Duckweed-Derived Adsorbent for Efficient Methylene Blue Removal from Synthetic Wastewater

Abstract

The main problem is the untreated azo-reactive pollutants and textile dyes, such as methylene blue, which are toxic to both the environment and human health. Chemical and physical treatment methods are not only expensive but also have subordinate environmental weaknesses. Duckweed was used as an economical, sustainable, and costeffective adsorbent to remove methylene blue from synthetic wastewater. The main objectives of the study include isolation and conversion of DW into an eco-friendly adsorbent, to evaluate the effect of physical parameters, including pH, adsorbent dose, time, and contaminant concentration, and to apply reaction kinetics and reaction isotherm models. The adsorbent was prepared and then examined using various methods, including scanning electron microscopy, X-Ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. Different concentrations of methylene blue were prepared, and batch experiments were performed involving various conditions of pH, adsorbent dose, time, and contaminant concentration to evaluate the optimal removal efficiency of MB by the prepared adsorbent. Citric acid was used as an activator that increases the efficiency of duckweed and reduces the leaching of chlorophyll color. The results were analyzed based on absorbance using a UV spectrophotometer at 580 nm, and the maximum removal efficiency of 93.3 % was achieved at a pH of 10, MB concentration of 50 mg/L, an adsorbent dose of 50mg, and in 30 minutes. Desorption studies were done to verify the removal efficiency, which decreases after two to three uses, so it is suitable for a particular use. Duckweed acts as a favorable substance for regulating methylene blue dye pollution in industrial wastewater