Umudike Journal of Engineering and Technology

Coconut Shell (CS) was carbonised, activated with NaOH and used to adsorb Congo Red (CR) dye from its aqueous solution. Proximate and ultimate analyses, Fourier Transform Infra-red (FTIR) and Scanning Electron Microscope (SEM) were used to characterize both the raw and the Coconut Shell Activated Carbon (CSAC) while UV spectrophotometer was used to monitor the CR dye concentration. Batch adsorption experiments were carried out using 100 ml each of 50 mg/l to 250 mg/l CR dye solution at different contact times, and temperature. To establish optimum adsorption conditions, Central Composite Design (CCD) in Response Surface Methodology (RSM) was employed using the initial dye concentration, contact time and temperature as variables at a fixed pH of 3 and 0.2 g/100ml of adsorbent. Adsorption capacity of 122.00 mg/g was obtained with CR concentration, contact time and temperature of 250 mg/l, 180 min and 30oC, respectively. Pseudo first order kinetic model best fitted the experiment. The coefficients of determination of Langmuir, Freundlich and Temkin isotherms were 0.978, 0.974 and 0.863, respectively, with Langmuir isotherm giving a better fit for the adsorption. The maximum monolayer adsorption capacity from Langmuir isotherm was 121.56 mg/g at pH 3 and a temperature of 30oC.