Removal Of Cobalt Ions Research Articles

Adsorption of cobalt(II) from aqueous solution onto hydroxyapatite/zeolite composite

The Hydroxyapatite/Zeolite (HApZ) composite were synthesized by precipitation method and used as an adsorbent for the removal of cobalt ions from the aqueous solution. The materials were characterized by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) spectroscopy. It has been observed that there was slight enhancement in the % removal of cobalt ions from aqueous solution by HApZ (63%) than HAp (58%) and zeolite (47%). Batch experiments were performed to observe the effect of pH, adsorbent dose, contact time and initial cobalt (II) concentration. Kinetic study shows that the adsorption process follow pseudo-second order kinetic model. Equilibrium data were well fitted to Langmuir and Freundlich isotherm model.

Removal of Co (II) from aqueous solution by electrocoagulation process using aluminum electrodes

Electrocoagulation (EC) process is an effective method for the removal of heavy metal ions from water and wastewater effluents. In the present study, the removal of Cobalt ions from aqueous solutions has been studied by EC process with aluminum electrodes. The effect of several parameters such as pH, current density, time, conductivity and initial metal concentration of contaminant on the performance of EC process has been investigated. The results indicated that the initial pH has a significant effect on the removal efficiency. The current density and electrolysis period has a positive effect on the Co 2+ removal efficiency. Also, it was found that the electrical energy consumption decreased with an increase in the solution conductivity. By-products obtained from the EC process were analyzed by using SEM, EDAX and XRD, and the results have been explained.

An electrostatic shielding-based coupled electrodialysis/electrodeionization process for removal of cobalt ions from aqueous solutions

Electrode graphite powder beds were interposed between anode and cathode as intermediate electrodes inside an electrolytic setup. Due to electrostatic shielding they eliminate the applied electric field and therefore stop the electromigration of ions within their mass. It was found that the intermediate electrodes can act as ionic current sinks-ion concentrating compartments and therefore cause a new type of a membrane-less electrodialysis/electrodeionization process. The proposed electrostatic shielding based coupled electrodialysis/electrodeionization treatment of synthetic cobalt plating rinse water containing 300 mg L(-1) Co(2 + ) ions produced a low-volume Co(2 + ) concentrate which could be recycled to the electroplating bath for reuse and a diluate containing 43.8 mg L(-1) Co(2 + ) ions. The diluate was then used as feed in the subsequent electrostatic shielding electrodeionization process which produced pure water with a cobalt ion concentration less than 0.1 mg L(-1). The current efficiency was 22-29%, the enrichment factor 13.5-26.1, the current density 20-40 A m(-2) and the flow rate 1.54 × 10(-4)-4.06 × 10(-4) dm(3) s(-1). The proposed membrane free electrostatic shielding electrodialysis/electrodeionization process could be developed into a new alternative electrochemical method of cobalt or other heavy metal removal and water purification and recycling from industrial effluents laden with heavy metals.

Adsorptive removal of cobalt from aqueous solution by utilizing lemon peel as biosorbent

The present study was undertaken to evaluate the feasibility of lemon peel waste for the removal of cobalt ions from aqueous solutions. Batch experiments were performed to study the adsorption of c ...

Removal of cobalt ions from aqueous solutions by polymer assisted ultrafiltration using experimental design approach: Part 2: Optimization of hydrodynamic conditions for a crossflow ultrafiltration module with rotating part

Application of shear-enhanced crossflow ultrafiltration for separation of cobalt ions from synthetic wastewaters by prior complexation with polyethyleneimine has been investigated via experimental design approach. The hydrodynamic conditions in the module with tubular metallic membrane have been planned according to full factorial design in order to figure out the main and interaction effects of process factors upon permeate flux and cumulative flux decline. It has been noticed that the turbulent flow induced by rotation of inner cylinder in the module conducts to growth of permeate flux, normalized flux and membrane permeability as well as to decreasing of permeate flux decline. In addition, the rotation has led to self-cleaning effect as a result of the reduction of estimated polymer layer thickness on the membrane surface. The optimal hydrodynamic conditions in the module have been figured out by response surface methodology and overlap contour plot, being as follows: Δ P = 70 kPa, Q R = 108 L/h and W = 2800 rpm. In such conditions the maximal permeate flux and the minimal flux decline has been observed.

