Influence of 2-propanol on photocatalytic degradation of diclofenac in water

Diklofenak (DCF), nesteroidni je protuupalni lijek, dostupan u nizu komercijalnih pripravaka u obliku tableta ili gela. Jedan je od prvih farmaceutika identificiranih u prirodnim vodama, što je sukladno njegovoj čestoj primjeni. S obzirom na to da ne postoji puno podataka o ponašanju DCF-a u okolišu, Europska komisija je revizijom Direktive o vodama (2013/39/EU) odnedavno DCF uključila na tzv. ''watch'' listu kako bi se pratilo i ustanovilo njegovo potencijalno štetno djelovanje na ekosustav i ljudsko zdravlje. S obzirom na to da su kao glavni put dospijevanja farmaceutika u vodeni okoliš identificirane komunalne otpadne vode, nameće se potreba za pronalaskom učinkovitih tehnologija obrade za efikasnije uklanjanje farmaceutika među kojima i DCF-a. Kao najefikasnije metode pokazale su se kemijske metode, među kojima napredni oksidacijski procesi (engl. Advanced Oxidation Processes, AOP) posebice fotokatalitički. Cilj ovog rada bio je istražiti utjecaj 2-propanola na učinkovitost fotokatalitičke obrade vode. U tu svrhu primijenjeni su UV-A/TiO2 i UV-A/TiO2/H2O2 procesi za uklanjanje diklofenaka u vodenom mediju. Pokazano je da dodatak vodikovog peroksida pozitivno utječe na učinkovitost uklanjanja DCF-a. Dodatkom 2-propanola dolazi do inhibiranja OH radikalskog mehanizma razgradnje onečišćivala te se smanjuje učinkovitost istraživanih UV-A/TiO2 fotokatalitičkih procesa sa i bez dodatka oksidansa.Diclofenac (DCF) is a non-steroidal anti-inflammatory drug, available under a number of trade names in the form of tablets or gel. It is one of the first pharmaceuticals identified in natural waters, which corresponds to its frequent use. Since the role of DCF in the environment is not yet fully understood, the European Commission in revision of Directive 2013/39/EU has recently included the drug on the “watch” list, in order to monitor and determine its potentially harmful effects on the ecosystem and human health. The municipal wastewaters are found to be the main way the pharmaceutical enters the water. Therefore, there is a need to find efficient, economically and environmentally friendly methods for removing pharmaceuticals, including DCF. Chemical methods are found to be the most efficient, notably those with advanced oxidation processes (AOP), especially photocatalysis. The aim of this study was to investigate the influence of 2-propanol on photocatalytic water treatment. For this purpose, UV-A/TiO2 and UV-A/TiO2/H2O2 processes were applied during diclofenac removal in a water medium. The addition of hydrogen peroxide has a positive influence on DCF removal. The addition of 2-propanol causes the inhibition of OH radical cleaning mechanism, while decreasing the effectiveness of the studied UV-A/TiO2 photocatalytic processes with and without addition of oxidants