Synergistic effects of crosslinked chitosan bis-indole derivative in a removal of tropaeolin dyes and Cr(VI) from aqueous solution: Computational and antimicrobial studies.

A nano-composite-1 (NC-1) was created from bis-indole derivative (compound 1) using chitosan biopolymer to improve the crosslinking properties. NC-1 effectively removed some industrial pollutants such as Tropaeolin dyes; Tropaeolin OO (TOO), Tropaeolin OOO (TOOO) and Cr(VI) from water. Optimum batch conditions for the three pollutants were determined to be 1, 2 and 1 for pH values, NC-1 dose of 0.07, 0.08 and 0.1 g, initial pollutant concentration of 30, 25 and 45 ppm at contact time of 120, 140 and 140 min at room temperature for TOO, TOOO and Cr(VI) adsorption, respectively. Kinetic studies indicated that adsorption process followed the pseudo-second order model. The most fitted model in isotherm data is Langmiur with adsorption capacities of 88.49, 147.05, and 87.7 mg/g for TOO, TOOO, and Cr(VI), respectively. The adsorption processes were determined to be spontaneous and exothermic as confirmed through thermodynamic studies. NC-1 maintained around 80-85% of its capacity after five regeneration cycles. Furthermore, NC-1 was investigated to show the inhibition of bacterial growth in sewage water by 93.9% using 0.2 of its dosage. Statistical analyses, including regression analysis and ANOVA alongside computational studies reinforced the findings. Molecular dynamic simulations revealed stable hydrogen-bonded networks in chitosan at 300 K. Adsorption locator analysis indicates that the compounds TOO and TOOO interact favorably with NC-1 surface with TOO showing stronger adsorption (-3251.03 to -3240.86 kJ/mol). The study suggests that NC-1 forms a stable surface suitable for pollutant adsorption and potential applications.