Different Performances of H_2O_2 to Oxidise Aldicarb and Hexazinone in the Advanced Oxidation Process of Ozone/Hydrogen Peroxide

The degradations of hexazinone and aldicarb by direct ozonation combined an advanced oxidation process( AOP) of O3/H2O2 were investigated in this study focusing on the oxidation mechanism by identifying the hydrogen peroxide consumption during the oxidation process of the two chemicals. The results showed that H2O2 could enhance the removal rate of the triazine herbicide hexazinone,and it was consumed along with the variation of removal rate in the light of different pH levels. The addition of H2O2 contributed little to the removal of the thiocarbamate herbicide aldicarb and H2O2 content kept constantly throughout the degradation process. Tert-butyl alcohol( TBA) effectively scavenged the ·OH radical for hexazinone,but had no effect on the removal rate of aldicarb. Aldicarb removal was mainly attributed to direct ozonation molecule in both O3( 97.00%) and O3/H2O2( 96.76%)systems. Moreover,sole O3 could hardly oxidize hexazinone whereas·OH radicals contribute respective 74.70% and 97.50% of removal in O3 system and O3/H2O2 AOP. All of these findings suggest that the mechanism of ·OH radical generation and the chain reaction in O3/H2O2 AOP should be further discussed.

Inactivation of Cryptosporidium by ozone and cell ultrastructures

The fluorescence staining method and scanning electron microscopy （SEM） were used to study the effect of ozone （O3） inactivating Cryptosporidium in water and cell ultrastructures variation to shed light on the mechanism of inactivation preliminarily. Results indicated that O3 had a stronger inactivating capability. When the concentration of O3 was above 3.0 mg/L and the contact time was up to 7 min, a significant inactivating effect could be achieved. The turbidity on inactivation effects was also found to be statistically significant in artificial water. With increases in turbidity, the inactivating effect decreased. Inactivation rate improved with a temperature increase from 5 to 25℃, but decreased beyond this. The inactivating capability of O3 was found to be stronger under acidic than that under alkalic conditions. When the concentration of organic matter in the reaction system was increased, the competition between Cryptosporidium and organics with O3 probably took place, thereby reducing the inactivation rate. In addition, the cellular morphology of Cryptosporidium varied with different contact times. At zero contact time, cells were rotundity and sphericity, at 60 sec they became folded, underwent emboly, and burst at 480 sec, the cell membrane of Cryptosporidium shrinked and collapsed completely.

In situ biosynthesized silver nanoparticle-incorporated synthesized zeolite A using Orthosiphon aristatus extract for in vitro antibacterial wound healing

The capability of synthesized zeolite A(SZ)to immobilize Ag ions(Ag-SZ)and Ag nanoparticles(AgNp-SZ)were comparatively studied.A novel approach of in situ biosynthesized AgNP-incorporated synthesized zeolite A(AgNp-SZ)was synthesized at an optimum volume of 0.4mL of the Orthosiphon aristatus(O.aristatus)leaves plant extract(5%)using an in situ approach.In comparison,Ag-Sz was produced by loading the synthesized zeolite with Ag ions.All synthesized materials were characterized for their morphologies and physicochemicalproperties.The characterization analysesvalidate thathe biosynthesized AgNP(<100 nm)using O.aristatus leaves extract was incorporated into the zeolite A.The antibacterial testing confirmed that these materials have antibacterial activity against Escherichia coliATCC11229 and Staphylococcus aureus ATCC 6538.MIC/MBC analysis demonstrated that in 0.9%saline solution,AgNP-SZ had higher antibacterial activity than Ag-Sz.The in vitro cell viability and migration assays were further examined towards human skin fibroblast cells HSF 1184.Results show that the materials are not cytotoxicto HSF1184,and the biosynthesized AgNP-SZ promotes cell migration and proliferation higher than Ag-SZ.This research proved that the biocompatible antibacterial wound healing agent of AgNP-SZ can be synthesized using an in situ approach where the reduction process of Ag ions in the zeolite Acan be performed using plant extract.