Isotherm, Thermodynamics, and Kinetics of Methyl Orange Adsorption onto Magnetic Resin of Chitosan Microspheres

Abstract

Severe environmental pollution problems arising from toxic dyestuffs (e.g., methyl orange) are receiving increasing attention. Therefore, dyes’ safe removal has become a research hotspot. Among the many physical–chemical removal techniques, adsorption using renewable biological resources has proved to be more advantageous over others due to its effectiveness and economy. Chitosan is a natural, renewable biopolymer obtained by deactivated chitin. Thus, the magnetic resin of chitosan microspheres (MRCM), prepared by reversed-phase suspension cross-linking polymerization, was used to remove methyl orange from a solution in a batch adsorption system. The main results are as follows: (1) The results of physical and swelling properties of MRCM indicated that MRCM was a type of black spherical, porous, water-absorbing, and weak alkali exchange resin, and it had the ability to adsorb methyl orange when it was applied in solutions above pH 2.0. (2) In batch adsorption studies, the maximum adsorption capacity was obtained at pH 5; the adsorption equilibrium time was 140 min; and the maximum adsorption was reached at 450 mg/L initial concentration. (3) Among the three isotherm adsorption models, Langmuir achieved the best fit for the adsorption of methyl orange onto MRCM. (4) The adsorption thermodynamics indicated that the adsorption was spontaneous, with increasing enthalpy, and was driven by the entropy. (5) The pseudo-second-order kinetics equation was most suitable to describe the adsorption kinetics, and the adsorption kinetics was also controlled by the liquid–film diffusion dynamics. Consequently, MRCM with relatively higher methyl orange adsorption exhibited the great efficiency for methyl orange removal as an environment-friendly sorbent. Thus, the findings are useful for methyl orange pollution control in real-life wastewater treatment applications.

Remediation of Methyl Orange Dye in Aqueous Solutions by Green Microalgae (Bracteacoccus sp.): Optimization, Isotherm, Kinetic, and Thermodynamic Studies

“…In addition, the positive value of ΔS° indicated an increase in entropy (randomness) at the solid-solution interface during MO adsorption [56]. Similar trends were reported in previous studies of MO adsorption using activated carbon [57] and magnetic resin in chitosan microspheres [55].…”

“…In addition, the positive value of ∆S • indicated an increase in entropy (randomness) at the solid-solution interface during MO adsorption [56]. Similar trends were reported in previous studies of MO adsorption using activated carbon [57] and magnetic resin in chitosan microspheres [55]. of ΔG° increased with increasing temperature, and the maximum value of ΔG° was −13.909 KJ mol −1 , in the range from 0 to −20 KJ mol −1 ; therefore, MO adsorption by the Bracteacoccus sp.…”

“…of ΔG° increased with increasing temperature, and the maximum value of ΔG° was −13.909 KJ mol −1 , in the range from 0 to −20 KJ mol −1 ; therefore, MO adsorption by the Bracteacoccus sp. is physisorption [55]. In addition, the positive value of ΔS° indicated an increase in entropy (randomness) at the solid-solution interface during MO adsorption [56].…”

Exploring the potent hydrolytic activity of chitosan-cerium complex microspheres resin for organophosphorus pesticide degradation

“…Physical properties, including moisture content, cross-linking degree, pile-up density, skeleton density, pore degree, free aldehyde groups, and weak basic exchange capacities of CS-CCMR and CSMR were determined using the methods of Yu et al [ 41 ].…”

Chitosan: Structural and Chemical Modification, Properties, and Application

“…The effectiveness of magnetic-filled chitosan microspheres (MRCM) in removing dyes from real solutions has been studied through reversed-phase suspension crosslinking polymerization. According to Yu et al [ 53 ], MRCM is a suitable adsorbent for removing methyl orange from water, considering its physical and chemical properties and adsorption thermodynamics. Moreover, MRCM has the potential to be developed as a sorbent for removing other cationic dyes similar to methyl orange from water, as it is an environmentally friendly and reusable sorbent that can be regenerated.…”