Improvement and characterization of alum sludge by nano-iron oxide and rice husk for removal of methylene blue dye from aqueous solution

Abstract

In the present study, the adsorption characteristics of the alum sludge (AS) waste from Rod El-Farag water treatment plant was improved by treatment with acidic rice husk (RH) and Nano-Magnetite (N.M) to form Nano-Magnetite composite (ASRHNMC). This composite gained new characteristics of large surface area, mesoporous structure and magnetic properties and it was used as a low cost adsorbent for the removal of methylene blue (MB) as a cationic dye from aqueous solution. (AS) and (ASRHNMC) were characterized by FT-IR, XRD, BET N2, EDX, SEM, TEM and XRF and were compared to adsorption ability against MB dye. The pH of the solution, sorbent dose, initial dye concentration, contact time and temperature were investigated using batch sorption technique for (MB) dye. The experimental results have pointed out that the adsorption equilibrium data is fitted well to the Langmuir isotherm reflecting favor formation of monolayer of MB dye on composite surface. The value of enthalpy change indicating that the removal process is endothermic. The adsorption process follows pseudo-second order rate equation and the negative values of standard free energy (DG◦) suggested that the adsorption process is spontaneous. The repeatability and regeneration studies of (ASRHNMC) for adsorption of MB were investigated and the results indicated the ability of reuse this composite several times in removal of MB from aqueous solutions.