Novel magnetite nanoparticles coated with waste sourced bio- based substances as sustainable and renewable adsorbing materials

This study examines the possibility of using bio-based product isolated from urban solid wastes as a material for environmental technological applications. To this end, Fe3O4 nanoparticles coated with different amounts of soluble bio-based products (SBO) were synthesized as low-cost nanoadsorbent for the removal of pollutants in wastewater. Particles of 10 nm diameter with Fe3O4 core and SBO shell were obtained. The concentration of SBO employed in the synthesis had no effect on the size and structure of the NPs, but ruled the pHPZC and aggregation of the nanoparticles in water. The cationic dye crystal violet (CV) was used as a model pollutant to test the adsorption capacity of the nanoparticles. The results indicated that both the medium pH and NP dosage were significant parameters to enhance the removal of CV. The results contribute to the studies which show how wastes can become a source of revenue through the industrial exploitation of their chemical value.Fil: Magnacca, Giuliana. Università di Torino; ItaliaFil: Allera, Alex. Università di Torino; ItaliaFil: Montoneri, Enzo. Università di Torino; ItaliaFil: Celi, Luisella. Università di Torino; ItaliaFil: Benito, Damián Ezequiel. Universidad Nacional de La Plata. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de La Plata. Laboratorio de Investigación y Desarrollo de Métodos Analíticos; ArgentinaFil: Martire, Daniel Osvaldo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Gonzalez, Monica Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Carlos, Luciano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico la Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

SrCo1−xTixO3−δ perovskites as excellent catalysts for fast degradation of water contaminants in neutral and alkaline solutions

Perovskite-like oxides SrCo1−xTixO3−δ (SCTx, x = 0.1, 0.2, 0.4, 0.6) were used as heterogeneous catalysts to activate peroxymonosulfate (PMS) for phenol degradation under a wide pH range, exhibiting more rapid phenol oxidation than Co3O4 and TiO2. The SCT0.4/PMS system produced a high activity at increased initial pH, achieving optimized performance at pH  ≥ 7 in terms of total organic carbon removal, the minimum Co leaching and good catalytic stability. Kinetic studies showed that the phenol oxidation kinetics on SCT0.4/PMS system followed the pseudo-zero order kinetics and the rate on SCT0.4/PMS system decreased with increasing initial phenol concentration, decreased PMS amount, catalyst loading and solution temperature. Quenching tests using ethanol and tert-butyl alcohol demonstrated sulfate and hydroxyl radicals for phenol oxidation. This investigation suggested promising heterogeneous catalysts for organic oxidation with PMS, showing a breakthrough in the barriers of metal leaching, acidic pH, and low efficiency of heterogeneous catalysis

Photodegradation of 4-chlorophenol sensitized by wastederived soluble organic substances using experimental design

Advanced Oxidation Techniques represent an alternative to more traditional water treatments since they are able to promote the degradation of organic substrates, leading to their complete mineralization. These processes are based on the production of highly reactive species (mainly radicals) and are often light assisted. Among the compounds able to photogenerate reactive species, humic and fulvic acids (HS) have been widely studied in order to understand the water autopurification mechanisms. It is thus in principle possible to propose the use of HS in wastewater photodegradation treatments; however neither waters nor soils can be considered as exploitable source of HS. The organic fraction of urban wastes has been demonstrated to be an interesting source of soluble organic substances (SOS), structurally similar to HS and exhibiting good photosensitizing properties. In the present research the photodegradation of 4-chlorophenol (4-CP), a toxic and hardly biodegradable pollutant, has been studied in the presence of one type of SOS. In order to optimize experimental conditions and to evaluate possible synergistic effects with other photoactive compounds (TiO2 and H2O2) a chemometric approach has been chosen. Two designs of experiments (D-Optimal, DoE) have been planned and the following parameters have been considered: 4-CP concentration (from 10 to 100 mg L-1), SOS concentration (from 0 to 1000 mg L-1), TiO2 concentration (from 0 to 500 mg L-1) or H2O2 concentration (from 0 to 10-2 M), cut-off filter for the light source (340 nm, 400 nm and without filter). By mean of the Modde software, 39 experiments were selected for the TiO2-DoE and 25 experiments for the H2O2-DoE. The resulting response surfaces evidenced that, in the presence of TiO2, a competition for the active photogenerated species seems to take place between 4-CP and SOS, since also SOS can be in turn photodegraded. On the contrary, a synergistic effect between SOS and H2O2 occurs, when the 400 nm cut-off filter is used. After three hours of irradiation 25% of 4-CP abatement was achieved in the presence of 500 mg L-1 of SOS, 35 % was achieved in the presence of 5 mM of H2O2, whereas 45% of 4-CP abatement was obtained in the presence of both SOS and H2O2 at the above mentioned concentrations. These results encourage the use of chemometric tools and give useful information for a possible scale-up of the process in pilot plants exploiting the solar light as radiation sourc

