水合氧化锆改性污泥生物炭对磷酸盐的吸附特性研究

将剩余污泥在 600 ℃下热处理得到污泥生物炭（SBC）,以 SBC为载体通过一步共沉淀法制得新型水合氧化锆改性污泥生物炭（SBC-Zr）,对其进行了表征,并研究了其对磷酸盐的吸附行为。表征结果表明,该吸附剂成功负载水合氧化锆,比表面积为 183.03 m²/g,孔容为 0.07 cm³/g。吸附实验结果表明：SBC-Zr 在 pH=2 时获得较高吸附量;随着投加量的减少,吸附量逐渐减小;SO₄^2-对吸附性能影响较 Cl^-、NO₃^-以及腐殖酸（HA）明显;准二级动力学模型能更好地拟合吸附动力学数据,且吸附过程较好地符合 Langmuir 等温吸附模型;SBC-Zr 吸附磷酸盐的机理包括静电吸引和磷酸盐取代表面 O-H 基团形成内层配合物。应用其处理实际含磷污水,可将磷酸盐浓度从 1.30 mg/L 降低到0.36 mg/L。     

给水厂污泥制备高强度磷吸附剂研究

给水厂污泥对水体中的磷有良好的吸附作用,但其颗粒强度差,在水中易松散解体。为制备强度高,吸附容量大的吸附剂,以给水厂污泥为原料,添加硅酸盐水泥、生石灰和石膏,采用免烧法制备高强度颗粒状磷吸附剂,探究制备条件对吸附剂强度和吸附性能的影响。结果表明,随着pH增加,吸附剂对磷的吸附量先升后降,在pH值为5.0时,对磷的吸附量最大。磷在固相和液相之间的平衡分配符合Freundlich等温吸附模型,吸附剂表面的吸附位点分布是不均匀的,对磷的吸附介于单层与双层吸附之间。     

Zn-Al类水滑石磷吸附剂的制备及其吸附性能

采用共沉淀法制备了一系列Zn-Al类水滑石吸附剂,并考察了制备条件对其磷酸盐吸附性能的影响。结果表明,在制备温度为70℃、共沉淀剂为NaOH、陈化时间为6 h及焙烧温度为300℃时得到的Zn-Al类水滑石对城市污水处理厂污泥脱水液中磷酸盐的吸附效果最好,其饱和吸附容量达72.46 mg P·(g吸附剂)^-1。该吸附剂吸附水中磷的动力学拟合效果表现为假二级动力学方程>Elovich方程>假一级动力学方程。吸附等温线符合Langmuir吸附模型。     

镧镁改性海泡石对黑臭水体中磷的吸附机理

磷是导致黑臭水体形成的关键元素之一，本研究以天然海泡石作为载体、硝酸镧和氯化镁为原料，采用共沉淀法制备了一种镧镁改性海泡石吸附除磷材料，考察了镧镁改性海泡石吸附除磷效果及影响因素并探究了其吸附除磷机制。结果表明，镧镁改性海泡石对磷酸盐的吸附是一个自发、吸热、熵增过程，其对磷酸盐的最大吸附量达117.2 mg/g,对磷酸盐的去除效果受共存阴离子(Cl^-、NO^-₃、SO₄^2-和HCO^-₃)和腐植酸影响小。该材料的pH值适用范围(6～9)较宽，循环使用4次后性能较为良好。镧镁改性海泡石对磷酸盐的吸附机制包括配体交换、化学沉淀和静电吸引作用，生成了La-O-P配合物及MgHPO₄、Mg₃(PO₄)₂沉淀。实际轻度和重度黑臭水样中的磷经镧镁改性海泡石处理后可达到《地表水环境质量标准》(GB 3838—2002)Ⅱ类水质。     

