介孔碳CMK-3对苯酚的吸附动力学和热力学研究

研究了介孔碳CMK-3对苯酚的吸附性能, 与传统商用活性碳(CAC)进行了比较, 结果表明, CMK-3比CAC的吸附量大、吸附速率快、达到平衡时间短, 是一种较好的吸附剂. 同时探讨了介孔碳CMK-3对苯酚的吸附热力学和动力学特征. CMK-3对苯酚的吸附行为可用Langmuir和Freundlich等温式进行描述, 相关性都较好, 但更符合Freundlich经验公式. 分别采用模拟一阶反应和二阶反应模型考察了吸附动力学, 并计算了这些动力学模型的速率常数. 模拟二级反应模型和实验数据之间有较好的相关性. 分别计算了热力学参数ΔG0, ΔS0和ΔH0, 结果表明, CMK-3对苯酚的吸附过程是吸热和自发的.     

Amin-functionalized magnetic-silica core-shell nanoparticles for removal of Hg2+ from aqueous solution

Magnetic nanoparticles with monodisperse shape and size were prepared by a simple method and covered by silica. The prepared core-shell Fe₃O₄@silica nanoparticles were functionalized by amino groups and characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR) techniques. The synthesized nanoparticles were employed as an adsorbent for removal of Hg²⁺ from aqueous solutions, and the adsorption phenomena were studied from both equilibrium and kinetic point of views. The adsorption equilibriums were analyzed using different isotherm models and correlation coefficients were determined for each isotherm. The experimental data were fitted to the Langmuir–Freundlich isotherm better than other isotherms. The adsorption kinetics was tested for the pseudo-first-order, pseudo-second-order and Elovich kinetic models at different initial concentrations of the adsorbate. The pseudo-second-order kinetic model describes the kinetics of the adsorption process for amino functionalized adsorbents. The maximum adsorption occurred at pH 5.7 and the adsorption capacity for Fe₃O₄@silica-NH₂ toward Hg²⁺ was as high as 126.7 mg/g which was near four times more than unmodified silica adsorbent.     

复合改性膨胀石墨的制备及对酸性艳蓝染料的吸附

采用相同反离子协同磷酸活化法, 以十六烷基三甲基溴化铵(CTAB)-KBr为复合改性剂, 制备了一种高效吸附剂复合改性膨胀石墨(M-EG), 通过扫描电子显微镜(SEM)、 傅里叶变换红外光谱(FTIR)及X射线电子能谱(XPS)等对膨胀石墨(EG)和改性膨胀石墨(M-EG)的形貌结构、 组成和价态进行了表征, 考察了EG和M-EG对酸性艳蓝染料废水的处理效果. 结果表明, 复合改性后的膨胀石墨孔隙度变大, 表面含氮和溴官能团增多. 吸附剂M-EG对酸性艳蓝染料废水具有较高的吸附性能, 在pH=1.0及30 ℃条件下对染料的去除率达到94.13%; EG符合二级动力学吸附模型, 用Langmuir等温线方程拟合效果较好; M-EG符合二级吸附动力学方程, 同时符合Langmuir和Freundlich等温吸附模型; M-EG的吸附动力学常数大于EG吸附动力学常数.     

Highly efficient removal of diazinon pesticide from aqueous solutions by using coconut shell-modified biochar

This study evaluates the adsorption of diazinon from aqueous solutions onto coconut shell-modified biochar using a batch system. The amount of dosage and initial pH are the main parameters being studied to obtain maximum adsorption capacity of the probe molecules. The carbonized coconut shell biochar (BC1), activated coconut shell biochar (BC2), chemically modified phosphoric acid (BC3) and sodium hydroxide coconut shell biochar (BC4) were prepared and tested as variables in the adsorption experiment. The characteristic of biochar via SEM, EDX and BET analysis revealed the large porous of surface morphology and slight changes in the composition with high surface area (405.97 – 508.07 m²/g) by following the sequence of BC3 > BC2 > BC4. Diazinon removal percentage as high as 98.96% was achieved at pH 7 with BC3 as adsorbent dosing at 5.0 g/L. The high coefficient of determination, R² with a small value of ERRSQ and χ² error analysis present the BC1 (0.9971) and BC2 (0.9999) are best fitted with Freundlich isotherm indicates multilayer sorption onto heterogeneous surface whereby the Langmuir isotherm model is the best fitting is described of monolayer adsorption process onto the homogenous surface of BC3 and BC4. The results indicated the maximum adsorption capacity (q_m) was achieved by BC3 with 10.33 mg/g, followed by BC2 (9.65 mg/g) in accordance to the Langmuir isotherm while Freundlich isotherm showed the highest adsorption capacity (k_F) with 1.73 mg/g (L/mg)^1/n followed by BC4 with 0.63 mg/g (L/mg)^1/n at favorable adsorption isotherm (1 ≤ n ≤ 10). Thus, the results obtained depicted that BC2 and BC3 are highly efficient adsorbents and both exhibit great potential in removing diazinon from aqueous solutions.     

