Parametric Evaluation of Batch Equilibria for Storm-Water Phosphorus Adsorption on Aluminum Oxide Media

Elevated and variable aqueous and granulometric concentrations of phosphate species (P) are commonly observed in urban rainfall runoff. Though physical operations such as sedimentation can potentially separate particulate P, aqueous P requires a unit process approach such as adsorption. Therefore, adsorption of aqueous P on aluminum oxide coated media (AOCM), a porous soil-type substrate coated with aluminum oxide, is investigated. Parameters studied include media size, phosphate concentration as total dissolved phosphorus (0–25 mg/L), pH (5–9), ionic strength (0.000?5–0.2 M as KCl), and the presence of coexisting ions such as Ca2+, SO42?, and NO31?. Results indicate that adsorption (mg/g) increased with decreasing AOCM size and decreasing pH. Ca2+ enhanced P adsorption by forming ternary complexes; SO42? inhibited P adsorption by competing for available adsorption sites. Ionic strength and NO31? had minor to negligible effects on adsorption equilibrium, respectively. Chemical adsorption between P and AOCM resulted in low desorption potential. Adsorption data were modeled with Freundlich isotherms. After batch adsorption by AOCM, results indicate that P could be significantly reduced, meeting most surface water discharge requirements.     

pH及离子强度对石英砂负载羟基磷灰石吸附锰的影响

制备石英砂负载羟基磷灰石复合材料去除铀尾矿库重金属锰,以PHREEQC计算不同pH锰的赋存形态,并用五种经典动力学模型对吸附过程进行拟合、分析其吸附机理;阐述不同离子强度、阴阳离子对锰的去除效果。试验表明,不同pH对锰的吸附效果具有较大差异,CO32-、PO43-可促进去除,Cd2 、Mg2 则与Mn2 竞争吸附位点,降低复合材料吸附量。     

Removal of Nickel(II) from Dilute Aqueous Solution by Sludge-Ash

This work examines the adsorption of Ni(II) onto sludge–ash, a waste produced from a fluidized bed incinerator combusted primarily with biosolids. Results of kinetic experiments showed that the adsorption was rapid. The kinetic adsorption data can be well described by an empirical modified Freundlich equation. The rate of adsorption decreased with either increasing surface loading and ionic strength or decreasing solution pH. The results of equilibrium studies showed that the solution pH was the key factor affecting the adsorption. The modified Langmuir model fit revealed that the hydrogen ion acts as a competitive inhibitor for the adsorption of Ni onto ash. The maximum adsorption capacity for Ni is 5.41 μmol/g. Experimental results indicate that the adsorption is favorable at higher temperature. Thermodynamic adsorption parameters for ΔG°, ΔH°, and ΔS° are ?7.41 kcal/mol, 7.25 kcal/mol, and 48.9 cal/mol?K, respectively.     

Equilibrium and Kinetic Study on Reactive Dyes Adsorption by Palm Kernel Shell-Based Activated Carbon: In Single and Binary Systems

The adsorption of two reactive dyes, Reactive Black 5 and Reactive Red E, onto palm kernel shell-activated carbon (PKSAC) was studied. The effect of the presence of more than one dye in solution on the equilibrium and kinetics of adsorption was investigated. Equilibrium isotherm models were applied to describe the adsorption capacities of single and binary systems. Adsorption of reactive dyes for single system can be represented by the Freundlich and the Redlich-Peterson models. For binary system, the equilibrium was described successfully by the modified extended Freundlich model. Experimental data showed that competitive adsorption for active sites on the carbon surface resulted in a reduction in the overall uptake capacity of the reactive dyes. The rates of adsorption in single system were found to agree well with the pseudosecond-order kinetic model. Finally, the chemical oxygen demand (COD) of the treated reactive dye solutions from single and binary systems showed that a minimum of 4 g/L dosage of PKSAC was needed to reduce the COD to an acceptable level according to the Water Quality Guidelines and the Pollutant Fact Sheets Guidelines.     

