Investigation of methylene blue adsorption on alum sludge using full factorial 2k design

Alum sludge (AS) wasted from water treatment plant (WTP) was prepared by a simple drying method and tested as an adsorbent for removal of methylene blue (MB) dye from water. Laboratory batch experiment was conducted using full factorial 2k experimental design in order to investigate the influence of experimental factors including adsorbent dose (0.5-1 g/L), dye concentration (0.05-0.15 g/L), pH (4-8), and temperature (30-60 degrees C). Characterisation of AS adsorbent was performed using SEM-EDX and XRF analysis. SEM-EDX and XRF analysis showed that AS particles have a heterogeneous size, with irregular shape and rough surface, and contains SiO2, Fe(2)O(3 )and Al2O3. Results showed that all experimental factors affected the dye removal and adsorbent dosage was found as the most significant factor. The highest removal up to 75% in 3 hours can be achieved at adsorbent dosage of 1 g/L, dye concentration 50 mg/L, pH 8, and temperature 60 degrees C.