Montmorillonite- hydrothermal carbon nanocomposites: Synthesis, characterization and evaluation of pesticides retention for potential treatment of agricultural wastewater

[Display omitted] Montmorillonite (M) was modified by addition of hydrothermal carbon (HC) in order to obtain pesticide adsorbent materials. Carbohydrates were used as carbon source, and in some cases, also phosphoric acid was applied as activation agent. The M-HC hybrids maintain the negative electrical surface charge of their precursors (between −35 mV and −15 mV), while lower specific surface areas (around 6 m2 g−1) than that of M sample (66 m2 g−1) were found. The loss of specific surface could be assigned to the carbon location on both the external and the interlayer surface of the M sheets, as was confirmed by FTIR, zeta potential measurements and XRD analysis. For M-HC products obtained by acid treatment, despite their structure alteration, the specific surface values remained similar to that of M sample (around 70 m2 g−1). The M-HC products with or without acid treatment retain almost 100% adsorption of chlorpyrifos (CPF) and thiabendazole (TBZ) as that obtained for M sample, under the tested conditions. Coagulation studies revealed that M-HC products evaluated showed better precipitation property than that of M sample, which would preclude the typical montmorillonite gel formation that usually block filters and reactors.