镧改性核桃壳生物炭制备及吸附水体磷酸盐性能

为研发低成本的磷酸盐吸附剂,以核桃壳为原料,LaCl₃为改性试剂热解制备核桃壳生物炭。通过SEM-EDS、ICP-OES、FTIR和XRD对生物炭进行表征,采用吸附等温模型和动力学模型拟合生物炭的吸磷特征,并研究热解温度、La改性浓度、添加量、初始溶液pH和共存离子对生物炭吸附磷的影响。结果表明：La改性后,生物炭表面由于负载了La₂O₃和LaOCl,其吸附能力明显提高。热解温度为400℃、La浸渍浓度为0.1mol/L时获得的生物炭（BC-La400）,其Langmuir最大磷吸附容量为12.18mg/g,吸附过程主要受化学吸附和颗粒内扩散控制。热解温度和La改性浓度过高均不利于磷的吸附。磷初始浓度为50mg/L时,BC-La400添加量为2.7g/L可获得较理想的吸附能力,但当添加量超过4.0g/L时,磷脱除率可超过98%。BC-La400吸磷时最佳初始pH为3,CO{}_{\mathrm{3}}^{\mathrm{2}-}共存会明显削弱BC-La400对磷的吸附能力。     

Kinetics, mechanism, isotherm and thermodynamic analysis of adsorption of cadmium ions by surface-modified Strychnos potatorum seeds

The surface-modified Strychnos potatorum seeds (SMSP) were used as an effective low-cost adsorbent for the removal of cadmium ions from aqueous solution. SMSP was characterized by Fourier transform infrared spectroscopy and scanning electron microscopic analyses. The effect of operating variables such as solution pH, adsorbent dose, contact time, initial cadmium ions concentration and temperature on the removal of cadmium ions were studied in a batch mode adsorption operation. The optimum conditions for the adsorption of cadmium ions onto the SMSP were found to be: pH of 5.0, SMSP dose of 2 g/L, contact time of 30min, temperature of 30 °C for an initial cadmium ions concentration of 100 mg/L. Kinetic data were analyzed using the pseudo-first order and pseudo-second order kinetic equations, intraparticle diffusion model, Boyd kinetic model and shrinking core model. The characteristic parameters for each model have been estimated. Adsorption of cadmium ions onto the SMSP follows the pseudo-second order kinetic model. The rate-limiting steps in the adsorption process were found to be external and internal diffusion. Equilibrium data were well described by the Langmuir isotherm model than the Freundlich isotherm model, which yields a maximum monolayer adsorption capacity of 200 mg/g. Thermodynamic parameters such as standard free energy change, enthalpy change and entropy change were also estimated. The results show that the removal of cadmium ions by the SMSP was found to be spontaneous and exothermic.     

Adsorption isotherms,kinetic, and desorption studies on removal of toxic metal ions from aqueous solutions by polymeric adsorbent

Adsorption of Cd(II), Co(II), and Ni(II) on aminopyridine modified poly(styrene‐alt‐maleic anhydride) crosslinked by 1,2‐diaminoethane as an ion exchange resin has been investigated in aqueous solution. Adsorption behavior of these metal ions on the resin was studied by varying the parameters such as pH (2–6), adsorbent dose (0–4.0 g/L), contact time (0–240 min), and metal ions concentration (20–300 mg/L). Adsorption percentage was increased by increasing each of these parameters. The isotherm models such as: Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich were used to describe adsorption equilibrium. The results showed that the best fit was achieved with the Langmuir isotherm equation, yielding maximum adsorption capacities of 81.30, 49.02, and 76.92 mg/g for Cd(II), Co(II), and Ni(II), respectively. The pseudo‐first‐order, pseudo‐second‐order, and intra‐particle diffusion kinetics equations were used for modeling of adsorption data and it was shown that pseudo‐second‐order kinetic equation could best describe the adsorption kinetics. The intra‐particle diffusion study revealed that external diffusion might be involved in this case. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41642.     

