Adsorption of malachite green and crystal violet cationic dyes from aqueous solution using pumice stone as a low-cost adsorbent: kinetic, equilibrium, and thermodynamic studies

Abstract

In this study, the sorption potential of pumice was investigated as geomaterial adsorbent for removal of two cationic dyes, malachite green (MG) and crystal violet (CV), from aqueous solution. In batch experiments, the effects of contact time, particle size, absorbent dose, solution pH, initial dye concentration, and temperature of MG and CV ions on the pumice adsorption capacity was studied. The characterization of the pumice has been accomplished by X-ray fluorescence spectroscopy, scanning electron microscope, and Brunauer-EmmettTeller technologies. Equilibrium data were accurately fitted onto Langmuir, Freundlich, and Temkin isotherms. The results showed that the adsorption isotherm data were fitted well to the Langmuir isotherm and the maximum adsorption capacities calculated were 22.57 and 6.99 mg/g for MG and CV at 25˚C, respectively. The kinetic data for both dyes were better described by the pseudo-second-order kinetic model. The thermodynamic parameters such as ΔG˚, ΔH˚, and ΔS˚were also evaluated. The positive ΔH˚and ΔS˚values described endothermic nature of the adsorption and the affinity of pumice for MG and CV adsorption, respectively. It is expected that pumice can be considered as a low-cost adsorbent for the removal of dyes from wastewater.

Synthesis of a green magnetic biopolymer derived from oak fruit hull tannin for the efficient and simultaneous adsorption of a mixture of Malachite Green and Sunset Yellow dyes from aqueous solutions

“…In this study, Langmuir, Freundlich, Tamkin, and Dubinin-Radskovich isotherms were used for the adsorption analysis of the dyes. 11,51 The results of this study are presented in Table S4 (ESI †) and Fig. 9.…”

“…Among the advantages of this process compared to other separation processes are simplicity of operation, insensitivity to toxic substances, and low cost with high efficiency. 11 Nowadays, researchers are focusing more on synthesizing low-cost adsorbents with high adsorption capacity to remove dye contaminants from wastewater. A wide range of materials has been studied to remove dyes, including bentonite, clay, activated carbon, polymers, and wheat bran.…”

Basic Dye Adsorption onto Clay/MnFe2O4 Composite: A Mechanistic Study

“…The negative DG indicates the spontaneous nature of the adsorption process of CV onto clay adsorbents, whereas the positive value of DH indicated that the adsorption process was endothermic in nature and positive values of DS indicate an increase the disorder on adsorption surface of solid/solution interphase with the rise in temperature. Crystal violet adsorption process onto red mud activated by acid and pumice stone also showed similar behavior (Shayesteh et al, 2016;Zhang et al, 2014). CV adsorption onto bentonite clay was also endothermic in nature (Eren, 2009).…”

Selective Enrichment of Clenbuterol onto Molecularly Imprinted Polymer Microspheres with Tailor-made Structure and Oxygen Functionalities

“…From the thermodynamic analysis results provided in Figure 9 and Table S4 in the ESI, significant parameters including Δ H °, Δ S °, and Δ G ° were calculated for the adsorption of clenbuterol onto the MIPMs. The positive Δ H ° and Δ S ° values indicate the endothermic nature and randomness of the adsorption of clenbuterol onto the MIPMs [54]. The positive Δ G ° value reveals that the adsorption reaction requires energy.…”