Abstract
Environmental pollution caused by the presence of toxic materials such as cadmium is becoming global problem and concern. This paper presents a report on kinetics of Cd2+ removal from aqueous solutions through adsorption using powdered corn cobs (PCC). Corn cobs were collected from a selected location, washed to remove sand, air dried, ground and sieved into different particle sizes. The selected properties of PCC were determined using acid digestion method. Adsorption capacities through kinetics of Cd2+ removal from synthetic solutions, typical raw water and domestic-institutional wastewater were studied. Effects of pH, PCC particle size, initial concentration of Cd2+ and temperature on adsorption capacities were monitored through pseudo first- and second-order models, Elovich and intraparticle diffusion models to present adsorption rate parameters.
The study revealed that PCC contained 86.89% volatile solids, had 4.56% acid solubility, 0.52 water solubility and 2.33% ash content. FCC removed Cd2+ from aqueous solutions (synthetic, raw water, and wastewater). The relationship between time and concentration of Cd2+ remaining in the solution followed exponential functions with squared correlation coefficient ranging from 0.9928 to 0.9993, 0.8701 to 0.9284, and 0.8514 to 0.9290 for synthetic solution, raw water, and typical domestic-institutional wastewater, respectively. Mechanism of cadmium adsorption onto PCC was in two separate stages linear portions in the first parts, while the final parts are curves indicating intraparticle diffusion. It was concluded that PCC is an effective adsorbent for Cd2+ removal. The estimated production cost was 0.068 USD as against 0.50, 2.12, and 3.12 USD for producing adsorbents from empty fruit bunches; pencom shell and sugar cane based activated carbons, respectively.