Impact of carbon based nanomaterials on behavior selected hydrophobic organic compounds in aquatic systems

U prvom delu rada ispitana je adsorpcija četiri grupe organskih jedinjenja: (1) nitroaromatičnih (nitrobenzen), (2) nepolarno alifatičnih (heksan), (3)  monoaromatičnih (benzen, toluen, 1,2,3- i 1,2,4-trihlorbenzen) i (4) policikličnih aromatičnih ugljovodonika, PAH (naftalen, fenantren, piren i fluoranten) na višeslojnim ugljeničnim nanocevima (od eng. multiwalled carbon nanotubes, MWCNTs). Cilj ovog dela rada bio je pronaći korelaciju između parametara adsorpcije i fizičko-hemijskih karakteristika organskih molekula, kao i parametara  adsorpcije i karakteristika adsorbenata. Na osnovu dobijenih korelacija predložiti mehanizam adsorpcije ispitivanih organskih molekula na MWCNT-u. U cilju ispitivanja uticaja kiseoničnih funkcionalnih grupa na površini MWCNT-a odabrane su tri vrste MWCNT-a: originalni, nemodifikovani MWCNT (OMWCNT) i dve vrste funkcionalno modifikovanog MWCNT-a koji su dobijeni tretiranjem sa kiselinom tokom 3 h (FMWCNT3h) i 6 h (FMWCNT6h). Sve adsorpcione izoterme opisane  su Freundlich-ovim modelom. Nelinearnost izotermi bila je u opsegu od 0,418 do 0,897. Rezultati pokazuju da dobijeni afiniteti adsorpcije (za ravnotežnu koncentraciju 50% rastvorljivosti jedinjenja u vodi, Kd0,5 SW) za PAH-ove rastu sa povećanjem specifične površine (SP) adsorbenta. Veći afiniteti adsorpcije dobijeni su za velike molekule kao što su PAH-ovi u poređenju sa malim molekulima (benzen, toluen i heksan) što može biti posledica veće kontaktne površine između većih molekula i površine adsorbenta. Pozitivna korelacija između afiniteta adsorpcije i hidrofobnosti molekula ukazuje da hidrofobne interakcije dominantno kontrolišu adsorpciju ispitivanih organskih jedinjenja, osim u slučaju nitobenzena. Da bi se ispitao uticaj π-π interakcija,  Kd za odabranu ravnotežnu koncentraciju su normalizovane sa hidrofobnošću molekula pri čemu su dobijeni odgovarajući  Kd/KOW odnosi. Za sva ispitivana jedinjenja Kd/KOW odnosi na svim ispitivanim MWCNT rastu u sledećem nizu: nepolarni alifatični < monoaromatični < PAH-ovi < nitrobenzen, što ukazuje da π-π interakcije značajno poboljšavaju adsorpciju aromatičnih jedinjenja na MWCNT-u. Snažne interakcije između MWCNT-a i nitrobenzena posledica su formiranja π-π elektron donorsko-akceptorskih (EDA) interakcija izemđu nitroaromatičnih molekula (elektron akceptori)i visoko polarizovane ugljenične površine nanocevi (elektron donori). Na osnovu dobijenih rezultata može se uočiti da se pri adsorpciji ispitivanihorganskih molekula na MWCNT-u istovreme odigrava više mehanizama. U drugom delu rada ispitan je uticaj ugljeničnog nanomaterijala (od eng. carbon based nanomaterial, CNM) natransport odabranih organskih jedinjenja (1,2,3- i 1,2,4-trihlorbenzena, naftalena, fenantrena, pirena i fluorantena) kroz sediment Dunava. Cilj ovog dela rada bio je ispitati mehanizam transporta odabranih organskih jedinjenja u prisustvu i odsustvu CNM. C/C0 vrednosti, dobijene za vreme trajanja eksperimenta  (t=96 h), ispitivanog jedinjenja u eluatu kolone napunjene samo sedimentom rastu u sledećem nizu: fluoranten < piren < fenantren < 1,2,4-trihlorbenzen < 1,2,3-trihlorbenzen < naftalen. U cilju ispitivanja uticaja hidrofobnosti ispitivanih molekula na sorpciju u neravnotežnim uslovima, dobijene vrednosti C/C0 ispitivanih molekula su korelirane sa hidrofobnošću molekula. Uočena je negativna korelacija što ukazuje da hidrofobniji molekuli pokazuju duže vreme zadržavanja na koloni, a time i veću neravnotežnu sorpcijutokom transporta.  U prisustvu FMWCNT3h u koloni kojaje napunjena sedimentom može se uočiti da su koncentracije ispitivanih jedinjenja u eluatu manje za 2-3 puta. Pri datim uslovima procenat detektovane koncentracije ispitivanog jedinjenja u eluatu raste u sledećem nizu: fluoranten < fenantren < piren < naftalen < 1,2,4-trihlorbenzena < 1,2,3-trihlorbenzen. Predloženi mehanizam je sledeći: na eksperimentalnoj pH (pH=6,5) karboksilne grupe na FMWCNT3h su negativno naelekrisane, s druge strane tačka nultog naelektrisanja sedimenta Dunav je 4, što ukazuje da je ukupna površina pri pH=6,5 negativno naelektrisana. Međutim, metalni oksidi i hidroksidi gvožđa, aluminijuma i nikla na površini sedimenta uzrokuju pozitivno naelektrisane centre što dovodi do depozicije FMWCNT3h kao posledica elektrostatičkog privlačenja. Pri transportu organskih jedinjenja kroz sediment Dunava u prisustvu FMWCNT3h dolazi do simultane sorpcije organskih jedinjenja na organskom ugljeniku sedimenta i do adsorpcije na FMWCNT3h. Kada se pH vrednost poveća smanjuje se pozitivno naelekrisanje metalnih  oksida i hidroksida na površini sedimenta što dovodi do povećane mobilnosti FMWCNT3h, a time i organskih jedinjenja adsorbovanih na njima. Svi rezultati ukazuju da pH vrednost ima veoma značajnu ulogu i može povećati  transport funkcionalizovanog