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

Predmet izučavanja ove disertacije je ispitivanje mogućnosti primene homogenog, heterogenog i Fentonsličnog procesa u tretmanu obojenih otpadnih voda grafičke industrije.  Kao Fenton katalizatori korišćeni su sintetisani gvožđe(III)-molibdat i nano nula valentno gvožđe, kao i komercijalni gvožđe(II)-sulfat. Istraživanja  su sprovedena u četiri faze. U prvoj fazi  je izvršena sinteza  i karakterizacija  Fenton  katalizatora, pri čemu su ustanovljene njihove osnovne morfološke karakteristike. Nano nula valentno gvožđe je sintetisano iz ekstrakta  lišća hrasta, dok je  gvožđe(III)-molibdat sintetisan putem tzv. vlažnog hemijskog postupka. U drugoj fazi je  izvršena optimizacija Fenton procesa u tretmanu sintetičkih rastvora grafičkih  boja primenom nove statističke  metode,  definitive screening design.  U  cilju postizanja  maksimalnog stepena obezbojavanja i mineralizacije tretiranog uzorka  ispitan  je  uticaj  sledećih  procesnih parametara: inicijalne koncentracije boje, koncentracije gvožđa, pH vrednosti i koncentracije vodonik-peroksida. Nakon ustanovljenih optimalnih uslova i izvršene verifikacije predloženog optimuma, sproveden je tretman realnog efluenta.  Stepen mineralizacije  tretiranog  efluenta  ustanovljen  je  na  osnovu  vrednosti  sadržaja  ukupnog  organskog  ugljenika  i  hemijske  potrošnje kiseonika.  U cilju razumevanja mehanizma degradacije grafičkih boja u Fenton procesu, kao i identifikacije prirode  degradacionih  produkata,  izvršena  je  kvalitativna  gasno-hromatografska/maseno  spektrometrijska analiza. Kinetika obezbojavanja realnog  efluenta  najbolje  je opisana primenom  Behnajady  -  Modirshahla  -Ghanbary  modela,  koji  definiše  inicijanu  brzinu  i  oksidacioni  kapacitet  posmatranog  procesa.  Rezultati  su ukazali  na  moguću  primenu  Fenton  procesa  u  tretmanu  CMYK  boja  usled  postizanja  visokih  efikasnosti obezbojavanja i mineralizacije tretiranih efluenata. Nedostatak primenjene metode se ogleda u činjenici da je većina  uzoraka  okarakterisana  kao  visoko  toksična,  a  ujedno  i  izrazito  kisela,  budući  da  je  ustanovljena optimalna  pH  vrednost  Fenton  tretmana  2  -  3.  Stoga  je  u  okviru  treće  faze  istraživanja  primenjen  dodatni tretman  realnog  efluenta,  adsorpcija  na  aktivnom  uglju  sintetisanom  iz  koštica  divlje  šljive.  Adsorpcioni tretman  je rezultovao smanjenjem  toksičnosti  kod  svih tretiranih uzoraka, koji  se  karakterišu  kao nisko do umereno toksični, te je sa tog aspekta moguće njihovo bezbedno ispuštanje 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  životne  sredine,  dok  bi  se  proces  sinteze  nano  nula  valentnog  gvožđa  mogao  unaprediti modifikovanjem ekstrakcione faze uz korišćenje alternativnih materijala i obnovljivih izvora energije. Značaj  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.The subject of this thesis is  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  phases.  In  the  first  phase,  the  catalyst  synthesis  and  their  characterization  were  performed,  whereby  the morphological characteristics were established. Nano zero valent iron was synthesized from  oak leaf extract  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  following  process parameters was conducted: initial dye concentration, iron concentration, pH value  and hydrogen peroxide concentration.  The treatment of printing effluent was performed  after  establishing optimal  conditions  and  verifying  the  proposed  optimum  values.  Mineralization  degree  of  treated  effluent  was determined based on the results of total organic carbon and chemical oxygen demand. In order to understand the dye  degradation  mechanism  in  Fenton  process,  as  well  as  to  identify  degradation  products,  a  qualitative  gaschromatographic/mass spectrometric analysis was carried out. The  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,  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.  Adsorption  treatment  resulted  in  toxicity  reduction  in  all  treated  samples,  characterized  as  low  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.  The significance of the obtained results is high decolorization efficiency achieved by Fenton treatment of printing dye wastewater,  which was used for the first time

Adsorption kinetics and mechanism analysis of cyan printing dye on polyethylene microplastics

Printing on polymer materials might result with generation of coloured wastewater, enriched with a certain amount of microplastics in a form of polyethylene or polypropylene. In that way, microplastics may acquire the function of carriers of synthetic dyes, heavy metals and other polluting substances. In this paper, kinetics and adsorption mechanism of printing Cyan dye on polyethylene (powdered and granulated), as one of the most common types of microplastics, were investigated. The experiments were performed in a batch mode, in laboratory conditions. Based on the obtained results, a similar adsorption rate degree of selected printing dye was determined on granulated (adsorbed amount was 48.04 µg/g) and powdered material (adsorbed amount was 44.32 µg/g). The adsorption data were fitted well by pseudo-second-order kinetics, while isotherm studies were evaluated using two models: Langmuir and Freundlich. Freundlich and Langmuir equations showed similar performances to fit the solid/liquid distribution of Cyan dye on powdered polyethylene (R2 = 0.987), whereas Langmuir equation showed slightly better performances for granulated polyethylene than Freundlich equation

