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In this study, the potassium adsorption for the purification of crude ammonium perrhenate solutions in the presence of various cheap and available ion exchange resins is reported for the first time. After the resin screening test, the optimum resin (Purolite® C100 resin as a strong acid cation ion exchange resin in the sodium form) was selected for morphological analysis using field emission scanning electron microscopy, which was further examined by energy-dispersive spectroscopy. Moreover, X-ray elemental mapping of the surface of C100 resin revealed homogeneous potassium adsorption. BET and TGA tests confirmed the adsorbed potassium on the C100 resin. Among the isotherm models, the Langmuir isotherm provided the best fit according to the correlation coefficients. The adsorption parameters have been scrutinized, including contact time, initial potassium concentration, temperature, and competitive binary potassium and sodium adsorption. The result of the binary system exhibited a decrease in the potassium adsorption capacity of the resin in the presence of secondary ions due to competition for adsorption sites. Kinetic characteristics of the potassium adsorption process were investigated by pseudo-first-order and pseudo-second-order, intraparticle diffusion, and Elovich models. The adsorption process has been found to match the pseudo-first-order reaction. The continuous/extended experiments and the elution test were also evaluated. [ABSTRACT FROM AUTHOR]

Adsorption process is an effective and promising procedure for the removal of contaminations from wastewater. Nanocomposites have attracted extensive attention in the adsorption field owning to large surface/volumes ratio and large number of active sites. We aim at fabricating a novel binary g‐C3N4/ZnV2O4 nanocomposite, which can be used for removal of crystal violet dye from aqueous solution via the adsorption process. The as‐synthesized nanocomposite was well characterized by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), field emission scanning microscope (FESEM), energy‐dispersive X‐ray (EDX), and mapping analyses. The effects of four key experimental parameters on the adsorption process, including adsorbent dosage, initial concentration of crystal violet dye, adsorption time, and solution pH, were investigated by using central composite design‐based response surface methodology. The high adsorption efficiency of 99.67% was obtained at the adsorbent dosage of 19.776 mg, initial crystal violet concentration of 20.048 ppm, contact time of 59.20 min, and pH of 8. The correlation coefficients values (R2 of 0.9969, predicted‐R2 of 0.9910, and adjusted‐R2 of 0.9948), model p value = 0.0001, and model F value = 489.78 confirm the adequacy and predictability of the proposed model. The results of adsorption kinetics demonstrate that the adsorption of crystal violet by g‐C3N4/ZnV2O4 was performed by chemical adsorption. Also, the Langmuir model was fitted effectively with the adsorption data. Furthermore, the mechanism of adsorption was explained via π–π stacking interaction, n–π stacking interaction, electrostatic attraction, coordination bonding, and hydrogen bonding. [ABSTRACT FROM AUTHOR]