改性吸附剂去除废水中磷的应用研究进展

去除废水中过量的磷可以减缓水体富营养化。吸附除磷因具有能耗低、容量大、污染少等优点而备受关注，改性吸附剂则可在此基础上提高除磷的靶向性，拓宽操作条件，增大吸附容量。本文分析了改性硅酸盐类、改性金属氧化物类、改性固体废弃物类和聚合物类4类除磷吸附剂的改性方法和吸附性能。硅酸盐类吸附材料以及固体废弃物类材料除磷效果略差，但因来源丰富、价格低廉而具有极大的吸引力。聚合物类吸附剂具有高吸附容量、高选择性，但价格昂贵。金属（氢）氧化物具有出色的磷酸盐吸附性能，且选择性好、吸附速度快，这些化合物已被掺入到沸石、介孔二氧化硅和生物炭等材料中，进一步增强其吸附性能，并在工程材料应用中取得重大突破，主要包括磁性吸附剂和颗粒吸附剂。4类吸附剂的作用机理可归纳为两种：一种是吸附剂上的金属与磷酸盐离子发生配位反应，形成沉淀；另一种是酸性条件下吸附剂上的羟基质子化，使羟基带正电，质子化的羟基通过静电吸引使磷得以去除。通过对不同类别吸附剂的吸附特性进行对比分析，提出将高分子技术运用到吸附剂制备过程中，开发同时具有较强解吸能力的改性吸附剂将成为除磷吸附剂研究的新热点。     

铁、锆改性生物炭对水中磷的吸附特性及机理研究

针对水体富营养化现象,以青霉素菌渣为原料制备生物炭,通过共沉淀法在所制备生物炭上负载铁、锆离子,得到了一种新型除磷吸附剂 Zr Fe-HBC,研究了其对水中磷酸盐的吸附特性及吸附机理。结果表明,Zr FeHBC 具备多层级孔隙结构,铁、锆离子以氧化物形式结合于生物炭之上。Zr Fe-HBC 吸附磷酸盐的过程符合准二级动力学和 Freundlich 模型,为多分子层的化学吸附,在 25 ℃时饱和吸附量为 18.26 mg/g。Zr Fe-HBC 对磷酸盐的吸附量随 p H 降低而增加,适合在酸性条件下对磷酸盐进行吸附处理。共存阴离子可与磷酸盐竞争吸附位点,其中 CO₃^2-对磷酸盐吸附产生严重干扰。选择 1 mol/L Na OH 溶液对吸附后的 Zr Fe-HBC 进行解吸,经过 5 次吸附-脱附循环,Zr Fe-HBC 仍保持 78% 的吸附容量。综合吸附实验与表征结果分析 Zr Fe-HBC 对磷酸盐的吸附机理,结果表明,Zr Fe-HBC 主要通过静电吸附、配体交换和表面沉淀作用对磷酸盐进行吸附。     

纳米羟基铁改性阴离子交换树脂用于富营养化水体中磷的吸附净化

为探索一种改良的磷酸盐吸附材料,以优化其在去除富营养化水体中无机磷的应用效果,提出了一种纳米羟基铁（FeOOH）与阴离子交换树脂D-201复合的方法。首先将FeOOH分散于阴离子交换树脂D-201中,得到FeOOH@D-201复合树脂。然后进行批量吸附实验,通过比较FeOOH@D-201与纯D-201对磷酸盐的吸附量来评估其改善程度。并采用准二级动力学模型和Langmuir吸附等温线模型进行拟合,从而分析复合树脂的吸附过程及其机理。结果表明,FeOOH@D-201复合树脂的最大磷酸盐吸附量达到了132.1 mg/g,比纯D-201的吸附量提高了46%,突破了常规阴离子交换树脂在去除无机磷应用中的局限性。模型拟合结果表明,其吸附过程与准二级动力学模型和Langmuir模型较吻合,推断吸附机理主要是静电吸引和配位络合的共同作用。FeOOH@D-201经过5次醋酸脱附-吸附再生循环后,吸附剂去除磷酸盐的能力仍然保持在70.4%以上,证实了复合树脂的良好再生性能。     

铁改性杭锦土对磷的吸附及对沉积物磷释放的控制

以天然粘土矿物杭锦土(HJ)为原料,采用浸渍法制备表面负载铁氧化物的铁改性杭锦土(FHJ)吸附剂.采用BET、SEM、XRD等技术对其进行表征,并考察了铁负载比例、pH、共存离子对FHJ除磷的影响.结果表明,浸渍法成功将铁氧化物负载在杭锦土表面;溶液pH越低越有利于FHJ对磷酸盐的吸附;除磷性能受CO32-、SiO32...     

