Uranium(VI) and Thorium(IV) Adsorption Studies on Chelating Resin Containing Pentaethylenehexamine as a Functional Group

A new chelating resin (glycidyl methacrylate/divinylbenzene/pentaethylenehexamine (GMA/DVB/PEHA)) for uranium(VI) and thorium(IV) has been developed by functionalizing GMA/DVB with PEHA. The adsorption of U(VI) and Th(IV) ions onto the functionalized GMA/DVB/PEHA were investigated as a function of pH value, contact time, and temperature using batch adsorption technique. The results showed that U(VI) and Th(IV) adsorption onto GMA/DVB/PEHA was strongly dependent on pH. Kinetic studies revealed that the adsorption process achieved equilibrium within 15 and 90 minutes for Th(IV) and U(VI), respectively, and followed a pseudo-second-order rate equation. The isothermal data correlated with the Langmuir model better than the Freundlich model. Thermodynamic data indicated the spontaneous and endothermic nature of the process. The maximum adsorption capacity of U(VI) and Th(IV) were found to be 114 and 78 mg/g, respectively. Quantitative recovery of uranium and thorium were achieved by desorbing the loaded GMA/DVB/PEHA with 0.5 M HNO₃      

Evaluation of Pomegranate (Punica Granatum L.) Pulps for the Removal of Copper(II) Ions: Kinetic,Equilibrium, and Desorption Studies

Pomegranate pulp has been used as novel adsorbent for removing Cu(II) ions from aqueous solution. The optimum conditions for removal of Cu(II) ions were found to be pH 5.32, biosorbent dose 0.1 g, contact time 120 minutes, initial concentration 50 mg/L, and temperature 30°C. The kinetic data were well fitted to the pseudo-second-order model. The biosorption process agreed with the Langmuir isotherm model. Maximum monolayer biosorption capacity was 7.30 mg/g. Thermodynamic parameters suggest that the biosorption process is spontaneous and exothermic. Desorption studies were carried out with different desorbing agents.      

Adsorption Isotherm,Kinetic, Thermodynamic,and Desorption Studies of Lanthanum and Dysprosium on Oxidized Multiwalled Carbon Nanotubes

The adsorption behavior of La(III) and Dy(III) onto multiwalled carbon nanotubes oxidized (MWCNTs-oxidized) with concentrate nitric acid as a function of pH and adsorbent dosage was studied by batch technique. Maximum adsorption uptakes, according to the Langmuir model were obtained as 99.01 mg/g for La(III) and 78.12 mg/g for Dy(III). The results showed that adsorption process of both metals ions followed well the pseudo-second-order kinetics. The results of Thermodynamic parameters showed that the adsorption of La(III) and Dy(III) onto MWCNTs-oxidized is a feasible, spontaneous, and exothermic process. The results of desorption indicated that most of the adsorbed La(III) and Dy(III) can be easily desorbed from MWCNTs-oxidized at low pH values.     

Comparison Between Long- and Short-Chain Organoclays for Oil Removal from Salty Waters

Two commercial powdered organoclays, Cloisite 15A and Cloisite 30B, as long-chain organoclays, and two organically modified clays with tetramethylammonium chloride (TMA-clay), as short-chain organoclays were used in this study to investigate their potentials for crude oil removal from salty waters. Batch experiments were performed to examine the effect of contact time and pH on the adsorption process. The results showed that the equilibrium time was reached within 25–30 and 50–55 minutes of contact time for long and short-chain organoclays, respectively. In addition, adsorption isotherms were obtained at an optimum pH value of 11.73 and temperature of 19°C for which initial oil contents varied in the range of 100 to 2000 ppm. Experimental results indicated that the sorption of oil onto Cloisite 15A, Cloisite 30B and the organically modified clays can be described by Freundlich isotherm and oil sorption followed the order of modified Cloisite Na > Cloisite 30B > Cloisite 15A > a modified local clay.      

Influence of PZC (Point of Zero Charge) on the Static Adsorption of Anionic Surfactants on a Malaysian Sandstone

Static adsorption studies of two anionic surfactants produced in our lab are reported. The adsorption of surfactants on the rock samples was investigated with and without the presence of alkali. The point of zero charge (PZC) values were determined for the sandstone samples employing three titrimetric methods and it was found to be at pH 7.98. The relationship between the adsorption degree and pH value of brine below and above the PZC is discussed. It was found that at the pH of solution exceeds the PZC of the rock, the adsorption was 0.43 and 0.86mg/g of rock for the two surfactants. However, at pH values below PZC, the adsorption as high as 3.66 and 4.49mg/g for the two surfactants. The synthesized surfactants are found to be suitable for the EOR applications at pH values higher than the PZC of the rock sample.     

