Removal of Pb, Zn, Cu, and Cd by Two Types of Eichhornia crassipes

摘要

Long-root Eichhornia crassipes (L.R.E. crassipes), as a new kind of macrophyte, was used in Dianchi Lake in recent years, but its comparison in eliminating metals with traditional Eichhornia crassipes was never conducted. In this article, a comparative study on the removal of toxic metals from aqueous solutions by L.R.E. crassipes and E. crassipes was first studied. In total, the removal percentage of toxic metals followed the order of PbCdCuZn, and L.R.E. crassipes was better than that with E. crassipes. Meanwhile, L.R.E. crassipes had a higher relative growth rate than E. crassipes, and solutions had a better physicochemical property after dealing with L.R.E. crassipes. Results also showed that maximum removal capacity for Zn, Cu, and Cd with L.R.E. crassipes was reached at pH 5. An orthogonal of L16 (4(4)) in the multimetal system was designed to study the effects of cometals on removal of a single metal. Metal removal from the solution involves two stages: adsorption and absorption. Removal mainly occurred in the roots, and the main removal process was adsorption. Adsorption percentages of Pb, Zn, Cu, and Cd were 75%, 43%, 29%, and 61% in the root surface, respectively. Bioconcentration factors of Pb, Zn, Cu, and Cd were 267, 102, 230, and 173 with L.R.E. crassipes, respectively. Based on these results, L.R.E. crassipes could be used as a biodegradable absorbent to purify polluted water bodies fast and effectively.