MWCNT-a, a time i transport organskih molekula adsorbovanih na njima.The first part of the thesis investigates the adsorption of four groups of organic compounds (OCs): (1) nitroaromatics (nitrobenzene), (2) nonpolar aliphatics (hexane), (3) monoaromatics (benzene, toluene, 1,2,3- and 1,2,4-trichlorobenzene) and (4) polycyclic aromatic hydrocarbons (PAHs, napthalene,  phenanthrene, pyrene and fluoranthene) on multiwalled carbon nanotubes (MWCNTs). This part of the work aimed to find a correlationbetween the adsorption parameters and physical-chemical properties of the organic molecules, as well as the parameters of adsorption and the characteristics of the adsorbents. On the basis of the obtained correlations the adsorption mechanism was proposed. In order to investigate the influence which oxygen containing functional groups exert on the adsorption process, three MWCNTs were used: the pristine (original, as-received) MWCNTs (OMWCNT) and two  MWCNTs functionally modified by acid treatment of OMWCNT over 3 h and 6 h (FMWCNT3h, FMWCNT6h). All adsorption isotherms well fitted with the Freundlich model. The nonlinearity of the isotherms ranged from 0.418 to 0.897. The results show that Kd values for PAHs increased with increasing specific surface areas (SSAs). The adsorption affinities of the larger molecular size OCs (PAHs) were higher  than those of the smaller size OCs (benzene, toluene and hexane) which is probably due to their large contact area with the surface of the adsorbent. Adsorption of OCs on MWCNTs was mainly controlled by hydrophobic interactions, except for the nitroaromatic compound, as shown by the increasing adsorption affinities with the compound’s hydrophobicity. KOW-normalized adsorption coefficients (Kd/KOW) for all the investigated compounds on all the MWCNTs followed the order: nonpolar aliphatic < monoaromatics < PAHs < nitroaromatic, implying that π-π interactions enhanced the adsorption of aromatics on the MWCNTs. It can be concluded that the strong adsorptiveinteractions between the MWCNTs and nitroaromatics was due to the π-π electron-donor–acceptor (EDA) interaction between nitroaromatic molecules (electron acceptors) and the highly polarisable graphene sheets(electron donors) of the carbon nanotubes. Based on the obtained results, it can be concluded that multiple mechanisms control the adsorption of organic compounds on MWCNTs. In the second part, the influence of carbon based nanomaterials CNM on transport of selected organic compounds (1,2,3 - and 1,2,4-trichlorobenzene, naphthalene, phenanthrene, pyrene and fluoranthene) through sediment Danube was investigated.  The aim of this part of the work was to investigate the transport mechanism of selected organic compounds in the presence and absence of CNM. The C/C0 values for the tested compounds in the eluate of the column filled with sediment only increased in the following order: fluoranthene <pyrene <phenanthrene <1,2,4-trichlorobenzene <1,2,3-trichlorobenzene <naphthalene. In order to investigate the influence of  hydrophobicity of the investigated compounds on the nonequilibrium sorption, the obtained C/C0 values (for the duration of the experiment, t = 96 h) for these molecules were correlated with the hydrophobicity of the molecules. There was a negative correlation, indicating that more hydrophobic molecules show long residence times in the column, and thus had higher non-equilibrium sorption during transport. In the presence of FMWCNT3h in the column filled with sediment, it can be observed that the concentrations of compounds in the column eluate decreased by factors of 2-3. C/C0 values for the investigated compounds in the eluate increased in the following order: fluoranthene <phenanthrene <pyrene <naphthalene <1,2,4-trichlorobenzene <1,2,3-trichlorobenzene. The proposed mechanism is as follows: under the experimental pH (pH = 6.5), carboxyl groups are negatively charged on the surface of FMWCNT3h and the point of zero charge of the Danube sediment is 4, which indicates thatthe total surface of the Danube sediment at pH 6.5 isnegatively charged. However, metal oxides and hydroxides of iron, aluminum and nickel on the surface of the sediment cause a positively charged centre that leads to the deposition of FMWCNT3h as a result of electrostatic attraction. Transport of organic compounds through the Danube sediment in the presence FMWCNT3h leads to the simultaneous  sorption oforganic compounds on the sediment organic carbon and the adsorption of  FMWCNT3h. When the pH increased, the positive charge of metal oxides and hydroxides on the sediment surface decreased, which leads to increased FMWCNT3h mobility and thus the organic compounds adsorbed on them. All results indicate that the pH value plays animportant role and can increase the transport of functionally modified MWCNT's, and thus the transport of organic molecules adsorbed on them.