Optimization of Copper and Lead Removal by a Novel Biosorbent: Cucumber (Cucumis Sativus) Peels—Kinetic,Equilibrium, and Desorption Studies

Cucumber peels biosorption efficiency for copper(II) and lead(II) was studied in batch mode. The optimum conditions for removal of Cu(II) and Pb(II) ions were found to be pH 5.0, biosorbent dose of 0.1 g, contact time of 60 and 85 minutes, and initial concentration of 100 and 150 mg/L, respectively. The kinetic data were best described by pseudo-second order model. The biosorption process followed by the Langmuir isotherm model. Maximum monolayer biosorption capacities were 88.50 and 147.06 mg/g for Cu(II) and Pb(II) ions, respectively. Thermodynamic parameters suggest that the biosorption process is spontaneous and endothermic. Desorption studies were carried out with different desorbing agents.     

Adsorption of Cd(II) Ions onto Activated Carbon Prepared from Hazelnut Husks

In this study, a batch adsorption of Cd(II) ions onto activated carbon (AC) produced from hazelnut husks were investigated. The factors controlling the adsorption process such as initial pH, agitation time, dosage and initial concentration have been examined. The AC was showed a high affinity to Cd(II) ions at pH values between 5.0 and 7.0. The equilibrium time was found to be 300 minutes. Cd(II) adsorption equilibrium was analyzed with both Langmuir and Freundlich isotherm equations and it was found that Langmuir equations fitted well with the experimental data. Maximum Cd(II) adsorption capacity of AC was calculated to be 20.9 mg g^?1. Cd(II) adsorption kinetics described well with the pseudo second order model. The activated carbon prepared from hazelnut husks is efficient sorbent material for the removal of Cd(II) ions from aqueous solutions.     

Adsorption of Fe(III) from Aqueous Medium onto Glycine-Modified Chitosan Resin: Equilibrium and Kinetic Studies

The adsorption of Fe(III) onto glycine-modified chitosan (G@Chs) resin has been investigated. The parameters studied include the effects of pH, contact time, and initial metal ion concentrations by batch method. The optimal pH for the adsorption of Fe(III) was found to be 2.5. The results obtained from equilibrium adsorption studies are fitted in various adsorption models such as Langmuir and Freundlich, and each model parameter were evaluated. Kinetics and thermodynamic parameters of the adsorption process were also investigated. The maximum uptake was found to be 0.9 mmol g^?1 at 25°C.     

Adsorption of Lead Ion Using Polymer-Modified Wheat Straw Carboxymethylcellulose

The wheat straw carboxymethylcellulose (WSC), a typical natural polymer, was modified by functional poly(acrylic acid) (PAA) with in situ polymerization, which afforded natural and synthetic polymer composite (WSC/PAA). The polymer (WSC/PAA) was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis techniques. WSC/PAA was used as polymer adsorbent for removing Pb(II) ions in wastewater. The removal rate of 99.8% was obtained when the experimental conditions were chosen as follows: initial Pb(II) ion concentration; 600 mg/L, WSC/PAA concentration; 0.1 g/100 mL, pH; 5.0, contact time; 60 minutes at 20°C. Adsorption dynamics were consistent with pseudo-second-order kinetic model and the isotherm model can meet the Langmuir isotherm.     

Kinetics and Equilibria of Synthesized Anionic Surfactant onto Berea Sandstone

We present static adsorption studies of anionic surfactants on crushed Berea sandstone. The maximum adsorption density was 0.9604 mg/g. The kinetics of adsorption process was modeled using pseudo-first-order and pseudo-second-order rate equations at 25°C and 70°C. The equilibrium adsorption process was validated using Langmuir and Freundlich adsorption models. In addition, the effects of different parameters that govern the effectiveness of these surfactants such as pH and temperature were also investigated. The kinetic study results show that the surfactant adsorption is a time dependent process. The apparent rate constant of adsorption process determined by the first-order kinetic model at 25°C and 70°C were 0.11768 and ?0.04513, respectively. The rate constant for pseudo-second-order kinetic model was 0.0086 at 25°C and 0.0101 at 70°C. The adsorption of anionic surfactant followed pseudo-second-order kinetic model. The Freundlich and Langmuir model constant were 1.6509 × 10^?4 and ?9.775 × 10^?5, respectively. The equilibrium results showed that the adsorption of anionic surfactant onto Berea sandstone was well described by Langmuir adsorption model. It was concluded that anionic surfactants performed better at higher pH and temperature.      

Preparation and Characterization of Modified Cellulose Adsorbents with High Surface Area and High Adsorption Affinity for Hg(II)

Cellulose was modified via chlorination using phosphorous oxychloride followed by functionalization with amine and thiol moieties. The obtained modified cellulose samples were investigated by means of FTIR, TGA, TEM, and nitrogen-adsorption surface area (BET). The BET measurements showed a remarkable increase in the surface area of Cell-N-S (477.7 m²/g) and Cell-N (706 m²/g). The resins gave an uptake capacities of 38 and 7.2mmol/g for Cell-N-S and Cell-N, respectively toward Hg(II) from its solutions. These values are considered much better compared with other reported resins. Regeneration of the resins was achieved effectively using acidified thiourea.     