Surfactant-modified bentonite as adsorbent for the removal of humic acid from wastewaters

The effectiveness of surfactant-modified bentonite (SMB) in removing humic acid (HA) from wastewaters was evaluated. Hexadecyl trimethylammonium (HDTMA) chloride was used to modify the surface of the clay mineral. The SMB exhibits very high adsorption potential for HA and at pH 3.0 more than 99% removal was achieved from an initial concentration of 25 μmol/L. The experimental kinetic data were analyzed using the pseudo-first-order kinetic model. Adsorption occurs through film diffusion at low as well as at higher concentrations and temperatures. The adsorption of HA using SMB was an exothermic process. HA adsorption was found to decrease with increase of ionic strength due to the formation of outer-sphere surface complexes on SMB. The equilibrium isotherms were determined and data were analysed using the Langmuir isotherm model. The maximum adsorption capacity, Q° was 73.52 μmol/g with binding constant, b = 0.155 L/μmol at 30 °C and pH 3.0. The adsorbent was suitable for repeated use (more than 3 cycles) without any noticeable loss of capacity.     

海藻酸钠-氢氧化镧改性Y型分子筛颗粒除氟研究

为解决除氟吸附剂分离困难、有效成分流失等问题,以海藻酸钠（SA）与氢氧化镧改性Y型分子筛（LHMS）为原料,采用滴球法制备了SA@LHMS颗粒吸附剂,并采用模拟废水对其进行了除氟研究。通过正交实验确定了吸附剂最佳制备条件,并通过间歇吸附实验测试了吸附剂投加量、pH、共存离子等因素对吸附的影响,探究了吸附速率、吸附等温线等吸附性能。结果表明,SA@LHMS吸附速率曲线符合拟二级反应速率方程;吸附等温线符合Ⅱ型等温线,为多分子层吸附;初始pH（3~12）对吸附效果没有显著影响;高浓度共存阴离子（50 mg/L）对吸附过程有一定抑制;1 mol/L和2 mol/L氢氧化钠溶液对SA@LHMS再生效果较好,经3次再生仍然保留较高的吸附能力。SA@LHMS颗粒表面和截面形态以及吸附前后颗粒的表面形态差异明显;吸附前后颗粒表面能谱（EDS）分析以及红外光谱（FT-IR）分析结果显示,吸附过程中溶液中的氟离子（F^-）与颗粒表面及内部的羟基（—OH）发生配体交换。     

Arsenic adsorption on goethite nanoparticles produced through hydrazine sulfate assisted synthesis method

Goethite nanoparticles synthesized using hydrazine sulfate as a modifying agent were evaluated for As(V) adsorption capacity. The nanoparticles were characterized for their morphological and structural features. The precipitated goethite particles were spherical with particle size of less than 10 nm. Batch adsorption study was carried out systematically varying parameters such as pH, contact time, initial As(V) concentration and adsorbent doses. The Langmuir isotherm represented the equilibrium data well and the estimated monolayer adsorption capacity at ambient temperature was 76 mg/g, which is significantly higher than most of the adsorbents reported in the literature. Adsorption kinetic data were better represented by the pseudo-second order kinetic model. Intra-particle diffusion played a significant role in the rate controlling process in the initial hour. Desorption study showed that the loaded adsorbent could be regenerated when treated with dilute sodium hydroxide solution of pH 13.     

PBMA/GMA-SiO2吸附剂的制备及其高效去除铅离子

以甲基丙烯酸丁酯(BMA)和甲基丙烯酸缩水甘油酯(GMA)功能化的纳米SiO2为单体,通过可逆加成-断裂链转移自由基聚合(RAFT)法制备了PBMA/GMA-SiO2有机/无机复合吸附材料,并将其用于吸附含Pb2+的水溶液。考察了吸附时间、温度、pH以及Pb2+初始质量浓度对吸附效果的影响,并对其吸附动力学和热力学特性进行了探讨。结果表明,PBMA/GMA-SiO2对Pb2+具有良好的吸附性能,其对Pb2+的饱和吸附量为423.84mg/g,吸附最佳pH=5~6,平衡时间为1 h,去除率随Pb2+初始质量浓度的减小而增加。优化实验条件下,50 mg吸附剂在298 K时,对pH=6的50 mL 0.02 g/L含Pb2+溶液的去除率高达100%。热力学和动力学过程模拟结果表明,吸附的动力学过程比较符合准二级动力学速率方程,Langmuir等温方程比Freundlich等温方程更适合于描述此吸附行为。颗粒内扩散过程是吸附速率的控制步骤,但不是唯一的速率控制步骤。吸附剂经过5次脱附、吸附后,依然具有较强吸附Pb2+的能力。     

Adsorption of anionic textile dye Acid Green 9 from aqueous solution onto weak or strong base anion exchangers

