Application of TiO2 photocatalyst for the removal of cytostatic drugs from water

Zaštita i očuvanje vodenih resursa izazov je na globalnoj razini s kojim se današnjica susreće. Uz konvencionalne postupke obrade voda razvijaju se i napredni oksidacijski procesi koji su se zbog svog neselektivnog ponašanja pokazali učinkovitijim za uklanjanje malih organskih molekula poput farmaceutika čija prisutnost u okolišu više ne iznenađuje. Među raznim vrstama lijekova, svoj put u okolišu, ponajviše kroz otpadne vode pronašli su i lijekovi protiv raka (citostatici) koji zahtijevaju pažnju zbog povećane potrošnje i bioloških učinaka na organizme, već pri niskim koncentracijama. U ovome radu izabrana su dva citostatika, imatinib i krizotinib čija se mogućnost uklanjanja iz vode ispitala kroz sorpcijsku i fotokatalitičku aktivnost primjenom TiO2 fotokatalizatora. Prema mehanizmu fotokatalitičkog procesa, ispitivana komponenta podlijegat će razgradnji ako se prethodno sorbira na katalizator pa se sukladno tome, u prvom nizu eksperimenata proučavao sorpcijski afinitet citostatika prema različitim oblicima TiO2 fotokatalizatora, koristeći nekoliko modela sorpcijskih izotermi. Općenito se, na temelju određene količine sorbirane tvari, ispitala i primjenjivost sorpcije kao jednostavnije i jeftinije metode za uklanjanje imatiniba i krizotiniba iz vode ili kao preteča neke druge oksidacijske metode. Priroda procesa sorpcije, provedenog pri tri različite temperature opisana je promjenom početne koncentracije analita, pH-vrijednosti i ionske jakosti otopine te promjenom mase sorbensa. Visoke vrijednosti regresijskog koeficijenta, R2 upućuju na prikladnost linearne, Freundlichove i Langmuirove izoterme za opisivanje sorpcije citostatika na suspendirani i imobilizirani oblik TiO2. Oba analita pokazuju rastući trend koeficijenta sorpcije s porastom vrijednosti pH u rasponu od 5 do 9 s naglaskom na veću mobilnost imatiniba u slučaju imobiliziranog TiO2. Pozitivna korelacija određena je i između temperature, mase sorbensa i koeficijenta sorpcije, dok je porastom ionske jakosti otopine krizotinib pokazao suprotan trend. Termodinamika sorpcije opisana je kao spontan proces fizikalne prirode koji slijedi kinetiku pseudo-drugog reda. Što se tiče eksperimenata fotokatalize, prvo su se odredile vrijednosti početne koncentracije analita i pH otopine pri kojoj citostatici postižu optimalnu razgradnju, primjenom modeliranja odzivnih površina (RSM). Pri dobivenim uvjetima (pH 5 i 5 mg/L) ispitan je mehanizam fotokatalitičke reakcije, određivanjem radikalskih vrsta odgovornih za razgradnju. Vodeću ulogu u razgradnji imatiniba i krizotiniba pokazali su hidroksilni radikali i singletni kisik. U sljedećim eksperimentima pokazana je važnost provođenja fotokatalize u prisustvu raznih anorganskih i organskih tvari kao sastavnica matice vode koji su većinski usporili razgradnju. Kao i svaki drugi proces razgradnje, fotokataliza imatiniba i krizotiniba također je bila popraćena stvaranjem nusprodukata čije su strukture i putevi razgradnje predloženi korištenjem spektrometrije masa visokog razlučivanja. Potencijalna opasnost razgradnih produkata procijenjena je testom akutne toksičnosti prema morskoj bakteriji Vibrio fischeri, pri čemu je postignuta značajna inhibicija luminiscencije tijekom fotokatalitičke razgradnje krizotiniba u razdoblju od 90. do 180. minute. Kao fotokatalizator koristio se TiO2 imobiliziran na staklene mrežice koji je olakšao samu provedbu eksperimenata pritom misleći na filtriranje uzoraka.The protection and conservation of water resource is a global challenge facing humanity today. In addition to conventional water treatment, advanced oxidation processes are also being developed to non-selectively and efficiently remove small organic molecules such as pharmaceuticals, whose presence in the environment is no longer surprising. Among the different classes of pharmaceuticals, anti-cancer drugs (cytostatics) have also found their way into the environment, mostly through wastewater, which requires attention due to their increased consumption and biological effects, even at low concentrations. In this work, two cytostatics, imatinib and crizotinib, were selected and their ability to be removed from water was tested by sorption and photocatalytic activity with TiO2 photocatalysts. The prerequisite step of the photocatalytic process is the sorption of the tested component on the catalyst, so in the first series of experiments the sorption affinity of cytostatics to different forms of TiO2 was investigated. In addition, based on the studied sorption affinity, the applicability of sorption as a simpler and less expensive method for the removal of imatinib and crizotinib or as a complementary method to some oxidation processes was tested. The nature of the sorption process was described by changing the initial concentration of the analyte, the pH value and the ionic strength of the solution, and by performing experiments at three different ambient temperatures and different sorbent dosages. The suitability of the linear, Freundlich, and Langmuir isotherm models for describing the sorption of cytostatics on the suspended and immobilized forms of TiO2 was indicated by high values of the regression coefficient, R2. Both analytes showed an increasing trend in the sorption coefficient with increasing pH values in the range of 5 to 9, highlighting the greater mobility of imatinib in the case of immobilized TiO2. A positive correlation was also observed between temperature, sorbent mass and sorption coefficient, while the increase in ionic strength of crizotinib solution showed the opposite trend. The thermodynamics of sorption is described as a spontaneous process of physical nature that follows pseudo-second-order kinetics. In the first step of the photocatalytic experiments, the initial concentration of the analyte and the pH of the solution, at which the cytostatic reaches the optimal degradation, were tested using response surface modelling (RSM). Under the conditions obtained (pH 5 and 5 mg/L), the mechanism of the photocatalytic reaction was studied by determining the main radical species involved in the degradation. Hydroxy radicals and singlet oxygen played the main role in the degradation of imatinib and crizotinib. The importance of performing photocatalysis in the presence of various organic and inorganic substances as common components of the water matrix was also demonstrated, since most of them slow down the degradation. Like any other degradation process, photocatalysis of imatinib and crizotinib was accompanied by the formation of by-products, whose structures and degradation pathways were suggested by high-resolution mass spectrometry. The hazard potential of the degradation products was assessed by an acute toxicity assay with the marine bacterium Vibrio fischeri, with significant inhibition of luminescence during photocatalytic degradation of crizotinib over period of 90 to 180 minutes. TiO2 immobilized on glass meshes was used as the photocatalyst, which facilitated the performance of the experiments by avoiding filtering of the samples

