REMOVAL OF HEAVY METAL IONS FROM LOCAL BATTERY RECYCLING WASTEWATER USING FUNCTIONALIZED CORN HUSK DERIVED ACTIVATED CARBON

Abstract

The synthesis of functionalized corn husk derived activated carbon was aimed at studying the potentials of the adsorbent in the removal of heavy metals from local battery recycling wastewater. The synthesis emphasizes on the pretreatment, particle size, amine functionalization and thermal treatment of the adsorbent while the effect of contact time, adsorbent dosage, effluent temperature, pH and concentration forms the basis of the batch adsorption study. The characterization of the raw corn husk and functionalized corn husk derived activated carbon was carried out using thermo gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR), BranauerEmmett-Teller analysis (BET), and scanning electron microscopy-elemental disperse spectroscopy (SEM-EDS). The results of TGA shows a temperature profile with steep degradation between 300 and 500 0C while the FT-IR results reveals the presence of various functional groups before and after modification, the SEM-EDS results also revealed enhanced pores in the activated carbon with broad elemental dispersion containing carbon, nitrogen, oxygen and hydrogen suggests the presence of related functional groups. Effect of contact time was studied between 5 and 140 min while the effect of temperature and dosage were studies between 28 to 70 0C and 0.5 to 5 g respectively. Further study on the effect of concentration and pH were conducted between the ranges of 10 to 100 % effluent initial concentration and 2 to 11 pH respectively. The experimental adsorption capacity (qe) was 7.95, 6.08 and 4.99 mg/g for Pb Cu and Ni respectively. The Langmuir, Fruendlich, Harkin-Jura, Elovich, Dubinin, Temkin, Jovanovic and D-R isotherms were used to describe the process with a best fit in Fruendlich isotherm which suggests multi-layer adsorption. The study of Pseudo-first, Pseudo second order, Elovich and Intra-particle diffusion kinetic models reveals best fit for second order rate which suggests chemisorption. Further thermodynamic studies also suggest exothermic reaction with negative enthalpy and Gibbs free energy. Desorption study also reveals the viability of the adsorbent for recycle and reuse as 99 % removal efficiency was observed after three cycles.