The aim of this work is to study the thermodynamic and kinetic studies with regard to the adsorption of Acid Green 9 (AG9) on the most efficient resin, namely, acrylic weak base anion exchange resin with ethylenediamine‐functional groups (A1) selected from several anion exchange resins. The influence of the various experimental parameters such as, pH, initial dye concentration, contact time, temperature, and adsorbent dose was investigated by batch experiments. The extent of the dye adsorption increased with the decrease of the initial dye concentration and the increase of the contact time, temperature, and amount of the adsorbent. Adsorption process was quantitative and very fast at low concentrations of the dye. To investigate the mechanism of the adsorption and potential rate‐controlling steps, pseudo first‐ and second‐order, as well as intraparticle diffusion kinetic equations have been used. The adsorption kinetic of AG9 dye from aqueous solution onto A1 could be described by the pseudo second‐order reaction model. The obtained results are in agreement with the Langmuir and Freundlich models. In the optimum conditions established, an adsorption capacity of 500 mg textile dye (72% purity) g^?1 adsorbent (at 293 K) was reached. Desorption experiments by batch and dynamic methods were performed using a solution of 0.05 mol L^?1 NaOH. A series of 13 adsorption–desorption cycles were carried out by the dynamic method with a quantitative adsorption and the desorption efficiency higher than 95%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Removal of arsenic from aqueous solution using polyaniline/rice husk nanocomposite

The present study deals with the adsorption of arsenic ions from aqueous solution on polyaniline/rice husk (PAn/RH) nanocomposite. Batch studies were performed to evaluate the influence of various experimental parameters like pH, adsorbent dosage, contact time and the effect of temperature. Optimum conditions for arsenic removal were found to be pH 10, adsorbent dosage of 10 g/L and equilibrium time 30 minutes. Adsorption of arsenic followed pseudo-second-order kinetics. The equilibrium adsorption isotherm was better described by Freundlich adsorption isotherm model. The adsorption capacity (q _max ) of PAn/RH for arsenic ions in terms of monolayer adsorption was 34.48 mg/g. The change of entropy (ΔS⁰) and enthalpy (ΔH⁰) was estimated at −0.066 kJ/(mol K) and −22.49 kJ/mol, respectively. The negative value of the Gibbs free energy (ΔG⁰) indicates feasible and spontaneous adsorption of arsenic on PAn/RH.     

Adsorption of Pb(II) by Peanut Hull Carbon from Aqueous Solution

Abstract

Carbon prepared from peanut hulls (PHC) has been used for the adsorption of Pb(II) over a range of initial metal ion concentrations (10–20 mg/L), agitation times (5–140 minutes), adsorbent dosages (5–100 mg/100 mL), and pH values (1.5–10.0). Adsorption of Pb(II) obeyed the Langmuir isotherm. The applicability of the Lagergren kinetic model has also been investigated. Quantitative removal of 20 mg/L Pb(II) by 0.3 g carbon per liter aqueous solution was observed in the pH range of 3.0 to 10.0. A comparative study with a coal-based commercial granular activated carbon (CAC) showed that the adsorption capacity of PHC was 18 times larger than that of CAC.     

Removal of methylene blue dye from aqueous solutions by a new chitosan/zeolite composite from shrimp waste: Kinetic and equilibrium study

The adsorption of methylene blue dye (MBD) from aqueous solutions was investigated using a new composite made up of shrimp waste chitosan and zeolite as adsorbent. Response surface methodology (RSM) was used to optimize the effects of process variables, such as contact time, pH, adsorbent dose and initial MBD concentration on dye removal. The results showed that optimum conditions for removal of MBD were adsorbent dose of 2.5 g/L and pH of 9.0, and initial MBD concentration of 43.75 mg/L and contact time of 138.65 min. The initial concentration of dye had the greatest influence on MBD adsorption among other variables. The experimental data were well fitted by the pseudo-second order kinetic model, while the Freundlich isotherm model indicated a good ability for describing equilibrium data. According to this isotherm model, maximum adsorption capacity of the composite was 24.5 mg/g. Desorption studies showed that the desorption process is favored at low pH under acidic conditions.     