嗜镍菌吸附Ni~（2＋）条件与机理的关系研究

为了有效解决环境中镍离子的污染问题,研究了实验室筛选的嗜镍菌吸附镍离子条件与机理的关系。实验结果表明：嗜镍菌吸附镍离子条件的确定要考虑体系的离子强度和活度系数、pH值和溶度积、菌体表面活性位点及与Ni2＋的碰撞几率、吸附趋于平衡的最短时间和最大限度地节省原材料和时间等因素。将诸因素与吸附量、吸附率结合,确定的最佳吸附条件：pH值为6、离子强度为0.01 mol/L、菌的质量浓度为2 g/L、Ni2＋的质量浓度为25 mg/L、温度为25℃,吸附2 h趋于平衡,吸附率最高达到98%。实验条件下,嗜镍菌的最大吸附量为80 mg/g,具有较好的应用价值。     

钍(Ⅳ)离子在泥炭上的吸附研究

采用静态批次吸附法研究了泥炭对Th4+的吸附行为。探讨了泥炭粒径、固液质量体积比、振荡时间、溶液pH值、离子强度等因素对吸附的影响,并确定了室温下不同离子强度时的吸附等温线。试验结果表明:溶液pH值对泥炭吸附Th4+影响较大,离子强度的影响较小;吸附过程符合Langlmuir方程;泥炭对Th4+的吸附主要通过表面络合进行。     

Adsorption and Precoat Filtration Studies of Synthetic Dye Removal by Acid Mine Drainage Sludge

Adsorption tests of Congo Red, a commercial azo dye, by acid mine drainage (AMD) sludge were carried out at different pH, temperature, dye concentration, contact time, and adsorbent dosage. Precoat filtration was conducted to test if the dye could be removed during continuous filtration by a precoated AMD sludge layer. Adsorption of Congo Red onto AMD sludge followed the Langmuir isotherm model with a maximum adsorption capacity of 389.1?mg/g. Based on thermodynamic studies, adsorption was found to be exothermic, and an increase in temperature led to a decline in dye removal. Dye removal decreased with an increasing pH. Through metal leaching tests, it was observed that most metals associated with AMD sludge remained insoluble when adsorption occurred at pH 6–10. A rather rapid process was observed for the adsorption of Congo Red onto AMD sludge with more than 80% adsorption taking place within 5?min. Adsorption kinetics followed pseudo-second-order model. Precoat filtration continuously removed Congo Red from aqueous solution with success, and dye removal mechanism via precoat filtration was adsorption. The adsorption and precoat filtration studies showed dye removal could be a beneficial use of AMD sludge prior to its final disposal.     

Effect of pH and ionic strength on bovine m-calpain and calpastatin activity

The effects of bovine skeletal muscle m-calpain and calpastatin on the degradation of casein and isolated bovine myofibrils were characterized under various pH values (7.0, 6.2, 5.7) and ionic strengths (32 to 400 mM KCl) at 25 degrees C. Caseinolytic assays indicated that m-calpain activity increased with increasing pH (P < .01) but decreased with increasing ionic strength (P < .01). Regardless of the presence of m-calpain, SDS-PAGE of myofibrils showed increased solubilization of myofibrillar proteins as pH and ionic strength increased. However, only in the presence of m-calpain were changes normally observed during postmortem storage reproduced. Protein release attributed to m-calpain activity increased with pH, but the effects of elevated ionic strength on the ability of m-calpain to hydrolyze myofibrillar proteins were not evident from SDS-PAGE, except for the decreased troponin-T degradation by m-calpain at the higher ionic strengths. A pH x ionic strength interaction was observed for calpastatin activity determined by caseinolytic assays (P < .01). No changes in m-calpain inhibition were detected at pH 7.0 and 6.2 at different ionic strengths. However, at pH 5.7 the ability of calpastatin to inhibit m-calpain decreased with increasing ionic strength. No changes in m-calpain inhibition could be detected with SDS-PAGE. Based on these results, it can be concluded that although m-calpain and calpastatin activities decrease with increasing ionic strength, their activities in the presence of myofibrils were not affected by ionic strengths typically found in postmortem muscle.     

