Low-cost bio-based sustainable removal of lead and cadmium using a polyphenolic bioactive Indian curry leaf (Murraya koengii) powder

There is an increasing trend of developing various low-cost biogenic sorbents for the efficient and economical removal of noxious metals. Curry leaf powder (CLP), a promising non-toxic biosorbent containing several bioactive compounds was prepared by the pulverization of the dried leaves for the effective removal of Lead (Pb) and Cadmium (Cd). Various batch sorption experiments were carried out under constant temperature (25 degrees C), different pH (4.5-10.5), initial concentrations (50-200 mg L-1), adsorbent dosages (0.10-0.40 g) and contact times (0-60 min) to understand the optimum experimental conditions and simultaneously evaluate the adsorption isotherms and removal kinetics of CLP. Adsorption equilibrium was established in less than an hour interval (50 min). The pseudo-equilibrium process was best described by the pseudo-second-order kinetic (R-2 >= 0.99), Freundlich and Langmuir isotherm model (R-2 >= 0.94). The removal rate of Pb and Cd gradually increased (15.7 and 12.7 mg g(-1) for Pb and Cd) at 100 mg L-1 of initial concentration fill 60 min of contact period in a single contaminant system, the effect was non-significant for multiple adsorbent dosage systems (p > 0.05; t-test) though. The regeneration potential of the exhausted biosorbent was excellent upto 5 cycles with the better efficiency observed for Pb. The obtained results explicitly validated the probable utilization of CLP as a promising green adsorbent for metal removal. Future study may highlight the decontamination aspects of emerging contaminants with such green bio sorbents in large scale as well as mimicing the stomach conditions.