改性粉煤灰处理含锌废水的研究

利用改性粉煤灰吸附混凝作用,研究了含锌离子浓度为50～200mg/L的模拟废水去除锌离子的一般规律。研究结果表明,以氧化钙为改性剂改性的粉煤灰对含锌废水具有良好的吸附性能,在含锌离子浓度为50～250mg/L,改性粉煤灰用量每100mL为20g,pH为4～11的实验条件下,锌离子的去除率最高可达99.7%。     

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。     

Sorption of As, Cd and Tl as influenced by industrial by-products applied to an acidic soil: equilibrium and kinetic experiments

In situ stabilization of toxic elements in contaminated soils by the addition of amendments is being considered as an effective technique for remediation. In this paper, we performed both kinetics and equilibrium-based sorption experiments of three toxic elements (As, Cd and Tl) in soils amended with two by-products (phosphogypsum and sugar foam, rich in gypsum and calcium carbonate, respectively) to ascertain the feasibility of their application for improving the sorption capacity of As, Cd and Tl from the soil at 25, 35 and 50 °C. Kinetic studies indicated that the sorption follows a pseudo-second-order (PSO) kinetics and the sorption is a two-step diffusion process where both film and intraparticle diffusion played important roles in the sorption mechanisms of the elements. The Langmuir isotherms applied for sorption studies showed that the estimated maximum sorption capacity of the elements in control and amended soils decreased in the order of Cd > As > Tl. Using the thermodynamic equilibrium parameters obtained at different temperatures, the thermodynamic constants of sorption (ΔG, ΔH and ΔS) were also evaluated, indicating spontaneous and endothermic nature of the process, except Tl which was exothermic. An optimal scaling procedure was undertaken to determine the relationships between the kinetic and equilibrium sorption parameters. By means of statistical analysis it was seen that these inter-parametric relationships are dependent on the element nature.     

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.     

Mechanism research on coal and gas outburst during vibration blasting

The coal and gas outburst results from plenty of factors, while vibration is the most important factor among them. Therefore, the influences of vibration acting on gas desorption and coal structure had been conducted. And the mechanism of coal and gas outburst induced by vibration was illustrated through examples. The results showed that the gas desorption accelerates under the action of vibration, and then the gas gradient increases. Meanwhile, vibration would increase and expand fractures in the internal coal body, which aggravates the risk of coal and gas outburst greatly. In conclusion, vibration is a more important factor attributable to coal and gas outburst compared with other coal mining method, mining technology and construction method.     

Removal of Fe(II) from the wastewater of a galvanized pipe manufacturing industry by adsorption onto bentonite clay

Bentonite clay has been used for the adsorption of Fe(II) from aqueous solutions over a concentration range of 80-200 mg/l, shaking time of 1-60 min, adsorbent dosage from 0.02 to 2 g and pH of 3. The process of uptake follows both the Langmuir and Freundlich isotherm models and also the first-order kinetics. The maximum removal (>98%) was observed at pH of 3 with initial concentration of 100 mg/l and 0.5 g of bentonite. The efficiency of Fe(II) removal was also tested using wastewater from a galvanized pipe manufacturing industry. More than 90% of Fe(II) can be effectively removed from the wastewater by using 2.0 g of the bentonite. The effect of cations (i.e. zinc, manganese, lead, cadmium, nickel, cobalt, chromium and copper) on the removal of Fe(II) was studied in the concentration range of 10-500 mg/l. All the added cations reduced the adsorption of Fe(II) at high concentrations except Zn. Column studies have also been carried out using a certain concentration of wastewater. More than 99% recovery has been achieved by using 5 g of the bentonite with 3M nitric acid solution.     

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.     

Influence of the inherent properties of drinking water treatment residuals on their phosphorus adsorption capacities

Batch experiments were conducted to investigate the phosphorus（P） adsorption and desorption on five drinking water treatment residuals（WTRs） collected from different regions in China. The physical and chemical characteristics of the five WTRs were determined. Combined with rotated principal component analysis, multiple regression analysis was used to analyze the relationship between the inherent properties of the WTRs and their P adsorption capacities. The results showed that the maximum P adsorption capacities of the five WTRs calculated using the Langmuir isotherm ranged from 4.17 to8.20 mg/g at a p H of 7 and further increased with a decrease in p H. The statistical analysis revealed that a factor related to Al and 200 mmol/L oxalate-extractable Al（Alox） accounted for 36.5% of the variations in the P adsorption. A similar portion（28.5%） was attributed to an integrated factor related to the p H, Fe, 200 mmol/L oxalate-extractable Fe（Feox）, surface area and organic matter（OM） of the WTRs. However, factors related to other properties（Ca,P and 5 mmol/L oxalate-extractable Fe and Al） were rejected. In addition, the quantity of P desorption was limited and had a significant negative correlation with the（Feox＋ Alox） of the WTRs（p 〈 0.05）. Overall, WTRs with high contents of Alox, Feoxand OM as well as large surface areas were proposed to be the best choice for P adsorption in practical applications.     

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。