Impact of carbon based nanomaterials on behavior selected hydrophobic organic compounds in aquatic systems

U prvom delu rada ispitana je adsorpcija četiri grupe organskih jedinjenja: (1) nitroaromatičnih (nitrobenzen), (2) nepolarno alifatičnih (heksan), (3)  monoaromatičnih (benzen, toluen, 1,2,3- i 1,2,4-trihlorbenzen) i (4) policikličnih aromatičnih ugljovodonika, PAH (naftalen, fenantren, piren i fluoranten) na višeslojnim ugljeničnim nanocevima (od eng. multiwalled carbon nanotubes, MWCNTs). Cilj ovog dela rada bio je pronaći korelaciju između parametara adsorpcije i fizičko-hemijskih karakteristika organskih molekula, kao i parametara  adsorpcije i karakteristika adsorbenata. Na osnovu dobijenih korelacija predložiti mehanizam adsorpcije ispitivanih organskih molekula na MWCNT-u. U cilju ispitivanja uticaja kiseoničnih funkcionalnih grupa na površini MWCNT-a odabrane su tri vrste MWCNT-a: originalni, nemodifikovani MWCNT (OMWCNT) i dve vrste funkcionalno modifikovanog MWCNT-a koji su dobijeni tretiranjem sa kiselinom tokom 3 h (FMWCNT3h) i 6 h (FMWCNT6h). Sve adsorpcione izoterme opisane  su Freundlich-ovim modelom. Nelinearnost izotermi bila je u opsegu od 0,418 do 0,897. Rezultati pokazuju da dobijeni afiniteti adsorpcije (za ravnotežnu koncentraciju 50% rastvorljivosti jedinjenja u vodi, Kd0,5 SW) za PAH-ove rastu sa povećanjem specifične površine (SP) adsorbenta. Veći afiniteti adsorpcije dobijeni su za velike molekule kao što su PAH-ovi u poređenju sa malim molekulima (benzen, toluen i heksan) što može biti posledica veće kontaktne površine između većih molekula i površine adsorbenta. Pozitivna korelacija između afiniteta adsorpcije i hidrofobnosti molekula ukazuje da hidrofobne interakcije dominantno kontrolišu adsorpciju ispitivanih organskih jedinjenja, osim u slučaju nitobenzena. Da bi se ispitao uticaj π-π interakcija,  Kd za odabranu ravnotežnu koncentraciju su normalizovane sa hidrofobnošću molekula pri čemu su dobijeni odgovarajući  Kd/KOW odnosi. Za sva ispitivana jedinjenja Kd/KOW odnosi na svim ispitivanim MWCNT rastu u sledećem nizu: nepolarni alifatični < monoaromatični < PAH-ovi < nitrobenzen, što ukazuje da π-π interakcije značajno poboljšavaju adsorpciju aromatičnih jedinjenja na MWCNT-u. Snažne interakcije između MWCNT-a i nitrobenzena posledica su formiranja π-π elektron donorsko-akceptorskih (EDA) interakcija izemđu nitroaromatičnih molekula (elektron akceptori)i visoko polarizovane ugljenične površine nanocevi (elektron donori). Na osnovu dobijenih rezultata može se uočiti da se pri adsorpciji ispitivanihorganskih molekula na MWCNT-u istovreme odigrava više mehanizama. U drugom delu rada ispitan je uticaj ugljeničnog nanomaterijala (od eng. carbon based nanomaterial, CNM) natransport odabranih organskih jedinjenja (1,2,3- i 1,2,4-trihlorbenzena, naftalena, fenantrena, pirena i fluorantena) kroz sediment Dunava. Cilj ovog dela rada bio je ispitati mehanizam transporta odabranih organskih jedinjenja u prisustvu i odsustvu CNM. C/C0 vrednosti, dobijene za vreme trajanja eksperimenta  (t=96 h), ispitivanog jedinjenja u eluatu kolone napunjene samo sedimentom rastu u sledećem nizu: fluoranten < piren < fenantren < 1,2,4-trihlorbenzen < 1,2,3-trihlorbenzen < naftalen. U cilju ispitivanja uticaja hidrofobnosti ispitivanih molekula na sorpciju u neravnotežnim uslovima, dobijene vrednosti C/C0 ispitivanih molekula su korelirane sa hidrofobnošću molekula. Uočena je negativna korelacija što ukazuje da hidrofobniji molekuli pokazuju duže vreme zadržavanja na koloni, a time i veću neravnotežnu sorpcijutokom transporta.  