Adsorption of U (VI) ions from aqueous solution using silicon dioxide nanopowder

The adsorption kinetics for removal of uranium (V1) from aqueous solution using silicon dioxide nanopowder (nano-SiO₂) was investigated in batch and continuous techniques. Pseudo-first order and pseudo-second order were used to analyze the kinetics of batch experiments. In continuous technique the important parameters (initial concentration, flow rate and bed height) on the breakthrough curves were studied and the adsorption kinetics was analyzed using Thomas and Yoon and Nelson kinetic models. The comparison between the kinetic models was evaluated by the correlation coefficients (r²). The results indicated that the batch experiments fitted well with pseudo second-order kinetic model. The comparison of the experimental breakthrough curve to the breakthrough profile obtained from Thomas and Yoon and Nelson methods showed a satisfactory fit for silicon dioxide nanopowder.     

疏水层析蛋白质动力学与平衡过程的考察

疏水层析是分离生物大分子的常用技术之一，但对疏水层析中蛋白质吸附动力学和平衡过程的研究并不多见．本文对蛋白质疏水吸附动力学和平衡过程作了基本假设，并用实验进行了验证。制备了两种不同丁基密度的疏水琼脂糖介质，用其吸附牛血清白蛋白(BSA)以验证对疏水吸附动力学与平衡过程作的假设，考察了盐浓度及配基密度对蛋白质疏水吸附的影响．还对三种疏水性不同的蛋白质：核糖核酸酶、卵清蛋白和牛血清白蛋白的混合体系进行了分离性能的研究，获得了满意的分离效果．实验表明，蛋白质在疏水介质上的吸附动力学和平衡过程与所作假设相符，在实验条件下等温吸附线符合Langmuir吸附等温方程：研制的丁基琼脂糖疏水介质具有优良的使用性能。     

负载金属镧的壳聚糖对氟离子的吸附动力学

利用负载金属镧的壳聚糖对含氟水进行吸附处理.该除氟剂的最佳吸附条件:pH值为7,温度为323K,吸附时间为60min.吸附剂对F的吸附过程符合Langmuir等温线方程,对F的饱和吸附容量为476.190mg/g.吸附动力学符合拟二级速率方程,颗粒内扩散过程和液膜形成的边界层是吸附过程的主要限速步骤.     

Removal of Thiram from Aqueous Solutions

In this study activated carbon was used for the removal of thiram from aqueous solutions. Adsorption experiments were carried out as a function of time, initial thiram concentration and temperature. Equilibrium data fitted well to the Freundlich and Langmuir equilibrium models in the studied concentration range. Adsorption kinetics followed a pseudo second‐order kinetic model rather than pseudo first‐order model. The results from kinetic experiments were used to describe the adsorption mechanism. Both boundary layer and intraparticle diffusion played important role in the adsorption mechanism of thiram. Thermodynamic parameters (ΔG₀, ΔH₀, and ΔS₀) were determined and the adsorption process was found to be an endothermic one. The negative values of ΔG⁰ at different temperatures were indicative of the spontaneity of the adsorption process.     

Removal of methylene blue from aqueous solutions using Poly(AA-co-DVB)

Functional cross-linked polymers (Poly(AA-co-DVB)) were synthesized using a one-step method. The properties of Poly(AA-co-DVB) were measured by SEM, FTIR, and TGA. The adsorption capacity of the Poly(AA-co-DVB) was investigated using methylene blue as an adsorbate. The effect of the mole compositions of acrylic acid and divinylbenzene monomers on the adsorption capacity was investigated in detail. The initial pH of solutions and contact time were also studied. The kinetics and isotherms of the adsorption process were also investigated. The result showed that the maximum equilibrium adsorption capacity was 1698.9?mg/g at room temperature and the adsorption kinetic was well fitted by a pseudo-second-order model and the adsorption isotherm agreed well with the Langmuir model.     

