Raw water lily (nymphaea lotus) leaves powder as an effective adsorbent for the adsorption of malachite green dye from aqueous solution

In this present study, raw water lily leaves (RWL) powder was prepared and used as low cost, efficient and environmental friendly adsorbent for the removal of malachite green (MG) from aqueous solution. The adsorbent’s surface functional group, net neutral charge and morphology were analysed by FT-IR, Point of Zero charge and Scanning Electron (SEM) spectroscopic techniques which confirmed the effective adsorption of MG dyes onto the RWL adsorbent surface. Batch adsorption technique was employed under various optimized conditions including contact time, adsorbent dosage, adsorbate concentration, pH and temperature respectively with an adsorption capacity of ۲۱۶.۶۶mg/g and percentage adsorption of ۹۹.۵. The physical properties: moisture content (۱۳.۴۹%), ash content (۹.۸۱%), organic matter (۹۰.۱۹%), bulk density (۰.۲۶۳g/cm۳), pore volume (۱.۶۶cm۳), pH (۵.۷۴) of the adsorbent were obtained using standard methods. The kinetic data were best fitted by pseudo-second order in all the models tested under different operating temperatures. The adsorption isotherms were estimated, established and found to fit into Freundlich isotherm as compared to other models tested. Thermodynamics of the adsorption was found to be spontaneous and feasible with values of Gibb’s free energy (∆G) ranging between -۹.۴۸۱ to -۹.۸۸۰kJ/mol, exothermic with enthalpy (∆H) of -۱۱.۷۵kJ/mol and a decrease in randomness of the adsorption process during the transfer of molecules between the adsorbent and adsorbates with entropy (∆S) of -۶.۳۳kJ/mol. This study confirmed that RWL could be employed as a low cost and environmental friendly adsorbent for the removal of toxic dyes such as Malachite Green from aqueous solution

Keywords:

Raw water lily leaves , Malachite Green Dye , Adsorption , Thermodynamics , Kinetics