Extraction of Cu2+, Ni2+ and Zn2+ Using 2-Aminophenol Modified Quecertin and Red Onion Skin Extract from Aqueous Medium

Red onion skin extract and quercetin dihydrate modified with 2-aminophenol were used as adsorbents to extract Cu2+, Ni2+ and Zn2+ from their aqueous solutions. The unmodified and modified adsorbents were characterized using some physicochemical parameters such as melting point, solubility in different solvents, thin layer chromatography and FTIR. The FTIR revealed presence of various functional groups in the structure of modified and unmodified red onion skin extract and quercetin dihydrate. Extraction studies result showed that the maximum pH for metal removal is 3.30, 8.00 and 6.46 for Cu2+, Ni2+ and Zn2+ respectively. The percentage removal and adsorption capacities of the metal ions increased with increasing contact time, dosage and metal ion concentration. Quercetin dihydrate-diazonium salt (QDDS) showed a higher percentage removal for Cu2+ (99.19 %) than Ni2+ and Zn2+ while Red onions skin extract- diazonium salt (ROSEDS) showed a similar percentage removal for Cu2+ (98.57%) > Ni2+ (84.51%) > Zn (66.86%). Heavy metal ions were removed in this order; Cu2+ (99.19%) > Ni2+ (87.64%) > Zn2+ (71.56%) using QDDS. The adsorption kinetic studies and isotherm studies indicated that Pseudo-second order kinetics and Freundlich isotherm model best describe the adsorption processes. Therefore, ROSEDS and QDDS have proven to be an effective adsorbent for heavy metal ions from waste waters and industrial effluents.