Guar gum succinate: Dry synthesis, characterization and application as an efficient adsorbent for removal of safranin-O dye

The development of novel biopolymer derivatives is an emerging approach for remediation of toxic dye contaminated water. During current study guar gum succinate (GGS) was synthesized under dry condition without employing solvents and bases. An equi-proportion mixture of guar gum and succinic anhydride under heat treatment (120 °C, 40 min) resulted in highest degree of substitution (1.05 ± 0.07) for GGS. Further, GGS was characterized and explored as an adsorbent for removal of toxic safranin-O dye from aqueous solutions. The dye adsorption followed pseudo-second-order kinetics, with adsorption mechanism involving boundary layer diffusion followed by intra-particle diffusion into GGS matrix. Fourier transform infrared (FT-IR) and Carbon-13 Nuclear Magnetic Resonance (¹³C NMR) spectra revealed strong interactions between aromatic and methyl groups of dye with carbonyl and hydroxyl groups of GGS. Isotherm modelling using Langmuir and Freundlich models confirmed favourable nature of safranin-O adsorption on GGS. Adsorption studies showed maximum monolayer adsorption capacity of 113.64 mg/g, surpassing most reported adsorbents. Furthermore, reusability of GGS was established with over 85 % adsorption efficiency maintained across four cycles, emphasizing its economic viability. Compared to conventional adsorbents, GGS offered an environment friendly, biocompatible, and scalable solution for wastewater treatment, with significant potential in hazardous dye-laden industrial effluent management.