Investigation of Fenton-process application in the treatment of dye wastewater in printing industry

Abstract

<p>Predmet izučavanja ove disertacije je ispitivanje mogućnosti primene homogenog, heterogenog i Fentonsličnog procesa u tretmanu obojenih otpadnih voda grafičke industrije.&nbsp; Kao Fenton katalizatori kori&scaron;ćeni su sintetisani gvožđe(III)-molibdat i nano nula valentno gvožđe, kao i komercijalni gvožđe(II)-sulfat. Istraživanja&nbsp; su sprovedena u četiri faze. U prvoj fazi&nbsp; je izvr&scaron;ena sinteza&nbsp; i karakterizacija&nbsp; Fenton&nbsp; katalizatora, pri čemu su ustanovljene njihove osnovne morfolo&scaron;ke karakteristike. Nano nula valentno gvožđe je sintetisano iz ekstrakta&nbsp; li&scaron;ća hrasta, dok je&nbsp; gvožđe(III)-molibdat sintetisan putem tzv. vlažnog hemijskog postupka. U drugoj fazi je&nbsp; izvr&scaron;ena optimizacija Fenton procesa u tretmanu sintetičkih rastvora grafičkih&nbsp; boja primenom nove statističke&nbsp; metode,&nbsp;<em> definitive screening design</em>.&nbsp; U&nbsp; cilju postizanja&nbsp; maksimalnog stepena obezbojavanja i mineralizacije tretiranog uzorka&nbsp; ispitan&nbsp; je&nbsp; uticaj&nbsp; sledećih&nbsp; procesnih parametara: inicijalne koncentracije boje, koncentracije gvožđa, pH vrednosti i koncentracije vodonik-peroksida. Nakon ustanovljenih optimalnih uslova i izvr&scaron;ene verifikacije predloženog optimuma, sproveden je tretman realnog efluenta.&nbsp; Stepen mineralizacije&nbsp; tretiranog&nbsp; efluenta&nbsp; ustanovljen&nbsp; je&nbsp; na&nbsp; osnovu&nbsp; vrednosti&nbsp; sadržaja&nbsp; ukupnog&nbsp; organskog&nbsp; ugljenika&nbsp; i&nbsp; hemijske&nbsp; potro&scaron;nje kiseonika.&nbsp; U cilju razumevanja mehanizma degradacije grafičkih boja u Fenton procesu, kao i identifikacije prirode&nbsp; degradacionih&nbsp; produkata,&nbsp; izvr&scaron;ena&nbsp; je&nbsp; kvalitativna&nbsp; gasno-hromatografska/maseno&nbsp; spektrometrijska analiza. Kinetika obezbojavanja realnog&nbsp; efluenta&nbsp; najbolje&nbsp; je opisana primenom&nbsp; Behnajady&nbsp; -&nbsp; Modirshahla&nbsp; -Ghanbary&nbsp; modela,&nbsp; koji&nbsp; defini&scaron;e&nbsp; inicijanu&nbsp; brzinu&nbsp; i&nbsp; oksidacioni&nbsp; kapacitet&nbsp; posmatranog&nbsp; procesa.&nbsp; Rezultati&nbsp; su ukazali&nbsp; na&nbsp; moguću&nbsp; primenu&nbsp; Fenton&nbsp; procesa&nbsp; u&nbsp; tretmanu&nbsp; CMYK&nbsp; boja&nbsp; usled&nbsp; postizanja&nbsp; visokih&nbsp; efikasnosti obezbojavanja i mineralizacije tretiranih efluenata. Nedostatak primenjene metode se ogleda u činjenici da je većina&nbsp; uzoraka&nbsp; okarakterisana&nbsp; kao&nbsp; visoko&nbsp; toksična,&nbsp; a&nbsp; ujedno&nbsp; i&nbsp; izrazito&nbsp; kisela,&nbsp; budući&nbsp; da&nbsp; je&nbsp; ustanovljena optimalna&nbsp; pH&nbsp; vrednost&nbsp; Fenton&nbsp; tretmana&nbsp; 2&nbsp; -&nbsp; 3.&nbsp; Stoga&nbsp; je&nbsp; u&nbsp; okviru&nbsp; treće&nbsp; faze&nbsp; istraživanja&nbsp; primenjen&nbsp; dodatni tretman&nbsp; realnog&nbsp; efluenta,&nbsp; adsorpcija&nbsp; na&nbsp; aktivnom&nbsp; uglju&nbsp; sintetisanom&nbsp; iz&nbsp; ko&scaron;tica&nbsp; divlje&nbsp; &scaron;ljive.&nbsp; Adsorpcioni tretman&nbsp; je rezultovao smanjenjem&nbsp; toksičnosti&nbsp; kod&nbsp; svih tretiranih uzoraka, koji&nbsp; se&nbsp; karakteri&scaron;u&nbsp; kao nisko do umereno toksični, te je sa tog aspekta moguće njihovo bezbedno ispu&scaron;tanje u recipijent. Ujedno je ustanovljena i povećana mineralizacija uzoraka, kao posledica degradacije jedinjenja koja su inicijalno doprinela povećanoj toksičnosti. U četvrtoj fazi rada primenjena je metoda ocenjivanja životnog ciklusa sinteze Fenton katalizatora. Rezultati LCA su utvrdili da sinteza heterogenog Fenton katalizatora, gvožđe(III)-molibdata, ostvaruje najveće opterećenje&nbsp; životne&nbsp; sredine,&nbsp; dok&nbsp; bi&nbsp; se&nbsp; proces&nbsp; sinteze&nbsp; nano&nbsp; nula&nbsp; valentnog&nbsp; gvožđa&nbsp; mogao&nbsp; unaprediti modifikovanjem ekstrakcione faze uz kori&scaron;ćenje alternativnih materijala i obnovljivih izvora energije. Značaj&nbsp; predstavljenih rezultata se ogleda u činjenici da su uzorci obojenih otpadnih voda grafičke industrije prvi put podvrgnuti Fenton tretmanu koji je rezultovao visokim stepenom efikasnosti.</p>

