BIOSORPTION STUDIES ON NACL-MODIFIED CERATOPHYLLUM DEMERSUM: REMOVAL OF TOXIC CHROMIUM FROM AQUEOUS SOLUTION

The present research provides information on the Cr(VI) removal potential of NaCl-modified Ceratophyllum demersum, an aquatic plant biomass. The effects of various parameters including pH, biomass dosage, contact time, and initial concentration on Cr(VI) biosorption were investigated. The best conditions for Cr(VI) biosorption in the present study were: pH of 2, biosorbent dose of 8 g/L, and contact time of 60 min. Under these conditions, maximum adsorption capacity of modified C. demersum for Cr(VI) was 10.20 mg/g. The experimental biosorption data were modeled by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The biosorption process followed the Langmuir isotherm model with a high coefficient of determination (R² > 0.99). The biosorption process followed pseudo-second-order kinetics. Further, the biosorbent was characterized by Fourier transform-infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The results showed that biosorption of Cr(VI) on NaCl-modified C. demersum occurred through chemical sorption.     

APPLICATION OF SOME DOMESTIC WASTES AS NEW LOW-COST BIOSORBENTS FOR REMOVAL OF METHYLENE BLUE: KINETIC AND EQUILIBRIUM STUDIES

In this study, parsley stalks (PS), cucumber peels (CP), and watermelon seed hulls (WSH) were used as novel low-cost adsorbents to remove methylene blue (MB) from aqueous solutions. The biosorption of MB onto PS, CP, and WSH was investigated as a function of pH (2–10), initial dye concentration (25–450 mg/L), temperature (293–333 K), ionic strength (0.0–1.0 mol/L NaCl), and biosorbent dose (0.1–1.0 g/50 mL). While the biosorption of MB on PS followed the Freundlich isotherm, biosorption on CP and WSH followed the Langmuir isotherm at all the temperatures studied. The monolayer biosorption capacities of PS, CP, and WSH were found to be 400, 111.11, and 57.14 mg/g, respectively. The biosorption of MB onto PS followed pseudo-second-order kinetics, and the biosorption onto CP and WSH followed pseudo-first-order kinetics. Thermodynamic studies showed that the biosorption of MB onto PS, CP, and WSH was spontaneous and feasible. The pH_zpc values _of PS, CP, and WSH were found to be 6.26, 6.42, and 6.83, respectively. Desorption studies were also carried out with various desorbing agents. HCl and H₃PO₄ were more effective desorbents than other desorbents used.     

Note EXTRACTION EQUILIBRIUM OF MERCURY(II) FROM AQUEOUS AMMONIUM THIOCYANATE SOLUTION WITH TRIISOBUTYLPHOSPINE SULFIDE

The extraction equilibrium of mercury(II) from aqueous ammonium thiocyanate solution with triisobutyl-phosphine sulfide(=TIBPS=S¯) in toluene has been measured at 303 K. It was found that mercury(II) is extracted according to a solvation reaction by TIBPS as a mercurydl) :TIBPS 1:2 complex, Hg(SCN)₂S2, as follows:

The extraction equilibrium constant, K_e, was evaluated as K_e = 1.8 × 10⁶ (dm³/mol)².     

ADSORPTION,KINETICS, AND EQUILIBRIUM STUDIES ON REMOVAL OF 4,4-DDT FROM AQUEOUS SOLUTIONS USING LOW-COST ADSORBENTS

The removal of a chlorinated pesticide (4,4-DDT) from aqueous solutions by a batch adsorption technique using different low-cost adsorbents was investigated. Two adsorbents, wood sawdust (A) and cork wastes (B), were used to determine adsorption efficiency. The influence of the adsorbent particle size and the organic matter of water (humic acids) on the removal process was studied. The obtained results were compared to those obtained with a commercial powdered activated carbon (PAC, F400, Chemviron) (C). Kinetic studies were performed to understand the mechanistic steps of the adsorption process. The rate of the adsorption kinetics of 4,4-DDT on the low-cost adsorbents was found best fitted with a pseudo-second-order kinetic model. This is in contrast to the rate of the adsorption kinetics of the PAC F400, which was best fitted with the Lagergren model. The application of the Morris-Weber equation showed that the adsorption process of 4,4-DDT on these adsorbents was complex. Both the adsorption on the surface and the intraparticle diffusion were the rate-controlling mechanisms. Langmuir and Freundlich adsorption isotherms were applicable to the adsorption process and their constants were evaluated. The adsorption capacity (q_m) calculated from the Langmuir isotherm (69.44 mg·g^?1, 19.08 mg·g^?1, and 163.90 mg·g^?1, respectively, for A, B, and C) showed that the process is highly particle size dependent, that the organic matter influenced the adsorption process negatively, and that wood sawdust is the most effective adsorbent for the removal of 4,4-DDT from aqueous solutions. The adsorbents studied exhibited a possible application in water decontamination, as well as in treatment of industrial and agricultural waste waters.     