Application of TiO2 photocatalyst for the removal of cytostatic drugs from water

Zaštita i očuvanje vodenih resursa izazov je na globalnoj razini s kojim se današnjica susreće. Uz konvencionalne postupke obrade voda razvijaju se i napredni oksidacijski procesi koji su se zbog svog neselektivnog ponašanja pokazali učinkovitijim za uklanjanje malih organskih molekula poput farmaceutika čija prisutnost u okolišu više ne iznenađuje. Među raznim vrstama lijekova, svoj put u okolišu, ponajviše kroz otpadne vode pronašli su i lijekovi protiv raka (citostatici) koji zahtijevaju pažnju zbog povećane potrošnje i bioloških učinaka na organizme, već pri niskim koncentracijama. U ovome radu izabrana su dva citostatika, imatinib i krizotinib čija se mogućnost uklanjanja iz vode ispitala kroz sorpcijsku i fotokatalitičku aktivnost primjenom TiO2 fotokatalizatora. Prema mehanizmu fotokatalitičkog procesa, ispitivana komponenta podlijegat će razgradnji ako se prethodno sorbira na katalizator pa se sukladno tome, u prvom nizu eksperimenata proučavao sorpcijski afinitet citostatika prema različitim oblicima TiO2 fotokatalizatora, koristeći nekoliko modela sorpcijskih izotermi. Općenito se, na temelju određene količine sorbirane tvari, ispitala i primjenjivost sorpcije kao jednostavnije i jeftinije metode za uklanjanje imatiniba i krizotiniba iz vode ili kao preteča neke druge oksidacijske metode. Priroda procesa sorpcije, provedenog pri tri različite temperature opisana je promjenom početne koncentracije analita, pH-vrijednosti i ionske jakosti otopine te promjenom mase sorbensa. Visoke vrijednosti regresijskog koeficijenta, R2 upućuju na prikladnost linearne, Freundlichove i Langmuirove izoterme za opisivanje sorpcije citostatika na suspendirani i imobilizirani oblik TiO2. Oba analita pokazuju rastući trend koeficijenta sorpcije s porastom vrijednosti pH u rasponu od 5 do 9 s naglaskom na veću mobilnost imatiniba u slučaju imobiliziranog TiO2. Pozitivna korelacija određena je i između temperature, mase sorbensa i koeficijenta sorpcije, dok je porastom ionske jakosti otopine krizotinib pokazao suprotan trend. Termodinamika sorpcije opisana je kao spontan proces fizikalne prirode koji slijedi kinetiku pseudo-drugog reda. Što se tiče eksperimenata fotokatalize, prvo su se odredile vrijednosti početne koncentracije analita i pH otopine pri kojoj citostatici postižu optimalnu razgradnju, primjenom modeliranja odzivnih površina (RSM). Pri dobivenim uvjetima (pH 5 i 5 mg/L) ispitan je mehanizam fotokatalitičke reakcije, određivanjem radikalskih vrsta odgovornih za razgradnju. Vodeću ulogu u razgradnji imatiniba i krizotiniba pokazali su hidroksilni radikali i singletni kisik. U sljedećim eksperimentima pokazana je važnost provođenja fotokatalize u prisustvu raznih anorganskih i organskih tvari kao sastavnica matice vode koji su većinski usporili razgradnju. Kao i svaki drugi proces razgradnje, fotokataliza imatiniba i krizotiniba također je bila popraćena stvaranjem nusprodukata čije su strukture i putevi razgradnje predloženi korištenjem spektrometrije masa visokog razlučivanja. Potencijalna opasnost razgradnih produkata procijenjena je testom akutne toksičnosti prema morskoj bakteriji Vibrio fischeri, pri čemu je postignuta značajna inhibicija luminiscencije tijekom fotokatalitičke razgradnje krizotiniba u razdoblju od 90. do 180. minute. Kao fotokatalizator koristio se TiO2 imobiliziran na staklene mrežice koji je olakšao samu provedbu eksperimenata pritom misleći na filtriranje uzoraka.The protection and conservation of water resource