氧化石墨烯对水中内分泌干扰物双酚A的吸附性能

以氧化石墨烯(GO)为吸附剂, 内分泌干扰物双酚A (BPA)为目标污染物, 考察了GO对水中BPA的吸附性能. 结果表明: GO对BPA的最大吸附量(q_m)约为87.80 mg·g^-1 (25℃), 30 min左右即可达到吸附平衡, 远快于活性碳; 吸附动力学和等温线数据分别符合准二级动力学模型和Langmuir 吸附模型; 在溶液接近中性和低温的条件下有利于吸附的进行, 在溶液中存在电解质的条件下不利于吸附的进行. GO具有优异的循环吸附性能, 经过多次循环使用后依然可以保持良好的吸附能力. GO对BPA的吸附机理主要是由于GO本身的片状结构以及表面的含氧极性基团, 会与BPA之间产生π-π色散作用和氢键作用. 虽然GO对BPA的吸附能力不如石墨烯, 但是相比于石墨烯, GO表面含有大量极性基团, 具有良好的亲水性, 且GO合成方法相对简单, 可批量生产用于工业污水处理. 因此, 在水处理领域, GO有能力成为新型高效的吸附剂.     

Adsorption of fluoride from aqueous solution by graphene

A batch adsorption system was applied to investigate the adsorption of fluoride from aqueous solution by graphene. The adsorption capacities and rates of fluoride onto graphene at different initial pH, contact time, and temperature were evaluated. The experimental results showed that graphene is an excellent fluoride adsorbent with an adsorption capacity of up to 17.65 mg/g at initial fluoride concentration of 25 mg/L and temperature of 298 K. The isotherm analysis indicated that the adsorption data can be well described by Langmuir isotherm model. Thermodynamic studies revealed that the adsorption reaction was a spontaneous and endothermic process.     

Surface and biological activity of sophorolipid molecules produced by Wickerhamiella domercqiae var. sophorolipid CGMCC 1576

The ion-imprinted magnetic chitosan resins (IMCR) prepared using U(VI) as a template and glutaraldehyde as a cross-linker showed higher adsorption capacity and selectivity for the U(VI) ions compared with the non-imprinted magnetic chitosan resins (NIMCR) without a template. The results showed that the adsorption of U(VI) on the magnetic chitosan resins was affected by the initial pH value, the initial U(VI) concentration, as well as the temperature. Both kinetics and thermodynamic parameters of the adsorption process were estimated. These data indicated an exothermic spontaneous adsorption process that kinetically followed the second-order adsorption process. Equilibrium experiments were fitted in Langmuir, Freundlich, and Dubinin-Radushkevich adsorption isotherm models to show very good fits with the Langmuir isotherm equation for the monolayer adsorption process. The monolayer adsorption capacity values of 187.26 mg/g for IMCR and 160.77 mg/g for NIMCR were very close to the maximum capacity values obtained at pH 5.0, temperature 298 K, adsorbent dose 50 mg, and contact time 3 h. The selectivity coefficient of uranyl ions and other metal ions on IMCR indicated an overall preference for uranyl ions. Furthermore, the IMCR could be regenerated through the desorption of the U(VI) ions using 0.5 M HNO(3) solution and could be reused to adsorb again.     

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.     

Adsorption of Pb(II) and Ni(II) From Aqueous Solution by a High-Capacity Industrial Sewage Sludge-Based Adsorbent

In the present study, adsorption of Ni(II) and Pb(II) from aqueous solution was investigated using activated carbon synthesized with industrial wastewater sludge. The synthesized adsorbent was analyzed using nitrogen adsorption–desorption and Fourier transfer infrared (FTIR) techniques. Batch adsorption mode was used to evaluate the effect of solution pH, contact time, adsorbent dose, initial metal ion concentration, and temperature on the adsorption capacity of the synthesized adsorbent. The kinetic data were analyzed using different kinetic models. The pseudo-second-order equation gave the best fit to the experimental data for both metal ions. The equilibrium isotherm data were analyzed using the Langmuir, Freundlich, and Dubinin–Radushkevich (D–R) isotherm models. The results showed that the data obtained for the Ni(II) and Pb(II) adsorption are in good agreement with the Langmuir model. The Langmuir mono-layer maximum adsorption capacities for Ni(II) and Pb(II) ions were estimated to be 74.06 and 88.76 mg g^?1 at 25°C, respectively. In addition, the thermodynamic studies proved that the adsorption process of both metals could be considered endothermic.     

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.     