实验条件对减压膜蒸馏法脱除水溶液中MIBK的影响

本文采用平板式减压膜蒸馏技术对水溶液中MIBK的脱除进行了研究,分别考察了料液温度、料液流量及减压侧压力对MIBK的脱除及效率的影响。     

利用低浓度表面活性剂胶团强化超滤处理含锌废水

利用低浓度的阴离子表面活性剂十二烷基硫酸钠（SDS）,对含Zn^2＋废水进行了胶团强化超滤（MEUF）研究．结果表明：进料液的静置时间为3h时,Zn^2＋在SDS胶团上的吸附达到平衡状态。当Zn^2＋的浓度一定时,由于发生在膜表面的浓差极化现象的影响,在进料液中投加浓度低于1倍临界胶束浓度（CMC）的SDS,不但在很大程度上降低了SDS的用量,而且亦可获得较高的Zn^2＋截留率和渗透通量,Zn^2＋的截留率主要受膜表面SDS浓度的影响。随着进料液中SDS浓度的升高,渗透通量逐渐降低,而渗透液中SDS的浓度随之不断增大,但无论进料液中SDS浓度有多大,渗透液中SDS的浓度都不会高于1倍CMC（2．25g／L）,所以渗透液中的SDS的损失相对较小。Zn^2＋截留率随进料液中Zn^2＋浓度逐步增大而逐渐减小,基于低浓度表面活性剂的胶团强化超滤技术适宜处理低浓度含Zn^2＋废水．     

用生物活性炭纤维新技术去除水中有机污染物

研制了生物活性炭纤维，用于去除水中有机污染物。采用循环流动法把微生物固定在活性炭纤维上，并用扫描电镜观察微生物在炭表面的生长情况。测试了生物活性炭纤维去除微污染源水中有机物的性能，并通过GC—MS图谱分析了处理前后水中有机物的变化。经处理后，水中的CODMn降到了2．5mg／L(饮用水的标准)以下，UV254的平均去除率高达94％，处理容量达到2880mL／g。另外，在相同的实验条件下，将生物活性炭与活性炭纤维的吸附性能作了对比，结果表明以ACF作为载体的生物活性炭纤维(BACF)技术在处理容量和处理效果上均显著优于其它两种处理方法，显示了此项新技术在水的深度处理领域的巨大应用潜力。     

REMOVAL OF METAL IONS FROM AQUEOUS SOLUTIONS USING PYROLYZED RICE HUSKS: ADSORPTION KINETICS AND EQUILIBRIA

Four carbon/silica-containing materials obtained by pyrolysis of rice husks were characterized and their adsorption properties towards some metal ions were evaluated. GC/MS analysis and FT-IR spectroscopy were applied for identification of functional groups finely dispersed on the surface. Their amounts were gravimetrically determined after extraction with acetone. The specific surface area and porosity of the materials were characterized by the Brunauer-Emmett-Teller (BET) method and by mercury porosimetry, respectively. The adsorption properties of the carbonized rice husks towards Fe(III), Pb(II), Cr(III), and Cu(II) ions in single- and multicomponent aqueous solutions also containing Ni(II), Co(II), Mn(II), and Cd(II) were studied in a batch system. The effects of contact time, acidity of initial solutions, and metal ion concentrations were followed. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were used to analyze kinetic data. Equilibrium experimental data were fitted to linear Langmuir and Freundlich models. The maximum adsorption capacities for single- and multicomponent adsorption were calculated and compared with literature data. A correlation between the adsorption properties of pyrolyzed rice husks and their textural and surface parameters was established. Possibilities for desorption of the investigated ions were estimated.     

MODIFIED PLANTAIN PEEL AS CELLULOSE-BASED LOW-COST ADSORBENT FOR THE REMOVAL OF 2,6-DICHLOROPHENOL FROM AQUEOUS SOLUTION: ADSORPTION ISOTHERMS,KINETIC MODELING,AND THERMODYNAMIC STUDIES

In this study, the feasibility of using modified plantain peel to remove 2,6-dichlorophenol from iaqueous solutions was investigated under batch mode. The effects of physical factors such as initial 2,6-dichlorophenol concentration, contact time, biosorbent particle size, biosorbent dosage and temperature on the removal process were evaluated. The results showed that biosorption of 2,6-dichlorophenol was dependent on these factors. The equilibrium biosorption data were analyzed by the Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) adsorption isotherm models. The four tested isotherm models provided good fits to the experimental data obtained at 30°C; however, the Freundlich isotherm model provided the best correlation (R² = 0.9874) of the experimental data. The maximum monolayer biosorption capacity (Q _max ) was found to be 14.25 mg/g. The biosorption kinetics data of 2,6-dichlorophenol were analyzed by pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion, and liquid film diffusion models. The five kinetic models fitted well to the biosorption kinetic data; however, the pseudo-second-order kinetic model gave the best fit when the biosorption mechanism was controlled by film diffusion. Thermodynamic quantities such as standard Gibbs free energy (ΔG°), standard enthalpy (ΔH°), standard entropy change of biosorption (ΔS°), and activation energy (E_a) were evaluated, and it was found that the biosorption process was spontaneous, feasible, endothermic in nature and of dual nature, physisorption and chemisorption; however, the physisorption process was dominant. Therefore, modified plantain peel has potential for application as an effective bioadsorbent for removal of 2,6-dichlorophenol from aqueous solution.     

