Fabrication of lightweight and reusable salicylaldehyde functionalized chitosan as adsorbent for dye removal and its mechanism

Bio-resources have a very significant role in current research approach for the synthesis of benign functionalized biological macromolecules for their stable structural integrity and inherent nature-inspired potentialities. Here, chitosan is used as a core moiety for designing of a porous adsorbent after the attachment of salicylaldehyde to remove the toxic dyes. Salicylaldehyde linked chitosan, with excellent surface porosity, lightweight, non-glucose and low-cost feature, makes it as an efficient adsorbent. The dye loaded material is very easy to remove from the top of the water as it is suspended on water. The physico-chemical characterizations are done by FTIR, rheology, SEM and swelling study. The removal efficiency is 98% and 99% for Crystal Violet and Rose Bengal from water respectively. The thorough adsorption with mechanistic approach shows the Freundlich model as an appropriate one and follows closely pseudo-second-order kinetics model. Thermodynamic study reveals the endothermic nature of the process. Moreover, the reusability of Salicylaldehyde linked Chitosan shows its persistence with the same amount and concentration of dyes in water up to three consecutive cycles. So, the chitosan based macromolecules can be a sustainable candidate in the current scenario for the removal of dyes without the dislocation of the water container. [Display omitted] •Preparation of a functionalized light weight and porous salicylaldehyde linked chitosan as hydrogel.•The % removal efficiency of adsorbent is investigated for Crystal Violet: 98% and Rose Bengal: 99% from water.•Freundlich isotherm model and Pseudo-Second order kinetics model are found to be followed.•The reusability of hydrogel is studied up to three cycles without any loss of activity.•The forces responsible for adsorption are electrostatic interaction, π-π stacking, H- bonding and van-der-Waals force.