Increase In Initial Ion Concentration Research Articles

Study on removal performance of Fe3+ by biomass-based activated carbon and Liquefaction of Poplar Sawdust catalyzed by ferro activated Carbon

The adsorption experiment of iron ions on biomass based nut shell activated carbon was conducted to explore the adsorption capacity of iron ions on biomass based activated carbon and the key influencing factors: pH value, initial concentration of solution and adsorption time on the adsorption effect of activated carbon. The preparation of supported catalyst of activated carbon iron and its influence on the effect of catalytic liquefaction of poplar sawdust were investigated. The results showed that the optimal pH value of Fe3+ solution adsorbed by activated carbon was 5.0. The adsorption rate of activated carbon decreased with the increase of initial ion concentration, and the adsorption equilibrium of activated carbon reached at 250min. The optimum concentration of poplar sawdust liquefaction catalyzed by iron supported on activated carbon is between 6mg/L and 10mg/L.

Pristine and Magnetic Kenaf Fiber Biochar for Cd2+ Adsorption from Aqueous Solution

Development of strategies for removing heavy metals from aquatic environments is in high demand. Cadmium is one of the most dangerous metals in the environment, even under extremely low quantities. In this study, kenaf and magnetic biochar composite were prepared for the adsorption of Cd2+. The synthesized biochar was characterized using (a vibrating-sample magnetometer VSM), Scanning electron microscopy (SEM), X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). The adsorption batch study was carried out to investigate the influence of pH, kinetics, isotherm, and thermodynamics on Cd2+ adsorption. The characterization results demonstrated that the biochar contained iron particles that help in improving the textural properties (i.e., surface area and pore volume), increasing the number of oxygen-containing groups, and forming inner-sphere complexes with oxygen-containing groups. The adsorption study results show that optimum adsorption was achieved under pH 5–6. An increase in initial ion concentration and solution temperature resulted in increased adsorption capacity. Surface modification of biochar using iron oxide for imposing magnetic property allowed for easy separation by external magnet and regeneration. The magnetic biochar composite also showed a higher affinity to Cd2+ than the pristine biochar. The adsorption data fit well with the pseudo-second-order and the Langmuir isotherm, with the maximum adsorption capacity of 47.90 mg/g.

Kinetics and Diffusion Analysis for the Removal of Cadmium Ion from Aqueous Solutions Using Chitosan-iso-Vanillin Sorbent

Kinetic and diffusion analysis of the process of cadmium ion removal from water via sorption has been explored. The experimental kinetics data were approximated with pseudo-first and pseudo-second-order equations, Elovich equation, and Ritchie modified second-order models. Diffusion analysis is performed using homogeneous particle diffusion model and Weber–Morris kinetics. Kinetic results reveal that chemisorption is the sole-controlling step representing high sorption rate during the first 2 h of agitation with 50‒90% removal. Activation energy is also calculated (26.57 kJ mol−1) disclosing chemical interaction among solute-adsorbent phase. Weber–Morris plots show the sorption process is controlled by two or more simultaneous mechanisms with higher Kid values at higher initial concentrations. The study demonstrates that rate values of pore and film diffusion are improved with increase of initial ion concentration and the effect of diffusion resistance is not efficiently removed or minimized by sufficient agitation time.

Adsorption of As(V) from contaminated water over chitosan coated magnetite nanoparticle: Equilibrium and kinetics study

The efficacy of chitosan/magnetite nanocomposite (CTN) for remediation of arsenate ions [As(V)] from water was investigated. The prepared material could efficiently perform several cyclic runs with high As(V) removal efficiency and has the advantages over many established method. Different characterization techniques were performed to investigate the binding and structural properties of prepared materials. The study also focused on the effect of competing ions viz. phosphate and chloride on removal efficiency. The initial As(V) concentration (0.6mg/L) was found to decrease to less than 0.01mg/L at a contact time of 120min with an adsorbent dose of 1g/L. Increase in initial ion concentration of arsenate ions decreased the sorption rate, but the ion uptake capacity was increased. The sorption was reasonably explained with Langmuir (RL∼0.9851) and Freundlich isotherm models (n∼1.78). At low concentrations Langmuir monolayer sorption was followed but heterogeneity appeared at higher arsenate concentrations. The maximum adsorption capacity (Qo) calculated from Langmuir isotherm was found to be 10.81mg As(V)/g at room temperature and neutral pH. The sorption process was found to be governed by pseudo second order kinetics.

