嘉庚化学讲座题目：Heterogeneous Photo-Fenton Process for Organic Pollutants Wastewater Treatment

题  目：Heterogeneous Photo-Fenton Process for Organic Pollutants Wastewater Treatment          

报告人：胡喜军教授  香港科技大学

地  点：卢嘉锡楼202会议室

Abstract

Civilization and industrialization have resulted in serious problems with water supply. Industrial water effluents contain a variety of highly toxic organics such as dye pollutants.  Numerous processes have been investigated for treating such pollutants.  Among them, photo-Fenton’s reaction is effective for the organics mineralization with the hydroxyl radical generated from the Fenton’s reagents (Fe²⁺ and H₂O₂).  However, there are two major problems with the application of photo-Fenton process. One is that a separation system is required to recover the homogeneous ferrous ion in the treated wastewater and the other is that the oxidation performance deteriorates quickly as the solution pH goes up above 4.  The working pH range can be broadened by replacing Fe with Cu and the secondly pollutant (metal ions in the treated water) can be eliminated by immobilizing active metal onto the surface of porous solids.  In this study, a heterogeneous Cu catalyst supported on bentenite clay was synthesized using a chemical vapor deposition (CVD) technique.  To resolve the copper leaching problem during the catalyst’s application in aqueous reaction, a critical pretreatment step, acid activation by H₂SO₄, was applied to the original bentonite clay.  Such manufactured Cu/clay catalyst was characterized and evaluated in the photo-Fenton-like degradation of an azo organic dye, Acid Black 1 (AB1).  It was found that the acid activation process of clay could significantly reduce the leaching problem by almost 72% and improve the catalytic activity.  These improvements came from the active site and the addition of sulfonate functional group on the clay surface.  Moreover, in order to provide a best catalyst over a broad pH range, the pH insensitive Cu was integrated together with the typically affirmed Fenton (Fe) reagent to form a bimetallic catalyst.  The metals (Cu and Fe) were deposited onto the acid-activated bentonite clay by CVD to form a heterogeneous bi-functional catalyst.  The developed bimetallic catalyst is able to sustain the activity in catalysing the total organic carbon (TOC) removal of organic dye in a wide range of pH, viz acidic and alkaline condition.  To further minimize metal leaching, another highly porous solid, MCM-41, was used as the catalyst support.  An in-situ oxidation technique was developed to stabilize the metals on the support.  The bimetallic MCM-41 supported catalyst, FeCu/MCM-41, was found to achieve an extremely low leaching level (~0.3 ppm) and have an excellent degradation power of organics over a wide pH range, achieving TOC removals of 93%, 83%, and 78% at pHs of 3, 5.5, and 7, respectively.  Furthermore, this catalyst can maintain its high catalytic activity after 10 consecutive runs.