海藻酸锆/聚N-异丙基丙烯酰胺半互穿网络凝胶球的除磷性能

利用离子交联和自由基聚合反应制备了一种海藻酸锆/聚(N-异丙基丙烯酰胺)半互穿网络凝胶球(ZA/PNIPAM),用于吸附水中的磷酸盐.考察了溶液初始pH、吸附剂投加量、初始磷酸盐浓度和共存阴离子等因素对凝胶球吸附性能的影响.结果表明:ZA/PNIPAM在pH=2时可获得较大的吸附能力;随着投加量的减少、初始磷酸盐浓度的升高,凝胶球的吸附性能逐渐增大;SO_4~(2-)对吸附性能影响较Cl~-和NO_3~-明显.准二级动力学模型和颗粒内部扩散模型可以较好地拟合动力学吸附数据,表明表面吸附和颗粒内部扩散是吸附速率的主要控制步骤.吸附等温线数据可以较好地被Freundlich模型描述,表明吸附过程为非均匀多分子层吸附.FTIR、XPS、零电荷点(pH_(pzc))的结果以及相关吸附数据揭示凝胶球吸附磷酸盐的机制为静电吸附(物理吸附)以及配位交换(化学吸附)的共同作用.经过4次循环再生后,ZA/PNIPAM吸附性能保持稳定,具有良好的重复使用性.     

锆改性沸石对水中磷酸盐和铵的吸附特性

采用锆对天然沸石进行改性,并研究了锆改性沸石对水中磷酸盐和铵的吸附特性.结果表明,锆改性沸石对水中磷酸盐和铵均具有很好的吸附能力.锆改性沸石对水中磷酸盐和铵的吸附动力学过程满足准二级动力学模型.Langmuir、Freundlich和Dubinin–Radushkevich(D–R)等温吸附模型可以很好地描述锆改性沸石对水中磷酸盐的等温吸附行为.Langmuir等温吸附模型可以很好地描述锆改性沸石对水中铵的等温吸附行为.由Langmuir等温吸附模型计算得到锆改性沸石对磷酸盐和铵的最大吸附容量分别达到26.2,7.82 mg/g.热力学参数表明锆改性沸石对水中磷酸盐的吸附是自发的吸热反应过程.锆改性沸石对水中磷酸盐的吸附能力随着pH值的增加而降低.当pH4~8时,锆改性沸石对水中铵的吸附能力较高;当pH低于4或高于8时,对铵的吸附能力下降.水中共存的Cl-、SO42-、HCO3-和NO3-等阴离子对锆改性沸石吸附磷酸盐的影响很小,而共存的SiO32-对磷酸盐的吸附则具有较强的负面影响.水中共存的Ca2+和Mg2+对锆改性沸石吸附铵的影响较小,而共存的K+和Na+对铵的吸附则具有较强的负面影响.锆改性沸石吸附水中磷酸盐的主要机制是阴离子配位体的交换,吸附水中铵的主要机制是与沸石中可交换阳离子的离子交换.     

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.     

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.     

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.     

Preparation and evaluation of Zr-β-FeOOH for efficient arsenic removal

A Zr-β-FeOOH adsorbent for both As(V) and As(III) removal was prepared by a chemical co-precipitation method.Compared with β-FeOOH,the addition of Zr enhanced the adsorption capacities for As(V) and As(III),especially As(III).The maximum adsorption capacities for As(III) and As(V) were 120 and 60mg/g respectively at pH 7.0,much higher than for many reported adsorbents.The adsorption data accorded with Freundlich isotherms.At neutral pH,for As(V),adsorption equilibrium was approached after 3 hr,while for As(III),adsorption equilibrium was approached after 5 hr.Kinetic data fitted well to the pseudo second-order reaction model.As(V) elimination was favored at acidic pH,whereas the adsorption of As(III) by Zr-β-FeOOH was found to be effective over a wide pH range of 4-10.Competitive anions hindered the adsorption according to the sequence:phosphate > silicate > bicarbonate > sulfate > nitrate,while Ca2+ and Mg2+ increased the removal of As(III) and As(V) slightly.The high adsorption capability and good performance in other aspects make Zr-β-FeOOH a potentially attractive adsorbent for the removal of both As(III) and As(V) from water.     

