Uranium (as a hazardous and radioactive element) removal from wastewater requires reliable technology and proper functional materials. Carbon fiber species that are produced from agricultural solid waste can be a proper type of low-cost adsorbents for wide uses in wastewater treatment. In this work, two carbon fiber species labeled CF-RH and CF-SCB were synthesized from two different agricultural wastes, namely, rice husk and sugarcane bagasse respectively. The structural properties of carbon fiber were verified by XRD, FTIR, and Raman, spectroscopy. Both nitrogen-adsorption–desorption BET surface area and TEM were performed to figure out the textural characteristics of the presented sorbents. The charges on surfaces of the fibers were detected via zeta potential analysis. The prepared carbon fibers were applied for uranium removal from aqueous solution by adsorption technique. The acquired data display that the equilibrium time was 240 min. The results of adsorption process are nicely fitted with pseudo-second-order-kinetic and Langmuir isotherm models. The maximum sorption capacity was 21.0 and 29.0 mg/g for CF-RH and CF-SCB, respectively. Sorption thermodynamics declare that adsorption of U(VI) is an endothermic, spontaneous, and feasible process. The picked findings of this study could emphasize high reliability of the introduced adsorbents in efficient tackling of water contaminants.
Three commercial resins bearing sulfonic, amino phosphonic, or phosphonic/sulfonic reactive groups have been tested for the removal of iron and cadmium from phosphoric acid solutions. The sorption properties are compared for different experimental conditions such as sorbent dosage (0.5-2.5 g L −1), phosphoric acid concentration (from bi-component solutions, 0.25-2 M), and metal concentrations (i.e., in the range 0.27-2.7mmolCdL −1 and0.54mmolFe L −1) with a special attention paid to the impact of the type of reactive groups held on the resins. The sulfonic-based resin (MTC1600H) is more selective for Cd (against Fe), especially at high phosphoric acid concentration and low sorbent dosage, while MTS9500 (aminophosphonic resin) is more selective for Fe removal (regardless of acid concentration and sorbent dosage). Equilibrium is reached within 2-4 h. The resins can be ranked in terms of cumulative sorption capacities according the series: MTC1600H > MTS9570 > MTS 9500. Sulfuric acid (0.5-1 M) can be efficiently used for the desorption of both iron and cadmium for MTC1600H, while for MTS9570 (phosphonic/sulfonic resin) sulfuric acid correctly desorbs Cd (above 96% at 1 M concentration), contrary to Fe (less than 30%). The aminophosphonic resin shows much poorer efficiency in terms of desorption. The sulfonic resin (i.e., MTC1600H) shows much higher sorption capacity, better selectivity, comparable uptake kinetics (about 2 h equilibrium time), and better metal desorption ability (higher than 98% with 1 M acid concentration, regardless of the type of acid). This conclusion is confirmed by the comparison of removal properties in the treatment of different types of industrial phosphoric acid solutions (crude, and pre-treated H 3 PO 4 solutions). The three resins are inefficient for the treatment of crude phosphoric acid, and activated charcoal pre-treatment (MTC1600H reduced cadmium content by 77%). However, MTC1600H allows removing over 93% of Fe and Cd for H 3 PO 4 pre-treated by TBP solvent extraction, while the others show much lower efficiencies (< 53%).
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