改性聚氯化铝残渣吸附剂制备及其除磷性能

采用聚氯化铝生产压滤残渣(PACR)经改性制备新型吸附剂(M-PACR),考察该吸附剂对模拟含磷废水的吸附效果,并探讨其除磷性能。SEM测试结果表明,M-PACR表面变得疏松多孔,孔隙结构也较改性前更加明显;BET分析数据显示,M-PACR较改性前比表面积增大了近3倍。除磷实验效果表明:M-PACR的最佳投加量为0.8 g;在pH=7时,M-PACR对磷的去除率达到94.2%。M-PACR吸附剂对磷的吸附符合二级吸附动力学模型与Langmuir吸附等温模型。     

中和法制备磷酸根吸附剂的研究

采用氨水中和三氯化铁法制备无机水合氧化物的磷酸根吸附剂。该实验研究了吸附剂的制备、对磷酸根的吸附过程和再生实验,还讨论了影响吸附容量的各种因素:三氯化铁溶液浓度、熟化时间、中和时间、吸附时间、吸附剂粒径、吸附温度、pH、磷酸盐初始浓度、磷酸盐溶剂量等。实验结果表明:该吸附剂磷酸根的去除率最高达93%以上,且再生条件简单,再生效果较好。     

Resin-loaded cationic hydrogel: A new sorbent for recovering of grapefruit polyphenols

This paper presents a study of the recovering of polyphenols from grapefruit biowastes through extraction and batch adsorption process using novel resin-loaded cationic hydrogel. To prepare adsorbent, 2-(dimethylamino) ethyl methacrylate (DMAEMA) monomer was polymerized by free radical mechanisms in presence of resin particles and then tertiary amino groups on PDMAEMA residue were quaternized using methyl iodide. The developed adsorbent was then characterized by FTIR, SEM, XRD, and Brunauer, Emmet, and Teller analysis. The resin-loaded cationic hydrogel displayed an enhanced affinity for binding with polyphenols at pH value of 10 due to the strong electrostatic attraction between positively charged adsorbent surface and solute molecules. The adsorption capacity of 60 (mg-naringin-g^?1-adsorbent) was obtained when the other experimental conditions were chosen as follows: initial polyphenol concentration; 0.13?g?mL^?1, contact time; 30?min, temperature; 25°C. On the other hand, the adsorbent consisting solely of resin particles shown lower affinity for polyphenols. The adsorption results revealed that the resin-loaded cationic hydrogels exhibited significant improvement in the recovery of polyphenols from grapefruit peels through integrated extraction–adsorption process.     

Spirulina platensis‐capped mesoporous magnetic nanoparticles for the adsorptive removal of chromium

The magnetic nanoparticles prepared through the co‐precipitation method were surface modified using Spirulina platensis. The mesoporous and superparamagnetic nature of the adsorbent was confirmed by Brunauer‐Emmett‐Teller (BET) and vibrating sample magnetometer (VSM) analyses, respectively. Further, an increased specific surface area of 75.3 m²/g was reported in the BET studies. Parameters such as pH, contact time, concentration, and temperature were studied to optimize the operating conditions influencing adsorption. Thermodynamic studies justified the spontaneity and endothermic nature of adsorption. The adsorbent exhibited a better performance at 1.5 pH and 120 minutes of contact time. The monolayer adsorption capacity of the material was found to be 29.23 mg/g from the evaluation of Langmuir adsorption isotherm. The second‐ order kinetic studies suggest the predominance of chemisorption. Further, the X‐ray photoelectron spectroscopy (XPS) studies confirmed that the adsorption mechanism is electrostatic attraction accompanied by reduction. Notably, a regeneration efficiency of 75.26% was achieved with NaOH as the desorbing agent.     