U prisustvu FMWCNT3h u koloni kojaje napunjena sedimentom može se uočiti da su koncentracije ispitivanih jedinjenja u eluatu manje za 2-3 puta. Pri datim uslovima procenat detektovane koncentracije ispitivanog jedinjenja u eluatu raste u sledećem nizu: fluoranten < fenantren < piren < naftalen < 1,2,4-trihlorbenzena < 1,2,3-trihlorbenzen. Predloženi mehanizam je sledeći: na eksperimentalnoj pH (pH=6,5) karboksilne grupe na FMWCNT3h su negativno naelekrisane, s druge strane tačka nultog naelektrisanja sedimenta Dunav je 4, što ukazuje da je ukupna površina pri pH=6,5 negativno naelektrisana. Međutim, metalni oksidi i hidroksidi gvožđa, aluminijuma i nikla na površini sedimenta uzrokuju pozitivno naelektrisane centre što dovodi do depozicije FMWCNT3h kao posledica elektrostatičkog privlačenja. Pri transportu organskih jedinjenja kroz sediment Dunava u prisustvu FMWCNT3h dolazi do simultane sorpcije organskih jedinjenja na organskom ugljeniku sedimenta i do adsorpcije na FMWCNT3h. Kada se pH vrednost poveća smanjuje se pozitivno naelekrisanje metalnih  oksida i hidroksida na površini sedimenta što dovodi do povećane mobilnosti FMWCNT3h, a time i organskih jedinjenja adsorbovanih na njima. Svi rezultati ukazuju da pH vrednost ima veoma značajnu ulogu i može povećati  transport funkcionalizovanog MWCNT-a, a time i transport organskih molekula adsorbovanih na njima.The first part of the thesis investigates the adsorption of four groups of organic compounds (OCs): (1) nitroaromatics (nitrobenzene), (2) nonpolar aliphatics (hexane), (3) monoaromatics (benzene, toluene, 1,2,3- and 1,2,4-trichlorobenzene) and (4) polycyclic aromatic hydrocarbons (PAHs, napthalene,  phenanthrene, pyrene and fluoranthene) on multiwalled carbon nanotubes (MWCNTs). This part of the work aimed to find a correlationbetween the adsorption parameters and physical-chemical properties of the organic molecules, as well as the parameters of adsorption and the characteristics of the adsorbents. On the basis of the obtained correlations the adsorption mechanism was proposed. In order to investigate the influence which oxygen containing functional groups exert on the adsorption process, three MWCNTs were used: the pristine (original, as-received) MWCNTs (OMWCNT) and two  MWCNTs functionally modified by acid treatment of OMWCNT over 3 h and 6 h (FMWCNT3h, FMWCNT6h). All adsorption isotherms well fitted with the Freundlich model. The nonlinearity of the isotherms ranged from 0.418 to 0.897. The results show that Kd values for PAHs increased with increasing specific surface areas (SSAs). The adsorption affinities of the larger molecular size OCs (PAHs) were higher  than those of the smaller size OCs (benzene, toluene and hexane) which is probably due to their large contact area with the surface of the adsorbent. Adsorption of OCs on MWCNTs was mainly controlled by hydrophobic interactions, except for the nitroaromatic compound, as shown by the