https://cyberleninka.org/article/n/638974.pdf

Characteristics and adsorption capacities of low-cost sorbents for wastewater treatment: A review

Agricultural waste peels as versatile biomass for water purification – A review

Uranium(VI) adsorption on graphene oxide nanosheets from aqueous solutions

Present paper involved the review of fixed-bed column studies for removal of various contaminants from synthetic wastewater. Basic concept of adsorption, its types (i.e., chemisorption and physisorption) and its mechanism, adsorbents and adsorbates were included. Comparison of batch and column adsorption study is mentioned. Complete study of breakthrough curve for designing adsorptive column is interpreted. This paper explicates the detailed explanation of various process parameters and isotherm models for column study. Fixed-bed adsorption studies using various adsorbates, i.e., metal, ion, dye and other hazardous materials, are reviewed, in which adsorption of chromium metal is most exploitable. Conclusion and some challenges for utilization in real world are also exposed.

/pdf/fixed-bed-column-adsorption-study-a-comprehensive-review-2yl5oas4mv.pdf

Fixed-bed column adsorption study: a comprehensive review

Naturally occurring diatomaceous earth (diatomite) has been tested as a potential sorbent for Pb(II) ions. The intrinsic exchange properties were further improved by modification with manganese oxides. Modified adsorbent (referred to as Mn-diatomite) showed a higher tendency for adsorbing lead ions from solution at pH 4. The high performance exhibited by Mn-diatomite was attributed to increased surface area and higher negative surface charge after modification. Scanning electron microscope pictures revealed a birnessite structure of manganese oxides, which was featured by a plate-like-crystal structure. Diatomite filtration quality was improved after modification by manganese oxides. Good filtration qualities combined with high exchange capacity emphasised the potential use of Mn-diatomite in filtration systems.

19. Al-Degs Y., MAM Khraisheh, Tutunji, M.F, Sorption of lead ions on diatomite and manganese-oxides modified diatomite.

The uranium(VI) biosorption by grapefruit peel was studied from aqueous solutions. Batch experiments was conducted to evaluate the effect of contact time, initial uranium(VI) concentration, initial pH, adsorbent dose, salt concentration and temperature. The equilibrium process was well described by the Langmuir, Redlich–Peterson and Koble–Corrigan isotherm models, with maximum sorption capacity of 140.79 mg g−1 at 298 K. The pseudo second order model and Elovish model adequately describe the kinetic data in comparison to the pseudo first order model and the process involving rate-controlling step is much complex involving both boundary layer and intra-particle diffusion processes. The effective diffusion parameter Di and Df values were estimated at different initial concentration and the average values were determined to be 1.167 × 10−7 and 4.078 × 10−8 cm2 s−1. Thermodynamic parameters showed that the biosorption of uranium(VI) onto grapefruit peel biomass was feasible, spontaneous and endothermic under studied conditions. The physical and chemical properties of the adsorbent were determined by SEM, TG-DSC, XRD and elemental analysis and the nature of biomass–uranium (VI) interactions was evaluated by FTIR analysis, which showed the participation of COOH, OH and NH2 groups in the biosorption process. Adsorbents could be regenerated using 0.05 mol L−1 HCl solution at least three cycles, with up to 80% recovery. Thus, the biomass used in this work proved to be effective materials for the treatment of uranium (VI) bearing aqueous solutions.

Efficient uranium(VI) biosorption on grapefruit peel: kinetic study and thermodynamic parameters

Removal of Uranium (VI) by Fixed Bed Ion-exchange Column Using Natural Zeolite Coated with Manganese Oxide

A continuous fixed-bed study was carried out by using zeolite as a low-cost adsorbent for the removal of uranium(VI) ions from aqueous solution under the effect of various process parameters such as the pH the bed depth, the flow rate, the presence of salt and the initial U(VI) ion concentration. The U(VI) ion uptake by zeolite increased with initial U(VI) ion concentration and bed height, but decreased as the flow rate increased. The adsorption capacity reached a maximum at pH of 6.0. A shorter breakthrough time was observed in the presence of salt. The experimental data obtained from the breakthrough curves were analyzed using the Thomas model. The BDST model was also applied to predict the service times for other flow rates and initial concentrations. The results showed that the Thomas model was suitable for the description of the whole breakthrough curve, while the data were in good agreement with the BDST model. The columns were regenerated by eluting the bound U(VI) ions with 0.1 mol L−1 NaHCO3 solution after the adsorption studies. After desorption and regeneration with deionized water, zeolite could be reused to adsorb uranium(VI) at a comparable capacity.

Characterization and properties of zeolite as adsorbent for removal of uranium(VI) from solution in fixed bed column

Adsorbent, natural grapefruit peel (GFP) exhibit good efficacy to adsorb a highly toxic radioactive heavy metal, uranium(VI). Through the fixed-bed column technique adsorption characteristics of uranium(VI) is observed at different flow rate, bed depth, influent uranium(VI) concentration and particle size of adsorbent. The results showed that adsorption reached saturation faster with increasing the flow rate and influent uranium(VI) concentration while it was the advantage of column adsorption with the increase in the GFP bed. The data were fitted to the Thomas model, the Yan model, the Clark model and the mass transfer model by nonlinear regressive analysis. When the flow rate was 8.0 mL min−1 and the influent concentration of uranium(VI) was 90 mg L−1, the maximum adsorption quantity reached 104.1 mg g−1 according to the Thomas model. The bed depth service time model was applied to predict the service times with other flow rate and initial concentration. The theoretical breakthrough curve was compared with experimental breakthrough curve profile in the dynamic process. The results showed that the Yan model was better for the description of breakthrough curves at the experimental conditions than the Thomas and the Clark models. The saturated column was regenerated by 0.05 mol L−1 hydrogen chloride solution and GFP could be reused in uranium(VI) removal.

Adsorption of uranium(VI) by grapefruit peel in a fixed-bed column: experiments and prediction of breakthrough curves

This study described adsorption of uranium(VI) by citric acid modified pine sawdust (CAMPS) in batch and fixed-bed column modes at 295 K. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Koble–Corrigan and Dubinin–Radushkevich isotherm models. The results indicated that the Langmuir and Koble–Corrigan models provided the best correlation of the experimental data. The Elovish model was better to fit the kinetic process, which suggested that ion exchange was one of main mechanism. The effective diffusion parameter Di values indicated that the intraparticle diffusion was not the rate-controlling step. In fixed-bed column adsorption, the effects of bed height, feed flow rate, and inlet uranium (VI) concentration were studied by assessing breakthrough curve. The Thomas, the Yan and the bed-depth/service time (BDST) models were applied to the column experimental data to determine the characteristic parameters of the column adsorption. The results were implied that CAMPS may be suitable as an adsorbent material for adsorption of uranium (VI) from an aqueous solution.

Lei Zhao

Papers

Efficient uranium(VI) biosorption on grapefruit peel: kinetic study and thermodynamic parameters

Removal of Uranium (VI) by Fixed Bed Ion-exchange Column Using Natural Zeolite Coated with Manganese Oxide

Characterization and properties of zeolite as adsorbent for removal of uranium(VI) from solution in fixed bed column

Adsorption of uranium(VI) by grapefruit peel in a fixed-bed column: experiments and prediction of breakthrough curves

Removal of uranium(VI) from aqueous solution using citric acid modified pine sawdust: batch and column studies