Activated carbon from spent coffee grounds as an adsorbent for treatment of water contaminated by aniline yellow dye

One problem that convoys the industrial revolution is the worsening problem of wastewater containing dyes of the effluents from the growing number of dye-producing industries. This study exploited the use of spent coffee grounds (SCG) as a precursor in making activated carbon to treat water contaminated with aniline yellow dye (AYD). The activated carbon, chemically modified using potassium hydroxide, was characterized using Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy. The optimization of the operating parameters in AYD removal was done using Design Expert 7.0 software through the central composite design of response surface methodology to attain the maximum removal efficiency. The result showed that SCG activated carbon has mesopore and micropore structures with honeycomb particle shapes. Several functional groups were identified on the surface, a good indicator as a potential adsorbent. Optimum conditions were found, which are 35 ppm initial AYD concentration, 0.6 g adsorbent dose, and 2.5 h contact time; and achieved a removal of AYD at 88.72 +/- 1.88% with an adsorption capacity of 2.58 mg/g. The adsorption took place heterogeneously in multilayer as revealed in the isotherm analysis with Freundlich as most fitted having R-1 value of 0.9868. The adsorption mechanism is dependent on the physical amount of dye adsorbate or its concentration factor as revealed in kinetic studies with pseudo-first order as the most fitted model having R-2 value of 0.9832. The overall result demonstrated that the activated carbon from SCG is a good material in removing the dye in the contaminated water with huge implications for the future of treating dye-contaminated water from industries.