is a global challenge facing humanity today. In addition to conventional water treatment, advanced oxidation processes are also being developed to non-selectively and efficiently remove small organic molecules such as pharmaceuticals, whose presence in the environment is no longer surprising. Among the different classes of pharmaceuticals, anti-cancer drugs (cytostatics) have also found their way into the environment, mostly through wastewater, which requires attention due to their increased consumption and biological effects, even at low concentrations. In this work, two cytostatics, imatinib and crizotinib, were selected and their ability to be removed from water was tested by sorption and photocatalytic activity with TiO2 photocatalysts. The prerequisite step of the photocatalytic process is the sorption of the tested component on the catalyst, so in the first series of experiments the sorption affinity of cytostatics to different forms of TiO2 was investigated. In addition, based on the studied sorption affinity, the applicability of sorption as a simpler and less expensive method for the removal of imatinib and crizotinib or as a complementary method to some oxidation processes was tested. The nature of the sorption process was described by changing the initial concentration of the analyte, the pH value and the ionic strength of the solution, and by performing experiments at three different ambient temperatures and different sorbent dosages. The suitability of the linear, Freundlich, and Langmuir isotherm models for describing the sorption of cytostatics on the suspended and immobilized forms of TiO2 was indicated by high values of the regression coefficient, R2. Both analytes showed an increasing trend in the sorption coefficient with increasing pH values in the range of 5 to 9, highlighting the greater mobility of imatinib in the case of immobilized TiO2. A positive correlation was also observed between temperature, sorbent mass and sorption coefficient, while the increase in ionic strength of crizotinib solution showed the opposite trend. The thermodynamics of sorption is described as a spontaneous process of physical nature that follows pseudo-second-order kinetics. In the first step of the photocatalytic experiments, the initial concentration of the analyte and the pH of the solution, at which the cytostatic reaches the optimal degradation, were tested using response surface modelling (RSM). Under the conditions obtained (pH 5 and 5 mg/L), the mechanism of the photocatalytic reaction was studied by determining the main radical species involved in the degradation. Hydroxy radicals and singlet oxygen played the main role in the degradation of imatinib and crizotinib. The importance of performing photocatalysis in the presence of various organic and inorganic substances as common components of the water matrix was also demonstrated, since most of them slow down the degradation. Like any other degradation process, photocatalysis of imatinib and crizotinib was accompanied by the formation of by-products, whose structures and degradation pathways were suggested by high-resolution mass spectrometry. The hazard potential of the degradation products was assessed by an acute toxicity assay with the marine bacterium Vibrio fischeri, with significant inhibition of luminescence during photocatalytic degradation of crizotinib over period of 90 to 180 minutes. TiO2 immobilized on glass meshes was used as the photocatalyst, which facilitated the performance of the experiments by avoiding filtering of the samples

