165 JCHR (2020) 10(3), 165-174 Journal of Chemical Health Risks www.jchr.org ORIGINAL ARTICLE Comparative Evaluation of Cadmium Ion Uptake byWastes Generated from Zea mays Chidi Edbert Duru Surface Chemistry and Environmental Technology (SCENT) Research Unit, Department of Chemistry, Imo State University, Owerri, PMB 2000, Imo State, Nigeria (Received: 8 April 2020 Accepted: 16 June 2020) KEYWORDS Cadmium; Zea mays; Husk; Stalk; Cob; Seed chaff ABSTRACT: The removal of cadmium ions from aqueous solution by Zea mays husk (HK), stalk (SK), cob (CB) and seed chaff (SC) which are wastes generated after harvesting or processing this cereal were studied and compared. Batch adsorption studies were utilized to decide the impact of different parameters on the process. Cadmium ion uptake by the adsorbents increased with increase in pH from 3 – 6, with HK and CB showing a steady increase as pH changed. The removal efficiency of all the adsorbents increased with adsorbent dose. However, after 0.4 g load of adsorbent, the removal efficiency of SC became independent of adsorbent load. The maximum adsorption capacity of HK, SK and CB was attained in 12 minutes while SC reached this point in 9 minutes. The adsorption equilibrium data for all the adsorbents fitted well in the Freundlich isotherm model. The adsorption intensities of all the adsorbents from this model were greater than 1, and indicated that metal ion adsorption by these adsorbents were favourable physical processes. The rate of cadmium ion adsorption onto the adsorbents was better explained by the pseudo second-order kinetic model. The calculated equilibrium adsorption capacity of HK (16.36 mg/g) and SK (13.51 mg/g) showed that they had potentials for commercial application in the remediation of cadmium ion polluted water. INTRODUCTION Global industrialization has brought about improvement in the standard of living, but at the same time resulted in the production of environmental pollutants at unsustainable levels. These pollutants which are both organic and inorganic in form are difficult to dispose and most times persistent in the environment with adverse impact on health [1, 2]. The introduction of toxic heavy metals like chromium, lead, arsenic, nickel, mercury and cadmium into water bodies and soil by industrial production activities has jeopardized the survival of flora and fauna in these parts of the ecosystem [3 - 6]. Due to their toxic effects, soil and water bodies have been made unproductive and completely abandoned. Cadmium is a heavy metal found in the earth’s crust along with other heavy metals like zinc, lead, nickel and copper. It is used by many industries in the colouring of glass, production of alloys, production of pigments, plating of steel, production of batteries and stabilizing plastics. Waste materials containing cadmium stream from these industries and end up in soil polluting both soil and surface water within the giving area [7]. These wastes come in contact with humans either byinhalation or ingestion. Health effects of the accumulation of cadmium in human organs includes infertility, bone fracture, diarrhea and stomach pains, psychological disorders, damage to the central nervous system, reproductive failure, etc [8]. *Corresponding author: chidiedbertduru@gmail.com (Ch. E. Duru) DOI: 10.22034/jchr.2020.1897122.1122