A laboratory scale study on arsenic（Ⅴ） removal from aqueous medium using calcined bauxite ore

The present work deals with the As（Ⅴ） removal from an aqueous medium by calcined refractory grade bauxite （CRB） as a function of solution pH, time, As（Ⅴ） concentration and temperature. The residual As（Ⅴ） was lowered from 2 mg/L to below 0.01 mg/L in the optimum pH range 4.0-7.0 using a 5 g/L CRB within 3 h contact time. The adsorption data fits well with Langmuir isotherm and yielded Langmuir monolayer capacity of 1.78 mg As（Ⅴ）/g of CRB at pH 7.0. Presence of anions such as silicate and phosphate decreased As（Ⅴ） adsorption efficiency. An increase temperature resulted a decrease in the amount of As（Ⅴ） adsorbed by 6%. The continuous fixed bed column study showed that at the adsorbent bed depth of 30 cm and residence time of 168 min, the CRB was capable of treating 340 bed volumes of As（V） spiked water （C0 = 2 mg/L） before breakthrough （Ce = 0.01 mg/L）. This solid adsorbent, although not reusable, can be considered for design of adsorption columns as an efficiency arsenic adsorption media.     

Removal of phosphate ions from aqueous solution using Tunisian clays minerals and synthetic zeolite

Phosphate ions are usually considered to be responsible for the algal bloom in receiving water bodies and aesthetic problems in water. From the environmental point of view, the management of such contaminant and valuable resource is very important. The present work deals with the removal of phosphate ions from aqueous solutions using kaolinitic and smectic clay minerals and synthetic zeolite as adsorbent. The pH effect and adsorption kinetic were studied. It was found that phosphate could be efficiently removed at acidic pH (between 4 and 6) and the second order model of kinetics is more adopted for all samples. The isotherms of adsorption of phosphate ions by the two clays and the zeolite samples show that the zeolite has the highest rate of uptake (52.9 mg P/g). Equilibrium data were well fitted with Langmuir and Freundlich isotherm.     

锆-十六烷基三甲基氯化铵改性活性炭对水中硝酸盐和磷酸盐的吸附特性

采用锆(Zr)和阳离子表面活性剂十六烷基三甲基氯化铵(CTAC)对活性炭进行联合改性,考察了所制备的Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐的吸附去除作用,并探讨了相关的吸附去除机制.结果表明,Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐均具备较好的吸附去除能力.Zr-CTAC改性活性炭对硝酸盐和磷酸盐吸附动力学过程满足准二级动力学模型.Langmuir、Freundlich和Dubinin-Radushkevich(D-R)等温吸附模型可以较好地描述Zr-CTAC改性活性炭对水中硝酸盐的等温吸附过程,Langmuir和D-R等温吸附模型可以较好地描述Zr-CTAC改性活性炭对水中磷酸盐等温吸附过程,通过Langmuir模型计算得到吸附剂对硝酸盐和磷酸盐的最大单位吸附量分别为7.58 mg·g-1和10.9 mg·g-1.高的p H会抑制Zr-CTAC改性活性炭对水中硝酸盐和磷酸盐的吸附.水中共存的Cl-、HCO-3和SO2-4等阴离子均会抑制Zr-CTAC改性活性炭对硝酸盐和磷酸盐的吸附,且对吸附硝酸盐的抑制作用较强而对吸附磷酸盐的抑制作用较弱.水中共存的磷酸盐对Zr-CTAC改性活性炭吸附硝酸盐的抑制作用较强,而水中共存的硝酸盐对Zr-CTAC改性活性炭吸附磷酸盐的抑制作用较弱.1 mol·L-1Na Cl溶液可以使90%左右被吸附到Zr-CTAC改性活性炭表面上的硝酸盐解吸下来.1 mol·L-1的Na OH溶液可以使78%左右被吸附到Zr-CTAC改性活性炭表面上的磷酸盐解吸下来.Zr-CTAC改性活性炭对硝酸盐的吸附机制主要包括阴离子交换作用和静电吸引作用,对磷酸盐的吸附机制主要包括配位体交换作用、阴离子交换作用和静电吸引作用.上述结果说明Zr-CTAC改性活性炭适合作为一种吸附剂去除废水中的硝酸盐和磷酸盐.     

