Chapter 11 - Heterogeneous catalytic ozonation for achieving sustainable development goals

Abstract

Innovative materials and processes are imperative for the comprehensive treatment of wastewater to meet sustainable development goals (SDGs) for 2030 stipulated in the United Nations agenda. The SDGs include the reduction of waste by minimizing the discharge of hazardous chemicals into water resources, as well as recycling and reuse. Incomplete treatment of wastewater may reduce primary pollutants but produce significant amounts of toxic intermediates. Ozonation, a promising wastewater treatment option, directly contributes to oxidizing of double bonds and the destruction of aromatic rings of the primary organic pollutant. However, intermediates such as aldehydes, ketones, and acids accumulate, and complete mineralization is not achieved. Ozonation may be intensified with heterogeneous catalysis for sustained generation of nonspecific oxidants, namely, hydroxyl radicals which may completely mineralize adsorbed organic compounds. The extent of degradation must be carefully monitored through TOC and COD analyses. Quantifying the intermediates formed from catalytic ozonation through appropriate analytical techniques will aid in developing accurate degradation pathways and estimation of associated kinetic constants. There is considerable scope for optimizing the combined heterogeneous catalytic ozonation process by adjusting the material surface properties, composition, and operating conditions such as pH, initial concentration of pollutants, ozone dosage, and catalyst dosage. In addition to degradation efficiency, the sustainability of the supported catalysts must be tested for their stability and reusability. The investigated pollutant system may include model pollutants and synthetic and real industrial wastes to identify suitable metal/metal-oxide catalysts for the targeted class of pollutants and optimize process operations.