Phosphate removal by Ce(III)‐impregnated crosslinked chitosan complex from aqueous solutions

A novel adsorbent, Ce(III)‐impregnated crosslinked chitosan complex (Ce‐CCS) was prepared by the methods of membrane‐forming and crosslinking for the removal of phosphate from aqueous solutions. Ce‐CCS was characterized by FTIR, X‐ray diffraction, and scanning electron microscopy combined with EDAX techniques. The adsorption of phosphate onto the Ce‐CCS was determined in batch systems as a function of initial phosphate concentration, pH, contact time, and co‐anions. The maximum adsorption occurred at pH 3 or so. The presence of co‐anions decreased the adsorption of phosphate onto the Ce‐CCS. Ce‐CCS showed a higher adsorption capacity than crosslinked chitosan (CCS) due to the introduction of Ce(III). The equilibrious data by the Ce‐CCS were fitted well with Freundlich isotherm model. The kinetic data followed the pseudo‐second‐order model. Phosphate adsorption mainly included the surface complexation and electrostatic attraction between Ce‐CCS and phosphate. Besides, the Ce‐CCS was prone to regeneration with 0.1 mol/L HCl solution. POLYM. ENG. SCI., 57:44–51, 2017. © 2016 Society of Plastics Engineers     

Valine-Coated Magnetic Nanoparticles: Synthesis,Characterization, and Application in Removal of Cd(II) Ions from Aqueous Solution

A novel Valine coated magnetic nano-particles (MNPs-Val) has been synthesized for the removal of Cd(II) ions from aqueous solution. The MNPs-Val were developed by electrostatic attraction of valine (C₅H₁₁NO₂) on the bare surface of Fe₃O₄ nanoparticles and characterized by using FT-IR, XRD, SEM, and TEM analysis. The morphology and average particles size 15-27 nm of MNPs-Val were analyzed by SEM and TEM. The coated MNPs were applied for adsorptive removal of Cd(II) ions from aqueous solutions. Factors affecting the adsorption of Cd(II) ions on the MNPs-Val surface such as the pH, temperature, adsorbent dosage, and contact time were investigated which have significant effect on the metal ion removal. The Cd(II) ions adsorption equilibrium on the MNPs-Val could be achieved in 35 min at the optimized pH 5 and follow the pseudo-second order kinetics model. The experimental data for the adsorption of Cd(II) was followed by the Langmuir isotherm and the maximum adsorption capacity was obtained at 0.2 g L^?1 adsorbent dose at 308 K.     

A novel lanthanum-modified bentonite,Phoslock, for phosphate removal from wastewaters

Phoslock^®, a lanthanum-modified bentonite, has been investigated for phosphate uptake from synthetic and real wastewaters in laboratory and field. In laboratory tests, equilibrium and kinetics were studied at various temperatures, ionic strength, and pHs. The investigation indicated that phosphate adsorption occurs through a chemisorption process. The activation energy of the adsorption process was calculated based on pseudo-second order rate constant. The maximum adsorption capacity of Phoslock was unaffected at pH 5–7, but decreased at higher pHs. The monovalent phosphate anion, H₂PO₄⁻, had the greatest affinity for the adsorbent surface. Furthermore, it was also shown that the activation energy was lower at a higher solution pH attributed to the loss of adsorption sites at the higher pHs while it remained unaffected by the ionic strength of the solution. A field test also demonstrated that the Phoslock works well for phosphate uptake in polluted waters.     

