The green synthesis of silver nanoparticles (AgNPs) using a water extract of Ginger (Zingiber officinale) root by microwave irradiation and its antibacterial activities have been reported. However, AgNPs prepared from different parts of ginger root water or ethanol extract by ultrasound synthesis and their antioxidant activity and whether the biogenic could be used to catalyze the reduction of hazardous dye are unknown. This study concentrated on the facile green synthesis of AgNPs prepared from different parts (unpeeled ginger, peeled ginger, and ginger peel) of ginger root water or ethanol extract by the ultrasound-assisted method. We studied their antioxidant activity and catalytic degradation of hazardous dye Direct Orange 26 (DO26) and Direct Blue 15 (DB15). The surface plasmon resonance (SPR) peak of AgNPs was at 428–443 nm. The biogenic AgNPs were approximately 2 nm in size with a regular spherical shape identified from TEM analysis. The ethanol extracts of dried unpeeled ginger and peeled ginger, fresh peeled ginger and ginger peel. The Z. officinale AgNPs synthesized by dried unpeeled ginger ethanol extract showed the best antioxidant activity. Their scavenging activities were significantly better than BHT (p <0.05). The different parts of ginger extracts showed no catalytic degradation activities of DB15 and DO26. Still, the synthesized Z. officinale AgNPs exhibited good catalytic degradation activities, while their ability to catalytic degradation to DB15 was better than DO26. In the additive ratio of 3 mL DB15, 0.1 mL NaBH4 and 0.1 mL AgNPs, the degradation rates of DB15 (or DO26) at 15 min, 30 min and 60 min were only 1.8% (0.9%), 2.8% (1.4%) and 3.5% (1.6%) in the absence of AgNPs. When adding Z. officinale AgNPs prepared from dried ginger peel ethanol extract or fresh ginger peel water extract, the degradation rates of DB15 sharply increased to 97% and 93% after 30 min, respectively. In conclusion, ginger extract has good antioxidant properties. Z. officinale AgNPs biosynthesis from ginger extract exhibit excellent catalytic degradation activities, especially for the ginger peel extract. They have application value in the treatment of textile effluents and provide a new idea and method for the comprehensive development and utilization of ginger resources.

Based on A2O process in plateau environment, the correlation between the removal rate of chemical oxygen demand (COD), the total phosphorous (TP), total nitrogen (TN) and ammoniacal nitrogen (NH4 +-N) in anaerobic tank, anoxic tank and aerobic tank and the quantity of indicator microorganisms was analyzed with temperature, dissolved oxygen (DO) and the hydraulic retention time (HRT) as working conditions, and the curve regression model of water removal rule and the optimal working conditions were obtained through SPSS analysis. The results showed that the removal rates of COD, TN, TP and NH4 +-N were positively and negatively correlated with some indicator microorganisms. The three sets of curve regression models passed the significance test. The DO and COD were cubic models, HRT and COD were quadratic models, HRT and NH4 +-N were S curve models. When DO is 2∼3 mg/L, the removal rate of COD can reach 87%. When HRT is 30∼40 h, the removal rate of COD can reach more than 90%, and the removal rate of NH4 +-N can reach more than 50%.

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