INTRODUCTION Dyes are complex chemical substances that bear stable aromatic rings synthesized to impart strong and persistent colour that does not degrade on exposure to light (Ibrahim and Sani 2014). Dyes are generally applied in an aqueous solution, and may require a mordant to improve their fastness on fibres al., 2013; Saritha et al., 2015) contact of dyes has been reported to result in various types of health problems like hypersensitivity, mutagenic and carcinogenic effects, allergy and asthma, skin eczema and immunosuppressive effects chattopadhyaya, 2013; Omran This leads to raise concern regarding its use as well as its removal from aqueous dye impact toxicity and impedes light penetration and thus upsets the biological activity (Alwan et al., 2015; Sayan Hassan and Mahdi, 2016). Several methods including physical, chemical and biological processes have been used for the removal of dyes from effluents. Chemical and biological methods are effective for decolo ABSTRACT The adsorption of Bromophenol blue (BPB), and Bromothymol blue (BTB) onto raw maize cob from aqueous solution was studied using bach adsorption technique, in which the influence of contact time, dosage, concentration, temperature, and pH, were investigated characterizing the adsorbent using Fourier Transform Infrared (FTIR) spectroscopy, surface morphology using scanning electron microscopy and pH of point of zero charge (pH Results showed that Bromophenol blue and Bromothymol percentage about 96.53 %, and 94.39 % with equilibrium time within 125 and 110 minutes respectively. For both dyes the removal efficiency was found to increase with increasing initial dye concentration from 10 mg/l to 100 mg/l be high at lower pH. also, increase in the dosage of the adsorbent leads to increase in the adsorption process for BPB but shows decrease for BTB. The equilibrium adsorption data were analyzed using Langmuir, Freun results revealed that the experimental data fits Temkin isotherm with R and 0.971 for BPB and BTB respectively. Kinetic analyses were conducted using pseudo second-order models, elovich equation and the intra results in addition to q e experimental and q was more accurately represented by pseudo parameters such as free energy changes ((∆) were calculated using vant Hoff equation. All the adsorption was feasible and spontaneous. The result indicated that raw maize cob c be used as adsorbent for the removal of the

This study was aimed to evaluate the adsorption of Methyl orange (MO) onto raw maize cob (RMC) and maize cob activated carbon (MCAC) from aqueous solution using batch adsorption studies. The produced adsorbents were characterized by Scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). The influence of contact time, dosage, concentration, temperature, and pH were investigated as well as Isotherm and Thermodynamic studies. Effect of contact time showed that Methyl orange adsorption were found to reach equilibrium within 125 and 110 minutes with optimum percentage removal of about 86.98% and 94.57% for raw maize cob and maize cob activated carbon respectively. The dye removal efficiency was found to increase with increasing initial dye concentration from 10 mg/L to 100 mg/L, and adsorption efficiency was found to be high at lower pH. However, increase in the dosage of the adsorbents lead to the increase in the adsorption process. The equilibrium adsorption data were analyzed using four adsorption models: Langmuir, Freundlich, Temkin, and D-R. The results revealed that MO with raw maize cob and maize cob activated carbon fit well to Freundlich with R2 value 0.977 and Temkin with R2 value 0.990 respectively and mean adsorption energy calculated from D-R shows it is physical adsorption and also values of enthalpy and Gibbs free energy proves that. Values of activation parameters such as free energy changes (∆G), enthalpy change (∆H) and entropy change (∆S) were calculated using Van't Hoff equation. All ∆G values were negative indicating that the adsorption was feasible and spontaneous. The result indicated that RMC and MCAC can be used for removal of MO from aqueous solution. The maize cob waste which is discarded as waste material was found to be effective adsorbent for the removal of Methyl orange dye from aqueous solution.