Green Synthesis of Phytogenic Magnetic Nanoparticles and Their Applications in the Adsorptive Removal of Crystal Violet from Aqueous Solution

Abstract

An environment-friendly and cost-effective green recipe is employed for the production of green/phytogenic magnetic nanoparticle (PMNPs). Surfaces of PMNPs were functionalized by 3-mercaptopropionic acid (3-MPA) to investigate elimination performance of toxic dye, i.e., crystal violet (CV) from wastewater. Fabrication of functionalized PMNPs by 3-MPA (3-MPA@PMNPs) was characterized by various well-known techniques. Adsorption of CV onto 3-MPA@PMNPs has been experimentally investigated. The developed material showed high adsorptive rate (98.57% CV removal within 120 min) and adsorptive capacity (88.65 mg/g at $$25\,{^{\circ }}\hbox {C}$$ ). Moreover, various adsorption isotherm and kinetic models were applied to explore probable removal mechanism. Langmuir isotherm model successfully represented adsorption equilibrium of CV onto 3-MPA@PMNPs. Further, the adsorption kinetic data harmonized reasonably with pseudo-second-order model which revealed that the removal was mainly corroborated by the mechanisms of ion-exchange and/or chemisorption. Values of thermodynamic parameter ( $$\Delta {G}^{\mathrm{o}}$$ ) were − 5123.37, − 5313.46, − 6216.23, − 6764.21 and − 8548.97 KJ/mol, respectively, in the temperature range from 298.15 to 333.15 K. While the values of $$\Delta {H}^{\mathrm{o}}$$ and $$\Delta {S}^{\mathrm{o}}$$ were − 47.44 and − 8.67 KJ/mol, respectively. These values show that sorption was favorable, spontaneous and exothermic. The high adsorptive removal persisted at wide pH range of 6.0–12.0. The material indicated high selectivity in the presence of co-existing ions ( $$\hbox {Pd}^{2+}$$ and $$\hbox {Cd}^{2+}$$ ) and offered fastest separation times from aqueous solutions due to their superparamagnetic nature. Recovered adsorbent was re-employed for $$>\,5$$ times with removal efficiency of $$>\,85\%$$ . It is concluded that 3-MPA@PMNPs can be applied as alternative sorbent for cost-effective treatment of cationic dyes from textile wastewater.