Ispitivanje ekotoksičnosti proizvoda degradacije organskih zagađujućih supstanci u vodi nakon tretmana unapređenim oksidacionim procesima

Abstract

U okviru ove disertacije ispitana je degradacija 4CP (para-hlorfenol), reaktivnih azoboja i ibuprofena primenom unapređenih oksidacionih procesa (eng. Advanced OxidationProcesses, AOP) kao što su Fentonov reagens, DBD reaktor (eng. Dielectric BarrierDischarge) i elektrohemijske degradacije.Efikasnost degradacija zagađujućih organskih supstanci optimizovana je dodatkomhomogenog katalizatora (Fe2+ ili H2O2) u reaktor, primenom različitih elektrodnihmaterijala ili variranjem vremena tretmana. Dekolorizacija (%) je praćena UV-VIStehnikom, efikasnost degradacije je praćena jonskom hromatografijom (IC) i HPLCtehnikom. Identifikacija glavnih proizvoda degradacije, kao i mehanizmi degradacijeodređeni su LC-MS (TOF) tehnikom. Efikasnost mineralizacije je određena preko TOCvrednosti. Tretman netermalnom plazmom (eng. non-thermal plasma NTP) u DBDreaktoru je ispitan tokom degradaciji 4CP do biodegradabilnijih i manje toksičnihintermedijera. Eksperimentalni rad je organizovan u tri sistema za degradaciju 4CP: DBD,DBD/H2O2 i DBD/Fe2+. Praćena je efikasnost degrdacije 4CP u funkciji broja prolaza krozDBD reaktor, kao i količini unete energije po jedinici zapremine rastvora (gustina energije,kJ/L). Koncentracija 4CP, kao i koncentracija pojedinih proizvoda degradacije merena jenakon svakog prolaza.Koncentracije proizvoda degradacije 4CP kao što su sirćetna, mravlja ili oksalnakiselina, bile su niže u sistemu gde je kao katalizator upotrebljeno gvožđe DBD/Fe2+upoređenju sa sistemom gde je kao katalizator primenjen vodonik-peroksid DBD/H2O2.Koncentracija hlorida u sva tri sistema je rasla tokom procesa degradacije. Najvišakoncentracija hlorida, zabeležena je u sistemu sa dodatkom Fe2+ kao katalizatora.Procena toksičnosti početnog rastvora 4CP, kao i rastvora tretiranih u sva tri sistemaispitana je pomoću A.salina. U odnosu na početni (netretirani) rastvor 4CP, nakon tretmanaDBD/Fe2+porcenat preživelih larvi A. salina se povećao za 95%.Degradacija reaktivnih azo boja (RG15, RY125 i RB52) je ispitana primenomEAOP (eng. Eletrochemical Advance Oxidation Processes) tehnika u nepodeljenojdvoelektrodnoj ćeliji, gde je kao anoda primenjena Fišerova platinska elektroda, a kaokatoda korišćena je Pd, Zr ili C elektroda. Najefikasniji sistem za degradaciju RG15 iRY125 je bio Pt-Pd sistem, dok je za RB52 to bio Pt-Zr sistem. Ekotoksikološki efekat zaboje RG15 i RY125 bio je najniži ili nije detektovan u rastvoru boje nakon Pt-Pd tretmana.U slučaju RB52, uočeno je da se ekotoksikološki efekat uvećava i na A.salina i naV.fischeri nakon EAOP tretmana.U slučaju degradacije ibuprofena, nakon 15 min tretmana dodatak homogenogkatalizatora je poboljšao NTP tretman i doprineo efikasnosti degradacije ibuprofena (99%),kao i mineralizaciji zagađujuće supstance u odnosu na DBD i Fentonov proces (oko 80%).U svim tretmanima analizom masenih spektara, identifikovano je 12 proizvoda degradacijeibuprofena: pet aromatičnih i sedam alifatičnih proizvoda. Nakon DBD/Fe2+ tretmanadetektovane su samo 4 alifatične karboksilne kiseline. Ekotoksikološki efekat tretiranihrastvora ibuprofena u DBD reaktoru nije detektovan, kao ni u slučaju kada je gvožđekorišćeno kao katalizator. U odnosu na A.salina, V.fischeri je pokazao veću osetljivost naproizvode degradacije koji su nastali tokom Fenton tretmana. Toksični efekat rastvoraibuprofena nakon Fenton tretmana kategorisan je kao klasa III, tj. “toksičan”.Najviši procenat degradacije ibuprofena primenom EAOP- a je postignut tretmanomrastvora u Pt - Pd sistemu - 98%, pri jačini struje od 100 mA i pH od 3. Toksični efekatmortalitet (%) A. salina izazvan rastvorom ibuprofena tretiranog u Pt-Pd sistemu bio jeispod 30% pri najvišoj testiranoj koncentraciji od 100% (c, v/v). V.fischeri se pokazao kaoosetljiviji model za procenu toksičnog efekta proizvoda degradacije ibuprofena nakon Pt-Pdtretmana u odnosu na A.salina.

