Adsorption of Mn2+ from aqueous solution using Fe and Mn oxide-coated sand

The adsorption of Mn²⁺ onto immobilized Mn-oxide and Fe-oxide adsorbent such as manganese oxide-coated sand1 (MOCS1), manganese oxide-coated sand2 (MOCS2), iron oxide-coated sand2 (IOCS2), and manganese and iron oxide-coated sand (MIOCS) was investigated. The effects of pH (5.5 to 8.0) and temperature (25 to 45℃) on the equilibrium capacity were examined. Equilibrium studies showed that there is a good fit with both Freundlich and Langmuir isotherm, which indicates surface heterogeneity and monolayer adsorption of the adsorbents. Kinetic data showed high correlation with the pseudo second-order model, which signifies a chemisorption-controlled mechanism. The activation energies, activation parameters (ΔG^*, ΔH^*, ΔS^*), and thermodynamic parameters (ΔG⁰, ΔH⁰, ΔS⁰) confirmed that adsorption with MIOCS was endothermic and more spontaneous at higher temperature while an opposite trend was observed for the other adsorbents. Thermodynamic studies showed that adsorption involved formation of activated complex, where MOCS1 and MIOCS follow a physical-chemical mechanism, while MOCS2 and IOCS2 follows purely chemical mechanism.     

A high activity of Ti/SnO2-Sb electrode in the electrochemical degradation of 2,4-dichlorophenol in aqueous solution

Electrochemical degradation of 2,4-dichlorophenol (2,4-DCP) in aqueous solution was investigated over Ti/SnO₂-Sb anode. The factors influencing the degradation rate, such as applied current density (2-40 mA/cm²), pH (3-11) and initial concentration (5-200 mg/L) were evaluated. The degradation of 2,4-DCP followed apparent pseudo first-order kinetics. The degradation ratio on Ti/SnO₂-Sb anode attained > 99.9% after 20 min of electrolysis at initial 5-200 mg/L concentrations at a constant current density of 30 mA/cm² with a 10 mmol/L sodium sulphate (Na2SO4) supporting electrolyte solution. The results showed that 2,4-DCP (100 mg/L) degradation and total organic carbon (TOC) removal ratio achieved 99.9% and 92.8%, respectively, at the optimal conditions after 30 min electrolysis. Under this condition, the degradation rate constant (k) and the degradation half-life (t_1/2) were 0.21 min^-1 and (2.8±0.2) min, respectively. Mainly carboxylic acids (propanoic acid, maleic acid, propanedioic acid, acetic acid and oxalic acid) were detected as intermediates. The energy efficiencies for 2,4-DCP degradation (5-200 mg/L) with Ti/SnO₂-Sb anode ranged from 0.672 to 1.602 g/kWh. The Ti/SnO₂-Sb anode with a high activity to rapid organic oxidation could be employed to degrade chlorophenols, particularly 2,4-DCP in wastewater.     

工业冷凝液处理系统在川化的运行

川化股份有限公司第二化肥厂尿素装置采用水溶液全循环改良C法工艺，尿液加工采用结晶遣粒工艺。在生产过程中，产生的废水由凉水塔处理，不仅造成氨耗增加，而且还对大气造成了污染。经过研究，该公司与TEC公司合作，进行相关的节能改造，并增加了1套ACES工艺冷凝液处理系统。     

双极膜电渗析法处理谷氨酸水溶液的过程性能研究

对利用双极膜水解离技术处理谷氨酸水溶液的各种工艺参数进行了探索。讨论了电流效率、转化率及能耗等因素对双极膜水解离技术应用的影响。根据实验研究结果，提出了双极膜法处理谷氨酸水溶液的最佳工艺流程。     

Comments on "Adsorption of 2-mercaptobenzothiazole from aqueous solution by organo-bentonite" by P. Jing, M.H. Hou, P. Zhao, X.Y. Tang, H.F. Wan

Recently, ling et al. （2013） published the paper entitled as above. In Section 2.3, Adsorption kinetics of MBT, authors noticed that ＂The pseudo first-order kinetic model （Eq. （1）） and the pseudo second-order kinetic model （Eq. （2））＂ were used （Do,an et al., 2007; Eftekhari et al., 2010）：     

Removal of cobalt(Ⅱ) ion from aqueous solution by chitosan-montmorillonite

Montmorillonite （MMT） modified with chitosan （CTS, molecular weight = S x 104） was applied to remove heavy metal cations by using Co2＋ as a model ion. An increase in MMT interlayer distance observed from X-ray diffraction indicates the intercalation of CTS into MMT. Together with the results of scanning electron microscopy and Fourier transform infrared spectroscopy, it was concluded that the composite material of CTS and MMT （CTS-- MMT） was prepared successfully. The mass ratio of CTS to MMT had a strong influence on the adsorption performance of CTS-MMT. The highest adsorption value of 150 mg/g was obtained over the composite material with CTS to MMT mass ratio of 0.25, which is much higher than those reported in other studies. The adsorption isotherms and kinetic results indicated that Co2＋ was adsorbed over CTS-MMT in a multilayer model, and the chemical sorption of Co2＋ was determined to be the rate-limiting step.     

二氯苯在盐水溶液中活度系数的研究

本文采用紫外分光光度法测定了２５．００±０．００１℃下间位和对位二氯苯在ＨＣＯＯＮａ，ＣＨ３ｃＯＯＮａ，（ＮＨ４）２ＳＯ４，ＭｇＳＯ４和Ｎａ２ＳＯ４水溶液中活度系数（ｆ），它们的ｌｇｆ－Ｃ关系符合Ｓｅｔｓｃｈｎｏｗ盐效应公式。     

废旧可充电池资源化新工艺研究

本文研究了废旧可充电池中Ni、Cd、Co的回收新工艺.混合电池经消电后粉碎至柱径不大于5mm的粉末,在600℃下灼烧1 h.得到的粉末用碳酸铵水溶液浸取,过滤使Ni、Cd、Co与Fe分离;用催化氧化方法,将含氨滤液中形成的Co(OH)3沉淀析出;用含LIX64N的煤油作苹取剂从上述滤液中分离出Ni,再通过逐出溶液中的NH3,得到CdCO3沉淀.     

金属废水溶液的中和沉淀净化理论分析

含有害金属废水溶液的中和沉淀净化过程受诸多因素的影响,其中,最重要的有溶液中金属的价态和形态,溶液的离子强度,沉淀物的组成,结构和表面效应等,本文对上述问题作了较全面的理论分析。     

哌嗪水溶液脱硫性能的研究

提出了一种有机胺吸收二氧化硫的烟气脱硫工艺.采用填充柱常压吸收常压再生操作流程,以解吸率和有效吸收SO2容量为评价指标,研究了哌嗪水溶液的脱硫性能,并将其与甲基二乙醇胺(MDEA)和乙二胺(EA)溶液作了比较.实验表明,0.3-0.5m01.1-1的哌嗪水溶液在30℃的温度下能达到较佳的吸收效果,而在85℃的温度下解吸能有效地减少富液挥发损失并达到95%以上的解吸率.哌嗪水溶液的单位有效脱硫容量达到了3.49g·g-1,远高于MDEA和EA.