Phosphate adsorption characteristics of alunite to be used as a cement additive

The adsorption of phosphate from aqueous solution by alunite has been investigated as a function of calcination temperature, particle size, pH, agitation time and initial phosphate concentration. Phosphate adsorption was seen to increase with increasing calcination temperature, decreasing adsorbent particle size and pH. The adsorption isotherm data were fitted to the Langmuir isotherm. The alunite exhibited the highest phosphate uptake capacity at 1073 K calcination temperature, at a particle size of 90-150 μm, at the initial pH of 5.0, at an equilibrium time of 60 min and at the initial phosphate concentration of 20×10⁻⁴ mol/l. The adsorption capacity, Q, was 4.697×10⁻³ mol/g at initial pH 5.0.     

Adsorption study of hexavalent chromium using tamarind hull-based adsorbents

The adsorption characteristics of hexavalent chromium was studied with an adsorbent developed from waste tamarind hull. Experiments were conducted in batch mode to observe the influence of different parameters such as initial concentration of metal ions, adsorbent dosage, adsorbent particle size, stirrer speed, temperature and pH of the solution. Acidic pH strongly favored the adsorption. With decreasing the pH of the solution from 5.0 to 1.0, the removal of chromium was enhanced from 33% to 99%. The adsorption process was found to follow a pseudo-first-order rate mechanism and the rate constant was evaluated at 30 °C. The Freundlich, Redlich–Peterson and the Fritz–Schlunder isotherm fit the equilibrium data satisfactorily. Adsorption of chromium was found to increase with increase in the process temperature. Using an adsorbent dosage of 1.0 g/L and an acidic pH (2.0), the equilibrium adsorption capacity of the prepared adsorbent was found to be about 70 mg/g at 30 °C, which increased to about 81 mg/g at 50 °C. The entropy change, free energy change and heats of adsorption were determined for the process.     

Removal of Pb(II) from Aqueous Solutions by using Chitosan Coated Zero Valent Iron Nanoparticles

This study reports the synthesis, characterization, and application of chitosan coated zero valent iron nanoparticles (CTS-Fe⁰) in the removal of Pb(II) from aqueous medium. This nano adsorbent showed a high adsorption capacity and efficient adsorption towards Pb(II) in aqueous medium. Adsorption of Pb(II) on CTS-Fe⁰ obeyed pseudo-second order kinetics and was controlled by a film diffusion process. Among the various isotherm models the experimental data followed the Langmuir isotherm and the maximum adsorption capacity was found to be 666.6 mg/g at pH 5.0 and 318 K. The sorption mean free energy from D-R isotherm was found to be 72, 131, and 177 J/mol at 298, 308, and 318 K, respectively, indicating a physical sorption. The percentage of Pb(II) removal by CTS-Fe⁰ particles is more than 90% at 318 K. The calculated thermodynamic parameters showed that the adsorption of Pb(II) is feasible, spontaneous, and endothermic in nature. Experimental results indicated that the CTS-Fe⁰ appears to be a promising adsorbent for the removal of Pb(II) from aqueous media.     

高吸水性树脂Super-Ⅰ对Pb~(2+)的吸附性能

考察了聚(丙烯酸—co—丙烯酰胺)/凹凸棒黏土高吸水性树脂吸附剂(标记为Super-Ⅰ)对重金属Pb2+的吸附行为及溶液pH(3.0~7.0)、吸附时间(0~720 m in)、Pb2+溶液初始浓度(0.002 5~0.03 mol/L)和吸附剂加入量(0.08~0.30 g)等因素对吸附性能的影响。在pH=6.0、吸附时间60 m in、Pb2+溶液初始浓度0.02 mol/L和吸附剂用量0.1 g条件下,该吸附剂对Pb2+的吸附量达到296.0 mg/g。高吸水性树脂吸附剂对Pb2+的吸附行为符合准二级动力学模型和Langmu ir等温线模型。与常用多孔吸附剂相比,该三维网络吸附剂对Pb2+的吸附量高出1~2个数量级。     

Adsorption of Lignosulfonate Compound from Aqueous Solution onto Chitosan-Silica Beads

