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Two organic amendments, filter mud compost and Tithonia diversifolia leaves generated within a sugarcane growing area were used to enhance the degradation of chlorpyrifos in soil. Filter mud compost and T. diversifolia leaves significantly enhanced degradation of chlorpyrifos in soils (p < 0.05) with DT50 values of 21 and 24 days, respectively. Furthermore, field degradation of chlorpyrifos in soil with prior exposure to chlorpyrifos was significantly enhanced (p = 0.034) with DT50 of 21 days compared to 30 days in soil with no previous exposure. Degradation of chlorpyrifos in sterile and non-sterile soils were significantly different (p = 0.023) with DT50 values of 161 and 27 days, respectively. Results show enhanced degradation of chlorpyrifos in organically amended soils and soils with prior exposure to the pesticide. These amendments show promise in a continuing effort to reduce chlorpyrifos concentrations in soils.

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Molecular simulations have been used as a screening tool to identify promising zeolites for the removal of selected pharmaceutical pollutants. 40 zeolites with different structural and chemical configurations were studied. Galophosphate cloverite (CLO) of the chemical formula, F 24 Ga 96 P 96 O 372 (OH) 24 , with pores of 20 rings and the lowest observed bulk density, showed exceptionally preferred adsorption of diclofenac [2-(2,6-dichlorophenyl)amino benzeneacetic acid), ciprofloxacin [1,3,7-Trimethylpurine-2,6-dione] and chloramphenicol [2,2-dichloro-N-[(IR,2IR)-1, 3-dihydroxy-1-(4-nitrophenyl) propan-2-yl acetamide]. This selectivity was attributed to the geometry and structural composition of the cavities. We also investigated the most stable adsorbed compositions of the pollutants in the CLO zeolite. Our calculations show that diclofenac, ciprofloxacin and chloramphenicol molecules are adsorbed into the pores with adsorption energies of − 78.23, − 173.68 and − 84.46 kcal/mol respectively. Additional calculations were also made to obtain detailed information on desorbed products. It is seen that dechlorination is the most energetically preferred process compared to dehydrogenation and dehydroxylation.