increasing adsorption affinities with the compound’s hydrophobicity. KOW-normalized adsorption coefficients (Kd/KOW) for all the investigated compounds on all the MWCNTs followed the order: nonpolar aliphatic < monoaromatics < PAHs < nitroaromatic, implying that π-π interactions enhanced the adsorption of aromatics on the MWCNTs. It can be concluded that the strong adsorptiveinteractions between the MWCNTs and nitroaromatics was due to the π-π electron-donor–acceptor (EDA) interaction between nitroaromatic molecules (electron acceptors) and the highly polarisable graphene sheets(electron donors) of the carbon nanotubes. Based on the obtained results, it can be concluded that multiple mechanisms control the adsorption of organic compounds on MWCNTs. In the second part, the influence of carbon based nanomaterials CNM on transport of selected organic compounds (1,2,3 - and 1,2,4-trichlorobenzene, naphthalene, phenanthrene, pyrene and fluoranthene) through sediment Danube was investigated.  The aim of this part of the work was to investigate the transport mechanism of selected organic compounds in the presence and absence of CNM. The C/C0 values for the tested compounds in the eluate of the column filled with sediment only increased in the following order: fluoranthene <pyrene <phenanthrene <1,2,4-trichlorobenzene <1,2,3-trichlorobenzene <naphthalene. In order to investigate the influence of  hydrophobicity of the investigated compounds on the nonequilibrium sorption, the obtained C/C0 values (for the duration of the experiment, t = 96 h) for these molecules were correlated with the hydrophobicity of the molecules. There was a negative correlation, indicating that more hydrophobic molecules show long residence times in the column, and thus had higher non-equilibrium sorption during transport. In the presence of FMWCNT3h in the column filled with sediment, it can be observed that the concentrations of compounds in the column eluate decreased by factors of 2-3. C/C0 values for the investigated compounds in the eluate increased in the following order: fluoranthene <phenanthrene <pyrene <naphthalene <1,2,4-trichlorobenzene <1,2,3-trichlorobenzene. The proposed mechanism is as follows: under the experimental pH (pH = 6.5), carboxyl groups are negatively charged on the surface of FMWCNT3h and the point of zero charge of the Danube sediment is 4, which indicates thatthe total surface of the Danube sediment at pH 6.5 isnegatively charged. However, metal oxides and hydroxides of iron, aluminum and nickel on the surface of the sediment cause a positively charged centre that leads to the deposition of FMWCNT3h as a result of electrostatic attraction. Transport of organic compounds through the Danube sediment in the presence FMWCNT3h leads to the simultaneous  sorption oforganic compounds on the sediment organic carbon and the adsorption of  FMWCNT3h. When the pH increased, the positive charge of metal oxides and hydroxides on the sediment surface decreased, which leads to increased FMWCNT3h mobility and thus the organic compounds adsorbed on them. All results indicate that the pH value plays animportant role and can increase the transport of functionally modified MWCNT's, and thus the transport of organic molecules adsorbed on them.

