Morphological and structural analysis of Fe/Sn bimetal system and graphene oxide–chitosan modified Fe/Sn composite: a comparative study and their mechanistic role in degradative fixation of chlorazol black and reactive blue 4 from water

Efficient removal of an azo dye (chlorazol black, CB) and an anthraquinone dye (reactive blue 4, RB4) using magnetic binary Fe/Sn metal system (BMS) and ternary Fe/Sn@GO ~ CS nanocomposite (TNC) is evaluated and compared. To achieve the present study, TNC (Fe/Sn@GO ~ CS) and BMS (Fe/Sn) were synthesized via different synthetic approaches like co-reduction (CR), separate-reduction (SR) and partial-reduction (PR). TNCs and BMSs were characterized by SEM, EDS, HR-TEM, SAED, XRD, BET, TGA and FTIR techniques. Evaluation of SEM data revealed the average particle size ranging from 60 to 200 nm with a maximum BET surface area of 143m 2 g −1 . These composites were further employed for the evaluation of their efficiency in the removal of harmful azo and anthraquinone dyes from water. Development in the process of dye removal was monitored by UV–VIS spectrophotometer and ESI–MS. Ternary nanocomposites (Fe/Sn@GO ~ CS) presented excellent results in the removal of an azo dye (chlorazol black) and an anthraquinone dye (reactive blue 4) with the maximum removal efficiency of 99% and 95%, respectively. The efficiency of the TNC further turned up to 79% in even in the 3rd consecutive cycle of composite re-use. Maximum adsorption efficiency (q m ) was found to be 171.60 mg g −1 and 187.73 mg g −1 for TNC ~ PR and TNC ~ CR, respectively. Up-to 95% removal efficiency was also achieved for the TNC ~ CR when applied for mixture of CB & TB4 (1:1 v/v). Furthermore, industrial effluents from a local textile industry containing mixture of different dyes were also treated with TNCs and showed 58% removal in 60 min indicating the good efficacy of TNCs in real time application. Mechanism of the process has also been investigated and well supported by XRD and ESI–MS analysis revealing the degradation of dyes after the adsorption. Graphical abstract