Adsorptive removal of reactive yellow 145 dye from textile industry effluents using teff straw-activated carbon: RSM-based process optimization

Abstract

The study was focused on preparing activated carbon from one of the predominant agro-wastes, teff straw (TS), through chemical activation and investigating the optimum process condition for removing the reactive yellow 145 dye (RY 145) from simulated textile effluent and chemical oxygen demand (COD) from textile industry effluent. The prepared activated carbon (TSAC) was characterized using Fourier transform infrared (FTIR), scanning electron microscopy (SEM), point of zero charge (pHpzc), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) surface area. Response surface methodology (RSM) was adopted to optimize the process variables. Optimum parameters for the removal of RY 145 dye were contact time, pH, adsorbent dose, and initial dye concentration of 120 min, 2, 0.4 g, and 0.3 g/L, respectively, and 97% removal efficiency was achieved. The experimental data that well-fitted with the pseudo-second-order kinetic model, while examining isotherms, was the Langmuir model. Furthermore, the TSAC reusability study confirmed that TSAC can be used multiple times in dye removal from wastewater. These results suggested that a low-cost and eco-friendly bio-based adsorbent, TSAC, could be a promising and reusable adsorbent that could be an alternative for commercial activated carbon to be applied in polluted wastewater treatment. HIGHLIGHTS RSM was applied to optimize the RY 145 dye adsorption process by TSAC.; TSAC removed 98.71% of the RY 145 dye from simulated textile industrial wastewater.; TSAC removed 81.09% of COD from real textile wastewater.; The adsorption efficiency after the fourth desorption cycle was 89.93%.;

Keywords

• bioadsorbent
• central composite design
• optimization
• rsm
• teff straw
• wastewater