Application of TiO2 photocatalyst for the removal of cytostatic drugs from water

Zaštita i očuvanje vodenih resursa izazov je na globalnoj razini s kojim se današnjica susreće. Uz konvencionalne postupke obrade voda razvijaju se i napredni oksidacijski procesi koji su se zbog svog neselektivnog ponašanja pokazali učinkovitijim za uklanjanje malih organskih molekula poput farmaceutika čija prisutnost u okolišu više ne iznenađuje. Među raznim vrstama lijekova, svoj put u okolišu, ponajviše kroz otpadne vode pronašli su i lijekovi protiv raka (citostatici) koji zahtijevaju pažnju zbog povećane potrošnje i bioloških učinaka na organizme, već pri niskim koncentracijama. U ovome radu izabrana su dva citostatika, imatinib i krizotinib čija se mogućnost uklanjanja iz vode ispitala kroz sorpcijsku i fotokatalitičku aktivnost primjenom TiO2 fotokatalizatora. Prema mehanizmu fotokatalitičkog procesa, ispitivana komponenta podlijegat će razgradnji ako se prethodno sorbira na katalizator pa se sukladno tome, u prvom nizu eksperimenata proučavao sorpcijski afinitet citostatika prema različitim oblicima TiO2 fotokatalizatora, koristeći nekoliko modela sorpcijskih izotermi. Općenito se, na temelju određene količine sorbirane tvari, ispitala i primjenjivost sorpcije kao jednostavnije i jeftinije metode za uklanjanje imatiniba i krizotiniba iz vode ili kao preteča neke druge oksidacijske metode. Priroda procesa sorpcije, provedenog pri tri različite temperature opisana je promjenom početne koncentracije analita, pH-vrijednosti i ionske jakosti otopine te promjenom mase sorbensa. Visoke vrijednosti regresijskog koeficijenta, R2 upućuju na prikladnost linearne, Freundlichove i Langmuirove izoterme za opisivanje sorpcije citostatika na suspendirani i imobilizirani oblik TiO2. Oba analita pokazuju rastući trend koeficijenta sorpcije s porastom vrijednosti pH u rasponu od 5 do 9 s naglaskom na veću mobilnost imatiniba u slučaju imobiliziranog TiO2. Pozitivna korelacija određena je i između temperature, mase sorbensa i koeficijenta sorpcije, dok je porastom ionske jakosti otopine krizotinib pokazao suprotan trend. Termodinamika sorpcije opisana je kao spontan proces fizikalne prirode koji slijedi kinetiku pseudo-drugog reda. Što se tiče eksperimenata fotokatalize, prvo su se odredile vrijednosti početne koncentracije analita i pH otopine pri kojoj citostatici postižu optimalnu razgradnju, primjenom modeliranja odzivnih površina (RSM). Pri dobivenim uvjetima (pH 5 i 5 mg/L) ispitan je mehanizam fotokatalitičke reakcije, određivanjem radikalskih vrsta odgovornih za razgradnju. Vodeću ulogu u razgradnji imatiniba i krizotiniba pokazali su hidroksilni radikali i singletni kisik. U sljedećim eksperimentima pokazana je važnost provođenja fotokatalize u prisustvu raznih anorganskih i organskih tvari kao sastavnica matice vode koji su većinski usporili razgradnju. Kao i svaki drugi proces razgradnje, fotokataliza imatiniba i krizotiniba također je bila popraćena stvaranjem nusprodukata čije su strukture i putevi razgradnje predloženi korištenjem spektrometrije masa visokog razlučivanja. Potencijalna opasnost razgradnih produkata procijenjena je testom akutne toksičnosti prema morskoj bakteriji Vibrio fischeri, pri čemu je postignuta značajna inhibicija luminiscencije tijekom fotokatalitičke razgradnje krizotiniba u razdoblju od 90. do 180. minute. Kao fotokatalizator koristio se TiO2 imobiliziran na staklene mrežice koji je olakšao samu provedbu eksperimenata pritom misleći na filtriranje uzoraka.The protection and conservation of water resource