ABSTRACT:The objective of this study was to investigate the possibility of using maize tassel as an alternative adsorbent for the removal of chromium (VI) and cadmium (II) ions from aqueous solutions. The effect of pH, solution temperature, contact time, initial metal ion concentration and adsorbent dose on the adsorption of chromium (VI) and cadmium (II) by tassel was investigated using batch methods. Adsorption for both chromium (VI) and cadmium (II) was found to be highly pH dependent compared to the other parameters investigated. Obtained results gave an adsorption capacity of 79.1 % for chromium (VI) at pH 2, exposure time of 1h at 25 ºC. Maximum capacity of cadmium of 88 % was obtained in the pH range of 5-6 at 25 ºC after exposure time of 1 h. The adsorption capacities of tassel for both chromium (VI) and cadmium (II) were found to be comparable to those of other commercial adsorbents currently in use for the removal of heavy metals from aqueous wastes. These results have demonstrated the immense potential of maize tassel as an alternative adsorbent for toxic metal ions remediation in polluted water and wastewater.

In this study, various physicochemical parameters were evaluated for maize tassel, a novel adsorbent. The Brunauer-Emmett-Teller (BET) isotherm was used to experimentally model N 2 -adsorption data (up to a relative pressure of 0.30); the results indicated that the powdered material was mesoporous with a BET specific surface area, total pore volume (up to a relative pressure of 0.98), and average pore width (4V/A by BET) of 2.52 m 2 /g, 0.0045 cm 3 /g, and 7.2 nm, respectively, for the 150-300-lm fraction. Laser diffraction pattern analysis yielded particle size distributions for the 45-50-, 50-150-, and 150-300-lm fractions. High-resolution scanning electron microscopy revealed a microstructure showing predominantly flattish, rodlike particles. The material exhibited stability to thermal decomposition up to about 230 C, as evidenced by the results obtained from simultaneous thermogravimetry/differential thermal analysis and differential scanning calorimetry.