Biosorption of Pb~(2+) by Dried Powder of Duckweed ( Lemna aequinoctialis )

Abstract

In order to develop efficient biosorbent material for Pb 2+ removal from wastewater, this study explored the biosorption of duckweed (Lemna aequinoctialis) powder. Single-factor experiments were designed to investigate the dominant effect on Pb 2+ removal. The experimental data were fitted with adsorption kinetics and isotherms to investigate the adsorption properties. The infrared spectroscopy was used to probe the surface characteristics of the sorbent. The results of single-factor experiments suggested that initial pH, grain size of sorbent and initial concentration of Pb 2+ had significant effects on the removal efficiency of Pb 2+ . The infrared spectroscopy analysis indicated that the -OH groups of carbohydrate compounds and the -NH 2 groups of amide compounds may be the main groups involved in the adsorption of Pb 2+ by the powder of L. aequinoctialis. This process followed the pseudo second-order kinetic with a correlation coefficient (R 2 ) of 0.999 95 and the k 2 of 3.65 g min -1 mg -1 . The experimental data were well fitted with Freundlich isotherm model and the maximum Pb 2+ adsorption capacity was higher than 56.79 mg/g. This study suggested that the powder of L. aequinoctialis, as a new biosorbent material, has high Pb 2+ adsorption rate and capacity under various conditions. Fig 5, Tab 2, Ref 31

Effect of heavy metals on duckweed growth

“…(Wang et al, 2014a, b;Grijalbo et al, 2016;Wang et al, 2016) of duckweed depends on the concentration of pollutants and the toxicity level of the wastewater type. Furthermore, the success of heavy metal absorption by plants is associated with the ability of a specific phenotype and genotype of the plant to absorb and translocate heavy metals (Chen et al, 2013).…”

Duckweed: a model for phytoremediation technology

“…Tang et al [83] indicated dried biomass of L. punctata and S. polyrhiza to be promising adsorbents that may be used as alternative approaches for Pb 2+ removal from contaminated water. Further studies have suggested that dried powder of L. aequinoctialis and L. perpusilla effectively removes lead from aqueous solution [86,87]. Untreated dry powder of L. aequinoctialis has also proved to be a convincing adsorbent for cadmium [88].…”