阴离子型有机化合物在LDHs上的动力学和热力学研究

本文考察水滑石焙烧产物MgAl-LDO吸附3种阴离子染料AcidRed88（AR88）、AcidOrange 3（AO3）、AcidViolet90（AV90）过程中的热力学和动力学机理,并在不同温度下探究该吸附过程的热力学参数。实验结果表明：MgAl-LDO对染料阴离子的吸附过程复合Langmuir吸附等温模型,且为自发、放热的过程。3种染料在MgAl-LDO上的吸附过程均符合准二级反应动力学模型,且该吸附过程是由MgAl-LDO与阴离子染料之间的反应速率控制而不是两者之间的扩散作用。计算所得的吉布斯自由能绝对值在7~15kJ·mol^-1,这主要是由染料阴离子与MgAl-LDHs层板的氢键作用产生,结合MaterialsStudio 5.5软件模拟染料分子在MgAl-LDHs上的排列分布,推测MgAl-LDO对阴离子染料的吸附机理是表面吸附（占优势）与层间插层的协同作用。     

阴离子型有机化合物在LDHs上的动力学和热力学研究

考察了水滑石焙烧产物MgAl-LDO吸附3种阴离子染料Acid Red 88(AR88)、Acid Orange 3(AO3)、Acid Violet 90(AV90)过程中的热力学和动力学机理,并在不同温度下探究该吸附过程的热力学参数。实验结果表明:MgAl-LDO对染料阴离子的吸附过程复合Langmuir吸附等温模型,且为自发、放热的过程。3种染料在MgAl-LDO上的吸附过程均符合准二级反应动力学模型,且该吸附过程是由MgAl-LDO与阴离子染料之间的反应速率控制而不是两者之间的扩散作用。计算所得的吉布斯自由能绝对值在7~15 kJ·mol-1,这主要是由染料阴离子与MgAl-LDHs层板的氢键作用产生,结合Materials Studio 5.5软件模拟染料分子在MgAl-LDHs上的排列分布,推测MgAl-LDO对阴离子染料的吸附机理是表面吸附(占优势)与层间插层的协同作用。     

Oxalic acid removal from wastewater using multi-walled carbon nanotubes: Kinetic and equilibrium analysis

Oxalic acid adsorption from aqueous solution is studied in this work. Multi-walled carbon nanotubes (MWCNT) were used as an adsorbent. The investigated adsorption variables are equilibrium time, initial acid concentration, and temperature. The experimental results were presented using equilibrium isotherm and kinetic models. The used equilibrium models are Langmuir, Freundlich, and Temkin adsorption isotherms. And the kinetic models are Elovich, Lagergren pseudo-first-order and pseudo-second-order kinetic models. The thermodynamics studies were carried out at three different temperatures: 278, 298, and 318 K. Langmuir isotherm was the best fitted equilibrium model for the experimental data. The all applied kinetic models fitted the data suitably.     

Synthesis and characterization of bisphenol-A imprinted polymer as a selective recognition receptor

Molecularly imprinted polymers (MIPs) are currently used to provide selectivity in chemical sensors. In this context, a non-covalent bisphenol-A (BPA)-imprinted polymer using 4-vinylpyridine (4-Vpy) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as crosslinker and a low volatile solvent, triethylene glycol dimethyl ether (TRIGLYME), in combination with a non-reactive linear polymer, poly (vinyl acetate) (PVAc), as porogen, was synthesized with a simple polymerization procedure. Batch rebinding experiments were carried out to evaluate the binding and selectivity properties of the BPA-MIP. The experimental adsorption isotherms were fitted and a heterogeneous distribution of the binding sites was found. The selectivity of MIP demonstrated higher affinity for target BPA and BPA-analogues over other common water pollutants. The adsorption kinetics followed the pseudo-second-order kinetic model so that the specific adsorption in the imprinted cavities by two strong hydrogen bonds could be described as a chemisorption process. The diffusion mechanism was determined by the intra-particle diffusion and Boyd models, both of them revealing that the adsorption was mainly governed by intra-particle diffusion. MIP was shown to be promising for regeneration without significant loss in adsorption capacity.     

