Effective Removal of Industrial Textile Dye Using a Geopolymer-Based Adsorbent

Adsorption represents an effective and reliable method to treat wastewater effluents containing dyes. In this work, authors tested a geopolymer-based adsorbent for the removal of methylene blue. Constant mass of powdered geopolymer (15 mg) was weighed into flasks containing 50 mL of dye solution of specified concentration (ranging between 4 and 200 mg L−1). Operative conditions were pH 9.3 and 25 °C. The concentration of methylene blue of the supernatant solution was determined using an UV spectrophotometer at 668 nm. The adsorption capacity at equilibrium increases from 2.4 to 39 mg g−1 with an increase in the initial dye concentration from 4 to 200 mg L−1. The isotherms of dye adsorption on the geopolymer are well described by Langmuir model. Experimental kinetic data fit a pseudo-second-order kinetic model. The prepared geopolymer showed a high methylene blue removal efficiency.