Separation and Extraction of Uranium from Leach Liquor Containing Uranium and Molybdenum by Solvent Extraction with LIX 622N

The leach liquor (0.5 g/L Mo, 0.05 g/L U) obtained from the leaching process of molybdenum-uranium ore material was treated using solvent extraction to recover U(VI) by LIX 622N, which is a salicylaldoxime derivative. The influence of various basic variables such as pH, concentration of LIX 622N, temperature, different stripping reagents, phase ratio, and diluents was examined. Using 10% LIX 622N with the aqueous solution of equilibrium pH 6.0 and a phase ratio organic phase:aqueous phase (O:A) = 1:1, a two-stage McCabe-Thiele plot was constructed, which showed 99.9% of U extraction with no co-extraction of molybdenum. This was confirmed by a 6-cycle counter current simulation (CCS) study. The obtained data of temperature on the extraction of uranium showed that the extraction process is exothermic with enthalpy change of ?20.949 kJ mol^?1. The stripping of U(VI) was quantitative using 4 M H₂SO₄. The stable complex UO₂(HSO₄)R_org formed during extraction, which supports the cation exchange mechanism, and was confirmed by FTIR spectral analysis.      

氧化还原功能纤维的研究──Ⅴ．含胺基及乙二胺基功能纤维的合成及其对Au~（3＋）的吸附性能

本文以反应性氯甲基化纤维为基体，合成丁氮含量分别为４．０６、４．９２ｍｍｏｌ／ｇ的含胺基（－ＮＨ２）及乙二胺基（－ＮＨＣ２Ｈ４ＮＨ２）功能纤维．静态吸附实验结果表明：在ｐＨ２．０乙二胺基纤维对Ａｕ３＋的吸附量达最大（６２０ｍｇ／ｇ），含胺基纤维的吸附量为２４８ｍｇ／ｇ；ＷＡＸＤ证实它们对Ａｕ３＋都有还原作用；含乙二胺基纤维对吸附态Ａｕ３＋的还原百分率最大值为９１％（ｐＨ４．０），而含胺基纤维在ｐＨ２．０的还原百分率为１００％，但ｐＨ＜０．６后，含乙二胺基纤维对Ａｕ３＋无还原作用；含乙二胺基纤维对Ａｕ３＋的吸附量随溶液温度升高而增大；在乙醇、１、４－氧六环、乙酸乙酯中含乙二胺基纤维对Ａｕ３＋的吸附量分别为４２、１４３、０ｍｇ／ｇ，且在乙醇中它对Ａｕ３＋有还原作用．吸附动力学实验结果表明：吸附初期为快速离子交换过程，中期为螯合吸附占主导地位，后期则是氧化还原吸附占优势．在扫描电子显微镜可观察到部分吸附在含乙二胺基纤维上的金聚集成粒状．     

Removal of Pararosaniline Hydrochloride Dye (Basic Red 9) from Aqueous Solution by Electrocoagulation: Experimental,Kinetics, and Modeling

In this work, the removal of pararosaniline hydrochloride (Basic red 9) dye from aqueous solutions by electrocoagulation was investigated. The effect of parameters such as current density, initial pH, electrolysis time, inter-electrode distance, initial dye concentration and salt concentration on dye removal efficiency were investigated. The experimental results showed that 99% dye removal was observed after 30 minutes of electrolysis for an initial dye concentration of 100 mg/L, current density of 111.1 A/m² and initial pH of 7.0. It was observed that an increase in current density, time of operation and decrease in inter-electrode distance improved the dye removal efficiency. The optimum pH range for highest dye removal was 5.0–10.25. It was also observed that increase in salt concentration in the solution reduces the specific electrical energy consumption. The kinetic study inferred that the dye removal primarily follows a first order reaction. Finally, phenomenological models were proposed to illustrate the dependence of dye removal rate constant and specific electrical energy consumption on current density, inter-electrode distance, initial dye concentration and salt concentration.     

Study on the Physical Chemistry,Equilibrium, and Kinetic Mechanism of Azure A Biosorption by Zea Mays Biomass

The mechanism of Azure A (AA) biosorption by Zea mays biomass (ZMB) was studied. Surface chemistry and morphology were characterized by potentiometric titration, pH of zero charge, FTIR, and microscope analysis. The equilibrium data was modeled by Langmuir, Freundlich, Redlich-Peterson, Temkin, and multilayer models. AA biosorption was mainly limited by chemisorption, but the role of intraparticle diffusion could not be neglected. The integrative analysis of surface chemistry/biosorption studies showed that chemisorption, ion exchange, complexation, and/or electrostatic attraction were involved during AA biosorption. The maximum biosorption capacity of ZMB (q 5.84 mg/g) was registered at pH 7.6.