A Biosorption-Pyrolysis Process for Removal of Pb from Aqueous Solution and Subsequent Immobilization of Pb in the Char

Abstract

The application of biosorption in the removal of heavy metals from water faces a challenge of safe disposal of contaminated biomass. In this study, a potential solution for this problem was proposed by using a biosorption-pyrolysis process featured by pretreatment of biomass with phosphoric acid (PA). The PA pretreatment of biomass increased the removal efficiency of heavy metal Pb from water by sorption, and subsequent pyrolysis helped immobilize Pb in the residual char. The results indicate that most (>95%) of the Pb adsorbed by the PA-pretreated biomass was retained in the char, and that the lower pyrolysis temperature (350°C) is more favorable for Pb immobilization. In this way, the bioavailable Pb in the char was hardly detected, while the Pb leachable in acidic solution decreased to <3% of total Pb in the char. However, higher pyrolysis temperature (450 °C) is unfavorable for Pb immobilization, as both the leachable and bioavailable Pb increased to >28%. The reason should be related to the formation of elemental Pb and unstable Pb compounds during pyrolysis at 450 °C, according to the X-ray diffraction study.

Coupling Plant Biomass Derived from Phytoremediation of Potential Toxic-Metal-Polluted Soils to Bioenergy Production and High-Value by-Products—A Review

“…The fundamental base is leaching the contaminated plant biomass with acids to recover the adsorbed metal and to obtain biomass with metal concentrations in the range of environmental norms. Wang et al [57] combined this concept and found that acid treatments improved plant biomass to adsorb more metals and can be further used to prepare biochar by pyrolysis aimed to confine metals.…”

Fluorescence ‘off–on’ probe for lead (II) detection based on Atractylodes III CQDs and bioimaging

“…Pb(II) is hard to migrate and degrade, which have become an important cause of Pb(II) pollution in soil, water, air, and many other places. [5][6][7][8][9][10][11][12][13] Lead (II) exists in the environment will eventually be transmitted to plants and the human body through the food chain, [14][15][16][17][18][19] causing damage to organs [20] and hormone levels. [21] For children, a very small amount of Pb(II) may inhibit their brain development, [22] break their bones, [23] even damage their DNA.…”