内分泌干扰物在城市污水处理厂中的行为和归趋：综述

内分泌干扰物作为一类新型污染物,由于其在环境水体中微量的浓度即可对野生动物产生内分泌干扰效应,因此引起了人们的广泛关注.本文以两类主要内分泌干扰物(即类固醇雌激素和酚类内分泌干扰物)作为研究对象,综述了它们在城市污水处理厂中的浓度水平以及相应的去除效率,并探讨了不同生物处理工艺、运行操作条件等对去除效率的影响.此外,通...     

荞麦皮生物吸附去除水中罗丹明B的吸附条件响应面法及热力学研究

采用Box-Behnken响应面优化实验设计对荞麦皮生物吸附去除水中染料罗丹明B的影响因素（如温度、pH值、染料初始浓度、吸附剂用量）进行研究,建立了去除率与上述因素之间的二次多项式模型,得到荞麦皮去除罗丹明B的最佳条件为：温度50℃、pH=2、罗丹明B初始浓度100mg·L^-1、吸附剂用量11.75g·L^-1,最...     

三峡库区悬移质泥沙对磷污染物的吸附解吸特性

就三峡库区悬移质泥沙对磷污染物的吸附解吸特性从野外同步监测和室内试验研究两个方面展开研究。选取长江干流、嘉陵江和乌江共7个监测断面于2002年和2003进行野外同步监测,测试结果表明：水中的悬移质泥沙对水中各种覆存形态的磷污染物浓度具有显著影响,单位重量泥沙对磷的吸附量与水体总泥沙含量、泥沙粒径有密切关系。采集寸滩断面泥沙对磷酸盐吸附解吸特性进行室内试验研究,并根据Langmuir吸附动力学方程对吸附解吸过程进行了拟合,发现吸附速率常数k随着泥沙粒径的增加而呈递增变化,而磷酸盐初始浓度对k值的影响并不明显,同时,磷酸盐解吸量随着泥沙浓度的增加和粒径的增加呈递减变化,k值随着泥沙粒径的增加而呈递增变化,泥沙浓度对k值的影响不明显。     

生物活性炭去除水中挥发性苯系物的基础研究

采用连续流生物活性炭(BAC)工艺处理水中挥发性苯系物(BTEX,包括苯、甲苯、乙苯、二甲苯),评价进水负荷、活性炭炭型等因素对于BAC处理性能的影响.研究表明,在40d的处理时间内,除苯之外,其余BTEX的BAC出水中均未检出苯系物(进水为6mg/L).为了检验BAC在高BTEX负荷情况时的处理效果,将进水浓度设定为19~32mg/L左右,在EBCT为1.2min条件下同样只有苯的出水浓度上升至10mg/L(C/Cin为0.45),然后略有下降,最终保持在5~10mg/L(C/Cin为0.3以下),其余苯系物出水浓度均一直保持小于5mg/L.这表明BAC可以有效地处理高负荷BTEX(8.68~12.9kgTOC/(m3·d))的进水.生物活性炭对于活性炭吸附容量的恢复有比较明显的作用,煤质炭和椰壳炭的生物再生效率分别为53.6%和26.6%,煤质炭再生效率高的原因可能是其具备更多的大型中孔和大孔.     

Removal of copper ions from aqueous solution by calcium alginate immobilized kaolin

Kaolin has been widely used as an adsorbent to remove heavy metal ions from aqueous solutions. However, the lower heavy metal adsorption capacity of kaolin limits its practical application. A novel environmental friendly material, calcium alginate immobilized kaolin (kaolin/CA), was prepared using a sol-gel method. The e ects of contact time, pH, adsorbent dose, and temperature on Cu2+ adsorption by kaolin/CA were investigated. The Langmuir isotherm was used to describe the experimental adsorption, the maximum Cu2+ adsorption capacity of the kaolin/CA reached up to 53.63 mg/g. The thermodynamic studies showed that the adsorption reaction was a spontaneous and endothermic process.     

Removal of phosphate by Fe-coordinated amino-functionalized 3D mesoporous silicates hybrid materials

Phosphate removal from aqueous waste streams is an important approach to control the eutrophication downstream bodies of water. A Fe(III) coordinated amino-functionalized silicate adsorbent for phosphate adsorption was synthesized by a post-grafting and metal cation incorporation process. The surface structure of the adsorbent was characterized by X-ray di raction, N2 adsoropion/desoprotion technique, and Fourier transform infrared spectroscopy. The experimental results showed that the adsorption equilibrium data were well fitted to the Langmuir equation. The maximum adsorption capacity of the modified silicate material was 51.8 mg/g. The kinetic data from the adsorption of phosphate were fitted to pseudo second-order model. The phosphate adsorption was highly pH dependent and the relatively high removal of phosphate fell within the pH range 3.0–6.0. The coexistence of other anions in solutions has an adverse e ect on phosphate adsorption; a decrease in adsorption capacity followed the order of exogenous anions: F?? > SO2?? 4 > NO??3 > Cl??. In addition, the adsorbed phosphate could be desorbed by NaOH solutions. This silicate adsorbent with a large adsorption capacity and relatively high selectivity could be utilized for the removal of phosphate from aqueous waste streams or in aquatic environment.     