CL-P204萃淋树脂对溶液中钒的吸附性能研究

探究CL-P204萃淋树脂对溶液中V(Ⅳ)的吸附效果。考察溶液pH、反应时间、初始浓度、温度对钒吸附容量的影响,并对吸附过程进行了动力学和热力学分析。结果表明,CL-P204萃淋树脂在298K、pH=1.6的条件下,吸附8h即可达到平衡,对V(Ⅳ)的最大吸附容量为34.2mg/g。树脂循环使用4次后对钒依然有良好的吸附效果。CL-P204萃淋树脂对钒的吸附过程符合准二级动力学方程和Langmuir等温吸附方程,是吸热熵增加的自发反应。     

活性炭负载铁盐去除水中高氯酸盐

选用5种不同的铁盐对活性炭进行改性,采用浸润法制备活性炭负载铁盐的复合材料(GAC-Fe),并运用X射线衍射(XRD)和红外光谱(FTIR)对材料GAC-Fe进行表征。考察了在不同pH值和初始浓度条件下高氯酸盐的去除效果,分析了吸附等温模型和吸附动力学,并探讨反应机理。结果表明,活性炭负载FeCl₃制备的复合材料对ClO₄-的效果去除最好,去除效率达97 %;ClO₄-的去除效果在中性和弱偏酸性条件下较好,吸附等温实验表明Langmuir模型优于Freundlich模型描述复合材料(GAC-Fe)对ClO₄-吸附过程;吸附动力学结果表明复合材料(GAC-FeCl₃)对ClO₄-的吸附更加符合准二级动力学方程。      

Environmental Factors Affecting Selenite Reduction by a Mixed Culture

This study presents the results of batch experiments investigating selenite reduction by an enriched anaerobic mixed culture as a function of several environmental factors, including pH, temperature, different electron donors and acceptors, as well as initial selenite concentrations. The initial selenite reduction was a zero-order reaction and was inhibited at higher selenite concentrations (>33 mg Se∕L). The optimal temperature∕pH for microbial reduction occurred at 30°C and pH 7.2. Selenite reduction was affected in the presence of high concentrations of sulfate [45 times the Se(IV) molar concentration], significantly affected by nitrate [105 times the Se(IV) molar concentration], and completely inhibited by chromate and oxygen. Ethanol was the preferred carbon source for selenite removal, followed by acetate, citrate, lactate, and glucose. The selenite-acclimated culture also reduces selenate without any lag period.     

Selectivity adsorption of thiophene alkylated derivatives over modified Cu＋-13X zeolite

Solid adsorbents Cu+-13X and Cu+-13X loaded with La element were prepared by ion-exchange method. X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to characterize the structure of the prepared zeolite. Adsorption of thiophene with different groups over the two adsorbents was investigated by static adsorption equilibrium and kinetic test. Static equilibrium data were correlated based on the Langmuir model and the modified Langmuir model. Kinetic data were fitted very well by Crank diffusion model. The results revealed that the adsorption capacity of single component over the Cu+-13X loaded with La element increased about 10% as compared to the non-doped Cu+-13X. Fitting results of ηi and De illustrated that loading of the La element into zeolite could change the interaction force between binary components. The kinetic test showed that the competitive adsorption became moderate, and thus resulted in the improvement of the total desulfurization capacity.     

基于协同体系的磁性材料在稀土吸附中的应用研究

通过二氧化硅溶胶—凝胶法,将2-乙基己基膦酸单(2-乙基己基)酯（P507）与二(2,4,4’-三甲基戊基)膦酸（C272）的协同体系引入磁性固体吸附材料中,并将其用于吸附低浓度稀土离子。吸附剂的吸附试验结果表明,当溶液pH值为2时,吸附剂具有较优的协同效果,协同系数高达22,最大吸附量为0.07 mmol/g,但由于离子强度的增加会产生竞争吸附,使得稀土吸附量降低;吸附热力学分析表明,吸附为自发的吸热过程,且吸附量随着温度的升高而增大;动力学试验研究结果表明,吸附过程与二级动力学模型具有最高的拟合度,在吸附90 min后基本达到平衡。      

Hydrogen-Based Nitrate and Selenate Bioreductions in Flue-Gas Desulfurization Brine

