铁(β- FeOOH)球形棉纤维素吸附剂,球珠孔隙度大,强度好,活性成分铁的载入量可高达360mg/mL ,(质量分数达50%) ,活性好.研究表明,当铁含量为220mg/mL时,该吸附剂对As(V)的最大吸附量为15.6mg/mL(33.2mg/g) ,Langmuir和Freundlich方程能很好地描述吸附等温线.吸附速度较快,10h可达到吸附平衡,吸附动力学符合Lagergren二级方程.SiO₃^2- ,SO₄^2-,Cl^-干扰离子均不影响砷的去除.柱吸附实验表明,空床停留时间为5.9min ,进水As(V)浓度为500μg/L时,As(V)的穿透体积为5000BV .吸附剂可以用1.5mol·L^-1 NaOH再生,洗脱和再生效率可达90%以上.活性成分β-FeOOH形态稳定,柱操作和再生时铁无溶出.吸附剂制备方法简单,新颖,对地下水和饮用水砷去除具有较好的应用前景.     

Sequestration of toxic Pb（II） ions by chemically treated rubber （Hevea brasiliensis ） leaf powder

Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range for lead adsorption was 4–5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed. The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60–90 min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo second-order fitted well with correlation coefficients greater than 0.99.     

Enhanced phosphate removal using zirconium hydroxide encapsulated in quaternized cellulose

Zirconium-based materials are efficient adsorbent for aqueous phosphate removal. However, current zirconium-based materials still show unsatisfied performance on adsorption capacity and selectivity. Here, we demonstrate a zirconium hydroxide encapsulated in quaternized cellulose (QC–Zr) for the selective phosphate removal. Zirconium hydroxide nanoparticles were simultaneously generated in situ with the QC framework and firmly anchored in the three-dimensional (3D) cross-linked cellulose chains. The maximum P adsorption capacity of QC–Zr was 83.6 mg P/g. Furthermore, the QC–Zr shows high P adsorption performance in a wide pH range, generally due to the electrostatic effects of quaternized cellulose. The enhanced adsorption of P was also achieved in the presence of competing anions (including Cl^?, NO₃^?, ${\text{SO}}_4^{2?}$, ${\text{SO}}_4^{\mathrm{4}?}$) and humic acid (HA) even at a molar ratio up to 20 levels. The column adsorption capacity of QC–Zr reached 4000 bed volumes (BV) at EBCT = 0.5 min as the P concentration decreased from 2.5 to 0.5 mg/L. Mechanism study revealed that both –N⁺(CH₃)₃ groups and zirconium hydroxide were involved in phosphate adsorption via electrostatic interactions between –N⁺(CH₃)₃ and phosphate, and the formation of zirconium hydrogen phosphate (Zr(HPO₄)x). The ³¹P nuclear magnetic resonance (NMR) study implied that P surface–precipitated and inner–sphere complexed with zirconium hydroxide at a ratio of 3:1.     

EXAFS研究Zn在δ-MnO2上的吸附-解吸机理

用延展X-ray吸收精细结构光谱(EXAFS)研究了重金属Zn(Ⅱ)在δ-MnO₂上吸附产物的微观结构及其吸附机制.在pH 5.50,0.1mol/L NaNO₃介质中,吸附在δ-MnO₂表面上Zn(Ⅱ)以六配位的水合离子八面体形式存在.水合锌离子八面体从δ-MnO₂层状结构的空位上下方,与δ-MnO₂的结构单元MnO₆八面体通过共用O原子结合,形成角-角结合的弱吸附,Zn-O平均原子间距为(2.071±0.007)A(n=3),Zn-Mn平均原子间距为(3.528±0.006)A(n=3).在同一条等温线上随着吸附量增加,以角-角结合的弱吸附形式基本上没有变化.宏观的吸附-解吸实验结果显示Zn(Ⅱ)在δ-MnO₂上的吸附可逆性很高,解吸等温线和吸附等温线几乎重合在一起EXAFS结果从分子水平表明,Zn(Ⅱ)在δ-MnO₂上的高吸附可逆性是由角-角形式弱吸附所导致的.     

Pb(Ⅱ) biosorption using chitosan and chitosan derivatives beads: Equilibrium,ion exchange and mechanism studies

The study examined the adsorption of Pb(II) ions from aqueous solution onto chitosan, chitosan-GLA and chitosan-alginate beads. Several important parameters influencing the adsorption of Pb(II) ions such as initial pH, adsorbent dosage and different initial concentration of Pb(II) ions were evaluated. The mechanism involved during the adsorption process was explored based on ion exchange study and using spectroscopic techniques. The adsorption capacities obtained based on non-linear Langmuir isotherm for ch...     

介孔γ -Al2O3的制备及其对F-的吸附性能研究

以硝酸铝和碳酸氢铵为原料,采用溶胶-凝胶法合成具有较高活性的介孔γ-Al2O3纳米材料.对合成的样品进行XRD、TEM和BET表征.结果表明:在N2气氛下煅烧所得样品与在空气中煅烧所得样品相比,其比表面积略有增加;在溶胶-凝胶过程中,用乙醇洗涤凝胶能显著提高产物的比表面积,所得产物比表面积高达390 m2/g,呈多孔结...     

天然菱铁矿改性及强化除砷研究

我国高砷地下水分布广泛,经济、高效地饮用水除砷技术受到广泛关注.静态批实验采用资源丰富、价格便宜的天然菱铁矿为主要原材料,考虑灼烧温度、时间及添加黏合剂等因素确定最优改性条件使除砷效果达到最佳.结果表明,在加铝量为10 mg.g-1、350℃下恒温灼烧90 min后造粒达到强度要求并除砷效果较优.25℃、固液比为0.5 g∶50 mL、As(Ⅲ)和As(Ⅴ)初始浓度为5 mg.L-1时,吸附后溶液中残留As浓度均<10μg.L-1.静态吸附批实验结果表明,25℃时,接触反应时间为12 h可达到吸附平衡,吸附过程较好地符合Lagergren假二级吸附速率方程;最优改性天然菱铁矿对砷的吸附规律可用Langmuir和Freundlich等温吸附模型很好地描述,As(Ⅲ)、As(Ⅴ)饱和吸附容量分别可以达到1 039、1 026μg.g-1.结合XRD、SEM等研究方法和比表面及孔结构分析初步探讨天然菱铁矿改性以及除砷的主要机制.分析表明,改性后天然菱铁矿比表面积大幅度增大,孔径减小,且在表面活化生成一层圆球状的含Fe(Ⅱ)和Fe(Ⅲ)的化合物.改性天然菱铁矿是一种值得进一步研究并实际应用的除砷材料.