Preparation and characterization of magnetic biosorbent based on oil palm empty fruit bunch fibers, cellulose and Ceiba pentandra for heavy metal ions removal

This study prepared, characterized and developed agro-based magnetic biosorbents (AMBs) from Ceiba pentandra (RKF), oil palm empty fruit bunches (EFB) and celluloses (CEL) extracted from EFB, using a novel, simple and cost-effective preparation technique for the removal of Pb(II), Cu(II), Zn(II), Mn(II) and Ni(II) ions from aqueous solutions. There has been no report on the methods to prepare and the use of magnetic biosorbent based on these biomaterials. The morphological, chemical and magnetic characterization suggested successful preparation of AMBs with good dispersion of magnetic nanoparticles on the surface of the base materials with clear magnetic properties. Optimum sorption was achieved between pH 5–7, and increase in initial ion concentration and solution temperature resulted in increased ion uptake. AMBs regeneration was successfully performed for 5 adsorption/desorption cycles. The magnetic biosorbent based on kapok showed the best Pb(II) removal efficiency of 99.4% and 49mg/g adsorption capacity compared to 98.2% for cellulose and 97.7% for EFB. The magnetic biosorbents exhibited 10.3% higher removal efficiency than the raw sorbents.

A comparative study on sorption of arsenate ions from water by crosslinked chitosan and crosslinked chitosan/MMT nanocomposite

Montmorillonite (MMT) clay incorporated chitosan (CT) nanocomposite was prepared by simplified ionic gelation method. Different characterization techniques were performed to investigate the binding and structural properties of prepared materials. It was found that incorporation of clay into chitosan followed by crosslinking with glutaraldehyde (GLU) enhances the arsenate sorption rate and better stability was observed on cyclic run compared to glutaraldehyde crosslinked chitosan (Ct/Glu). The sorption process attained equilibrium within 90min of treatment time and a dose of 2g/L of crosslinked chitosan/MMT (MMT/Ct/Glu) was sufficient to bring down the arsenate concentration below 0.01mg/L. Increase in initial ion concentration of arsenate ions decreases the sorption rate, but the ion uptake capacity increases. The sorption was reasonably explained with Langmuir (RL∼0.995 & 0.996 for MMT/Ct/Glu & Ct/Glu) and Freundlich isotherms (n∼2.75 & 3.12 for MMT/Ct/Glu & Ct/Glu). The R2 values indicated a monolayer type of chemisorption pattern. The sorption process was found to be governed by pseudo second order kinetics.

Analysis and modeling of fixed bed sorption of cesium by AMP-PAN

Cesium sorption on ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) from simulated acidic waste was investigated in a fixed-bed column. Batch equilibrium isotherm data were tested with Freundlich and Langmuir models and both were found to fit the sorption isotherm data well, but the Langmuir model was better. Cesium exchange on AMP-PAN followed pseudo second-order kinetics. The effects of influent Cs concentration (500–1000mg/L), feed flow rate (5–15mL/min) and bed height (14.5–21.5cm) on the breakthrough characteristics of the ion-exchange system were determined. The uptake capacity increased with increase in initial ion concentration and bed height but decreased with increase in flow rate. Breakthrough occurred earlier for higher concentrations, higher flow rates and lower bed heights. The dynamics of the mass transfer zone were described for different column operating conditions. The height of mass transfer zone decreased with increase in initial concentration and increased with increase in flow rate. No significant effect was observed in the height of mass transfer zone with increase in height of bed. Mathematical models of Thomas, Yoon–Nelson and Bohart–Adams model were applied to the experimental data to analyze the column performance. The results fitted well to the Thomas and Yoon–Nelson models with correlation coefficient, R2≥0.98.

Comparison of strontium and calcium adsorption onto composite magnetic particles derived from Fe 3O 4 and bis(trimethoxysilylpropyl)amine

The adsorption of strontium and calcium ions by composite magnetic particles derived from Fe 3O 4 and bis(trimethoxysilylpropyl)amine (TSPA) were comparatively studied. The effects of initial solution pH, ionic strength, initial strontium and calcium ion concentration, and temperature on the equilibrium adsorption amount of both strontium and calcium ions, and on the separation factor between strontium and calcium ions were investigated comprehensively. The adsorption occurs rapidly in the first 30 min. In general, the equilibrium adsorption amount of both strontium and calcium ions was found to increase with the increase in initial ion concentration and initial solution pH, but to decrease gradually with the increase in ionic strength. The equilibrium adsorption amount of strontium ions increases with the increase in adsorption temperature. However, the effect of temperature on the adsorption of calcium ions presents a complicated situation. Strontium ions have a higher affinity to the composite particles than calcium ions. The separation factor between strontium and calcium ions increases with the increase in adsorption temperature, but is not sensitive to ionic strength. The suitable experimental conditions for the separation between strontium and calcium ions are: initial solution pH 7–8, lower ionic strength, and higher adsorption temperature.

A note on the binding of nickel and copper ions by cellulosic materials

Cellulosic materials of tropical origin — bambara nuts ( Voandzeia subterranea) and rice husks ( Oryza sativa) — were treated with copper and nickel ions and the adsorption behaviour studied. The amount of metal ion removed from solution depended on the metallic ion-substrate contact time, the ion concentration and ion type. The amount of adsorption of these divalent ions varied with the cellulosic material. The cellulosic materials could bind substantial amounts of nickel and copper ions, and the amount of metal ion adsorbed per gram of the cellulose substrate increased with increase in initial ion concentration.