A reusable mesoporous adsorbent for efficient treatment of hazardous triphenylmethane dye wastewater: RSM-CCD optimization and rapid microwave-assisted regeneration

Abstract

In this research, mesoporous calcium aluminate nanostructures (meso-CaAl2O4) were synthesized using a citric acid-assisted sol–gel auto-combustion process as the potential adsorbent to eliminate toxic triphenylmethane dye malachite green (MG) from synthetic/real effluent. The surface morphology of meso-CaAl2O4 was highly porous with nanometric size and non-homogeneous surface. The specific surface area, total pore volume, and BJH pore diameter of meso-CaAl2O4 were 148.5 m2 g−1, 1.39 cm3 g−1, and 19 nm, respectively. The meso-CaAl2O4 also showed a very high heat resistance, due to losing only 7.95% of its weight up to 800 °C, which is mainly related to the moisture loss. The optimal adsorption conditions were obtained based on response surface methods (RSM)-central composite design (CCD) techniques. The Langmuir isotherm model was used for fitting the adsorption measurements, which presented 587.5 mg g–1 as the maximum adsorption capacity of the dye. The data obtained from the adsorption kinetics model were found to correspond to the pseudo-second-order model. Also, the thermodynamic parameters including enthalpy change (ΔH°), entropy change (ΔS°), and Gibbs free energy change (ΔG°) indicated that MG dye adsorption by the meso-CaAl2O4 was feasible, endothermic, and occurred spontaneously. Furthermore, the meso-CaAl2O4 was regenerated by microwave irradiation under 900 W at 6 min, and the MG dye removal efficiency was remained over 90% after the five cycles of microwave regeneration.

Bio-Stimulated Adsorption of Cr(VI) from Aqueous Solution by Groundnut Shell Activated Carbon@Al Embedded Material

“…These techniques have a few disadvantages, such as a particularly high amount of sludge disposal, the development of large-sized particles, blockage of membranes by metal hydroxide formation, and high operation costs. Hence, adsorption is considered an economical method because of its simple design, and a wide assortment of efficient adsorbents has been accounted for [12,13]. Activated carbon is a remarkable adsorbent of pollutants in water [14].…”

Effective removal of Pb(II) ions using piperazine-modified magnetic graphene oxide nanocomposite; optimization by response surface methodology

“…The optimal experimental conditions were pH, 6; initial concentration of Pb(II), 15 mg L −1 ; adsorbent dosage, 7 mg; and contact time, 27.5 min. The desirability function value under the optimum conditions was found to be 1, which indicate the accuracy of the RSM divination 55 .…”

In-situ hydrothermal synthesis of CNT decorated by nano ZnS/CuO for simultaneous removal of acid food dyes from binary water samples

“…The result indicates the highest removal efficiency took place in higher temperatures with lower dyes concentrations. It can be assumed that increasing the temperature increases the kinetic energy of the reacting particles and increases the probability of collisions between dye molecules and the adsorbent surface, as a result, the dye removal efficiency increases 58 . It can be assumed that increasing the temperature increases the kinetic energy of the reacting particles and increases the probability of collisions between dye molecules and the adsorbent surface, as a result, the dye removal efficiency increases, which in line with other previous reports 58 , 59 .…”

“…It can be assumed that increasing the temperature increases the kinetic energy of the reacting particles and increases the probability of collisions between dye molecules and the adsorbent surface, as a result, the dye removal efficiency increases 58 . It can be assumed that increasing the temperature increases the kinetic energy of the reacting particles and increases the probability of collisions between dye molecules and the adsorbent surface, as a result, the dye removal efficiency increases, which in line with other previous reports 58 , 59 .

Figure 8 Three-dimensional response surface plots of independent variables on the adsorptive removal efficiency of TA and P4R dyes by ZnS/CuO-CNT: ( a , b ) pH-sonication time, ( c , d ) adsorbent dosage-sonication time/concentration, and ( e , f ) temperature-dye concentration.

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