Effects of metal cations on sorption-desorption of p-nitrophenol onto wheat ash

The mutual e ects of metal cations (Cu2+, Pb2+, Zn2+, and Cd2+) and p-nitrophenol (NP) on their adsorption desorption behavior onto wheat ash were studied. Results suggested that Cu2+, Pb2+, and Zn2+ diminished the adsorption and increased the desorption of NP remarkably, while Cd2+ had no such e ect. In contrast, NP diminished the adsorption of Cu2+, Pb2+, and Zn2+ onto ash, however, this suppression e ect depended on the initial concentrations of metal cations. NP had no e ect on Cd2+ adsorption on ash. Fourier transform infrared (FT-IR) and X-ray absorption spectroscopic (XAS) studies suggested the following mechanisms responsible for the metal suppression e ect on NP adsorption: (1) large hydrated Cu2+, Pb2+, and Zn2+ shells occupied the surface of ash and prevent nonspecific adsorption of NP onto ash surface; (2) Cu2+, Pb2+, and Zn2+ may block the micropores of ash, resulting in decreased adsorption of NP; (3) complexation of Cu2+, Pb2+, and Zn2+ was likely via carboxyl, hydroxylic and phenolic groups of wheat ash and these same groups may also react with NP during adsorption. As a “soft acid”, Cd2+ is less e cient in the complexation of oxygencontaining acid groups than Cu2+, Pb2+, and Zn2+. Thus, Cd2+ had no e ect on the adsorption of NP on wheat ash.     

Removal of heavy metal ions from aqueous solution using red loess as an adsorbent

The adsorption behaviors of heavy metals onto novel low-cost adsorbent, red loess, were investigated. Red loess was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectra. The results indicated that red loess mainly consisted of silicate, ferric and aluminum oxides. Solution pH, adsorbent dosage, initial metal concentration, contact time and temperature significantly influenced the efficiency of heavy metals removal. The adsorption reached equilibrium at 4 hr, and the experimental equilibrium data were fitted to Langmuir monolayer adsorption model. The adsorption of Cu(II) and Zn(II) onto red loess was endothermic, while the adsorption of Pb(II) was exothermic. The maximum adsorption capacities of red loess for Pb(II), Cu(II) and Zn(II) were estimated to be 113.6, 34.2 and 17.5 mg/g, respectively at 25°C and pH 6. The maximum removal efficiencies were 100% for Pb(II) at pH 7, 100% for Cu(II) at pH 8, and 80% for Zn(II) at pH 8. The used adsorbents were readily regenerated using dilute HC1 solution, indicating that red loess has a high reusability. All the above results demonstrated that red loess could be used as a possible alternative low-cost adsorbent for the removal of heavy metals from aqueous solution.     

Evaluation of adsorption capacities of humic acids extracted from Algerian soil on polyaniline for application to remove pollutants such as Cd(Ⅱ), Zn(Ⅱ) and Ni(Ⅱ) and characterization with cavity microelectrode

The adsorption capacities of new humic acids isolated from Yakouren forest (YHA) and Sahara (Tamenrasset: THA) soils (Algeria) and commercial humic acid (PFHA) on polyaniline emeraldine base (PEB) were studied at pH 6.6. Also the adsorption of heavy metals such as Cd2+, Zn2+ and Ni2+ on humic acid-polyaniline systems (HA-PEB) was investigated at the same conditions. HA-PEB compounds were characterized by scanning electron microscopy (SEM), infrared spectrometry and cavity microelectrode. In addition, batch adsorption and cavity microelectrode were used in the adsorption study of Cd2+, Zn2+ and Ni2+ on HA-PEB. To develop biocaptors of polluting metals using a cavity microelectrode modified by HA-PEB systems, the adsorption kinetic and adsorption capacity were investigated. The SEM analysis showed that the presence of humic acid affected the PEB surface and caused the formation of a granular morphology. The maximum adsorption capacities (qmax) of PFHA, THA and YHA determined by adsorption isotherms were 91.31, 132.1 and 151.0 mg/g, respectively. Batch adsorption results showed that qmax of Cd2+, Zn2+ and Ni2+ on HA-PEB followed the order: THA-PEB > YHA-PEB > PFHA-PEB. The voltammograms obtained with HA-PEB modified cavity microelectrode showed the appearance of new redox couples reflecting the adsorption of HA on PEB. Metal-humic acid-polyaniline voltammograms were characterized by appearance of oxidation-reduction couples or reduction wave corresponding to metal. Finally, the result may be exploited to develop a biocaptor based on the cavity microelectrode amended by THA-PEB and YHA-PEB.     

Silver impregnated carbon for adsorption and desorption of elemental mercury vapors

The Hg0 vapor adsorption experimental results on a novel sorbent obtained by impregnating a commercially available activated carbon (Darco G60 from BDH) with silver nitrate were reported. The study was performed by using a fundamental approach, in an apparatus at laboratory scale in which a synthetic flue gas, formed by Hg0 vapors in a nitrogen gas stream, at a given temperature and mercury concentration, was flowed through a fixed bed of adsorbent material. Breakthrough curves and adsorption isotherms were obtained for bed temperatures of 90, 120 and 150°C and for Hg0 concentrations in the gas varying in the range of 0.8–5.0 mg/m3. The experimental gas-solid equilibrium data were used to evaluate the Langmuir parameters and the heat of adsorption. The experimental results showed that silver impregnated carbon was very effective to capture elemental mercury and the amount of mercury adsorbed by the carbon decreased as the bed temperature increased. In addition, to evaluate the possibility of adsorbent recovery, desorption was also studied. Desorption runs showed that both the adsorbing material and the mercury could be easily recovered, since at the end of desorption the residue on solid was almost negligible. The material balance on mercury and the constitutive equations of the adsorption phenomenon were integrated, leading to the evaluation of only one kinetic parameter which fits well both the experimentally determined breakthrough and desorption curves.