CHEMICAL ADSORPTION OF SELECTED HEAVY METAL IONS FROM AQUEOUSSAMPLE USING MANGO SEED POWDER

Abstract

The current work sought to establish a low-cost effective adsorbent by utilizing mango seed powder (MSP), agricultural waste, as a resource to prepare adsorbent material for the removal of selected heavy metals. Among the different approaches such as chemical precipitation, electrochemical method, ion exchange, reverse osmosis, membrane filtration, coagulation–flocculation and others, Adsorption is one of the promisingapproaches. Batchexperiments were carried out to determine the effect of pH, initial concentration of metal ions, dose, particle size of the adsorbentand contact time, on the percentage removal of Pb2+, Cd2+ and Cu2+. The adsorption capacity for Pb2+, Cd2+ and Cu2+ was 20.5,19.7 and 18.3 mg/g, respectively. Freundlich adsorption isotherm model for Pb2+, Cd2+and Cu2+ with R2 values of 0.368, 0.995, 0.994, respectively. Langmuir model with R2 value of 0.9996, 0.9996and 0.9994for pb2+, Cd2+and Cu2+, respectively. Physical characterization of the adsorbent was performed using Fourier transform infrared (FT-IR) spectroscopy to determine the participating functional groups of the adsorbent for Pb2+, Cd2+ and Cu2+ adsorption. The broad and strong band at 3414 cm-1 was attributed to the stretching of(-OH) of phenols, hydroxyl and carboxylic acid. The percentage removal was found to be 80.4%, 88.1%, 90.1% for Pb2+, Cd2+ and Cu2+ by MSP, at pH = 6, initial concentration of 25 mg/L, dose 0.5 gand particle size 300 μmfor Pb2+. Cd2+ and Cu2+, respectively. The adsorption equilibrium was achieved with in 90 min and the adsorptionfitted into the Langmuir adsorption isotherm with R2 values of 0.9996,0.9996 and 0.9994which indicate monolayer binding mechanism. Adsorption of MSP better described by the pseudo second order kinetic model with R2 value 0.974, 0.981 and 0.974, respectively. Based on the results observed in the present study, MSP can be taken as promising adsorbent for the removal of heavy metals from aqueous solution.