Synthesis of 3,5-diaminobenzoic acid containing crosslinked porous polyamine resin as a new adsorbent for efficient removal of cationic and anionic dyes from aqueous solutions

The synthesis of a novel cross-linked polymer TRIDABA is described for an efficient adsorption of MB, CR and RhB from dyes polluted water. The mesoporous resin having a surface area of 11.2 m² g⁻¹ was found to be thermally stable (T_d = 200 °C). The resin exhibited excellent adsorptive performance, showing maximum adsorption capacity of 1273.8 mg g⁻¹ of MB (pH = 8.0), 447.1 mg g⁻¹ of CR (pH = 5.1) and 680.5 mg g⁻¹ for RhB (7.2 pH) at 299.5 K. Various adsorption isotherms including Langmuir, Freundlich, Dubinin Russinovich, Temkin and Hill models were applied to understand the mechanism of adsorption of dyes onto the TRIDABA. Thermodynamic studies suggested that adsorption process was spontaneous and exothermic. Moreover, kinetic data was in good agreement with pseudo-second order model. The structural characterization and surface analysis of TRIDABA were extensively performed by several techniques including solid (CP-MAS) ¹³C NMR, FTIR, BET, XPS, and SEM/EDX.