Replacement of lemon juice wastes instead of strong inorganic acids in production of silica from rice husk and efficiency of produced adsorbents in removal of cadmium from aqueous solutions

Production of adsorbent using agricultural wastes has important economic and environmental advantages. The aim of this study was Production of silica absolutely using agricultural wastes and determination of efficiency of produced adsorbents in removal of cadmium from aqueous solutions.
In this experimental study, two different type of acidic pretreatment and then thermal treatment was used for silica production from rice husk. The efficiency of the produced adsorbents was studied in four pH states, four cadmium concentration values, five adsorbents dosages and six different contact times. Cadmium concentration was determined by atomic absorption spectrophotometry.
silica was produced in the two procedures and both produced silica had good morphological and physical characteristics. The maximum efficiency of cadmium removal at pH= 6, adsorbent dosage of 3 g/l, contact time of 120 min and initial cadmium concentration of 5 mg/l, for rice husk silica produced by strong inorganic acids and waste lemon juice were respectively %90.1, %60.8. The adsorption processes followed the Freundlich isotherm)generally R2 ≥0.99(.
According to the results of this study, good rice husk silica can be produced using absolutely agricultural wastes (rice husk and lemon juice) and produced silica can be used as an effective and cheap adsorbent for removal of cadmium from aqueous solutions