Efficiency of Acacia Gummifera powder as biosorbent for simultaneous decontamination of water polluted with metals

Biosorbent materials represent an interesting alternative to classic methods of metal removal from industrial effluents. Acacia biomass showed a higher absorption capacity for heavy metals than living biomass. This study aimed to evaluate the bioadsorption of Lead and Cadmium onto Acacia Gummifera gum, using batch experiment. The structural characterization of the biosorbent was carried out using FT-IR, SEM, BET, TGA and DSC analysis. The adsorption equilibrium was reached within 15 min. A maximum uptake of 18.3 mg.g⁻¹ Pb²⁺ and 9.57 mg.g⁻¹ Cd²⁺ was achieved at pH 6.5. The metal ions seemed to be removed exclusively by ion exchange, physical sorption and chelation. The biomass of A. Gummifera powder was found to be effective for lead and cadmium removal with respectively 97% and 86% sorption efficiency at a concentration of 100 mg/L, in aqueous media. Parameters affecting adsorption capacities such as biosorbent dosage, initial metal concentration, temperature, and pH are discussed in detail. Furthermore, adsorption thermodynamics, kinetics, and equilibrium were studied and fitted by different models. Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms were used to compare adsorption data at equilibrium. The adsorption kinetics data were found to be best fitted by the pseudo-second-order model, and the adsorption isotherm was well fitted with the Langmuir model. The calculated thermodynamic parameters (ΔG⁰, ΔS⁰ and ΔH⁰) indicated a spontaneous and exothermic biosorption of both metal ions onto Acacia Gummifera. Moreover, chromatograms obtained by size exclusion chromatography coupled with multi-angle laser light scattering detection system (SECMALLS) showed the formation of complexes between the arabinogalactan-peptide (AGP) and glycoprotein (GP) Acacia moieties and the two studied metal ions. The analysis of the FTIR spectra of dried Acacia and that of Acacia loaded with lead and cadmium in aqueous media suggests that the surface functional groups such as amides and carboxy groups might be involved in the metal removal process.The extent of adsorption for both metals increased along with an increase of the A. Gummifera biomass dosage. A. Gummifera biomass, which is safe, of low-cost, and highly selective, seems therefore to be a promising substrate for simultaneous trapping of Pd and Cd ions in aqueous solutions.     

疏水/亲水性聚二乙烯基苯/聚丙烯酸大孔互穿聚合物网络树脂对苯胺的吸附性能

采用分步悬浮聚合法制备了聚二乙烯基苯/聚丙烯酸甲酯（PDVB/PMA）大孔互穿聚合物网络,将其中的聚丙烯酸甲酯转化为聚丙烯酸,得到具有疏水/亲水性能的聚二乙烯基苯/聚丙烯酸（PDVB/PAA）大孔互穿聚合物网络（IPN）,研究了这类疏水/亲水大孔PDVB/PAA IPN对苯胺的吸附热力学和吸附动力学,测定了该树脂的孔结构、含水量、弱酸交换量和溶胀性能;测定了该树脂对苯胺在不同温度下的吸附等温线,利用热力学函数关系计算了吸附焓、自由能和熵。 红外光谱显示,成功合成了疏水/亲水PDVB/PAA IPN,与PDVB、PDVB/PMA IPN树脂相比,其BET表面积以及孔容均减小,含水量为62.73％,弱酸交换量为1.91 mmol/g;对苯胺的吸附为放热、自发的过程;溶胀实验、静态解吸实验表明,PDVB/PAA IPN树脂中疏水性的PDVB网具有疏水作用吸附能力,亲水性的PAA网具有氢键作用吸附能力。 对苯胺的吸附在90 min时即可达到吸附平衡,树脂吸附苯胺符合一级速率方程,吸附速率主要受颗粒内扩散的控制,同时还受液膜扩散的影响,吸附动力学可采用HSDM模型描述。     

Preparation and characterization of L-glutamic acid-functionalized graphene oxide for adsorption of Pb(II)

An efficient adsorbent (L-Glu/GO) was successfully synthesized by the reaction between L-glutamic acid (L-Glu) and graphene oxide (GO). The structure and morphology of this adsorbent were characterized by FTIR, SEM, XRD, and TGA. The SEM result indicated that the adsorbent was a nanomaterial with a size of about 50–400 nm. The adsorption experiments of various heavy ions on L-Glu/GO demonstrated that the adsorption performance of Pb(II) was better than others. Various variables affecting the adsorption of L-Glu/GO for Pb(II) were systematically explored. The experimental results indicated that the maximum adsorption capacity and equilibrium time of Pb(II) on L-Glu/GO were 513.4 mg g^?1 and 40 minute, respectively. The sorption kinetics and isotherm fitted well with the pseudo-second-order model and Langmuir model, respectively. The sorption mainly was a chemical process. Thermodynamic studies revealed that the adsorption was a spontaneous and exothermic process. The adsorbent could be regenerated with HCl solution. Hence, it was suggested that the L-Glu/GO could be applied in the removal of Pb(II) from wastewaters.     

