Chemically modified rhamnogalacturonans from linseed: a supersorbent for Cd2+ and Pb2+ uptake from aqueous solution

Herein, this study rhamnogalacturonans (RG) was isolated from linseed and chemically modified to its succinate (SRG) by reacting it with succinic anhydride. Then, SRG was converted into the sodic form using NaHCO3 (Na-SRG). The novel Na-SRG appeared a supersorbent hence it was utilized for the uptake of Cd2+ and Pb2+ from an aqueous solution. Chemical modification in the structures of the materials was easily characterized by Fourier-transformed infrared (FTIR) spectroscopy and sorbent surface charge was analyzed through zero-point charge (pH(ZPC)) analyses. Batch series of sorption experimentation were conducted to investigate the influence of initial concentration of Cd2+ and Pb2+, sorbent dosage, pH, contact time, and temperature on the sorption capacity of Na-SRG. Maximum sorption capacities (Q(max) in mg g(-1)) of sorbent Na-SRG as-evaluated from Langmuir isotherm were found to be 303.03 and 316.79 mg g(-1) for Cd2+ and Pb2+, respectively. The kinetics of sorption of the tested metals follows pseudo-second-order kinetics and reached within 30 min. Negative values of thermodynamic parameters (Delta G degrees, Delta S degrees, and Delta H degrees) were found, which indicated the feasibility and exothermic nature of the sorption process. Additionally, the regeneration studies of tested sorbent were also performed over five successive cycles and an insignificant decrease in sorption capacity was come across which showed that sorbent is regenerable.

Automated summary

In this study, a novel supersorbent Na-SRG was successfully prepared through chemical modification and utilized for the uptake of Cd2+ and Pb2+ from aqueous solution. The sorbent exhibited high sorption capacities for Cd2+ and Pb2+, reaching equilibrium within 30 minutes. Thermodynamic parameters indicated the feasibility and exothermic nature of the sorption process, and regeneration studies demonstrated the regenerability of the sorbent over multiple cycles.