Photocatalytic Degradation of a Herbicide Namely Glyphosate and Hexazinone from the Surface Water which will be Used as Drinking Water via Polyaniline/ZnWO4/WO3 and Evaluation of Acute Toxicity Assays

Polyaniline/Zinc tungsten oxide/Tungsten trioxide nanocomposites (PANI/ZnWO4/WO3 NCs) was prepared to remove glyphosate (GLP) and Hexazinone (HZN) herbicides from the surface water. The properties of PANI/ZnWO4/WO3 NCs was investigated using XRD, FTIR, FESEM, HRTEM, XPS analyses. The toxicity of NCs and treated wastewater were investigated using Microtox and Daphnia magna acute toxicity tests. The effects of increasing values of PANI/ZnWO4/WO3 NCs concentrations (0.1, 0.4, 0.6, 1.0 and 1.5 mg/l), PANI/ZnWO4/WO3 mass ratios (1:1:3, 1:2:3, 3:1:1 and 3:2:1), GLP concentrations (1, 2, 3 and 4 mg/l), photodegradation times (2, 10, 15 and 20 min), and solar light powers (20, 40, 60, 80 and 100 W/m2 ) on the GLP and HZN removals in the surface were examined. The results of the acute toxicity analysis performed showed that the acute toxicity in the surface water decreased significantly after photooxidation. The maximum removal conditions for 3 mg/l GLP (99.90%) were 1 mg/l PANI/ZnWO4/WO3 NCs with a PANI/ZnWO4/WO3 ratio of 1:2:3 after 15 min photodegradation time at 80 W/m2 sun light power while the maximum HZN removal was obtained as 96% after 15 min photodegradation, under 300 W solar light, at pH=7.0 and at 25oC. The crystalline monoclinic ZnWO4 and WO3 was detected from XRD analysis while PANI exhibited characteristic broad peak at 28.91° with an amorphous nature. FTIR spectra showed that pure ZnWO4 has the Zn–O–W vibrational bands. XPS analysis, exhibited reactive oxygen species. The charge/discharge analysis indicated that WO3 has a larger particle size that decreases surface density increasing the interplanar spacing between atoms. The introduction of ZnWO4 and WO3 nanoparticles into the PANI matrix enhanced the surface of the PANI/ZnWO4/WO3 NC.