Ethylenethiourea And Mesotrione In Wastewater: The Determination Using HPLC And Removal By Biochar

In this study, the determination methods of ethylenethiourea and mesotrione byhigh performance liquid chromatography (HPLC) were established. The adsorptionexperiments of different factors of pomelo peel biochar for ethylenethiourea andmesotrione were studied and the adsorption mechanism was preliminary explored.The HPLC determination conditions of ethylenethiourea were as followed: watersample was filtrated through a0.45μm membrane for determination. The mobilephase was methanol/water (10:90, v/v), the detection wavelength was233nm, LC UVdetector. For direct injection analyses, the method detection limit of ethylenethioureawas1.3μg/L, and the determination limit was5.2μg/L. The HPLC determinationconditions of Mesotrione were: adjust the pH value of water sample to pH3~4withphosphoric acid, then the sample was filtrated through a0.45μm membrane.,themobile phase was acetonitrile/phosphoric acid solution (pH=3.0)(45:55, v/v), thedetection wavelength was233nm, LC UV detector. For direct injection analyses, themethod detection limit of mesotrione was9.0μg/L, and the determination limit was36.0μg/L. If the sample was extracted by dichloromethane，the method detection limitof mesotrione was1.65μg/L, and the determination limit was6.6μg/L.Pomelo peel biochar heated at600°C has high aromaticity with developed holestructure and prodigious surface area.Adsorption experiments showed that the addition amount of BC600forethylenethiourea and mesotrione had a significant impact on the removal rate, whichincreased with the addition amount. However, the adsorption amount per unit massshowed a maximum, above which the adsorption amount per unit mass decreased.Therefore, various factors should be considered to select a reasonable amount ofbiochar. The adsorption amount of BC600for ethylenethiourea increasedwith thereaction temperature. However, the reaction temperature had no effect on the adsorption of pomelo peel biochar for mesotrione, which did not show a certainregularity.The pH varying from2to12did not affect the adsorption of BC600forethylenethiourea. However, when pH varied from2to8, the adsorption of BC600formesotrione increased as the pH decreased, mainly due to mesotrione is a weak acidion compound. The ionization degree of mesotrioneincreased as the pH increased.The adsorption reaction of BC600for ethylenethiourea and mesotrione followedthe pseudo-second-order equation, the adsorption behavior could be described byFreundlich and Langmuir isotherm equation, and the adsorption process wascontrolled by both physical and chemical adsorption. The adsorption reaction ofBC600for mesotrione was controlled by both physical and chemical adsorption.