Methods of treating residual organic pollutants in water
MSc. Nguyen Phung Anh and research team
One of the largest groups of water pollutants today is phenolic compounds, because of their widespread application in industrial and agricultural wastewater and as disinfectants. The negative impact of phenolic compounds on the environment and human health is related to their high toxicity and non-biodegradability. Cinnamic acid is a phenolic compound that is not highly toxic but causes high pollution.
To date, there are many methods used to decompose these compounds in water, but the application of photocatalysis is an advanced method. Highlights of photocatalysis in decomposing polluting compounds are low cost, high decomposition efficiency, recovery and reuse, harmless catalyst, treatment at high temperature and pressure. normal productivity and ability to convert pollutants into harmless or less toxic end products such as CO2, and H2O.
Besides TiO2 as a traditional, highly efficient photocatalyst, perovskite materials are attracting research interest as photocatalysts because some perovskites have small band gap energies that can be easily excited by light. both visible and UV. Compared with TiO2, ABO3 perovskite catalyst has outstanding advantages. However, research into the preparation and application of these materials as photocatalysts is still limited because of the ease of recombining electrons and holes.
One of the effective methods to improve photocatalytic systems is to combine them together to promote the advantages of these photocatalytic systems. There are not many studies combining perovskite catalysts with other catalysts. However, research on this issue for TiO2 is quite rich and can be applied to perovskite titanates. Therefore, based on the advantages of the two photocatalytic systems TiO2 and perovskite, MSc. Nguyen Phung Anh and his colleagues have researched and proposed a photocatalytic synthesis process based on perovskite Al2TiO5, Fe2TiO5 and NiTiO3 using the sol-gel method with low heating temperature.
Preparation process of TiO2 combined with SBA-15 modified Fe2TiO5
In addition, the group of scientists has researched the synthesis process of perovskite/TiO2 heterostructured catalytic systems: Al2TiO5/TiO2, Fe2TiO5/TiO2 and NiTiO3/TiO2, and CeO2 modified heterostructured catalytic systems. Ag and SBA-15 by hydrothermal method have large specific surface area, high photodegradation activity of cinnamic acid and glyphosate, good durability and easy recovery compared to hydrothermal TiO2 catalyst in water environment.
Photo-oxidation reaction equipment system to decompose cinnamic acid and glyphosate (1-Cooling unit for UV lamp; 2-Lamp control unit with computer connection; 3-Stirrer; 4-Reaction vessel; 5-Cooling water supply pipe; 6-Flow meter; 7-Thermometer; 8-Sampling location)
Research into finding a new catalytic system based on perovskite (dual metal oxide) with a small bandgap energy and the ability to absorb in the visible light region with high activity and easy recovery is a promising result. In addition, the hybridization of TiO2 and double metal oxide enhances absorption in the visible light region, improves specific surface area and limits recombination between electrons and holes, which is considered is a potential photocatalyst.
Research results based on optimal conditions for synthesizing perovskite-based catalysts have shown catalysts with high activity and easy recovery; Good photodegradation efficiency of typical polluting organic compounds in agricultural production such as cinnamic acid and glyphosate serves as a basis for future application orientation.
Based on the research results, the group published 01 article "Exceptional photodecomposition activity of heterostructure NiTiO3–TiO2 catalyst" in the journal Advanced Materials and Devices (SCIE, Q1) and 01 article on "Manufacturing nanocomposite material Environmentally friendly Fe2TiO5-TiO2 enhances the photodegradability of cinnamic acid solution” in the journal Nanoscience and Nanotechnology (VAST1, Q2). Research results show that hybridizing small band gap pseudobrookite Fe2TiO5 with large band gap semiconductor TiO2 is a promising method to fabricate highly active photocatalysts.
MSc. Nguyen Phung Anh said that in order to perfect the research results as well as develop applications, the group's next direction will be to continue studying the kinetics of the photo-oxidation reaction of cinnamic acid and glyphosate and research the mechanism of the photo-oxidation reaction of cinnamic acid and glyphosate. At the same time, the catalytic activity in the visible light region for the photo-oxidation reaction of cinnamic acid and glyphosate was investigated.
Translated by Quoc Khanh
Link to Vietnamese version
