蔗渣纤维素黄原酸酯的合成及其交换吸附性能研究

蔗渣纤维素经碱化后,与二硫化碳反应,得蔗渣纤维素黄原酸酯。研究了蔗渣纤维素黄原酸酯合成的最佳工艺条件,并探讨了它对重金属离子、阳离子染料的交换吸附性能以及再生性能。实验结果表明,蔗渣纤维素黄原酸酯的交换吸附性能优于粒状活性炭,是一种效率较高且价廉的污水处理材料。     

Nanoscale zero-valent iron supported on biochar for the highly efficient removal of nitrobenzene

• Biochar supported nanoscale zero-valent iron composite (nZVI/BC) was synthesized. • nZVI/BC quickly and efficiently removed nitrobenzene (NB) in solution. • NB removal by nZVI/BC involves simultaneous adsorption and reduction mechanism. • nZVI/BC exhibited better catalytic activity, stability and durability than nZVI. The application of nanoscale zero-valent iron (nZVI) in the remediation of contaminated groundwater or wastewater is limited due to its lack of stability, easy aggregation and iron leaching. To address this issue, nZVI was distributed on oak sawdust-derived biochar (BC) to obtain the nZVI/BC composite for the highly efficient reduction of nitrobenzene (NB). nZVI, BC and nZVI/BC were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). For nZVI/BC, nZVI particles were uniformly dispersed on BC. nZVI/BC exhibited higher removal efficiency for NB than the simple summation of bare nZVI and BC. The removal mechanism was investigated through the analyses of UV-Visible spectra, mass balance and XPS. NB was quickly adsorbed on the surface of nZVI/BC, and then gradually reduced to aniline (AN), accompanied by the oxidation of nZVI to magnetite. The effects of several reaction parameters, e.g., NB concentration, reaction pH and nZVI/BC aging time, on the removal of NB were also studied. In addition to high reactivity, the loading of nZVI on biochar significantly alleviated Fe leaching and enhanced the durability of nZVI.     

改性稻草吸附铜离子的热力学研究

研究表明稻草改性后吸附铜离子的能力得到很大提高。在4种温度下（15、27、37、50℃）,改性稻草吸附铜离子的最大吸附量分别为1．10、1．24、1．34、1．50mmol／g。不同温度下,吸附自由能△G大大小于零,吸附过程具有强烈的自发趋势。吸附焙△H和吸附熵△S都大于零,吸附过程是熵增加推动的。     

反应柱充填活性炭法处理轧钢含铬废水的研究

针对轧钢含铬废水,分别采用活性炭和离子交换树脂吸附处理的方法对其中的Cr^6＋和Cr^3＋的去除效果进行了系统的研究。静态试验考查了pH、吸附剂用量和搅拌速度等因素的影响,同时使用微型反应柱集成装置对穿透时间、吸附容量及活性炭再生方法进行了探讨,动态试验表明反应柱充填活性炭法能有效地处理含铬废水。     

Pomegranate husk as an adsorbent in the removal of toxic chromium from wastewater

The use of a new sorbent developed from the husk of pomegranate, a famous fruit in Egypt, for the removal of toxic chromium from aqueous solution has been investigated. The batch experiment was conducted to determine the adsorption capacity of the pomegranate husk. The effects of initial metal concentration (25 and 50 mg l^?1), pH, contact time, and sorbent concentration (2–6 g l^?1) have been studied at room temperature. A strong dependence of the adsorption capacity on pH was observed, the capacity increased as the pH decreased, and the optimum pH value was pH 1.0. Adsorption equilibrium and kinetics were studied with different sorbent and metal concentrations. The adsorption process was fast, and equilibrium was reached within 3 h. The maximum removal was 100% for 25 mg l^?1 of Cr⁶⁺ concentration on 5 g l^?1 pomegranate husk concentration, and the maximum adsorption capacity was 10.59 mg g^?1. The kinetic data were analysed using various kinetic models—pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion equations—and the equilibrium data were tested using several isotherm models, Langmuir, Freundlich, Tempkin, Dubinin–Radushkevich, and Generalized isotherm equations. The Elovich and pseudo-second-order equations provided the greatest accuracy for the kinetic data, while Langmuir and Generalized isotherm models were the closest fit for the equilibrium data. The activation energy of sorption has also been evaluated as 0.236 and 0.707 kJ mol^?1 for 25 and 50 mg l^?1 chromium concentration, respectively.     