Synthesis and characterization of <Emphasis Type="Italic">β</Emphasis>-cyclodextrin–carboxymethyl cellulose–graphene oxide composite materials and its application for removal of basic fuchsin

A novel β-cyclodextrin–carboxymethyl cellulose–graphene oxide composite material (β-CD–CMC–GO) was synthesized, and its application as excellent adsorbents was carried out for removal basic fuchsin (BF) in aqueous solution. The structure and morphology of β-CD–CMC–GO composite material were characterized by using FTIR, SEM, TEM, XRD, TG and DSC methods. The composites could remove basic fuchsin from aqueous solution efficiently. The adsorption experiment was carried out and the optimum experimental conditions were ascertained. The highest adsorption efficiency was obtained 97.3% at 0.015 g/mL dosage of β-CD–CMC–GO, the temperature of 25 °C and time of 2.5 h. Adsorption kinetics, adsorption isotherm and adsorption thermodynamic were used to analyze the adsorption system. The experimental data of adsorption kinetics of system were well followed by pseudo-second-order equation. The adsorption isotherm data were fitted using Langmuir isotherm model and Freundlich isotherm model. The maximum adsorption capacity of basic fuchsin reached 58.65 mg/g. The thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic. The adsorbent has excellent regeneration ability and reproducibility. The proposed method shows that the β-CD–CMC–GO could be applied to removal of basic fuchsin in wastewater with satisfactory result.     

Preparation and Characterization of Activated Carbon Fiber from Paper

Activated carbon fibers (ACFS) with surface area of 1388 m²/g prepared from paper by chemical activation with KOH has been utilized as the adsorbent for the removal of methy-lene blue from aqueous solution. The experimental data were analyzed by Langmuir and Freundlich models of adsorption. The effects of pH value on the adsorption capacity of ACFS were also investigated. The rates of adsorption were found to conform to the kinetic model of Pseudo-second-order equation with high values of the correlation coefficients (R>0.998). The Langmuir isotherm was found to fit the experimental data better than the Feundlich isotherm over the whole concentration range. Maximum adsorption capacity of 520 mg/g at equilibrium was achieved. It was found that pH played a major role in the adsorption process, higher pH value favored the adsorption of MB.     

Adsorption of Cr(VI) using activated neem leaves: kinetic studies

In the present study, adsorbent is prepared from neem leaves and used for Cr(VI) removal from aqueous solutions. Neem leaves are activated by giving heat treatment and with the use of concentrated hydrochloric acid (36.5 wt%). The activated neem leaves are further treated with 100 mmol of copper solution. Batch adsorption studies demonstrate that the adsorbent prepared from neem leaves has a significant capacity for adsorption of Cr(VI) from aqueous solution. The parameters investigated in this study include pH, contact time, initial Cr(VI) concentration and adsorbent dosage. The adsorption of Cr(VI) is found to be maximum (99%) at low values of pH in the range of 1-3. A small amount of the neem leaves adsorbent (10 g/l) could remove as much as 99% of Cr(VI) from a solution of initial concentration 50 mg/l. The adsorption process of Cr(VI) is tested with Langmuir isotherm model. Application of the Langmuir isotherm to the system yielded maximum adsorption capacity of 62.97 mg/g. The dimensionless equilibrium parameter, R _L, signifies a favorable adsorption of Cr(VI) on neem leaves adsorbent and is found to be between 0.0155 and 0.888 (0<R _L<1). The adsorption process follows second order kinetics and the corresponding rate constant is found to be 0.00137 g/(mg) (min).     

Mechanisms and kinetics of trisodium 2-hydroxy-1,1'-azonaphthalene-3,4',6-trisulfonate adsorption onto chitosan

Chitosan, a naturally abundant biopolymer, has widely been studied for metal adsorption from various solutions, but the extension of chitosan as an adsorbent to remove organic substances from water and wastewater has seldom been explored. In this study, the adsorption of an azo dye, trisodium 2-hydroxy-1,1'-azonaphthalene-3,4',6-trisulfonate (1), from aqueous solution onto the various degrees of deacetylated chitosan has been investigated. Equilibrium studies have been carried out to determine the capacity of chitosan for dye. The experimental data were analyzed using two isotherm correlations, namely, Langmuir and Freundlich equations. The linear correlation coefficients were determined for each isotherm and the Langmuir provided the best fit. The experimental adsorption isotherms were perfectly reproduced in the simulated data obtained from numerical analysis on the basis of the Langmuir model and the isotherm constants. Adsorption of (1) onto the chitosan flakes was found to be strongly depending on degrees of deacetylation in chitosan and temperatures. Significant amounts of (1) were adsorbed by chitosan 8B (higher degree of deacetylated chitosan), but the adsorption capacity was reduced remarkably with increasing solution temperatures. Thermodynamic parameters such as change in free energy (DeltaG), enthalpy (DeltaH), and entropy (DeltaS) were also determined. In addition, kinetic study indicated that the adsorption process mechanisms were both transport- and attachment-limited.     