Removal of cobalt ions from aqueous solutions by polymer assisted ultrafiltration using experimental design approach. part 1: Optimization of complexation conditions

The polymer assisted ultrafiltration process combines the selectivity of the chelating agent with the filtration ability of the membrane acting in synergy. Such hybrid process (complexation–ultrafiltration) is influenced by several factors and therefore the application of experimental design for process optimization using a reduced number of experiments is of great importance. The present work deals with the investigation and optimization of cobalt ions removal from aqueous solutions by polymer enhanced ultrafiltration using experimental design and response surface methodological approach. Polyethyleneimine has been used as chelating agent for cobalt complexation and the ultrafiltration experiments were carried out in dead-end operating mode using a flat-sheet membrane made from regenerated cellulose. The aim of this part of experiments was to find optimal conditions for cobalt complexation, i.e. the influence of initial concentration of cobalt in feed solution, polymer/metal ratio and pH of feed solution, on the rejection efficiency and binding capacity of the polymer. In this respect, the central compositional design has been used for planning the experiments and for construction of second-order response surface models applicable for predictions. The analysis of variance has been employed for statistical validation of regression models. The optimum conditions for maximum rejection efficiency of 96.65% has been figured out experimentally by gradient method and was found to be as follows: [Co 2+] 0 = 65 mg/L, polymer/metal ratio = 5.88 and pH 6.84.

Removal of Cobalt Ions from Aqueous Solution by Adsorption onto Cross-Linked Calcium Alginate Beads

The removal of cobalt ions from dilute aqueous solutions using cross linked calcium alginate beads as the adsorbent is reported in this article. The influence of various experimental parameters such as pH, initial metal ion concentration, contact time and solid to liquid ratio were studied. The adsorption data were applied to Langmuir and Freundlich isotherm equations and various static parameters were calculated. It was observed that the uptake of cobalt ions was found to increase with time and that maximum adsorption was obtained within the first 60 minutes of the process. These results indicate that the cross linked calcium alginate beads have potential for removing cobalt ions from industrial waste water.

Rapid removal of cobalt ion from aqueous solutions by almond green hull

Almond green hull, an agriculture solid waste, was chemically treated and used for the adsorption of Co (II) from aqueous solutions. The efficiency of this new adsorbent was studied using batch adsorption technique under different experimental conditions such as sorbent amount, initial metal-ion concentration, contact time, adsorbent particle size, and chemical treatment. Optimum dose of sorbent for maximum metal-ion adsorption were 0.25 g for 51.5 mg l −1 and 0.4 g for 110 mg l −1 solutions, respectively. High removal efficiencies of Co (II) were occurred in the first 1 min of sorbent contact time. The adsorption of Co (II) on almond green hull was also observed to follow the pseudo second-order kinetics. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models. The Langmuir adsorption model fits the experimental data reasonably well compared to the Freundlich model. The maximum adsorption capacity of this new sorbent was found to be 45.5 mg g −1. The present study revealed that such a low cost material could be used as an efficient sorbent for the removal of cobalt from wastewater streams.

Removal of Co 2+ from aqueous solutions by hydroxyapatite

A study on the removal of cobalt ions from aqueous solutions by synthetic hydroxyapatite was conducted in batch conditions. The influence of different sorption parameters, such as: initial metal concentration, equilibration time, solution pH and presence of EDTA on the amount of Co 2+ sorbed was studied and discussed. The sorption process followed pseudo-second-order kinetics with necessary time of 24 h to reach equilibrium. Cobalt uptake was quantitatively evaluated using the Langmuir and Dubinin–Kaganer–Radushkevich (DKR) model. The Langmuir adsorption isotherm constant corresponding to adsorption capacity, Xm, was found to be 20.92 mg/g. Sorption of Co 2+ is constant in the initial pH range 4–8, because HAP surface buffers these solutions to the constant final pH value of 5.1. In the presence of EDTA, sorption of Co 2+ decreases due to formation of complex with lower sorption affinities. Cobalt desorption depends on the composition of the extracting solution. The desorbed amount of cobalt decreased continuously with increasing pH, and increased with increasing Ca 2+ concentration in leaching solution.

Preparation and characterization of immobilized ion exchange polyurethanes (IEPU) and their applications for continuous electrodeionization (CEDI)

Immobilized ion-exchange polyurethanes (IEPU) were prepared as ion conducting spacers in continuous electrodeionization (CEDI) for the treatment of a synthetic primary coolant. Ion exchange resins were immobilized by using allophanate/biuret cross-linking in preparation of polyurethane. Synthesized IEPU was characterized in terms of mechanical strength, ion exchange capacity (TEC), electrical conductivity and the porous plug model, which schematically represents the transport pattern through the IEPU. CEDI was carried out in a laboratory scale with an effective area of 20 cm2. The CEDI operation with a layered bed configuration showed the main removal mechanism of cobalt ion was dependent on the active surface area between ion conducting materials. The performance of the CEDI operation showed over 98% removal of cobalt ions, suggesting the feasibility of IEPU as ion conducting spacers in a CEDI system.

Adsorption of 60Co2+ on hydrous manganese oxide powder from aqueous solution

Summary Hydrous manganese oxide (HMO) was synthesized and its ability to sorb 60Co2+ from aqueous solution was studied under static conditions as a function of contact time, cobalt concentration (10-2-10-7M), temperature (303-333K) and pH of adsorptive solution (2.2-11.4). X-ray diffraction was used in characterization of synthesized HMO. Low concentration of 60Co2+ solution, high pH and high temperature were the most favorable conditions for the adsorption process. The results show that the removal process is complete in 40 minutes, obeys a first order rate law and can be described using the Freundlich adsorption model. The standard enthalpy of the system was ΔH 0 = 12.5 ± 0.2 kJ mol-1 and cobalt desorption indicates that the uptake process proceeds via cation exchange. The removal of cobalt ions by HMO appears to be endothermic and irreversible. The values of calculated ΔG 0 and ΔS 0 were -17.0 ± 3.0 kJ mol-1 and (9.8 ± 0.2) × 10-2 kJ K-1 mol-1 respectively, this indicates spontaneity of the process and the degree of freedom of ions is increased by adsorption.