is a global challenge facing humanity today. In addition to conventional water treatment, advanced oxidation processes are also being developed to non-selectively and efficiently remove small organic molecules such as pharmaceuticals, whose presence in the environment is no longer surprising. Among the different classes of pharmaceuticals, anti-cancer drugs (cytostatics) have also found their way into the environment, mostly through wastewater, which requires attention due to their increased consumption and biological effects, even at low concentrations. In this work, two cytostatics, imatinib and crizotinib, were selected and their ability to be removed from water was tested by sorption and photocatalytic activity with TiO2 photocatalysts. The prerequisite step of the photocatalytic process is the sorption of the tested component on the catalyst, so in the first series of experiments the sorption affinity of cytostatics to different forms of TiO2 was investigated. In addition, based on the studied sorption affinity, the applicability of sorption as a simpler and less expensive method for the removal of imatinib and crizotinib or as a complementary method to some oxidation processes was tested. The nature of the sorption process was described by changing the initial concentration of the analyte, the pH value and the ionic strength of the solution, and by performing experiments at three different ambient temperatures and different sorbent dosages. The suitability of the linear, Freundlich, and Langmuir isotherm models for describing the sorption of cytostatics on the suspended and immobilized forms of TiO2 was indicated by high values of the regression coefficient, R2. Both analytes showed an increasing trend in the sorption coefficient with increasing pH values in the range of 5 to 9, highlighting the greater mobility of imatinib in the case of immobilized TiO2. A positive correlation was also observed between temperature, sorbent mass and sorption coefficient, while the increase in ionic strength of crizotinib solution showed the opposite trend. The thermodynamics of sorption is described as a spontaneous process of physical nature that follows pseudo-second-order kinetics. In the first step of the photocatalytic experiments, the initial concentration of the analyte and the pH of the solution, at which the cytostatic reaches the optimal degradation, were tested using response surface modelling (RSM). Under the conditions obtained (pH 5 and 5 mg/L), the mechanism of the photocatalytic reaction was studied by determining the main radical species involved in the degradation. Hydroxy radicals and singlet oxygen played the main role in the degradation of imatinib and crizotinib. The importance of performing photocatalysis in the presence of various organic and inorganic substances as common components of the water matrix was also demonstrated, since most of them slow down the degradation. Like any other degradation process, photocatalysis of imatinib and crizotinib was accompanied by the formation of by-products, whose structures and degradation pathways were suggested by high-resolution mass spectrometry. The hazard potential of the degradation products was assessed by an acute toxicity assay with the marine bacterium Vibrio fischeri, with significant inhibition of luminescence during photocatalytic degradation of crizotinib over period of 90 to 180 minutes. TiO2 immobilized on glass meshes was used as the photocatalyst, which facilitated the performance of the experiments by avoiding filtering of the samples

