Removal of direct blue 71 from aqueous solution by adsorption on rice husk carbon-clinoptilolite composite adsorbent

The adsorption performance of rice husk carbon-clinoptilolite (RHC-clinop) for the removal of Direct Blue 71 (DB71) in batch mode was investigated. The RHC-clinop was prepared by pre-determined mixes of clinoptilolite (clinop), rice husk carbon (RHC), and ordinary Portland cement (OPC). The OPC was used as binding agent. The adsorption experiments were conducted at different conditions of adsorbent dosage (0.21.2g), solution pH (2-12) and initial concentration (25-400 mg/L). DB71 adsorption uptake was found to increase with increase in initial concentration and contact time. The optimum adsorption of DB71 was favorable at pH 10 with adsorbent dosage of 1.0g. The experimental data was fitted well with Freundlich isotherm. Adsorption kinetic was found to follow the pseudo-second-order kinetic model with good correlation. The result indicates that the RHC-clinop is suitable for the removal of azo dye by adsorption process.