REMOVAL OF TOLUENE AND DICHLOROMETHANE FROM AQUEOUS PHASE BY GRANULAR ACTIVATED CARBON (GAC)

Chlorinated hydrocarbons and aromatics constitute the major class of volatile organic compounds that contaminate groundwater. In this study, the equilibrium uptake and column dynamics for the adsorption of dichloromethane (as a typical chlorinated hydrocarbon) and toluene (as a representative of aromatic compounds) from aqueous phase on coal-based granular activated carbon (GAC) were investigated. The adsorption isotherms were measured in a temperature range of 20–40°C. The experimental data obtained were correlated with several adsorption isotherm models. The Langmuir model was well adapted to describe the dichloromethane adsorption on GAC, while the adsorption of toluene on GAC was found to be well described by the Langmuir-BET hybrid model in the stated temperature range with R-squared value of about 0.99. The variations in adsorption breakthrough curves of toluene and dichloromethane with respect to operational parameters such as initial concentration, flow rate, column length, and temperature were investigated. The experimental breakthrough curves of both adsorbates are well fitted by Yan's model with high accuracy (R-squared value of 0.98–99) in most cases.     

胶束强化超滤脱除氯苯及其膜污染的研究

以十六烷基氯化吡啶 (CPC)作为表面活性剂 ,利用聚醚酰亚胺 (PEI)中空纤维超滤膜 ,对含氯苯废水进行了胶束强化超滤 (MEUF)研究 ,讨论了 CPC浓度对氯苯脱除的影响 ,以及料液流速、操作压力和操作时间对膜污染的影响。在 CPC浓度 (Cf)为 3 .1 g/L～ 1 8.6 g/L的范围内 ,氯苯浓度为 0 .45 g/L时 ,CPC的截留率可大于 95 % ,而氯苯的脱除率可达 98.0 %以上 ,渗透通量可达 1 .0× 1 0 -10 m3/m2·s·Pa。采用去离子水对膜清洗 1 h后 ,膜纯水通量恢复率可达 95 %。     

EXTRACTION OF NICKEL FROM AQUEOUS SULFATE SOLUTION INTO BIS(2,2,4-TRIMETHYLPENTYL)PHOSPHINIC ACID,CYANEX 272TM -EQUILIBRIUM AND KINETIC STUDIES

ABSTRACT

Equilibrium and kinetic studies have been carried out on the extraction of nickel from sulfate solutions using bis(2,2,4 trimethylpentyl) phosphinic acid HDTMPP, “Cyanex 272tm”- It was found that nickel extraction in HDTMPP was favored by the presence of sodium in the organic phase and that equilibrium nickel concentration could be written in terms of the pre-equilibrated extractant concentration

Kinetic studies were carried out using the rising drop method, reaction orders were determined with respect to the aqueous phase nickel concentration, Ni²⁺, the aqueous phase sodium concentration, Na ⁺ the pH, the organic phase dimer concentration ------ and the organic phase sodium salt concentration ---- In addition, it was found that the extraction kinetics could be explained in terms of an aqueous phase interfacial reaction accompanied by diffusion through the interface. Mass transfer coefficient values were determined indicating extraction rates for metal extraction into HDTMPP were the same order of magnitude as those found for HDEHP.     

有色高强丙纶长丝生产与技术探讨

论述了在国产二步法［１］生产装置上纺制有色高强丙纶长丝的生产技术特点,初步探讨了影响有色纤维强度的因素及色差现象的产生     

THERMODYNAMIC AND KINETIC STUDY OF ADSORPTION OF Ni(II) IONS ON CARBON ANODE DUST

In this study the use of carbon anode dust (CAD), which is the solid residue from aluminum production, as a low-cost adsorbent for the removal of Ni(II) ions from wastewater was investigated. A mechanism of adsorption kinetics and thermodynamics was proposed. In order to investigate the adsorption process of nickel ions on CAD three kinetic models were used: Lagergren's pseudo-first-order model, pseudo-second-order model, and the intra-particle diffusion model. Various thermodynamic parameters, such as the energy of activation (E_a), activation enthalpy (ΔH*), activation entropy (ΔS*), and free energy of activation (ΔG*), were evaluated. Observation of the value of the energy of activation suggests that the process uptake of Ni(II) ions can be described as activated chemisorption. The positive values of enthalpy of activation and free energy of activation, as well as negative values of entropy of activation, mean that the process of removal of Ni(II) ions is endothermic, non-spontaneous, and without structural changes in the solid carbon anode dust particles.     

