Design, characterization and appraisal of chemically modified polysaccharide based mucilage from Ocimum basilicum (basil) seeds for the removal of Cd(II) from spiked high-hardness ground water

Abstract Ocimum basilicum L. seed mucilage (OBM) was separated mechanically and esterified to form OBM succinate (OBMS) and sodium salt of OBMS (Na-OBMS). These products were then exploited for Cd(II) removal from spiked high hardness ground water (HGW) and distilled water (DW) solution. Na-OBMS was characterized by FT-IR (Fourier-transform infrared spectroscopy), SEM-EDS (scanning electron microscopy-energy dispersive spectroscopy), zero-point charge pH and solid-state CP/MAS 13 C NMR (nuclear magnetic resonance spectroscopy). Na-OBMS was found to be a good sorbent for Cd(II) removal from DW and HGW. Effects of pH (1–7), temperature (290–343 K), interaction time (5–120 min) and sorbent dose (10–60 mg) on sorption capacity of the sorbent Na-OBMS were investigated. Negative values of different thermodynamic parameters (Δ G °, Δ S °, and Δ H °) indicated the exothermic and spontaneous nature of sorption. Different isothermal and kinetic models were applied on sorption data. Langmuir isothermal model and pseudo second order kinetic model provided best fit to the experimental sorption data. Maximum sorption capacity of Na-OBMS for Cd(II) uptake as determined by Langmuir isothermal model was found as 443.06 and 405.63 mg g −1 for DW and HGW, respectively. The sorbent was recovered simply by treating with brine and utilized again for sorption. A negligible decrease (9.5 and 11.4% for DW and HGW, respectively) was found in the efficacy of sorbent after 5 cycles of recovery.