铝改性粉煤灰漂珠吸附水溶液中砷的性能研究

采用湿法与干法相结合的方法合成铝改性粉煤灰漂珠环境材料,借助静态吸附实验研究吸附剂量、pH值、离子强度、共存离子、反应时间和温度对其吸附水溶液中砷性能的影响,并进行吸附等温线和动力学拟合.结果表明:铝改性粉煤灰漂珠吸附水中As(V)的最佳pH值范围为中性偏酸;混合离子和H2PO4-对As(V)的吸附影响较大,CO32-次之;离子强度对As(V)吸附的影响不明显;在温度298K、吸附剂量2.5g/L和反应时间24h的条件下,最大吸附容量约5000μg/g;吸附等温线符合Langmuir单层吸附模型;动力学过程符合准二级动力学模型.     

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.     

Removal of trace arsenic（V） and phosphate from water by a highly selective ligand exchange adsorbent

The ligand exchange adsorbent could be used to remove the toxic arsenic(V) and phosphate efficiently from water even in the presence of foreign anions and possible to apply in chemical industry.     

Evaluation of zeolites synthesized from fly ash as potential adsorbents for wastewater containing heavy metals

Both pure-form zeolites (zeolites A and X) were synthesized by applying a two-stage method during hydrothermal treatment of fly ash prepared initial gel. The difference of adsorption capacity of both fly ash-synthesized zeolits was assessed under the same adsorption conditions. Copper and zinc were chosen as target heavy metal ions. It was found that adsorption capacity of zeolite A showed much higher value than that of zeolite X. Thus, attention was focused on investigating the removal performance of heavy metal ions in aqueous solution on the synthetic pure-form zeolite A from fly ash, zeolite HS (hydroxyl-solidate) prepared from the residual fly ash (after synthesis of pure-form zeolite A from fly ash) and a commercial grade zeolite A. Batch method was employed to study the influential parameters such as initial pH value, adsorbents dosage and adsorption temperature on the adsorption process. The equilibrium data were well fitted by the Langmuir model and showed the affinity: Cu2+ > Zn2+ (adsorbent FA-ZA). The removal mechanism of metal ions followed adsorption and ion exchange processes. Attempts were also made to recover heavy metal ions and regenerate adsorbents (adsorbent FA-ZA).     

载钠硅碳羟基磷灰石的制备及其对水中As(Ⅴ)的吸附特性

由于自然和人为活动导致自然水体和土壤被As（砷）污染,严重危及生态环境并已受到广泛关注.为实现更大程度地去除含As废水的新型吸附材料,以废弃蛋壳为原材料,采用超声波法制备多孔状且较大比表面积的Na-Si-CHAP[Ca_10-xNa_x（PO₄）_6-y-z（SiO₄）_z（CO₃）_y（OH）_2-α,载钠硅碳羟基磷灰石],深入分析去除含As（Ⅴ）废水的吸附特性.通过BET比表面积、扫描电镜（SEM）、EDX（能量色散X射线光谱）、X-射线衍射（XRD）等手段对样品进行表征,并进一步探讨了pH、吸附时间、初始ρ[As（Ⅴ）]以及反应温度等因素对吸附效果的影响.结果表明:在pH为6.0、作用时间为60 min、反应温度为313 K等优化条件下,0.2 g Na-Si-CHAP对100 mL 30 mg/L含As（Ⅴ）废水的去除率和平衡吸附容量分别为96.53%和14.48 mg/g.Langmuir等温吸附模型较好地拟合了吸附试验数据,313 K下相关系数（r2）高达0.998 0,饱和吸附容量达46.73 mg/g,明显高于其他同类材料;准二级动力学模型可较好地描述该吸附行为,相关系数高达0.999 9;热力学参数△G（吉布斯自由能变）、△H（焓变）和△S（熵变）的计算值显示,该吸附过程为自发吸热过程.研究显示,Na-Si-CHAP作为一种吸附剂,对含As（Ⅴ）的去除效果明显优于同类材料.      

