Enhancing lead removal from wastewater and alleviating lead stress in soil-wheat systems using starch-stabilized Fe-Ni/biochar composites: Synthesis and physico-chemical investigations

Abstract

In this study, starch-stabilized and Fe/Ni bimetal modified biochar composites of StFeNi-BC and StFeNi-BC-350 were successfully fabricated and applied in removing Pb(II) from aqueous solutions. The absorption of Pb(II) by StFeNi-BC and StFeNi-BC-350 were controlled by monolayer chemisorption and their maximum adsorption capacities were 122.767 and 148.043 mg/g, respectively. Mechanism studies showed that electrostatic attraction, ion exchange, complexation and physical adsorption occurred on the adsorbent surface. Studies on the influence of co-existing metal ions and water matrices on adsorption of Pb(II) demonstrated that StFeNi-BC-350 displayed high anti-interfering ability and promising application prospect for Pb(II) removal. In addition, StFeNi-BC-350 was applied in soil-wheat pot systems to further investigate its influence on reducing Pb induced oxidative stress on wheat. Compared with the control, the addition of StFeNi-BC-350 increased the biomass and total chlorophyll content in leaves, and decreased the activity of antioxidant enzymes (MDA, SOD, CAT, POD) together with ROS fluorescence intensity of wheat. The results indicated that StFeNi-BC-350 could alleviate Pb(II) stress of wheat. Furthermore, the addition of StFeNi-BC-350 improved the physicochemical properties of the soil, and increased the abundance as well as the number of soil microorganisms, thereby alleviating Pb stress on wheat. Therefore, StFeNi-BC-350 is suitable for the practical treatment of Pb-contaminated water and soil.