Pentachlorobenzene sequestration in sediment by carbon rich amendment

Organic pollutants in sediments are a worldwide problem because sediments act as sinks for hydrophobic, toxic, persistent and bioaccumulative hazardous compoundssuch as pentachlorobenzene (PeCB). PeCB can be involved in adsorption, desorption and transformation processes and can be made available to benthic organisms through the sediment-water interface. In order to reduce the risk, this study investigates effects of the dose and contact time between sediment and carbon-rich amendments (activated carbon (AC), biochar (BC) and hummus (HC)) on the effectiveness of detoxification. Four doses of carbon-rich amendments (0.5-10 %) and four equilibrations contact times (14 -180 days) were investigated. The present research highlights the need for further examination and process optimization of different carbon-rich materials used for contaminant removal. Results have shown that the smallest dose (0.5 %) of investigated sorbents was sufficient to reduce the bioavailable fraction of PeCB below 5 %, and the ageing process after 14 days for AC and 30 days for HM and BC negligibly influenced the bioavailable fraction

The combined electrocoagulation/flotation and adsorption processes for organic substances regeneration of waste printing developer

This paper investigates the possibility of reducing the content of organic substances in waste printing developer using a combination of electrocoagulation/flotation (ECF) and adsorption (AD) processes. The content of organic substances in waste printing developer was monitored by analysis of total organic carbon (TOC), chemical oxygen demand (COD) and biological oxygen demand (BOD5) before and after the ECF and AD processes, respectively. When combining the two processes, a removal of 99.4, 92.9 and 96.0% of the TOC, COD and BOD5 was achieved, respectively. Obtained results confirm the improvement in the printing industrial effluent quality and height removal of organic substances by the combined ECF and AD treatments

The efficiency of the hard wood origin biochar addition on the PAHs bioavailability and stability in sediment