Novel self assembled magnetic Prussian blue graphene based aerogel for highly selective removal of radioactive cesium in water

A novel self-assembled Magnetic Prussian Blue/Reduced Graphene Oxide (3D-MPBRGO) aerogel was prepared by an easy and cost effective process for elimination of radioactive Cesium from contaminated aqueous solution selectively. The 3D-MPBRGO displayed excellent adsorption capability of 3.64 mmol per g or (484.12 mg/g) for Cs (initial 50 mM cesium concentration, pH 7 and 30 °C) and quick separation from solution by applying magnetic field as compared to previously published results for graphene based adsorbents. This excellent removal efficiency of nanocomposite can be ascribed to enlarged adsorbent surface area (402.68 m²/g) and uniform distribution of nanoparticles on RGO which removes aggregation of sheets as well. The thermodynamic analysis displayed exothermic and spontaneous nature of Cs ion adsorption. The experimental data of adsorption isotherm followed the Langmuir isotherm model than that of Tempkin and Freundlich while adsorption kinetics followed pseudo second order.     

Biosorption characteristics of uranium(VI) from aqueous solution by pummelo peel

The biomass pummelo peel was chosen as a biosorbent for removal of uranium(VI) from aqueous solution. The feasibility of adsorption of U(VI) by Pummelo peel was studied with batch adsorption experiments. The effects of contact time, biosorbent dosage and pH on adsorption capacity were investigated in detail. The pummelo peel exhibited the highest U(VI) sorption capacity 270.71?mg/g at an initial pH of 5.5, concentration of 50???g/mL, temperature 303?K and contacting time 7?h. The adsorption process of U(VI) was found to follow the pseudo-second-order kinetic equation. The adsorption isotherm study indicated that it followed both the Langmuir adsorption isotherm and the Freundlich adsorption isotherm. The thermodynamic parameters values calculated clearly indicated that the adsorption process was feasible, spontaneous and endothermic in nature. These properties show that the pummelo peel has potential application in the removal of the uranium(VI) from the radioactive waste water.     

Adsorption of uranium from aqueous solution by graphene oxide nanosheets supported on sepiolite

Adsorptive behavior of uranium from aqueous solution on graphene oxide supported on sepiolite composites (GO@sepiolite composites) as a function of pH, ionic strength, temperature and initial uranium concentration was carried out by the batch techniques. GO@sepiolite composites was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and potentiometric acid–base titration. According to XRD patterns and SEM images, the graphene oxide nanosheets were grafted on sepiolite surface successfully. The macroscopic results showed that the adsorption of uranium on GO@sepiolite composites was significantly depended on pH, whereas no effect of ionic strength on uranium adsorption at high pH and high ionic strength conditions was observed. The uptake equilibrium is best described by Langmuir adsorption isotherm, and the maximum adsorption capacity (Q_e) of GO@sepiolite composites at pH 5.0 and T = 298 K were calculated to be 161.29 mg/g. Thermodynamic results indicated that the adsorption of uranium on GO@sepiolite composites is the spontaneous and exothermic process.     

Adsorption-desorption isotherm hysteresis of beta-lactoglobulin A with a weakly hydrophobic surface.

Adsorption-desorption isotherms of bovine beta-lactoglobulin A (beta-lact A) on a weakly hydrophobic stationary phase (C1-ether) were measured by frontal analysis. The adsorption isotherms obtained at different pH were found to be dramatically different in shape, column capacity and desorption reversibility. At pH 4.5, an S-shaped adsorption isotherm was observed whereas at pH 6.0 a Langmuir isotherm was found. In addition, the desorption isotherm at pH 6.0 was found to overlap with the adsorption isotherm, and the adsorption-desorption process of beta-lact A under this condition could be characterized by a fully reversible Langmuir model. The desorption isotherm at pH 4.5, however, did not retrace the adsorption isotherm, resulting in hysteresis loops. A higher aggregate (tetramer) of beta-lact A is shown to be in an equilibrium with the beta-lact A protomer (dimer) at pH 4.5 whereas the dimer alone is predominant at pH 6.0. It is further shown that changes in the absorption coefficient between the adsorption and the desorption cycles for the tetramer at pH 4.5 can account for the hysteresis. The results demonstrate that pH can be a sensitive parameter in protein adsorption isotherm behavior and ultimately the behavior of species in preparative-scale chromatography.     

磁性镍基氮掺杂多壁碳纳米管对双酚A的吸附性能及机理研究

通过简单的高温煅烧法制备了具有较大比表面积的磁性镍基氮掺杂多壁碳纳米管材料(Ni-NMC-NTs),将该材料用于双酚A(BPA)的吸附研究,对材料吸附前后的形貌和结构变化进行表征,探究其吸附机理.结果表明:具有中空管状结构的磁性Ni-NMCNTs对BPA具有良好的吸附能力和重复利用性,材料中n比啶氮的存在提供了吸附缺陷...     

