Synthesis, Characterisation and Application of Capped Chromic Oxide Nanoparticle(CCONP) forthe Removalof Cd2+and Pb2+ion from Aqueous Solution

Abstract

This research was designed to ascertain the removal efficiency ofCd2+andPb2+ion from aqueous solution using capped chromic oxide nanoparticle(CCONP) synthesized by method of co-precipitation and thermaldegradation of chromic hydroxide (Cr(OH)3),stabilized and capped usingpolyvinyl alcohol (PVA).The physicochemical characterization of thesynthesizedCCONPwas evaluated usingx-ray diffractograms (XRD),scanning electron microscope (SEM)andFourier Transform infraredspectrophotometer (FTIR). The CCONPobtained was more ofcrystallinethanamorphouswithvery small particlesinapparently soft agglomerateswith asize of 7.7 nm. The amountofCd2+and Pb2+ions before and aftertreatment of the aqueous solution was evaluated usingatomic absorptionspectrometer (AAS).Adsorption experiments were conducted in batches andthe adsorption property of CCONP was studied using adsorption isothermmodels and optimized using response surface methodology (RSM) Analysis.The adsorption isotherm models revealed thattheadsorption process of Cd2+and Pb2+ions onto CCONP was a physical process, favorable andexothermic. The energy of affinity for Pb2+ions on CCONP was higher. Theadsorption process for Cd2+ions on CCONP was spontaneous and theadsorption capacity of CCONP for Pb2+ions was higher. However,optimisation analysis revealed that the cadmium ions were slightly moreadsorbed on CCONP and removed from the aqueous solution compared tolead ions. This observation was in agreement with the kFvalues obtainedfrom Freundlich isotherm in which the kFvalue for cadmium ions (59.52)was higher than that of lead (51.99).