Statistical Optimization and Kinetic Studies of Water Hyacinth Stem-Based Activated Carbon Adsorbent for Synthetic Textile Dye Effluent Treatment

Industrial effluent from the textile industry has been the most important concern in the world for many decades. Most of the dyes used in the industry are harmful to human beings and also to the environment. In this study, the potential of water hyacinth stem-based activated carbon was studied for the decolorization of synthetic dye wastewater. The activated carbon is a carbonaceous material obtained from the degradation of biomass, which has high adsorption potential. Water hyacinth is available worldwide and has shown high potential to produce cheaper activated carbon. The adsorbent was characterized by using Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. The influence of parameters such as initial pH (5-9), adsorbent dosage (0.3-0.7 g/100 ml), contact time (1-6 h), and temperature (30-45 celcius) were examined. In response surface methodology (RSM), central composite design (CCD) was adopted to optimize the parameters that influence dye adsorption. The CCD and RSM predicted an optimal condition for dye removal in synthetic wastewater at pH 6, temperature 44 celcius, and a contact time of 4 h which removed 81 +/- 0.3% of dye, adopting an adsorbent dosage of 0.5 g/100 ml. Kinetic and adsorption study results agreed with the pseudo-second-order model, Langmuir's model, and Temkin's model. The kinetic study best fit with the Langmuir model showing that adsorption capacity was 59.52 mg g-1. It follows physical adsorption mechanism and temperature increases; the adsorption increases up to a certain temperature. After that, adsorption of dye decreases. Water hyacinth stem-based activated carbon has shown to be a promising feedstock for the degradation of textile dye effluents. This study demonstrates the use of water hyacinth stem-based activated carbon has a potential source for dye degradation in textile effluents.