Adsorption behavior of crystal violet from aqueous solutions with chitosan–graphite oxide modified polyurethane as an adsorbent

A series of chitosan (Ch)–graphite oxide (GO)‐modified polyurethane foam (PUF) materials as adsorbents were synthesized by a foaming technique. The adsorbent was characterized through IR spectroscopy, scanning electron microscopy, and thermogravimetric analysis (TGA). Batch adsorption experiments of the cationic dye crystal violet (CV) were carried out as a function of the Ch–GO content (1.0–8.0 wt %), solution pH (2–10), dye concentration (100–300 mg/L), adsorbent dosage (10–60 mg/mL), and temperature (20–45°C). At a lower pH value, the surface of Ch–GO/PUF acquired positive charge by absorbing H⁺ ions; this resulted in a decreasing adsorption of the cationic CV dye because of electrostatic repulsion. As the pH of the aqueous system increased, the numbers of negatively charged sites increased by absorbing OH⁻ ions, and a significantly high electrostatic attraction existed between the negatively charged surface of Ch–GO/PUF and the cationic dye (CV) molecules. This led to maximum dye adsorption. The kinetics, thermodynamics, and equilibrium of CV adsorption onto Ch–GO/PUF were investigated. The equilibrium data for CV adsorption fit the Langmuir equation, with a maximum adsorption capacity of 64.935 mg/g. The adsorption kinetics process followed the pseudo‐second‐order kinetics model. Thermodynamic parameters analysis revealed that the adsorption of CV from an aqueous solution by a Ch–GO modified PUF material was a spontaneous and endothermic process. We concluded that Ch–GO/PUF is a promising adsorbent for the removal of CV from aqueous solutions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41828.     

Ability of iron(III)‐loaded carboxylated polyacrylamide‐grafted sawdust to remove phosphate ions from aqueous solution and fertilizer industry wastewater: Adsorption kinetics and isotherm studies

Iron(III)‐loaded carboxylated polyacrylamide‐grafted sawdust was investigated as an adsorbent for the removal of phosphate from water and wastewater. The carboxylated polyacrylamide‐grafted sawdust was prepared by graft copolymerization of acrylamide and N,N′‐methylenebisacrylamide onto sawdust in the presence of an initiator, potassium peroxydisulfate. Iron(III) was strongly attached to the carboxylic acid moiety of the adsorbent. The adsorbent material exhibits a very high adsorption potential for phosphate ions. The coordinated unsaturated sites of the iron(III) complex of polymerized sawdust were considered to be the adsorption sites for phosphate ions, the predominating species being H₂PO ions. Maximum removal of 97.6 and 90.3% with 2 g L^?1 of the adsorbent was observed at pH 2.5 for an initial phosphate concentration of 100 and 250 μmol L^?1, respectively. The adsorption process follows second‐order kinetics. Adsorption rate constants as a function of concentration and temperature and kinetic parameters, such as ΔG^±, ΔH^±, and ΔS^±, were calculated to predict the nature of adsorption. The L‐type adsorption isotherm obtained in the sorbent indicated a favorable process and fitted the Langmuir equation model well. The adsorption capacity calculated by the Langmuir adsorption isotherm gave 3.03 × 10^?4 mol g^?1 of phosphate removal at 30°C and pH 2.5. The isosteric heat of adsorption was also determined at various surface loadings of the adsorbent. The adsorption efficiency toward phosphate removal was tested using industrial wastewater. Different reagents were tested for extracting phosphate ions from the spent adsorbent. About 98.2% of phosphate can be recovered from the adsorbent using 0.1M NaOH. Alkali regeneration was tried for several cycles with a view to recover the adsorbed phosphate and also to restore the adsorbent to its original state. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2541–2553, 2002     

Experimental design and batch experiments for optimization of Cr(VI) removal from aqueous solutions by hydrous cerium oxide nanoparticles