The H2-based membrane biofilm reactor (MBfR) was shown to simultaneously reduce nitrate and selenate in flue-gas desulfurization (FGD) brines (15–33 g/L TDS). The MBfR also used polyester fibers, which differ from the composite gas-transfer fibers used in previous MBfR studies. Selenate reduction was nearly 100% in all media tested and was immediate, which suggests that selenate was coreduced with nitrate, possibly by the same microorganisms. A step increase in the nitrate removal flux was observed at a H2 pressure greater than 20 psig (138 kPa) using polyester fibers. High concentrations of nitrate and sulfate had no inhibitory effect on selenate reduction as long as H2 was available. In comparison with previous MBfR experiments treating ion-exchange brine, total electron equivalent fluxes were 29% lower and in contrast to earlier work on selenate reduction in fresh water, sulfate reduction was inhibited, likely due to the high total dissolved solids in the FGD brine or insufficient H2 availability due to CaCO3 or Se° precipitation onto the tighter polyester fibers.     

Ultrathin films of charged polysaccharides assembled alternately with linear polyions

As a means of preparation of biocompatible molecular surfaces, an alternate assembly of charged polysaccharides and oppositely-charged synthetic polymers was conducted. Cationic chitosan was assembled alternately with anionic poly(sodium styrenesulfonate) (PSS) at pH 4. Regular film growth and its dependence on ionic strength were detected by the quartz crystal microbalance (QCM) method. Averaged film thicknesses for the chitosan + PSS layer were 15, 31, 46, and 69 A, respectively, when 0, 0.25, 0.5, and 1 M of NaCl was contained in aqueous chitosan. Adsorption of chitosan did not reach saturation in 20 min at 0 M NaCl, while the adsorption became saturated within 6 min with 0.25 M NaCl. Anionic sodium chondroitin sulfate was also assembled in alternation with cationic poly(dimethyldiallylammonium chloride) (PDDA) at pH 6.5. The adsorption of chondroitin sulfate was less sensitive to ionic strength. Surface morphology of chitosan-PSS films was investigated by non-contact atomic force microscopy (AFM) observation. Maximum height difference and Ra value for a 1000 x 1000 nm area were 11 and 0.69 nm, respectively, indicating the formation of a molecularly flat surface by alternate layer-by-layer adsorption.     

沸石负载纳米氧化铁处理氮磷污水研究

采用共沉淀法制备了沸石负载纳米氧化铁复合材料(沸石@Fe_3O_4),并采用静态吸附试验探究了pH、吸附动力学、等温吸附模型及热力学等对沸石@Fe_3O_4吸附模拟氨氮废水溶液的影响。试验表明,当溶液pH为6时,沸石@Fe_3O_4对水中氨氮的吸附能力达到最高值,随溶液中pH的升高,沸石@Fe_3O_4对水中磷的吸附能力逐渐降低。可采用准二级动力学模型描述沸石@Fe_3O_4对水中氨氮和磷的吸附动力学过程。Langmuir吸附等温线模型的线性拟合结果表明,氨氮和磷最大理论单位吸附量分别为7.92和9.09mg/g。     

A fosmid-based genomic map and identification of 474 genes of the hyperthermophilic archaeon Pyrobaculum aerophilum

