Adsorption of methyl violet dye from wastewater using poly(methacrylic acid-co-acrylamide)/bentonite nanocomposite hydrogels

Abstract

One of the major environmental problems is the entry of colored pollutants into the oceans and seas. Adsorption is one of the effective methods to eliminate colorant polluting materials from wastewater streams. In this study, nanocomposite hydrogels of poly(methacrylic acid-co-acrylamide) (Poly(MAA-co-AAm)) containing different weight percent bentonite clay nanoparticles (0, 5, 10, and 15 wt. %) were used to remove methyl violet (MV) dye. FTIR, SEM, TGA, and XRD were used to analyze the properties of adsorbents. Results showed that bentonite nanoparticles were successfully distributed in the hydrogel system. Bentonite nanoparticles at 10 wt. % gave the maximum MV dye adsorption efficiency. The highest adsorption was obtained at a pH of 5, an adsorbent dosage of 1.5 g/L, a temperature of 25°C, a contact time of 60 min, and a pollutant concentration of 10 mg/L. In thermodynamics studies, a negative values of Gibbs free energy (ΔG°) indicating that the adsorption process was spontaneous. In addition, Poly(MAA-co-AAm) hydrogels and Poly(MAA-co-AAm)/bentonite nanocomposite hydrogels gave the adsorption enthalpy (ΔH°) of 22.2 and 47.4 KJ/mol. Langmuir isotherm model was successfully applied in describing the equilibrium behavior of the adsorption process. To investigate the adsorption kinetics, we used pseudofirst-order, pseudo-second-order, and Elovich models. The kinetic study showed that the pseudo-secondorder model was more successful in describing the kinetic behavior of the adsorption process than pseudofirst-order and Elovich models. Incorporating bentonite clay nanoparticles in Poly(MAA-co-AAm) nanocomposite hydrogels significantly improved the adsorption and swelling efficiencies of these hydrogels.

Synthesis of Poly(methacrylamide‐co‐methacrylic acid) Nanogels: Effect of Synthesis Parameters on the Nanosize, Characterization and Stimuli‐Sensitive Characteristics

“…The weight loss up to 100 °C can be attributed to the moisture loss [12] . Safarzadeh et al [40] . prepared hydrogels based on acrylamide and methacrylic acid.…”

Green synthesis and environmental applications of alginate/polyacrylamide/titanium dioxide composite hydrogel

“…In the second stage, 236–341°C, the weight loss is attributed to the thermal degradation of unstable oxygen‐containing functional groups such as hydroxyl and carboxyl groups in the polymer, the breakage of CN bonds in the amide side arms in the PAM, and the MBA portion of the gel network 51 . Accordingly, the third and fourth stages of weight loss, in the range of 341–432°C and 432–579°C, are related to the thermal degradation of the polymer molecular chains occurring at higher temperatures 52 . When the temperature was increased to 600°C, the remaining mass of SA/PAM/TiO 2 accounted for 26.57% of the original mass.…”

“…51 Accordingly, the third and fourth stages of weight loss, in the range of 341-432 C and 432-579 C, are related to the thermal degradation of the polymer molecular chains occurring at higher temperatures. 52 When the temperature was increased to 600 C, the remaining mass of SA/PAM/TiO 2 accounted for 26.57% of the original mass. TiO 2 , indicating that the TiO 2 nanoparticles were well dispersed in the sodium alginate matrix, thus revealing the reason for the high degradation efficiency of the SA/PAM/TiO 2 hydrogels toward pollutants.…”

Magnetic, Biocompatible and Biodegradable Carboxymethyl Cellulose‐Based Hydrogel for Cationic Dye Adsorption

“…[26] Nanocomposite hydrogel can be developed using many techniques using different kinds of nanoparticles, such as metallic, polymeric, ceramic, carbonbased, and clay nanomaterials. [27,28] In recent years, Fe 3 O 4 magnetic nanoparticles have gained popularity due to their easy functionalization, good dispersion in water, ability to be separated using an external magnetic field and recoverability. [29] Incorporating Fe 3 O 4 nanoparticles into the pH-sensitive hydrogels makes nanocomposite hydrogels that can easily change their shape and swelling behavior concerning external pHs.…”

“…Therefore, the engineering of nanocomposite hydrogels has attracted many research subjects globally [26] . Nanocomposite hydrogel can be developed using many techniques using different kinds of nanoparticles, such as metallic, polymeric, ceramic, carbon‐based, and clay nanomaterials [27,28] . In recent years, Fe 3 O 4 magnetic nanoparticles have gained popularity due to their easy functionalization, good dispersion in water, ability to be separated using an external magnetic field and recoverability [29] .…”