Glycine‐functionalized reduced graphene oxide for methylene blue removal

Glycine‐functionalized reduced graphene oxide (GRGO) was prepared through the reaction of glycine and chlorine‐functionalized reduced graphene oxide. The product was characterized by SEM, HRTEM, IR, Raman, and XPS. The nitrogen content (8.28%) was high in product, peak at 285.8 eV was assigned to the C–N bond, which implied that the chlorine residues in raw material were substituted by amine group of glycine. The intensity ratio of D and G peak was about 1.5, which also implied that more saturated carbon atoms were present in the product. Results of SEM, IR, and XPS confirmed that glycine molecules were attached to graphene sheets. Compared with reduced graphene oxide (61.5 mg/g) and active carbon (45.2 mg/g), GRGO had a good adsorption capacity (98.9 mg/g) for methylene blue. The adsorption process was fitted to three kinetic models and three adsorption isotherm models. The adsorption process complied with pseudo‐second order kinetic model and Langmuir model.     

Competitive Adsorption of Methylene Blue and Rhodamine B on Natural Zeolite: Thermodynamic and Kinetic Studies

A batch system was applied to study the adsorption behavior of methylene blue (MB) and rhodamine B (RB) in single and binary component systems on natural zeolite. In the single component systems, the zeolite presents higher adsorption capacity for MB than RB with the maximal adsorption capacity of 7.95×10^?5 and 1.26×10^?5 mol/g at 55°C for MB and RB, respectively. Kinetic studies indicated that the adsorption followed pseudo‐second‐ order kinetics and could be described by a two‐step diffusion process. For the single component systems, the adsorption isotherm could be fitted by the Langmuir model. In the binary component system, MB and RB exhibit competitive adsorption on the zeolite. The adsorption is approximately reduced to 50% and 60% of single component adsorption systems of MB and RB, respectively at an initial concentration of 6×10^?6 mol·L^?1 at 25°C. In the binary component system, kinetic and adsorption isotherm studies demonstrate that the experimental data are following pseudo‐second‐order kinetics and Langmuir isotherm and kinetic data are fairly described by a two‐step diffusion model. Effect of solution pH on adsorption of MB and RB in both single and binary component systems was studied and the results were described by electrostatic interactions.     

Removal of copper(II) from aqueous solution with rape stalk modified by citric acid

In this paper, rape stalk was modified with citric acid (CA) to prepare copper ion biosorbent. The modified rape stalk (MRS) was characterized by Fourier transforms infrared (FTIR), zeta potential, and thermogravimetric analysis (TGA). The effects of various parameters like initial Cu²⁺ concentration, contact time, initial pH, and temperature on adsorption capacity were studied. The adsorption capacity of MRS at 298 K was 69.84 mg/g, far higher than 18.24 mg/g for native rape stalk (NRS). The adsorption mechanism was also evaluated in terms of kinetics and thermodynamics. The adsorption equilibrium data was well described by the Langmuir isotherm model. The adsorption process followed the pseudo-second-order rate kinetics. Thermodynamic study showed spontaneous and endothermic nature of the adsorption process. The ion exchange of the adsorption mechanism was affirmed. MRS could be a potentially low-cost and green adsorbent for removal of Cu²⁺ from aqueous solution.     

还原态氧化石墨烯对Zn(Ⅱ)的吸附动力学与热力学

以乙二胺(EDA)还原氧化石墨烯(GO)制得一种吸附材料,即还原态氧化石墨烯(RGO)。 采用批量平衡法研究了RGO对Zn(Ⅱ)的吸附动力学与热力学,利用Lagergren准一级及准二级动力学方程、Langmuir和Freundlich等温方程对实验数据进行了拟合分析。 研究结果表明,Lagergren准二级吸附动力学模型能够较好地描述实验结果,表明该吸附过程以化学吸附为主。 RGO的吸附在所研究的Zn(Ⅱ)浓度范围内更符合Langmuir等温吸附经验式,ΔH0=-21.60 kJ/mol,吸附焓变小于零,表明该吸附为放热过程;吸附吉布斯自由能变化ΔG0为正值,表明该吸附是一个非自发的过程。     

黄姜黄色素在大孔树脂上的吸附动力学研究

采用静态法考察了8种大孔吸附树脂对黄姜黄色素的吸附及解吸特性,筛选出LX-18G树脂具有较高的吸附选择性和良好的脱附性能.以LX-18G树脂对黄姜色素的吸附平衡和吸附动力学进行了深入探讨,测定了不同温度下黄姜色素在该树脂上的吸附等温线,以及不同温度,初始液浓度和转速下的吸附动力学曲线.结果表明,Langmuir方程可更好地描述黄姜色素在该树脂上的吸附平衡.吸附动力学规律可用二级速率方程表示,液膜扩散和颗粒内扩散分别是吸附初期和吸附后期的主要速率控制步骤,吸附活化能为5.37kJ/mol.