碳纤维/聚碳酸酯复合材料研究

本文制备了碳纤维增强聚碳酸酯(PC)复合材料并研究了其性能,相比玻璃纤维增强PC,碳纤维增强PC在机械性能、电性能和加工性等方面有明显的提高.随着碳纤维含量的增加,拉伸强度、弯曲强度、弯曲模量明显呈上升趋势.而伸长率和冲击强度在碳纤维含量为6%时达最大值,分别为10.4%kJ/m~2和8.7kJ/m~2.加工流动性有了明显的提高,且随碳纤维含量的增加而逐渐降低.碳纤维的加入,也改善了PC的导电性,当碳纤维含量为10%时,导电电阻率已达到9.0×10~6Ω/sq.     

EQUILIBRIUM OF CO2 IN AQUEOUS DIETHANOLAMINE(DEA) AND AMINO METHYL PROPANOL (AMP) SOLUTIONS

Equilibrium data of CO₂ in aqueous solutions of DEA and AMP for a range of CO₂ partial pressure (0.5-100 k Pa) and temperature (25-80^°C) obtained using a stirred cell reactor is presented in this paper. The data were analyzed using the Deshmukh and Mather Model. It has been found that this model is able to predict results which are close to the experimental data in terms of the total CO₂ loadings and the pH of the solution, an additional parameter which was monitored in this work. Comparison was also made with other published results using the different interaction parameters generated in this work. Good agreement between predicted and experimental values were also observed.     

铜（II）/明胶（酶解明胶）络合物的制备及其络合形态的探讨

许多金属元素对于生物体是必需的,Ｎａ、Ｋ、Ｍｇ、Ｃａ、Ｍｎ、Ｆｅ、Ｃｏ、Ｃｕ、Ｍｏ和Ｚｎ在人体中的含量约３％;各种金属离子在生物体中具有不同的作用,其功能是很复杂的．铜在生物体内主要是进行氧化还原反应,起输送氧气和电子载体的作用．如果人体内缺乏铜,则...     

柚子皮吸附活性艳蓝KN-R和活性艳橙X-GN性能研究

采用间歇实验,考察了初始pH、柚子皮投加量、柚子皮粒径、离子强度、染料初始含量及接触时间对柚子皮去除废水中的活性艳蓝KN-R及活性艳橙X-GN这2种染料影响。结果表明,酸性pH条件下吸附效果良好,柚子皮能有效地去除废水中的KN-R和X-GN,对KN-R和X-GN的去除率达到97.48%和95.63%;柚子皮粒径变化对吸附效果影响不明显,吸附时间宜控制在480 min以上。柚子皮可作为一种新型吸附剂应用于活性染料废水的处理,作为一种农业废物的资源化加以利用。     

超级电容器用活性炭纤维的研制(Ⅰ活性炭纤维的强度与比表面积)

分别以粘胶纤维和粘胶炭纤维为原料，经镍盐溶液浸渍后制备活性炭纤维。比较两种原料制得的活性炭纤维的强度和比表面积；考察它们随镍盐溶液浓度、活化温度和活化时间的变化情况。结果表明，两种原料制得活性炭纤维的强度和比表面积随上述三因素各自的变化趋势一致；并由此初步确定了比表面积～1200m^2／g,强度～0．3GPa的粘胶基活性炭纤维的制备工艺.     

KINETIC STUDY OF SYNTHESIZING DIALKOXYMETHANE USING 4-(TRIALKYLAMMONIUM) PROPANSULTANS AS NEW PHASE-TRANSFER CATALYSTS

In this work, sulfobetaine (4-(trialkylammonium) propansultan (TAAPS)) was first developed as a new phase-transfer catalyst for synthesizing dialkoxymethane. The addition reaction of 1,3-propane sultone (PS) and trialkylamines (TAA) was successfully carried out to synthesize sulfobetaines in a homogeneous organic solution. In this work, for the first time, five different TAAPSs, which possess high reactivity, stability, selectivity, and performance, were employed as phase-transfer catalysis to synthesize dialkoxymethane. The reaction of alcohol and dibromomethane in a highly alkaline solution of KOH/organic solvent two-phase medium to produce dialkoxymethane was carried out under phase-transfer catalysis using 4-(trialkylammonium) propansultan as the catalyst. From the experimental observation, a rational reaction mechanism using this new phase-transfer catalyst was proposed. Kinetics of the reaction are studied in detail.