Polydimethylsiloxane (PEP) is widely used in medical prostheses and therefore is in contact with plasma and secretory proteins. Two pair of globular proteins, lactoferrin (Lf) and transferrin (Trf), and bovine IgG1 and IgG2a, which differ substantially between pair members in their pl, were used to study the interaction of a PEP widely used in breast implants and soluble protein. Studies were done using iodinated proteins over a concentration range that resulted in an apparent protein monolayer. Secondary incubations with dilute protein solutions were needed to form the monolayer on PEP, possibly as a consequence of micro air bubbles trapped on its highly textured surface as shown by atomic force microscopy. Immunoassay quality polystyrene microtiter wells were used as controls. Adsorption studies were routinely performed at pH 4, 7 and 10 and at ionic strengths corresponding to 0.95, 9.5 and 90.0 mS. The protein capture capacity (PCC) of PEP for Lf and Trf was optimal at physiological pH and ionic strength and comparable under these conditions to that of Immulon 2 (Imm 2) microtiter wells. While increasing the ionic strength and pH further increases the PCC of Imm 2 for Lf and Trf, this markedly lowered the PCC of PEP for these proteins suggesting that initial polar interactions may precede subsequent hydrophobic bonding to PEP. This was tested using a hydrophilic variant of PEP, which when tested in a 90.0 mS buffer, showed a > five-fold lower PCC at neutral and alkaline pH. The greatly reduced PCC of the hydrophilic variant might also suggest that hydrophilic variants of silicone would be more biocompatible than those currently used. The PCC of PEP for the IgGs was less than that of Imm 2 but still optimal at physiological conditions. Consistent with the data on Lf/Trf, PCC progressively decreased with increasing ionic strength at alkaline pH. Differences in pl between the protein pairs had only a marginal effect on the PCC of PEP. Monolayer adsorption on both PEP and Imm 2 was slowly reversible and greater in the presence of free ligand (< 2% in 16 h) suggesting that the process follows Mass Law principles. However, even in the presence of non-ionic detergent and free ligand, 85-90% remained bound on either surface. Thus, desorption of proteins in the monolayer should not complicate subsequent immunochemical studies conducted on adsorbed monolayers.     

Cr(VI) Removal from Water with Amorphous Graphite Concentrate Contaminated by Iron

This work attempted to explore the feasibility of using iron-contaminated graphite concentrate as an effective adsorbent for Cr(VI) removal from polluted water. Adsorption isotherm and kinetics were conducted to investigate the Cr(VI) removal capacity by the iron-contaminated amorphous graphite concentrates. In addition, SEM-EDS, XPS were carried out to further examine the solid samples. The results showed that amorphous graphite concentrate had a 1.52 mg/g adsorption capacity of Cr(VI), with the adsorption being fitted well with the pseudo-second-order kinetics model. In addition, chemical adsorption of Cr(V) on iron-contaminated graphite concentrate due to the formation of ≡Fe-O₄HCr and Fe₂-(CrO₄)₃ complexes was proposed. This study revealed that iron-contaminated amorphous graphite concentrate would be a cheap and good adsorbent for the removal of Cr(VI) from contaminated water.     

Novel Approach to Characterization of Rare Earth Complexation with 1, 5-Bis（2-Hydroxy-5-Chlorphenyl）-3-Cyanoformazan in Presence of Cetyltrimethylammonium Bromide

The ternary interaction of 1, 5-bis ( 2-hydroxy-5-chlorphenyl )-3-cyanoformazan (HCPCF) with cetyhrimethylammonium bromide (CTAB) and rare earths (RE: Yb, Dy, Er and Eu) was investigated at pH 9.84 by the microsurface adsorption - spectral correction technique (MSASC). The aggregation of HCPCF on CTAB obeys the Langmuir isothermal adsorption and the interaction of RE with the HCPCF-CTAB aggregate was first found to accord with the monolayer binding. The effects of temperature and ionic strength of solution on the aggregations were made. The binary aggregate and the ternary complex were characterized.     

Competitive Sorption of Pesticides onto Treated Wood Charcoal and the Effect of Organic and Inorganic Parameters on Adsorption Capacity

This paper presents competitive sorption of coexisting pesticides onto treated wood charcoal and describes the effect of various water quality parameters, viz., pH, ionic strength, chloride concentration, presence of calcium and magnesium, fertilizers, humic acid, polyacrylic acid, and also the effect of coexisting pesticides on the sorption of endosulfan onto treated wood charcoal. The coexisting pesticides were found to hinder the performance of wood charcoal in removing endosulfan. Competitive uptake study revealed that endosulfan occupies more sites followed by atrazine and monocrotophos. Solubility in water could be one of the major reasons for this preferential order. The presence of humic acid was found to show much more significant influence on the performance of wood charcoal than the presence of polyacrylic acid. Among fertilizers, single superphosphate was found more influential. Most of it, among the other reasons, could be due to the competition of the coexisting molecules for the available adsorption sites on wood charcoal. Other parameters have resulted in some fluctuations in performance, but the effects are not significant. Endosulfan removal efficiency faltered at higher pH values, and ionic species did not affect the sorption as endosulfan is nonionic under neutral conditions.