The simultaneous and synergistic sorption of phenanthrene and cadmium using biomass derived from rice roots

Abstract

Evaluating the sorption performance of coexisting phenanthrene and cadmium on rice roots is critical for a better understanding of plant sorption and uptake of combined pollutants. Batch sorption kinetics and isotherms of phenanthrene and cadmium on rice root biomass, as well as key factors in both single and binary systems, were evaluated to access any potential synergistic effects. Results showed that rice root biomass effectively and simultaneously removed phenanthrene and cadmium from aqueous solutions. The presence of a co-solute led to synergistic effects on the sorption, enhancing the affinity parameters, i.e., the Kd (linear model), from 2530 to 3970 L/kg for phenanthrene, and the KF (Freundlich model), from 640 to 777 L/kg for cadmium. The well fitted pseudo-second-order kinetics implied that the coexisting pollutants slowed the sorption rates, decreasing the sorption rate (k2) from 0.185 to 0.155 g/mg/min for phenanthrene and from 0.0361 to 0.00146 g/mg/min for cadmium. The results suggested that further studies should carefully evaluate the remediation and risk-assessment in rice-arable soil under combined pollution.