Efficiency validation of TiO2/PPy nanocomposite photocatalysts for water treatment processes

U ovom radu pripremljen je kompozitni fotokatalizator, in situ sintezom vodljivog polimera polipirola (PPy) u prisustvu titanijevog dioksida (TiO2) kemijskom oksidacijskom polimerizacijom. Kao oksidans koristio se željezov (III) klorid (FeCl3). Sinteza se odvijala pri temperaturi od 5°C u trajanju od 270 minuta. Sintetizirani uzorak PPy/TiO2 modificiran je namakanjem u amonijaku različite koncentracije i različito vrijeme. Prva serija uzoraka PPy/TiO2 modificirana je s 0,1M otopinom amonijaka (NH4OH) a druga s 0,01M otopinom. Karakterizacija kompozitnih fotokatalizatora provedena je infracrvenom spektroskopijom s Fourierovim transformacijama (FTIR), uzorcima je određena elektrovodljivost te fotoaktivnost koja je određena UV/VIS spektroskopijom. Fotokatalitička učinkovitost sintetiziranih nanokompozitnih fotokatalizatora ispitana je praćenjem uklanjanja azo bojila Reactive Red 45 (RR45) pod simuliranim Sunčevim zračenjem. Stupanj obezbojenja vodene otopine praćen je mjerenjem promjene apsorbancije UV/Vis spektroskopijom dok je proces mineralizacije (potpune razgradnje) RR45 bojila određivan pomoću ukupnog organskog ugljika (TOC). Nadalje, provedena je optimizacija uvjeta fotokatalize određivanje konstanti brzine kinetičke razgradnje. Rezultati su pokazali da je u prvoj seriji PPy/TiO2 kompozitnih uzorka utvrđena visoka vodljivost PPy u kompozitu, čime je potvrđena uspješna sinteza vodljivog polimera. Također, utvrđeno je opadanje vodljivosti s povećanjem vremena modificiranja kompozita s NH4OH te smanjenje fotokatalitičke razgradnje RR45 bojila u vodi, a proces fotokatalize je usporen.In this paper, a composite photocatalyst was prepared by in situ synthesis from conductive polymer polypirrole (PPy) in the presence of titanium dioxide (TiO2) by chemical oxidative polymerization. Iron (III) chloride (FeCl3) was used as an oxidant and the synthesis took place at a temperature of 5°C for 270 minutes. The synthesized PPy/TiO2 sample was modified by soaking in ammonium hydroxide sloution at different concentrations and at different times. The first series of PPy/TiO2 samples was modified with 0,1M NH4OH and the second with 0,01M solution. The characterization was performed by infrared spectroscopy with Fourier transformations (FTIR). Samples were subjected to electrical conductivity and their photoactivity was determined by UV/Vis spectroscopy. The photocatalytic efficiency of synthesized nanocomposite photocatalysts was determinated by monitoring Reactive Red 45 (RR45) azo dye degradation under simulated Solar radiation. The discoloration of aqueous solution was monitored by measuring the change in absorbance with UV/Vis spectroscopy, while the mineralization process (complete degradation) of color RR45 was determined by measuring the total organic carbon (TOC) content. Furthermore, photocatalysis conditions optimization was carried out by determination of the constants of kinetic degradation rate. The results showed that in the first series of PPy/TiO2 composite sample high conductivity of PPy in the composite was found, confirming the successful synthesis of the conductive polymer. Also, a decrease in conductivity with increased modification time of the composite with NH4OH was observed and reduction of photocatalytic degradation of RR45 azo dye, and the process of photocatalysis is slowed down