Preparation of novel and recyclable chitosan-alumina nanocomposite as superabsorbent to remove diazinon and tetracycline contaminants from aqueous solution.

This work presents a novel, strong and efficient adsorbent (CS@TDI@EDTA@γ-AlO(OH)) prepared through the green process using three components, chitosan, BNPs and EDTA using amide and ester bridges. An eco-friendly and easy approach was used for the preparation of this novel adsorbent, the low cost, easy access to the used materials, and the simplicity of the preparation method are some of the interesting advantages of this work. Also, this prepared adsorbent was used as an adsorbent to remove diazinon organophosphate poison and tetracycline antibiotic from aqueous solutions. In order to confirm the prepared adsorbent structure, the CS@TDI@EDTA@γ-AlO(OH) composite was investigated by various analyses including FT-IR, EDX, XRD, FESEM and TGA. The adsorption behavior of the adsorbent prepared for the removal of tetracycline and diazinon was investigated under different conditions by varying the concentration, temperature, the adsorbent dose, pH and contact time. Based on various tests, the highest diazinon adsorption capacity was obtained for 0.12 g/L adsorbent at pH 7 and 60 °C with 40 mg/L initial concentration. Also, the maximum adsorption capacity of the tetracycline was obtained for 0.12 g/L adsorbent at pH 9 and 60 °C with 30 mg/L initial concentration. The equilibrium results for diazinon and for tetracycline were in good accordance with the Langmuir and Freundlich isotherm models, respectively. Also, the highest adsorption capacities for diazinon at pH 7 and tetracycline at pH 9 were 1428.5 and 555.5 mg/g, respectively. Also the kinetic investigations revealed that the correlation factor (R