Removal of lead (Pb+2) from contaminated water using a novel MoO3-biochar composite: Performance and mechanism

Abstract

Removal of toxic chemicals from the environment using novel adsorbents is of great concern. In this study, a novel composite of molybdenum trioxide (MoO3)-engineered biochar (MoO3-BC) was derived from corn straw and synthesized for the removal of Pb(II) from water. The pyrolysis temperature of 600 °C was suitable for the thermal self-assembly of MoO3-BC. Although MoO3-BC had lower SBET (59.3 m2/g) than the pristine BC (157.8 m2/g), it had a stronger adsorption affinity to Pb(II). The Pb(II) removal capacity of MoO3-BC was 229.87 mg/g at pH 4.0, and the adsorptive removal of Pb(II) was fit using a pseudo-second-order model and the Langmuir model. High temperature favored the removal of Pb(II) by MoO3-BC; However, the removal of Pb(II) was inhibited with increasing the ion strength. The MoO3-BC revealed an acceptable stability and reusability, since the removal efficiency of Pb(II) remained above 80.7%, even after 8 cycles. The MoO3-BC effectively reduced ≥99.9% of Pb(II) in the polluted irrigation water. The Pb(II) removal mechanisms involved surface electrostatic attraction, ion exchange and surface complexation. These findings conclude that the MoO3-BC is a novel composite that can be used for the removal of Pb from contaminated water. More studies are needed to investigate the potentiality of MoO3-biochar composite for the removal of other metals from water in a mono and competitive sorption system.