O3/TiO2催化氧化工艺对饮用水中AOC的影响

以陶粒、硅胶和沸石为载体,分别负载二氧化钛（TiO₂）进行臭氧催化氧化去除硝基苯的实验,并对饮用水中生物可同化有机碳（AOC）所代表的小分子有机物(酮、醛、醇和羧酸类物质)的生成情况进行了研究.发现臭氧催化氧化比单纯的臭氧氧化能更彻底地将部分大分子有机物氧化成小分子中间产物,陶粒、硅胶和沸石负载TiO₂ 3种催化剂分别将AOC从大约300　μg·L^-1增加到 674.1　μg·L^-1、847.2　μg·L^-1和882.1　μg·L^-1,并且分别使AOC/TOC从原水的4.68%升高到30.5%、33.21%和46.04%,大大地提高了水中有机物的可生物降解性.如果增加臭氧投量,催化氧化可使小分子有机物部分被氧化,致使水样AOC又略有回降.在这一过程中,AOC-NOX所代表的羧酸类物质急剧增加,达到总AOC的90％以上,取代AOC-P17成为了AOC的主体组成部分.

Impacts of AOC by O3/TiO2 Catalytic Oxidation in Drinking Water

This paper presents catalytic oxidation with titanium dioxide nano-particles loaded on several selected carriers, which are ceramic, silica gel and zeolite, to remove nitrobenzene from drinking water in ozonation. In this study assimilable organic carbon (AOC) is our interest and assumed as a parameter responsible for low molecule organic carbon such as ketone, aldehyde, alcohols and carboxyl acids in drinking water. Catalytic oxidation is more effective than ozonation alone in the degradation of larger fractions of organics to lower fractions. AOC was increased from 300 microg/L to 674.1 microg x L(-1), 847.2 microg x L(-1) and 882.1 microg x L(-1) by the catalysis ozonation of cerami/TiO2, silica gel/TiO2, cerami/TiO2 respectively, and the proportion of AOC in TOC can be increased from 4.68% to 30.5%, 33.21% and 46.04%, respectively. The catalytic oxidation enhanced the biologradability of organics in the water greatly. With the ozone dosage increase, AOC began to reduce slightly because the low molecular size organic carbon was mineralized. In the processes, AOC-NOX consisting of carboxyl acid mostly increased rapidly, resulting in increase of the proportion of AOC-NOX in AOC over 90% and the majority of AOC turned from AOC-P17 to AOC-NOX.