Tailoring the Biochar Physicochemical Properties Using a Friendly Eco-Method and Its Application on the Oxidation of the Drug Losartan through Persulfate Activation

In this study, spent malt rootlet-derived biochar was modified by a friendly eco-method using a low temperature (100 degrees C) and dilute acid, base, or water. The modification significantly enhanced the surface area from 100 to 308-428 m(2)g(-1) and changed the morphology and the carbon phase. In addition, the mineral's percentage and zero-point charge were significantly affected. Among the examined materials, the acid-treated biochar exhibited higher degradation of the drug losartan in the presence of persulfate. Interestingly, the biochar acted as an adsorbent at pH 3, whereas at pH = 5.6 and 10, the apparent kinetic constant's ratio k(oxidation)/k(adsorption) was 3.73 +/- 0.03, demonstrating losartan oxidation. Scavenging experiments indirectly demonstrated that the role of the non-radical mechanism (singlet oxygen) was crucial; however, sulfate and hydroxyl radicals also significantly participated in the oxidation of losartan. Experiments in secondary effluent resulted in decreased efficiency in comparison to pure water; this is ascribed to the competition between the actual water matrix constituents and the target compound for the active biochar sites and reactive species.

Automated summary

Spent malt rootlet-derived biochar was modified by a friendly eco-method, which significantly enhanced the surface area and changed the morphology and carbon phase. The acid-treated biochar exhibited better degradation of the drug losartan. The oxidation of losartan mainly occurred through a non-radical mechanism.