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In this work, the stability of imidacloprid in fresh water and sludge was studied. The results revealed that the pesticide is unstable in both media. In fresh water, it underwent hydrolysis whereas a degradation to several metabolites has been observed in sludge. The rate constants for the hydrolysis and degradation at 25°C were 0.0.0067 and 0.0.0099 d–1, respectively. Monitoring the degradation of imidacloprid in sludge by high-pressure liquid chromatography-mass spec trometry (HPLC-MS) revealed that five metabolites have emerged during the study. These metab-olites include imidacloprid urea, imidacloprid-guanidine, 6-hydroxynicotinic acid, an olefin, and 5-hydroxy, 1-(6-chloro-3-pyridylmethyl)-2-(nitroimino)-imidazolidin-5-ol. The efficiency of Al-Quds University Wastewater Treatment Plant towards the removal of imidacloprid indicates that the ultrafiltration-hollow fiber unit was insufficient, whereas the ultrafiltration-spiral wound, activated carbon, and reverse osmosis units were efficient for complete removal of the pesticide. Adsorption experiments of imidacloprid using either activated charcoal or micelle-clay complex were found to fit Langmuir isotherms better than Freundlich isotherm. The data demonstrate a higher Langmuir Qmax value for the activated charcoal (126.6 mg g–1) when compared to the micelle-clay complex (11.76 mg g–1). Filtration column experiments conducted with mixed micelle-clay complex and sand (using a ratio of 1/50 by mass) at a flow rate of 2 mL min–1 and influent concentration of 50 mg L–1 revealed that a sufficient removal of imidacloprid was achieved in the first fraction of 100 Ml elution. These findings indicate that the adsorption technology using the micelle-clay comple provides efficient removal of imidacloprid in continuous flow mode.

AbstractIn this study, the stability of chlorpyrifos, a known pesticide, in fresh water and sludge was investigated. The results showed that chlorpyrifos underwent hydrolysis in both media to give two main metabolites: 3,5,6-trichoro-2-pyridiniol (TCP) and diethylthiophosphoric acid (DETP). The hydrolysis reaction in both media was found to follow first-order kinetics with a rate constant of 7.10 × 10−8(R2 = 0.999) in pure water and of 9.30 × 10−8(R2 = 0.996) in sludge. Chlorpyrifos degradation’s half-life value in pure water was 112 d and in sludge was 85.9 d. The efficiency of Al-Quds University wastewater treatment plant demonstrated that the ultrafiltration-hollow fiber unit (UF-HF) was insufficient in removing chlorpyrifos from spiked secondary treated wastewater samples, whereas the combination of ultrafiltration-spiral wound unit (UF-SW) followed by activated carbon (AC) column was quite efficient and yielded a complete removal of the pesticide. Batch adsorption experiments using either AC or micelle–clay complex were performed and the experimental results were fitted to Langmuir and Freundlich isotherms. Adsorption analysis using Langmuir isotherm revealed that Qmaxfor the AC was higher than that of the micelle–clay complex, while Freundlich isotherm showed almost similar values of n(3.413 vs. 3.745) for both adsorbents, despite the fact that the activated carbon filter showed higher kFvalue. Filtration column of mixed micelle–clay complex and sand demonstrated a breakthrough point after the third fraction for chlorpyrifos removal and a complete removal for all fractions collected in the TCP experiment. This result reveals that mixed micelle–clay complex and sand column is much more efficient in removing TCP than removing its parent compound, chlorpyrifos.

In this study, the stability of chlorpyrifos, a known pesticide, in fresh water and sludge was investigated. The results showed that chlorpyrifos underwent hydrolysis in both media to give two main metabolites: 3,5,6-trichoro-2-pyridiniol (TCP) and diethylthiophosphoric acid (DETP). The hydrolysis reaction in both media was found to follow first-order kinetics with a rate constant of 7.10 × 10−8(R2 = 0.999) in pure water and of 9.30 × 10−8(R2 = 0.996) in sludge. Chlorpyrifos degradation’s half-life value in pure water was 112 d and in sludge was 85.9 d. The efficiency of Al-Quds University wastewater treatment plant demonstrated that the ultrafiltration-hollow fiber unit (UF-HF) was insufficient in removing chlorpyrifos from spiked secondary treated wastewater samples, whereas the combination of ultrafiltration-spiral wound unit (UF-SW) followed by activated carbon (AC) column was quite efficient and yielded a complete removal of the pesticide. Batch adsorption experiments using either AC or micelle–clay complex were performed and the experimental results were fitted to Langmuir and Freundlich isotherms. Adsorption analysis using Langmuir isotherm revealed that Qmaxfor the AC was higher than that of the micelle–clay complex, while Freundlich isotherm showed almost similar values of n(3.413 vs. 3.745) for both adsorbents, despite the fact that the activated carbon filter showed higher kFvalue. Filtration column of mixed micelle–clay complex and sand demonstrated a breakthrough point after the third fraction for chlorpyrifos removal and a complete removal for all fractions collected in the TCP experiment. This result reveals that mixed micelle–clay complex and sand column is much more efficient in removing TCP than removing its parent compound, chlorpyrifos.

AbstractStability and removal of the anti-anxiety drug diazepam (valium) from spiked wastewater samples were studied. An advanced wastewater treatment plant (WWTP), utilizing ultrafiltration (UF), activated charcoal (AC), and reverse osmosis (RO) after the secondary biological treatment showed that UF and RO were relatively sufficient in removing spiked diazepam to a safe level. Kinetic studies in both pure water (abiotic degradation) and in sludge (biotic degradation) at room temperature were investigated. Diazepam showed high chemical stability toward degradation in pure water, and underwent faster biodegradation in sludge providing two main degradation products. The degradation reactions in sludge and pure water showed first-order kinetics with rate constant values of 2.6 × 10−7 s−1and 9.08 × 10−8 s−1, respectively (half-life = 31 and 88 d, respectively). Adsorption of diazepam by activated carbon and composite micelle–clay (octadecyltrimethylammonium montmorillonite) complex was studied using both Langmuir and Freundlich isotherms. Based on the determination coefficient, Langmuir isotherm was found to better fit the data, indicating the retention of diazepam monolayer on both adsorbents. Filtration of 100 mg L−1solutions of diazepam by micelle–clay filter yielded almost complete removal at flow rates of 2 mL min−1.

Stability and removal of the anti-anxiety drug diazepam (valium) from spiked wastewater samples were studied. An advanced wastewater treatment plant (WWTP), utilizing ultrafiltration (UF), activated charcoal (AC), and reverse osmosis (RO) after the secondary biological treatment showed that UF and RO were relatively sufficient in removing spiked diazepam to a safe level. Kinetic studies in both pure water (abiotic degradation) and in sludge (biotic degradation) at room temperature were investigated. Diazepam showed high chemical stability toward degradation in pure water, and underwent faster biodegradation in sludge providing two main degradation products. The degradation reactions in sludge and pure water showed first-order kinetics with rate constant values of 2.6 × 10−7 s−1and 9.08 × 10−8 s−1, respectively (half-life = 31 and 88 d, respectively). Adsorption of diazepam by activated carbon and composite micelle–clay (octadecyltrimethylammonium montmorillonite) complex was studied using both Langmuir and Freundlich isotherms. Based on the determination coefficient, Langmuir isotherm was found to better fit the data, indicating the retention of diazepam monolayer on both adsorbents. Filtration of 100 mg L−1solutions of diazepam by micelle–clay filter yielded almost complete removal at flow rates of 2 mL min−1.