Adsorption of chemical oxygen demand from surface water using bagasse activated carbon

This study aimed to evaluate the adsorption of COD from surface water using bagasse-driven activated carbon (BAC). The BAC was characterized using proximate analysis, SEM, FTIR, XRD, and BET methods. The optimization of COD removal was studied using the Box-Behnken-Design method under response surface methodology. The moisture content, volatile matter, ash content, fixed carbon, bulk density, and point of zero charge of the BAC were 4.13%, 17.21%, 15.31, 63.34%, 0.28 g/mL, and 5.3, respectively. Many heterogeneous, small, and irregular pores were observed in the SEM micrograph. The different peaks in the FTIR analysis indicate the presence of different functional groups. The presence of amorphous carbon arrangement was indicated by the decrement of peak intensity with the increment of 2 theta values. The surface area of the BAC before and after adsorption is 875.665 m(2)/g and 742.718 m(2)/g, respectively. A maximum COD removal of 93.66% was achieved at pH (7), contact time (75 min), and adsorbent dose (0.75 g/200 mL). The adsorption process was optimized at pH, contact time, and adsorbent dose of 7.804, 57.634 min, and 0.517 g, respectively. The experimental data best fits with Langmuir isotherm, and pseudo-second-order kinetics model with R2 of 0.9951 and 0.9880, respectively. Intragranular and extragranular diffusion processes affect the rate control step. The BAC showed a good regeneration capacity for four cycles in both desorbing solutions (NaOH and HNO3). Generally, the BAC has a promising potential to be used as a low-cost adsorbent in developing countries including Ethiopia. However, further assessment is required before industrial-level application.