Shellac-coated iron oxide nanoparticles for removal of cadmium(II) ions from aqueous solution

This study describes a new effective adsorbent for cadmium removal from aqueous solution synthesized by coating a shellac layer, a natural biodegradable and renewable resin with abundant hydroxyl and carboxylic groups, on the surface of iron oxide magnetic nanoparticles. Transmission Electron Microscopy (TEM) imaging showed shellac-coated magnetic nanoparticle (SCMN) adsorbents had a core-shell structure with a core of 20 nm and shell of 5 nm. Fourier Transform Infrared Spectroscopic analysis suggested the occurrence of reaction between carboxyl groups on the SCMN adsorbent surface and cadmium ions in aqueous solution. Kinetic data were well described by pseudo second-order model and adsorption isotherms were fitted with both Langmuir and Freundlich models with maximum adsorption capacity of 18.80 mg/g. SCMN adsorbents provided a favorable adsorption capacity under high salinity conditions, and cadmium could easily be desorbed using mild organic acid solutions at low concentration.     

Removal of ammonium ion from water by Na-rich birnessite: Performance and mechanisms

Na-rich birnessite (NRB) was synthesized by a simple synthesis method and used as a high-efficiency adsorbent for the removal of ammonium ion (NH₄⁺) from aqueous solution. In order to demonstrate the adsorption performance of the synthesized material, the effects of contact time, pH, initial ammonium ion concentration, and temperature were investigated. Adsorption kinetics showed that the adsorption behavior followed the pseudo second-order kinetic model. The equilibrium adsorption data were fitted to Langmuir and Freundlich adsorption models and the model parameters were evaluated. The monolayer adsorption capacity of the adsorbent, as obtained from the Langmuir isotherm, was 22.61 mg NH₄⁺-N/g at 283 K. Thermodynamic analyses showed that the adsorption was spontaneous and that it was also a physisorption process. Our data revealed that the higher NH₄⁺ adsorption capacity could be primarily attributed to the water absorption process and electrostatic interaction. Particularly, the high surface hydroxyl-content of NRB enables strong interactions with ammonium ion. The results obtained in this study illustrate that the NRB is expected to be an effective and economically viable adsorbent for ammonium ion removal from aqueous system.     

Fe3O4/BC复合材料的制备及其吸附除磷性能

为解决磁性吸附剂Fe₃O₄不稳定、易在水中团聚以及吸附效率较低的问题,以BC（生物炭）为载体,采用化学共沉淀法制备了Fe₃O₄/BC（生物炭负载的纳米四氧化三铁）复合材料,并将其应用于水体中PO₄3--P的吸附去除;探究了Fe₃O₄/BC对水中PO₄3--P的吸附-解析性能,考察了纳米Fe₃O₄负载比例、吸附体系pH和初始ρ（PO₄3--P）等因素对Fe₃O₄/BC吸附PO₄3--P效率的影响,并考察了吸附机制.结果表明:所制备的Fe₃O₄纳米颗粒呈球形,均匀散布在生物炭表面;Fe₃O₄/BC复合材料能高效吸附水中的PO₄3--P,在pH=3、温度为25℃、ρ（PO₄3--P）为50 mg/L、Fe₃O₄/BC投加量为400 mg（二者质量比为1:1）,吸附3 h达到平衡后,Fe₃O₄/BC吸附PO₄3--P效率达到92.14%. Fe₃O₄/BC复合材料吸附PO₄3--P的机制包括配位体交换和静电吸引,吸附过程较好地符合准二级动力学模型和Langmuir等温吸附方程. Fe₃O₄/BC具有良好的解析性能,用c（NaOH）为2.0 mol/L的溶液对吸附PO₄3--P饱和后的Fe₃O₄/BC进行解析,解析效率达到80%.研究显示,Fe₃O₄/BC重复利用性好,在第4次利用后还能保持75%以上的吸附效率.      

