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Table 4

Degradation rate and half-lives of imidacloprid (1 mg/L) at different pH values with ZnO and H₂O₂ concentration of 1,000 mg/l and 20 mM, respectively

Process	pH value	Degradation rate constant, k, (min⁻¹)	Half-life t_1/2 (min)
ZnO(normal)/H₂O₂/artificial sunlight	pH 5	0.0081 ± 0.0001	141.72 ± 2.45^e
	pH 7	0.0048 ± 0.00002	85.89 ± 2.65^b
	pH 9	0.0056 ± 0.00002	123.23 ± 1.68^d
ZnO (nano)/H₂O₂/artificial sunlight	pH 5	0.0095 ± 0.0001	88.57 ± 2.41^c
	pH 7	0.0078 ± 0.0001	72.68 ± 2.35^a
	pH 9	0.0083 ± 0.00001	83.36 ± 0.56^b

Process	pH value	Degradation rate constant, k, (min⁻¹)	Half-life t_1/2 (min)
ZnO(normal)/H₂O₂/artificial sunlight	pH 5	0.0081 ± 0.0001	141.72 ± 2.45^e
	pH 7	0.0048 ± 0.00002	85.89 ± 2.65^b
	pH 9	0.0056 ± 0.00002	123.23 ± 1.68^d
ZnO (nano)/H₂O₂/artificial sunlight	pH 5	0.0095 ± 0.0001	88.57 ± 2.41^c
	pH 7	0.0078 ± 0.0001	72.68 ± 2.35^a
	pH 9	0.0083 ± 0.00001	83.36 ± 0.56^b

Statistical comparisons were made among treatments within a single column.

The different letters represent significant differences using Fisher's LSD test at P≤0.05.

Data presented in mean value (three replicates) ± standard deviation.