Lead removal from water using organic acrylic amine fiber (AAF) and inorganic-organic P-AAF, fixed bed filtration and surface-induced precipitation

Granular porous sorbents were normally used for heavy metals removal from water. To search for the new commercial sorbent and treatment strategy, an organic acrylic amine fiber (AAF) and phosphorus loading inorganic-organic AAF (P-AAF) were prepared and used for lead (Pb) removal from water. A new strategy of inorganic-organic coupling technology was proposed for Pb removal, based on the hypothesis of surface-induced precipitation mechanism. The AAF showed a Pb adsorption capacity of 417 mg/g from the Langmuir fitting, while the column filtration technology was further applied to measure the adsorption edge and applications. Effects of different initial Pb concentrations, hydraulic retention time, and co-existing P were considered in the filtration experiments. The presence of 0.8 mg/L P in water significantly improved the Pb breakthrough point from 15,000 to 41,000 bed volumes of water spiked with 85 µg/L Pb, while the P-AAF fixed bed showed better removal of Pb than AAF SEM/EDX and XRD spectra were employed for determining the surface functional groups and the formation of surface-induced precipitation of pyromorphite (Pb₅(PO₄)₃OH) on AAF. This study verified the application of AAF sorbent for Pb removal and the enhanced effect of coating P on AAF, thus improved our fundamental understanding and application of the surface chemistry process of Pb with P.     

Comparative adsorption of Pb(II) and Cd(II) ions on chestnut shell in aqueous system

In this study, high capacity Chestnut shell, a waste product from the chestnut sugar production industry, was successfully applied to remove Pb (II) and Cd (II) ions from aqueous solutions. Maximum adsorption capacities were found as 541.25?mg/g and 75.86?mg/g for Pb(II), and Cd(II) respectively. Several important parameters influencing the adsorption of Pb(II) and Cd(II) ions such as contact time, pH, temperature and effect of metal concentration were investigated systematically by batch experiments. Langmuir and Freundlich adsorption models were used to describe adsorption isotherms and constants. The thermodynamic parameters, such as standard free energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°), of the adsorption process were calculated. The adsorbents were characterised by scanning electron microscopy. It has been observed from the experimental results that in case of both Cd (II) and Pb (II), pseudo 2nd order kinetic model. From the results, Chestnut Shell are considered as an effective, low cost and environmental friendly adsorbent for the removal of Pb (II) and Cd (II) from wastewater.     

Preparation of cross-linked magnetic chitosan with quaternary ammonium and its application for Cr(VI) and P(V) removal

Pollutants that exist in anionic species are issues of concern in water treatment. Compared to cationic pollutants, the removal of anionic pollutants by adsorption is more difficult because most adsorbents carry predominantly negative charges in neutral and alkaline environments. In this study, a cross-linked chitosan derivative with quaternary ammonium and magnetic properties（QM-chitosan） was prepared and employed to remove chromium（VI） and phosphorus（V）（Cr（VI） and P（V）） from aqueous environments. The QM-chitosan was characterized by Fourier transform infrared spectrometry（FT-IR）,thermogravimetric analysis（TGA）, energy dispersive X-ray（SEM-EDX） and zeta potential.Batch experiments show that QM-chitosan can effectively remove Cr（VI） and P（V）, and the main mechanism was believed to be electrostatic interaction. A pseudosecond-order model was fitted to describe the kinetic processes of Cr（VI） and P（V） removal. The adsorption isotherms of both Cr（VI） and P（V） on the QM-chitosan were well fitted by the Langmuir isotherm equation. The saturated adsorption capacity of P（V）（2.783 mmol/g） was found to be higher than that of Cr（VI）（2.323 mmol/g）, resulting from the size of the H2PO-4ions being smaller than that of the HCr O-4ions. However, the theoretical calculation and experimental results showed that QM-chitosan had a stronger affinity for Cr（VI） than P（V）. The adsorption–desorption of the QM-chitosan was evaluated, and high regeneration rates were demonstrated.     

Se（IV）在改性水滑石和膨润土的吸附行为

79Se是高放废物地质处置安全评价中的重点关注的核素之一,如何有效地阻滞其在处置库环境中的迁移扩散是目前研究的热点。将金属盐溶液和有机溶剂与水滑石和膨润土混合制备,分别得到2种无机改性水滑石和9种不同的有机和无机改性膨润土,通过批次实验研究这些改性材料对Se(IV)的吸附性能。结果表明无机改性的水滑石和膨润土对Se(IV)均有较好的吸附,吸附率超过57%。而有机改性的膨润土吸附效果很差,吸附率低于10%。采用SEM和XRD对这些改性材料进行表征,结果表明：无机改性后的膨润土的比表面积和层间距均增大,有利于对Se(IV)的吸附。     

印染废水吸附处理研究现状

随着染料纺织工业迅速发展,产生的印染废水成了水系环境的主要污染源之一,而染料品种的日益增加,及产品结构和印染工艺的不断改变,使得印染废水的水质也发生了变化,处理难度也随之加大。本文主要介绍不同的吸附处理法的优缺点及它们对不同污染因素的吸附效率。通过对几类吸附方法的比较,发现新兴的秸秆纤维素类生物吸附剂,既可以有效的解决农业固体废弃物的处理问题,又能低成本高效率的处理印染废水,对我国建立发展可持续发展,环境友好型社会具有重要的意义。