The main objective of this study is to investigate the possibility of crosslinked chitosan-tetraethoxy orthosilane (TEOS) (chitosan-silica) beads to be used as an adsorbent material to adsorb the lignosulfonate compound in solution. Different parameters affecting the adsorption capacity such as contact time, adsorbent dosage, initial concentration, pH, ionic strength, and temperature have been investigated. Adsorption isotherms of lignosulfonates onto chitosan-silica beads were also studied. Batch adsorption experiments were carried out and the optimum lignosulfonate adsorption onto chitosan-silica beads occurred at contact time of 30 minutes, the adsorbent dosage of 40 g/L, initial concentration of 50 mg/L, pH 5, and a temperature of 45°C. Adsorption isotherms studied through the use of graphical methods revealed that the adsorption of lignosulfonates onto chitosan-silica beads follows the Langmuir model, with the maximum adsorption capacity being 238.3 mg/g at pH 7. Adsorption is dependent on the ionic strength. The adsorption of lignosulfonate on chitosan-silica beads was best described with the pseudo-second-order kinetic model with a rate constant of 0.32 g · mg^?1 · min^?1, while intra-particle-diffusion was the main rate-determining step in the lignosulfonate adsorption process. The chitosan-silica beads investigated in this study were thus exhibited as a high potential adsorbent for the removal of lignosulfonate from solution.     

活性污泥对垃圾渗滤液吸附等温线的研究

采用MLSS为6000mg／L的活性污泥为吸附剂,对水样进行三级吸附试验,研究了在不同的曝气时间、pH和污泥浓度对活性污泥吸附量的影响及活性污泥吸附深度处理垃圾渗滤液的吸附等温线。试验结果表明：活性污泥吸附平衡时间为2h,pH为3～9时,活性污泥吸附量几乎不变。随着污泥浓度的升高,活性污泥的吸附量增大,污泥浓度升至6000mg／L后吸附量变化不大。一级、二级活性污泥吸附等温线更好的符合Freundlich公式等温式,吸附常数n介于1～10之间,说明活性污泥是良好的吸附剂,三级活性污泥吸附等温线则更好的符合Iangmuir公式等温式。     

Radiation synthesis of poly(N‐vinylpyrrolidone‐co‐methacrylic acid) hydrogels and their usability in uranyl ion adsorption

In this study, N‐vinylpyrrolidone(VP)/methacrylic acid (MAA) mixtures have been prepared at three different mole percents which the methacrylic acid composition around 5, 10, and 15%. Poly(N‐vinylpyrrolidone‐co‐methacrylicacid) P(VP/MAA) hydrogels irradiated at 3.4 kGy have been used for swelling and diffusion studies in water and uranyl ion solutions. The influence of dose, pH, relative amounts of monomers in MAA/VP monomer mixtures on the swelling properties have been investigated. P(VP/MAA) hydrogels were swollen in distilled water at pH 7.0. P(VP/MAA)1 hydrogel containing 36% (mole percent) methacrylic acid showed the maximum percent swelling in water. Adsorption isotherms were constructed for uranyl ions and P(VP/MAA) hydrogel systems. It has been found that P(VP/MAA) hydrogels have very high uptake of the uranyl ions succesfully in water containing uranyl ions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Application of ethylenediamine hydroxypropyl tamarind fruit shell as adsorbent to remove Eriochrome black T from aqueous solutions – Kinetic and equilibrium studies

Ethylenediamine Hydroxypropyl Tamarind Fruit Shell (EDAHP-TFS) was synthesized to remove Eriochrome Black T (EBT) from aqueous solutions. Maximum adsorption occurred at pH 2.0 and equilibrium time 2 h. Adsorption increased with increase in initial concentration and temperature. Adsorption kinetics obeyed the pseudo-second-order model and indicates a partial ion exchange, followed by the complexation mechanism. Lower E^# (4.48 kJ/mol) represents film diffusion as the rate-limiting step. EBT removal followed the Sips isotherm model with a maximum adsorption capacity of 0.237 mmol/g at 30ºC. Isosteric heat of adsorption (ΔH_i) decreased with increase in surface loading, indicating heterogeneous adsorption sites. Desorption studies were carried out and 96.4% recovery was achieved at pH 11.0.     

活性炭吸附处理化学镀镍废液的研究

研究了粉状活性炭对水溶液中低质量浓度柠檬酸络合镍离子的吸附行为,在静态吸附条件下,考察了柠檬酸络合剂质量浓度、吸附剂投加量、pH、温度等因素对粉状活性炭吸附镍离子的影响.试验结果表明,溶液pH和粉状活性炭投加量是影响镍离子吸附的重要因素.溶液初始pH为11.0,ρ(活性炭)为10.0g/L时,镍离子的去除率达到72.3...