In this thesis the degradation of 4CP (para-chlorophenol), reactive azo dyes andibuprofen was studied using the Advanced Oxidation Processes (AOP) such as Fenton'sreagent, Dielectric Barrier Discharge (DBD) reactor and electrochemical degradation.The efficiency of degradation was optimized by addition of a homogenous catalyst(Fe2+ or H2O2) to the reactor and also by applying different electrode materials or byvarying the duration of the treatment. The decolorization (%) of reactive azo dyes wasmonitored by UV-VIS technique and the efficiency of degradation was monitored by ionchromatography (IC) and HPLC. Identification of the main degradation products as well asthe degradation mechanisms were determined by LC-MS (TOF) technique. Themineralization efficiency was determined through the value of TOC.Treatment by non-thermal plasma (NTP) in the DBD reactor was studied during thedegradation of 4CP to biodegradable and less toxic intermediates. Experimental work wasorganized into three systems for 4CP degradation: DBD, DBD/H2O2 and DBD/Fe2+. Theefficiency of 4CP degradation was evaluated by the number of passing of the solutionthrough the DBD reactor, as well as the amountn of the introduced energy density (kJ/L).The concentration of 4CP, as well as the concentration of the individual degradationproducts were measured after the each pass.The concentrations of the 4CP degradation products such as acetic, formic or oxalicacid were lower in the system where the iron was used as the catalyst (DBD/Fe2+) incomparison to the system with hydrogen peroxide as the catalyst (DBD/H2O2). Theconcentration of chloride in all three systems increased during the degradation process. Thehighest concentration of chlorides was recorded in the system with the addition of Fe2+as acatalyst. The toxicity assessment of initial solution of 4CP as well as the solution which hasbeen treated in all three systems was performed using A.salina. In comparison to untreatedsolution of 4CP the solution treated in DBD/Fe2+ system had increased percentage of larvalsurvival by 95%.Degradation of reactive azo dyes (RG15, RY125 or RB52) was studied using theEAOP (Eletrochemical Advance Oxidation Processes) techniques in undividedtwoelectrode cell, where the Fisher platinum electrode was applied as anode and the Pd, Zror C electrodes were applied as cathode. The most effective system for the degradation ofRG15 and RY125 was Pt-Pd system, while for the RB52 the Pt-Zr system was moreapplicable. Ecotoxicological effect of reactive dyes RG15 and RY125 was the lowest or notdetected in the dye solution after the Pt-Pd treatment. In the case of RB52 ecotoxicologicaleffect increased for both A.salina and V.fischeri after the EAOP treatment.In the case of ibuprofen degradation, the NTP treatment (15 min) was improved byaddition of a homogeneous catalyst, which contributed to the efficiency of degradation(99%) and the mineralization of polluting substances in comparison to DBD and the Fentonprocess (about 80%). After all treatments, by analysis of mass spectra 12 degradationproducts of ibuprofen were identified: five aromatic and seven aliphatic products. In thesolution after the DBD/Fe2+treatment only 4 aliphatic carboxylic acids were detected.Ecotoxicological effect of the ibuprofen solution treated in the DBD reactor as well as inthe DBD/Fe2+ system was not detected. In relation to A.salina, V. fischeri has shown greatersensitivity to degradation products which appeared during the Fenton treatment. The toxiceffect of ibuprofen solution after the Fenton treatment was categorized as class III, that is"Toxic".The highest degradation percentage of ibuprofen was achieved by application ofEAOPs in the Pt - Pd system (98%), with the current of 100 mA and at the pH value of 3.The toxic effect expressed as the mortality (%) of A. saline was less than 30% at the highesttested concentration 100% (c, v/v) of ibuprofen solution treated in the Pt-Pd system. TheV.fischeri was the more sensitive model for the assessment of the ibuprofen degradationproducts toxic effect after the Pt-Pd treatment in comparison to A.salina.