Characterization and kinetic study of magenta printing effluent after homogeneous fenton treatment

The objectives of this study were to determine the physico-chemical characterization of Magenta printing effluent treated with homogeneous Fenton process, as well as kinetic model that best describes degradation process of organic pollutant. Physico-chemical characterization of printing effluent before and after homogeneous Fenton treatment included measurements of pH, electrical conductivity, temperature, turbidity, chemical oxygen demand, biochemical oxygen demand, total organic carbon and toxicity test. Three kinetic models (first-order, second-order, and Behnajady-Modirshahla-Ghanbary) were evaluated in order to best describe Magenta degradation process. Results indicated that dye degradation process is followed with the increase of conductivity and biological oxygen demand due to the formation of various by-products and release of inorganic ions. The obtained results are in accordance with the established dye mineralization degree on the basis of chemical oxygen demand and total organic carbon content. However, treated printing effluent is characterized as nontoxic due to the Vibrio fischeri inhibition of 18.16%

Pyrite Cinder as an Effective Fenton-like Catalyst for the Degradation of Reactive Azo Dye: Effects of Process Parameters and Complete Effluent Characterization

This research investigates the potential use of pyrite cinder (PC) as an efficient Fenton-like catalyst for the removal of the reactive azo dye Reactive Red 120 (RR120) from aqueous solutions. The characterization of its PC structure and composition confirmed its great potential to act as catalytic iron source in a heterogeneous Fenton system. Dye removal optimization was performed in terms of PC dosage (0.4–8 g/L), H2O2 concentration (2–25 mM), pH value (2–4.6), initial dye concentration (50–200 mg/L), and mixing time. The highest decolorization efficiency (92%) was achieved after a reaction time of 480 min under following conditions: RR120 = 50 mg/L, PC = 4 g/L, H2O2 = 10 mM, and pH = 3. After decolorization, an extensive analysis of the generated effluent was performed regarding metal leaching, mineralization, toxicity, and degradation product formation. The metal leaching indicated the necessity for a pH increase in order to remove the settled metal hydroxides. The mineralization efficiency was satisfactory, reaching 85% and 62% of the COD and TOC removal, respectively. The respirometry measurements and bioluminescence tests indicated the detoxification of the treated solution. The absorption spectra and GC/MS analysis confirmed the changes in the molecular structure in the form of the destruction of the azo bond, with a simpler aromatic and aliphatic intermediates formation. This study provides an effective method for removing azo dye in polluted water by employing waste tailings as alternative Fenton-like catalysts, while also using waste tailings as the secondary resource

Photocatalytic Degradation of Magenta Effluent Using Magnetite Doped TiO2 in Solar Parabolic Trough Concentrator

Due to population growth and industrial development consumption of non-renewable energy sources, and consequently pollution, has increased. In order to reduce energy utilisation and preserve the environment, developed and developing countries are increasingly trying to find solutions based on renewable energy sources. Cost-effective wastewater treatment methods using solar energy would significantly ensure effective water source utilisation, thereby contributing towards sustainable development goals. In this paper, special emphasis is given to the use of solar energy as the driving force of the process, as well as the use of highly active magnetic TiO2-based catalysts. Therefore, in this study, we investigated the possibility of photocatalytic degradation of aqueous magenta graphic dye using titanium dioxide as a catalyst and DSD model in order to achieve the best process optimisation. TiO2 was successfully coated with magnetic nanoparticles by one step process and characterized using different techniques (BET, SEM/EDS, FTIR, XRD). Based on DSD statistical method optimal reaction conditions were pH = 6.5; dye concentration 100 mg/L; TiO2–Fe3O4 0.6 g/L, at which the highest degree of magenta dye decolourisation was achieved (85%). Application of solar energy coupled with magnetic TiO2 catalyst which could be recovered and reused makes this approach a promising alternative in green wastewater treatment

Photocatalytic Degradation of Magenta Effluent Using Magnetite Doped TiO₂ in Solar Parabolic Trough Concentrator

Due to population growth and industrial development consumption of non-renewable energy sources, and consequently pollution, has increased. In order to reduce energy utilisation and preserve the environment, developed and developing countries are increasingly trying to find solutions based on renewable energy sources. Cost-effective wastewater treatment methods using solar energy would significantly ensure effective water source utilisation, thereby contributing towards sustainable development goals. In this paper, special emphasis is given to the use of solar energy as the driving force of the process, as well as the use of highly active magnetic TiO2-based catalysts. Therefore, in this study, we investigated the possibility of photocatalytic degradation of aqueous magenta graphic dye using titanium dioxide as a catalyst and DSD model in order to achieve the best process optimisation. TiO2 was successfully coated with magnetic nanoparticles by one step process and characterized using different techniques (BET, SEM/EDS, FTIR, XRD). Based on DSD statistical method optimal reaction conditions were pH = 6.5; dye concentration 100 mg/L; TiO2–Fe3O4 0.6 g/L, at which the highest degree of magenta dye decolourisation was achieved (85%). Application of solar energy coupled with magnetic TiO2 catalyst which could be recovered and reused makes this approach a promising alternative in green wastewater treatment