新型铁铜铝三元复合氧化物除磷性能与机制研究

采用共沉淀法制备了一种新型铁铜铝三元复合氧化物吸附剂,系统研究了其对磷的吸附行为,并对吸附磷前后的吸附剂进行了表征.吸附实验结果表明,铁铜铝三元复合氧化物对磷具有优异的吸附去除效能,Freundlich吸附等温线模型能更好地拟合其对磷的吸附,最大吸附量为62.6 mg·g-1(pH=7.0),显著高于多数文献报道的磷吸附剂;吸附速率较快,吸附动力学更符合Elovich模型;溶液pH对磷吸附有一定影响,随着pH的升高,磷吸附量降低,离子强度则影响不大;共存阴离子对磷吸附具有抑制作用,影响的大小顺序为SiO_3~(2-)SO_4~(2-)CO_3~(2-)Cl~-,而共存阳离子Ca2+和Mg2+则对磷吸附略有促进作用.Zeta电位、红外谱图(FTIR)和X射线光电子能谱(XPS)表征分析表明,磷在铁铜铝三元复合氧化物表面发生了特性吸附,磷酸根主要通过取代复合氧化物表面的羟基形成内表面络合物而被吸附去除.溶出实验结果表明,当pH在5.0~8.5范围内,Fe~(3+)、Cu~(2+)、Al~(3+)的溶出量均较低.由此可知,铁铜铝三元复合氧化物是一种具有良好应用前景的除磷吸附剂.     

Removal of cadmium using MnO2 loaded D301 resin

MnO2 loaded weak basic anion exchange resin D301 （Anion exchange resin, macroreticular weak basic styrene） as adsorbent has been prepared and applied to the removal of cadmium. The adsorption characteristics have been investigated with respect to effect of pH, equilibrium isotherms, removal kinetic data, and interference of the coexisting ions. The results indicated that the Cd^2＋ could be efficiently removed using MnO2 loaded D301 resin in the pH range of 3-8 from aqueous solutions with the co-existence of high concentration of alkali and alkaline-earth metals ions. The saturate adsorption capacity of the Cd^2＋ was 77.88 mg/g. The adsorption process followed the pseudo first-order kinetics. The equilibrium data obtained in this study accorded excellently with the Langmuir adsorption isotherm.     

活化赤泥去除猪场废水生化处理出水中的磷和重金属

以铝矿工业废渣赤泥为原材料,采用焙烧活化方法进行活化处理,并将其用于畜禽废水生化处理出水中磷和重金属的吸附去除.同时,研究考察了吸附剂除磷、除重金属的能力以及投加量、pH值和反应时间对去除效果的影响.结果表明,赤泥和活化赤泥对磷、铜、锌、砷吸附规律符合Langmuir吸附等温方程;焙烧改性后,赤泥对磷、铜、锌、砷的去除能力显著提高,900℃焙烧活化饱和吸附量可分别由46.26、18.18 、15.45、18.83 mg·g-1提高至149.00、65.17、99.20、27.51 mg·g-1;pH显著影响除磷、除重金属的效果,高pH条件有利于磷、铜、锌、砷的去除;赤泥和活化赤泥除磷、铜、锌、砷的作用机理包含金属氧化物表面的表面络合作用机理,其对砷和磷的去除机理还包括共沉淀作用.