Polluted sediments with organic pollutants like PAHs represent a potential danger to environment, human health and potential obstacle to water management. Removal of polluted sediment provides the potential for reuse of nutrients from sediment, for crop production or for materials in building industry. The purpose of this study was to determine the efficacy of using hard wood biochar for the immobilization of bioaccessible polycyclic aromatic hydrocarbons (PAHs) in historically polluted sediment. The main question is would carbon materials' presence (in this case biochar) have influence on PAH bioavailability and their stability in sediment. This is important because the world trend is to go for sediment reuse in agriculture purposes, and biochar is proven to be good amendment for increasing soil organic carbon (SOC) stabilization and increasing soil carbon stock. The manuscript provides a detailed consideration of the supersorption performance of the biochar and PAH sequestration in different types of PAHs with aging period up to 6 months in ex situ treatment. The efficiency of biochar to sequester the PAHs was evaluated by assessing the bioavailable fraction (Frap) using desorption method with Amberlite XAD4 resin assistance. In untreated sediment, Frap ranged from 22% up to 42% for 2–4 rings, and around 9% for 5–6 rings PAHs. 180-days amendment of biochar led to a further decrease in the bioavailable portion of PAHs. The results of this laboratory study shown that biochar produced from hard wood gave promising results for binding and further stabilizing PAH in historically polluted sediments

Sorption-desorption behaviour of hydrophobic organic compounds on Danube sediment

The sorption-desorption hysteresis of naphthalene and phenanthrene onto Danube sediment was investigated. Hysteresis indices (HI) are calculated for three equilibrium concentration (Ce=1%, 5% i 50% of the solubility in water). The results of sorption-desorption hysteresis indicated that it exists for both investigated sorbates on the Danube sediment. For more hydrophobic compound, phenanthrene (logKOW< 4.55) hysteresis is less pronounced in comparison with naphthalene (logKOW< 3.36). In the case of naphthalene, the existence of hysteresis may be due to irreversible pore deformation of the sorbent which causes the formation of meta-stable states in the sorbate mesopores

Photochemical degradation of alachlor in water

This study investigates the photochemical degradation of alachlor, a chloroacetanilide herbicide. All experiments were conducted in ultra-pure deionized water (ASTM Type I quality) using direct ultraviolet (UV) photolysis and the UV/H2O2 advanced oxidation process. The direct UV photolysis and UV/H2O2 experiments were conducted in a commercial photochemical reactor with a quartz reaction vessel equipped with a 253.7 nm UV low pressure mercury lamp (Philips TUV 16 W). The experimental results demonstrate that UV photolysis was very effective for alachlor degradation (up to 97% removal using a high UV fluence of 4200 mJ/cm2). The UV/H2O2 process promoted alachlor degradation compared to UV photolysis alone, with a high degree of decomposition (97%) achieved at a significantly lower UV fluence of 600 mJ/cm2 when combined with 1 mg H2O2/L. The application of UV photolysis alone with a UV fluence of 600 mJ/cm2 gave a negligible 4% alachlor degradation. The photo degradation of alachlor, in both direct UV photolysis and the UV/H2O2 process, followed pseudo first-order kinetics. The degradation rate constant was about 6 times higher for the UV/H2O2 process than for UV photolysis alone

Enhanced coagulation with pre-oxidation for the removal of arsenic from groundwater

One of the most wide-spread problems with current drinking water resources globally is the natural presence of arsenic in groundwaters. The aim of this work was to investigate the removal of arsenic by a variety of combined oxidation/coagulation processes, in order to identify and optimise the most critical process parameters. The most significant gains made by both preoxidation steps were observed in the techniques which combined aluminum and ferric chloride based coagulation. The most efficient coagulation treatment investigated involved application of preozonation at a dose of 7.5 mg O3/l with subsequent combined coagulation with PACl–FeCl3 (30 mg Al/l and 10 mg FeCl3/l)

Supplementary material for the article: Mihajlović, M.; Petrović, J.; Maletić, S.; Isakovski, M. K.; Stojanović, M.; Lopičić, Z.; Trifunović, S. Hydrothermal Carbonization of Miscanthus × giganteus: Structural and Fuel Properties of Hydrochars and Organic Profile with the Ecotoxicological Assessment of the Liquid Phase. Energy Convers. Manage. 2018, 159, 254–263. https://doi.org/10.1016/j.enconman.2018.01.003

Supplementary material for: [https://doi.org/10.1016/j.enconman.2018.01.003]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2100