A novel silica xerogel synthesized from volcanic tuff as an adsorbent for high-efficient removal of methylene blue: parameter optimization using Taguchi experimental design

Abstract

BACKGROUND In this study, silica xerogel was synthesized using volcanic tuff instead of expensive silica precursors at ambient pressure drying. The mesoporous silica xerogel with unique structural and textural properties was evaluated as an adsorbent for methylene blue (MB) removal from aqueous solution. Taguchi method was applied to optimize controllable factors (contact time, initial MB concentration, silica xerogel dose, temperature and pH) for MB removal. RESULTS The temperature was determined as the most significant factor with percentage contribution of 54.50%. MB removal efficiency was 96.18% at optimum conditions (contact time: 60 min, initial MB concentration: 20 ppm, silica xerogel dose: 0.0016 g mL(-1), temperature: 40 degrees C, pH: 5). The experimental data fitted with the Langmuir isotherm, yielding a maximum adsorption capacity of 51.967 mg g(-1). MB desorption process was performed depending on eluent concentration and contact time. Maximum desorption efficiency was specified as 88% using 1 M hydrochloric acid for 4 h. The silica xerogel was easily recycled with retaining approximately 70% of adsorption efficiency after five cycles. CONCLUSION In the light of the promising results, the silica xerogel can be used as an effective adsorbent in many environmental applications. (c) 2019 Society of Chemical Industry