<p>The subject of this thesis is&nbsp; exploring the possibility of homogeneous, heterogeneous and Fenton-like process application in the treatment of dye wastewater in printing industry. Synthesized iron(III)-molybdate and nano zero valent iron, as well as commercial iron(II)-sulfate were used as a Fenton catalyst. The research was carried out in four&nbsp; phases.&nbsp; In&nbsp; the&nbsp; first&nbsp; phase,&nbsp; the&nbsp; catalyst&nbsp; synthesis&nbsp; and&nbsp; their&nbsp; characterization&nbsp; were&nbsp; performed,&nbsp; whereby&nbsp; the morphological characteristics were established. Nano zero valent iron was synthesized from&nbsp; oak leaf extract&nbsp; and iron(III)-molybdate was synthesized by wet chemical process. In the second phase, the optimization of Fenton process was performed within the treatment of synthetic printing dye solution using a new statistical method, a definitive screening design. In order to achieve maximum decolorization and mineralization of the treated sample, the influence of&nbsp; following&nbsp; process parameters was conducted: initial dye concentration, iron concentration, pH value&nbsp; and hydrogen peroxide concentration.&nbsp; The treatment of printing effluent was performed&nbsp; after&nbsp; establishing optimal&nbsp; conditions&nbsp; and&nbsp; verifying&nbsp; the&nbsp; proposed&nbsp; optimum&nbsp; values.&nbsp; Mineralization&nbsp; degree&nbsp; of&nbsp; treated&nbsp; effluent&nbsp; was determined based on the results of total organic carbon and chemical oxygen demand. In order to understand the dye&nbsp; degradation&nbsp; mechanism&nbsp; in&nbsp; Fenton&nbsp; process,&nbsp; as&nbsp; well&nbsp; as&nbsp; to&nbsp; identify&nbsp; degradation&nbsp; products,&nbsp; a&nbsp; qualitative&nbsp; gaschromatographic/mass spectrometric analysis was carried out. The&nbsp; kinetic studies of the printing effluent were best described by using the Behnajady- Modirshahla-Ghanbary model, which defines the initial speed and oxidation capacity of the process. The results indicated the possible application of the Fenton process in the treatment of CMYK dyes due to the high decolorization and mineralization efficiency of treated effluent. Disadvantage of the applied method is reflected in the fact that most of the samples are characterized as highly toxic and,&nbsp; at the same time, extremely acidic since the optimum pH value of Fenton treatment is 2 - 3. Therefore, in the third phase of the study, adsorption process on functionalized biochar prepared from wild plum kernels was applied on real printing effluent.&nbsp; Adsorption&nbsp; treatment&nbsp; resulted&nbsp; in&nbsp; toxicity&nbsp; reduction&nbsp; in&nbsp; all&nbsp; treated&nbsp; samples,&nbsp; characterized&nbsp; as&nbsp; low&nbsp; to moderately toxic. Therefore, from this aspect, treated effluent can be safely released into the recipient. At the same time, increased mineralization of the samples was established as a result of the compounds degradation that initially contributed to high toxicity. In the fourth phase, a life cycle assessment method of Fenton catalyst was applied. The results of the LCA indicated that the synthesis of the heterogeneous Fenton catalyst, iron(III) molybdate, achieved the highest environmental burden, while the synthesis of nano zero valent iron could be improved by modifying the extraction phase using alternative materials and renewable energy sources.&nbsp; The significance of the obtained results is high decolorization efficiency achieved by Fenton treatment of printing dye wastewater,&nbsp; which was used for the first time.</p>