Poplar wood and tea biochars for trichloroethylene remediation in pure water and contaminated groundwater

Abstract

Four biochars from pyrolysis of poplar wood (biochar P) and tea (biochar T) at 450 and 750 °C have been tested in a first time as adsorbents for trichloroethylene (TCE) removal in groundwater. The physico-chemical properties of biochars were systematically investigated with organic elemental analyser, scanning electron microscopy, N2 adsorption measurement, IR spectroscopy and X-ray photoelectron microscopy. Three kinetic models were used to follow the TCE removal by biochars. The best kinetic performances were obtained with biochars P with the smallest particle size diameter (50 – 100 µm) due to their porosity and the mass transfer limitation for the TCE remediation. Remediation of a real sample of groundwater polluted by chlorinated organic compounds showed that biochar P produced at 750 °C is more efficient to remove vinyl chloride (65% adsorbed) than commercial activated carbon powder (40%). The TCE sorption capacity is similar in pure water and in polluted groundwater. The results also highlighted better retention capacity for the most substituted molecules (tri and tetrachloroethylene) for biochar P750.