Abstract

Chitosan obtained from shrimp shells and SiO₂ nanoparticles obtained from rice husk ash were used to synthesize chitosan - SiO₂ composite materials. In order to obtain a porous chitosan adsorbent, the SiO₂ particles in the chitosan - SiO₂ composite material were removed with NaOH solution. With the orientation of applying adsorbent in wastewater treatment of textile industry, the ability of methylene blue adsorption of chitosan with porous structure has been investigated. Survey results show that chitosan has porous structure with good adsorption capacity of methylene blue. The adsorption capacity of materials depends on many factors such as: structure of particles; pH of adsorption medium and temperature. Adsorbent material is made of composite chitosan - SiO₂ with the ratio of chitosan/SiO₂ equal to 1/1 (w/w) with the best adsorption capacity. Materials with good adsorption capacity at pH = 6, at low pH, the adsorption capacity of the material is significantly reduced. Temperature has a great influence on the adsorption capacity of the material. The suitable temperature for adsorption of materials is 40 ^oC. With a higher temperature, the desorption process will be accelerated. This makes the adsorption capacity of the material decrease. The maximum methylene blue adsorption capacity of the material is determined about 7.25 mg/g after 40 minutes of adsorption time.