Removal of malathion from various waters by advanced oxidation processes

Summary: The degradation of malathion was investigated under various conditions, including ultrasound (US) irradiation, ultraviolet (UV) irradiation, and the combination of US/UV, UV/ZnO, UV/H2O2, and US/UV/ZnO/H2O2. In addition, the effect of the operational parameters, such as the initial concentration of the catalyst, the initial malathion concentration, the initial salt concentration (NaHCO3 and Na2SO4), and pH, were studied. Analyses were performed by a gas chromatography-mass spectroscopy instrument. The k values were in the following order: US/UV/H2O2/ZnO > US/UV > UV/ZnO > UV/H2O2 > UV > US. ZnO concentration of 100 mg/l, malathion initial concentration of 200 μg/l, H2O2 concentration of 30 mg/l, pH of 9, and irradiation time of 105 min were the optimum conditions for degrading malathion by the US/UV/H2O2/ZnO system. Additionally, the optimized parameters were also tested for the treatment of an actual water sample containing the pesticide. As a result, the efficiency of the US/UV/H2O2/ZnO system was higher in the distilled water sample than in the actual water sample. © 2015, Chemical Society of Pakistan. All rights reserved

(Z)-3-Diethyl­amino-6-({2-[(E)-4-(diethyl­amino)-2-hy­droxy­benzyl­idene­amino]-4,5-dimethyl­phen­yl}amino­methyl­idene)cyclo­hexa-2,4-dienone–5,5′-bis­(diethyl­amino)-2,2′-[4,5-dimethyl-o-phenyl­enebis(nitrilo­methyl­idyne)]diphenol

The asymmetric unit of the title Schiff base compound, C30H38N4O2, comprises two crystallographically independent mol­ecules, A and B. The structure is non-merohedrally twinned with a refined BASF ratio of 0.219 (6):0.701 (6). Mol­ecule B shows both phenol–imine and keto–amine tautomeric forms in a single structure. The dihedral angles between the central ring and the two outer rings are 5.9 (3) and 48.4 (3)° in mol­ecule A, and 48.3 (3) and 6.9 (3)° in mol­ecule B. Strong intra­molecular O—H⋯N and N—H⋯O hydrogen bonds generate S(6) ring motifs. The crystal structure is further stabilized by inter­molecular C—H⋯O, C—H⋯π and π–π inter­actions [centroid–centroid distances = 3.870 (4)–3.871 (4) Å]

3,3′-Dimeth­oxy-2,2′-[(4,5-dimethyl-o-phenyl­ene)bis­(nitrilo­methanylyl­idene)]diphenol

The asymmetric unit of the title compound, C24H24N2O4, comprises two crystallographically independent mol­ecules A and B. The dihedral angles between the central dimethyl-substituted benzene ring and the two outer benzene rings are 49.5 (1) and 5.06 (11)° in mol­ecule A, and 42.55 (8) and 5.77 (9)° in mol­ecule B. In each mol­ecule, two strong intra­molecular O—H⋯N hydrogen bonds generate two S(6) ring motifs. The crystal structure is further stabilized by inter­molecular π–π [centroid–centroid distances of 3.591 (1)–3.876 (1) Å] inter­actions