The Removal of Azo Dyes from an Aqueous Solution Using NaOH-Activated Carbon from Phenolic Resin

Liquid dyes are discharged usually from different industries, such as textile factories, into water bodies. They are toxic compounds that can cause significant harm to humans, animals, and aquatic life due to increased water pollution. For this reason, removing dyes from wastewater is of great importance to control their negative impact and meet the standards of water quality. In this study, activated carbons were produced from phenolic resin through a chemical activation process with NaOH at high temperatures. The sample that had highest porosity and pore volume was used to adsorb two types of azo dyes Remazol Brilliant Blue R (RBBR) and Remazol Yellow dye (RY) from an aqueous solution under different conditions, i.e., changing contact time, pH, dosage, initial concentration, and temperature. The maximum removals of RBBR and RY were recorded separately at low concentration (10 ppm), acidic condition (pH < 7), adsorbent dose of 0.3 g, temperature of aqueous solution 20°C and contact time of 120 min. The Freundlich adsorption isotherm model, with its higher correlation coefficient, provided a better fit for the equilibrium data compared with the Langmuir isotherm model. The activated carbon derived from phenolic resin, which is chemically activated with NaOH at 850°C, is a promising adsorbent for the removal of azo dyes from aqueous solutions. The optimum conditions can increase the efficiency of the adsorption process.