Hydrous cerium oxide (HCO) was synthesized by intercalation of solutions of cerium(III) nitrate and sodium hydroxide and evaluated as an adsorbent for the removal of hexavalent chromium from aqueous solutions. Simple batch experiments and a 2⁵ factorial experimental design were employed to screen the variables affecting Cr(VI) removal efficiency. The effects of the process variables; solution pH, initial Cr(VI) concentration, temperature, adsorbent dose and ionic strength were examined. Using the experimental results, a linear mathematical model representing the influence of the different variables and their interactions was obtained. Analysis of variance (ANOVA) demonstrated that Cr(VI) adsorption significantly increases with decreased solution pH, initial concentration and amount of adsorbent used (dose), but slightly decreased with an increase in temperature and ionic strength. The optimization study indicates 99% as the maximum removal at pH 2, 20 °C, 1.923 mM of metal concentration and a sorbent dose of 4 g/dm³. At these optimal conditions, Langmuir, Freundlich and Redlich–Peterson isotherm models were obtained. The maximum adsorption capacity of Cr(VI) adsorbed by HCO was 0.828 mmol/g, calculated by the Langmuir isotherm model. Desorption of chromium indicated that the HCO adsorbent can be regenerated using NaOH solution 0.1 M (up to 85%). The adsorption interactions between the surface sites of HCO and the Cr(VI) ions were found to be a combined effect of both anion exchange and surface complexation with the formation of an inner-sphere complex.     

Fluoride ions adsorption from water by CaCO3 enhanced Mn–Fe mixed metal oxides

Novel CaCO₃-enhanced Mn–Fe mixed metal oxides (CMFC) were successfully prepared for the first time by a simple-green hydrothermal strategy without any surfactant or template combined with calcination process. These oxides were then employed as an adsorbent for adsorptive removal of excess fluoride ions. The adsorbent was characterized by SEM, XPS, XRD, FTIR, and BET analysis techniques. The adsorption property of CMFC toward fluoride ion was analyzed by batch experiments. In fact, CMFC exhibited adsorption capacity of 227.3 mg∙g^‒1 toward fluoride ion. Results showed that ion exchange, electrostatic attraction and chemical adsorption were the main mechanism for the adhesion of large amount of fluoride ion on the CMFC surface, and the high adsorption capacity responded to the low pH of the adsorption system. When the fluoride ion concentration was increased from 20 to 200 mg∙L^‒1, Langmuir model was more in line with experimental results. The change of fluoride ion adsorption with respect to time was accurately described by pseudo-second-order kinetics. After five cycles of use, the adsorbent still maintains a performance of 70.6% of efficiency, compared to the fresh adsorbent. Therefore, this material may act as a potential candidate for adsorbent with broad range of application prospects.     

Reuse of a waste adsorbent poly(AAc/AM/SH)‐Cu superabsorbent hydrogel,for the potential phosphate ion removal from waste water: Matrix effects,adsorption kinetics,and thermodynamic studies

The most commonly applied methods for the treatment of used adsorbents is to recover them in acid/alkaline medium or direct enflame them. This work dealt with a new potential and economic method to utilize a waste adsorbent. Poly(AAc/AM/SH) superabsorbent hydrogels have proved to be a good adsorbent for Cu²⁺ ions and after adsorption the hydrogels were recovered in acid medium. In this report, the Cu²⁺ ion adsorbed hydrogel has not undergone any regeneration process and applied directly to phosphate ion adsorption. The Cu²⁺ ions‐loaded poly(AAc/AM/SH) hydrogels, were stable within a wide pH range and suitable for phosphate ion adsorption. The factors affecting the phosphate adsorption, such as pH, ionic strength, contact time, temperature, initial concentration of the phosphate ion, and coexisting ions were systematically investigated. The phosphate adsorption was highly pH dependent; and the maximum adsorption of 87.62 mg/g was achieved at pH 6.1. The adsorption data fitted the Langmuir adsorption isotherm better than the Freundlich isotherm. The concomitant anions show profounder adverse influence on phosphate ion adsorption of poly(AAc/AM/SH)‐Cu hydrogel and the effect follows the order citrate > sulfate > bicarbonate > chloride > nitrate. The thermodynamic parameters including ΔH°, ΔG°, and ΔS° for the adsorption processes of phosphate ions on the gel were also evaluated, and the negative ΔG° and ΔH° confirmed that the adsorption process was spontaneous and exothermic. The adsorption kinetic results suggest that the adsorption process was well described by the pseudo second‐order kinetic model. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013