Photocatalytic Activity of TiO₂ for the Degradation of Anticancer Drugs

To prevent water pollution, photocatalysis is often used to remove small molecules such as drugs by generating reactive species. This study aimed to determine the photocatalytic activity of two anticancer drugs, imatinib and crizotinib, and to investigate various influences that may alter the kinetic degradation rate and ultimately the efficacy of the process. In order to obtain optimal parameters for the removal of drugs with immobilized TiO2, the mutual influence of the initial concentration of the contaminant at environmentally relevant pH values was investigated using the response surface modeling approach. The faster kinetic rate of photocatalysis was obtained at pH 5 and at the smallest applied concentration of both drugs. The photocatalytic efficiency was mostly decreased by adding various inorganic salts and organic compounds to the drug mixture. Regarding the degradation mechanism of imatinib and crizotinib, hydroxyl radicals and singlet oxygen showed a major role in photochemical reactions. The formation of seven degradation products for imatinib and fifteen for crizotinib during the optimal photocatalytic process was monitored by high-resolution mass spectrometry (HPLC-QqTOF). Since the newly formed products may pose a hazard to the environment, their toxicity was studied using Vibrio fischeri, where the significant luminescence inhibition was assessed for the mixture of crizotinib degradants during the photocatalysis from 90 to 120 min

Influence of Organic Matter on the Sorption of Cefdinir, Memantine and Praziquantel on Different Soil and Sediment Samples

Pharmaceuticals are known for their great effects and applications in the treatment and suppression of various diseases in human and veterinary medicine. The development and modernization of science and technologies have led to a constant increase in the production and consumption of various classes of pharmaceuticals, so they pose a threat to the environment, which can be subjected to the sorption process on the solid phase. The efficiency of sorption is determined by various parameters, of which the physicochemical properties of the compound and the sorbent are very important. One of these parameters that determine pharmaceutical mobility in soil or sediment is the soil–water partition coefficient normalized to organic carbon (Koc), whose determination was the purpose of this study. The influence of organic matter, suspended in an aqueous solution of pharmaceutical (more precisely: cefdinir, memantine, and praziquantel), was studied for five different types of soil and sediment samples from Croatia. The linear, Freundlich, and Dubinin–Raduskevich sorption isotherms were used to determine specific constants such as the partition coefficient Kd, which directly describes the strength of sorbate and sorbent binding. The linear model proved to be the best with the highest correlation coefficients, R2 > 0.99. For all three pharmaceuticals, a positive correlation between sorption affinity described by Kd and Koc and the amount of organic matter was demonstrated

Sorption Potential of Different Forms of TiO2 for the Removal of Two Anticancer Drugs from Water

Anticancer drugs pose a potential risk to the environment due to their significant consumption and biological effect even at low concentrations. They can leach into soils and sediments, wastewater, and eventually into drinking water supplies. Many conventional technologies with more effective advanced oxidation processes such as photocatalysis are being extensively studied to find an economical and environmentally friendly solution for the removal of impurities from wastewater as the main source of these pharmaceuticals. Since it is impossible to treat water by photocatalysis if there is no sorption of a contaminant on the photocatalyst, this work investigated the amount of imatinib and crizotinib sorbed from an aqueous medium to different forms of photocatalyst. In addition, based on the sorption affinity studied, the applicability of sorption as a simpler and less costly process was tested in general as a potential route to remove imatinib and crizotinib from water. Their sorption possibility was investigated determining the maximum of sorption, influence of pH, ionic strength, temperature, and sorbent dosage in form of the suspension and immobilized on the fiberglass mesh with only TiO2 and in combination with TiO2/carbon nanotubes. The sorption isotherm data fitted well the linear, Freundlich, and Langmuir model for both pharmaceuticals. An increasing trend of sorption coefficients Kd was observed in the pH range of 5–9 with CRZ, showing higher sorption affinity to all TiO2 forms, which was supported by KF values higher than 116 (μg/g)(mL/μg)1/n. The results also show a positive correlation between Kd and temperature as well as sorbent dosage for both pharmaceuticals, while CRZ sorbed less at higher salt concentration. The kinetic data were best described with a pseudo-second-order model (R2 > 0.995)