Electrochemical Characterization of Ion-Exchange Resin Beds and Removal of Cobalt by Electrodeionization for High Purity Water Production

The characterization of three cation exchange resins, IRN77, SKN1, and IR120, for the removal of cobalt ions from an aqueous solution by electrodeionization (EDI) was studied. The study includes investigation of resin beds in terms of their ion exchange capacity, electrical conductivity, and zeta potential. The conductivity of a resin bed was analyzed using a porous-plug model to understand the current path. From the experiments, more than a 97% cobalt ion removal was achieved under optimal conditions. Furthermore, production of ultrapure water with a two-stage EDI process was tested for the reuse of treated water.

BIOALGA reactor: preliminary studies for heavy metals removal

Microalgae have a high affinity for polyvalent metals, for that reason they could be used to reduce the concentration of heavy metals present in water and wastewater. In the present work an evaluation of a rotary biofilm reactor for algae immobilization (BIOALGA) with the subject of heavy metal removal was investigated. The BIOALGA reactor consisted of a pilot scale model that was operated with synthetic wastewater with an initial concentration of 3000 μg/l of cobalt ion. Scenedesmus obliquus was immobilized in the reactor, which was operated in batch mode for a period of 20 days. The rotary velocity used, 2 rpm, was constant during the experiment. A maximum removal of cobalt ion of 94.5% was reached at 10 days. The experimental results obtained were evaluated using a pseudo first-order kinetic model to obtain values for the kinetic constant and the maximum cobalt ion removal efficiency of the process. The proposed model predicted accurately the behaviour of the reactor, showing deviations lower than 7% between the experimental and theoretical values of cobalt ion removal efficiencies.

Microscale Demonstration of Charge Modification upon Complexation by Ion Exchange

A small plastic syringe (or a Pasteur pipet) is used as an ion-exchange microcolumn model to demonstrate the principles of ion exchange and charge modification upon complexation. In the first part of the experiment, the removal of cobalt ions (cations) from aqueous solution is visually demonstrated. Then, Co2+ is reacted with the negatively charged EDTA (ethylenediaminetetraacetate) ion to form a complex anion. When passed through a cation exchange column, the Co2+ ions are completely retained whereas the complexed cobalt ions are not removed at all. This experiment is appropriate for a first-year chemistry laboratory, and takes approximately one hour to complete.

拡散透析を用いたベントナイトからのコバルトイオンの除去

万一、土壌中に漏洩した放射性金属イオンが土壌に吸着したとき、その土壌を処理しイオンを除去回収する必要がある。このような状態を想定し、微細な土壌粒子 (ベントナイト) からの放射性イオン (コバルト) の除去法として拡散透析法を用いた処理について研究を行った。微細な土壌粒子を含む溶液側を希釈槽、ストリップ液を含む溶液側を濃縮槽とし、両槽の間に陽イオン交換膜を挟み、回分操作による実験を行った。実験ではストリップ液として塩酸水溶液を用いたときが高度分離が達成できた。また、回分操作のシミュレーションを行った結果、ストリップ液の濃度、膜の選択、液と膜の接触状態を示す物質移動係数等がイオンの除去に大きな影響を及ぼすことが分かった。

Sorption kinetics of cobalt in chelating porous membrane

Glycidyl methacrylate was grafted onto a microfiltration hollow-fiber membrane. Subsequently, the produced epoxide group was converted into an iminodiacetate (IDA) group. The cobalt solution was permeated across the chelating porous membrane through the submicron-diameter pores. The efficient removal of cobalt ion during permeation was demonstrated by the resulting breathrough curve. Furthermore, the prove of the amount of cobalt sorbed across the membrane was determined as a function of the effluent volume by X-ray microanalysis (XMA)

Effects of ultrasound on the cementation of cobalt on zinc

Studies on the effects of ultrasound on the reaction of zinc powder in aqueous cobaltous sulphate solution showed that ultrasound was effective in increasing both the rate and the degree of completion of the removal of cobalt ions from solution at temperatures greater than 50°C. At lower temperatures ultrasound had negligible effects and under some conditions it was actually unfavourable to the reaction. This is likely to be due to the acceleration of other reactions by ultrasound, in particular the formation of zinc hydroxide. The formation of a hydroxide precipitate is readily noted when ultrasound is applied to zinc powder in water, even at room temperature. The effects of the variation of particle size and of some additives were also studied and provided some counter-intuitive results.