Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C1835664 (TOC)
 2,763 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The influences of initial pH on the degradation efficiency of nitrobenzene in aqueous solution were investigated with a semicontinuous batch reactor in the processes of ozone alone, ozone/ceramic honeycomb, and adsorption of ceramic honeycomb. The results indicated that initial pH significantly affected the concentrations of offgas, residual ozone, and the utilization efficiency of ozone. The experiments also detected the generation of hydroxyl radicals (*OH), the removal of TOC, and the formation and evolution of byproduct at different initial pHs in the ceramic honeycomb catalytic ozonation process. It was found that the systems of different initial pHs exhibited the different extent of the conversion of pH, the leaching of effective components, and the establishment of pH at the point of zero charge (pH(PZC)) in the catalytic oxidation process. The experimental findings presented a good correlation between initial pH and terminal pH and the establishment of pHpzc with terminal pH, and indicated the relationship between the absolute value of the difference between terminal pH and terminal pH(PZC) (A) and the density of surface hydroxyl groups. Based on the correlation between the density of surface hydroxyl groups in the neutral state and A, possible mechanism of influence of initial pH on the degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation was proposed, suggesting that the conversion of initial pH determines the establishment of pHpzc, and the synergistic effect of pH terminal and pHpzc terminal affects the density of surface hydroxyl groups in the neutral state, which controls the concentration of *OH, determining the degradation of nitrobenzene and the formation of byproduct.
 ...
PMID:Mechanism of influence of initial pH on the degradation of nitrobenzene in aqueous solution by ceramic honeycomb catalytic ozonation. 1858 58

The use of cordierite or Cu-cordierite for heterogeneous catalytic ozonation enhances significantly the degradation efficiency and the TOC removal of nitrobenzene in aqueous solution relative to ozonation alone, owing to the synergistic effect between ozone and the catalysts, and the modification process with Cu can increase the catalytic activity of cordierite forthe ozonation of nitrobenzene. The adsorption of nitrobenzene is too small to make a significant contribution to the degradation of nitrobenzene in either of the processes of catalytic ozonation. The initiation of hydroxyl radical (*OH) improves as the amount of Cu-cordierite catalyst is increased, meaning that the degradation of nitrobenzene is mainly attributed to *OH oxidation. The modification by loading Cu increases the density of surface hydroxyl groups and the pH at the point of zero charge (pH(PZC)) of raw cordierite. The investigation of the enhancement mechanism confirms that the modification by loading Cu causes changes of density of surface hydroxyl groups, pH(PZC), and /pH - pH(PZC)/, resulting in the acceleration initiation of *OH which can promote the degradation of nitrobenzene. The result shows that the optimal critical loading percentage of Cu is 3% under the present experimental conditions.
 ...
PMID:Enhancement mechanism of heterogeneous catalytic ozonation by cordierite-supported copper for the degradation of nitrobenzene in aqueous solution. 1936 12

This paper reports on the application of a simultaneous combination of ozone and a granular activated carbon (O(3)/GAC) as a tertiary treatment of a wastewater generated from the activity of various food-processing industries. Prior to the O(3)/GAC treatment, the wastewater was subjected to conventional primary and secondary treatments in a full-scale wastewater treatment plant (WWTP). The effluent from the WWTP presented high organic load (COD>500 mg/l and TOC>150 mg/l), which could be much reduced by the O(3)/GAC treatment. Results from the O(3)/GAC experiments were compared with those obtained in single ozonation, single adsorption onto GAC and sequential O(3)-GAC adsorption experiments. While single processes and the sequential one showed limited capacity to remove organic matter for the food-processing effluent (COD removal <40%), the simultaneous O(3)/GAC process led to decreases of COD up to 82% at the conditions here applied. The combined process also improved the ozone consumption, which decreased from about 19 g O(3)/g TOC (single ozonation process) to 8.2-10.7 g O(3)/g TOC (O(3)/GAC process). The reusability of the GAC throughout a series of consecutive O(3)/GAC experiments was studied with no apparent loss of activity for a neutral GAC (PZC = 6.7) but for a basic GAC (PZC = 9.1).
 ...
PMID:Granular activated carbon promoted ozonation of a food-processing secondary effluent. 2098 Jan 1