Modeling adsorption rate of organic micropollutants present in landfill leachates onto granular activated carbon

The overall adsorption rate of single micropollutants present in landfill leachates such as phthalic acid (PA), bisphenol A (BPA), diphenolic acid (DPA), 2,4-dichlorophenoxy-acetic acid (2,4-D), and 4-chloro-2-methylphenoxyacetic acid (MCPA) on two commercial activated carbons was studied. The experimental data obtained were interpreted by using a diffusional model (PVSDM) that considers external mass transport, intraparticle diffusion, and adsorption on an active site. Furthermore, the concentration decay data were interpreted by using kinetics models. Results revealed that PVSDM model satisfactorily fitted the experimental data of adsorption rate on activated carbon. The tortuosity factor of the activated carbons used ranged from 2 to 4. The contribution of pore volume diffusion represented more than 92% of intraparticle diffusion confirming that pore volume diffusion is the controlling mechanism of the overall rate of adsorption and surface diffusion can be neglected. The experimental data were satisfactorily fitted the kinetic models. The second-order kinetic model was better fitted the experimental adsorption data than the first-order model.     

有机改性凹凸棒土对腐殖酸的吸附性能研究

合成了十六烷基三甲基氯化铵(CTAC)改性的凹凸棒土吸附剂,并研究了其对水中腐殖酸的吸附行为。通过FTIR、TG对改性前后凹凸棒土进行表征。结果表明,十六烷基三甲基氯化铵成功结合到凹凸棒土表面,结合到凹凸棒土表面的量为9.78%。在25℃时,腐殖酸在吸附剂上吸附行为符合Freundlich方程,吸附动力学符合拟二级动力学方程,初始浓度为54.60~200.20mg/L时,ATP-CTAC对腐殖酸的最大吸附量为253mg/g;温度对吸附行为影响不大;改性后的凹凸棒土对腐殖酸的吸附随pH的增大而降低;改性后的凹凸棒土显著地提高了对腐殖酸的吸附量。     

Preparation and Kinetic Modeling of Cross-Linked Chitosan Microspheres Immobilized Zn(II) for Urea Adsorption

The preparation of Zn(II)-immobilized glutaraldehyde-crosslinked chitosan microspheres which was modified with epichlorohydrin, tetraethylenepentamine, and bromoacetic acid was presented in this work. The Zn(II)-immobilized value of the microspheres (Ac-TEPA-CS) is 43.6 mg g^?1, which is higher than the blank microspheres. The adsorption of urea onto Zn-Ac-TEPA-CS was studied in a batch system. Langmuir and Freundlich adsorption models were applied to describe the experimental isotherm and isotherm constant, and the kinetic of adsorption process were estimated. These data fits well with Langmuir isotherm and also indicated that the adsorption process is exothermic and follow the pseudo-second-order kinetics. The adsorption capacity depends upon the pH, the temperature and the initial concentration of urea. It observed that Zn-Ac-TEPA-CS could be repeatedly used by elution and regeneration without significant loss of adsorption capacity.     

Preparation of molecularly imprinted polymer by surface imprinting technique and its performance for adsorption of dibenzothiophene

The novel surface imprinted polymer composites (MIP/K(2)Ti(4)O(9)) were prepared using dibenzothiophene (DBT) as the template, 4-vinylpyridine as the functional monomer and potassium tetratitanate whisker (K(2)Ti(4)O(9)) as the carrier. The synthetic product was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Parameters influencing DBT adsorption such as contact time, temperature and DBT initial concentration were investigated. The adsorption kinetics were evaluated with the pseudo-first-order and pseudo-second-order models, and the adsorption isotherms were fitted by Langmuir and Freundlich models. Selectivity experiments showed that MIP/K(2)Ti(4)O(9) exhibited excellent recognition capacity and binding affinity to DBT compared with the comparative substrates. MIP/K(2)Ti(4)O(9) could also be easily regenerated and reused ten times with only about 20% loss of adsorption capacity.