Photodegradation of 4-chlorophenol sensitized by wastederived soluble organic substances using experimental design

Advanced Oxidation Techniques represent an alternative to more traditional water treatments since they are able to promote the degradation of organic substrates, leading to their complete mineralization. These processes are based on the production of highly reactive species (mainly radicals) and are often light assisted. Among the compounds able to photogenerate reactive species, humic and fulvic acids (HS) have been widely studied in order to understand the water autopurification mechanisms. It is thus in principle possible to propose the use of HS in wastewater photodegradation treatments; however neither waters nor soils can be considered as exploitable source of HS. The organic fraction of urban wastes has been demonstrated to be an interesting source of soluble organic substances (SOS), structurally similar to HS and exhibiting good photosensitizing properties. In the present research the photodegradation of 4-chlorophenol (4-CP), a toxic and hardly biodegradable pollutant, has been studied in the presence of one type of SOS. In order to optimize experimental conditions and to evaluate possible synergistic effects with other photoactive compounds (TiO2 and H2O2) a chemometric approach has been chosen. Two designs of experiments (D-Optimal, DoE) have been planned and the following parameters have been considered: 4-CP concentration (from 10 to 100 mg L-1), SOS concentration (from 0 to 1000 mg L-1), TiO2 concentration (from 0 to 500 mg L-1) or H2O2 concentration (from 0 to 10-2 M), cut-off filter for the light source (340 nm, 400 nm and without filter). By mean of the Modde software, 39 experiments were selected for the TiO2-DoE and 25 experiments for the H2O2-DoE. The resulting response surfaces evidenced that, in the presence of TiO2, a competition for the active photogenerated species seems to take place between 4-CP and SOS, since also SOS can be in turn photodegraded. On the contrary, a synergistic effect between SOS and H2O2 occurs, when the 400 nm cut-off filter is used. After three hours of irradiation 25% of 4-CP abatement was achieved in the presence of 500 mg L-1 of SOS, 35 % was achieved in the presence of 5 mM of H2O2, whereas 45% of 4-CP abatement was obtained in the presence of both SOS and H2O2 at the above mentioned concentrations. These results encourage the use of chemometric tools and give useful information for a possible scale-up of the process in pilot plants exploiting the solar light as radiation source

Use of soluble bio-based substances isolated from urban biowastes as organic photocatalysts for the degradation of 4-chlorophenol

Natural organic matter (NOM) present in terrestrial waters and soil is known to contain light-absorbing species capable of promoting photochemical reactions that are considered as the major abiotic pathway for the removal of xenobiotics from natural waters. Recently it has been shown that soluble bio-based substances (SBO) isolated from urban biowastes (UBW) have similar chemical composition and photosensitizing properties as NOM. Since SBO may be obtained from easily available cost-effective sources, their performances as organic photocatalysts have been recently considered and encouraging results have been obtained. Moreover the use of urban wastes as source of bio-based photocatalysts is rather appealing in the context of the current issues of waste management. The present work aims to optimize the photodegradation promoted by SBO of 4-chlorophenol, a priority toxic and hardly biodegradable pollutant. Many aspects of the process have been investigated at the laboratory scale using simulated solar light: the effect of SBO concentration, the operative pH, the degradation mechanism, the main reactive species involved and the toxicity evolution. Moreover the effect of added hydrogen peroxide on 4-chlorophenol degradation rate has been considered, since the presence of iron inside SBO structure let envisage synergistic Fenton-like processes; at this purpose design of experiments (DOE) was choosen as methodologic approach to evaluate the influence of irradiation wavelength, hydrogen peroxide, substrate and SBO concentration on the degradation of 4-chlorophenol. Finally the potential of the SBO-based photochemical process to be feasibly scaled up has been evaluated using a pilot plant working under real sunlight irradiation

Use of soluble bio-based substances isolated from urban biowastes as organic photocatalysts for the degradation of 4-chlorophenol

Natural organic matter (NOM) present in terrestrial waters and soil is known to contain light-absorbing species capable of promoting photochemical reactions that are considered as the major abiotic pathway for the removal of xenobiotics from natural waters. Recently it has been shown that soluble bio-based substances (SBO) isolated from urban biowastes (UBW) have similar chemical composition and photosensitizing properties as NOM. Since SBO may be obtained from easily available cost-effective sources, their performances as organic photocatalysts have been recently considered and encouraging results have been obtained. Moreover the use of urban wastes as source of bio-based photocatalysts is rather appealing in the context of the current issues of waste management. The present work aims to optimize the photodegradation promoted by SBO of 4-chlorophenol, a priority toxic and hardly biodegradable pollutant. Many aspects of the process have been investigated at the laboratory scale using simulated solar light: the effect of SBO concentration, the operative pH, the degradation mechanism, the main reactive species involved and the toxicity evolution. Moreover the effect of added hydrogen peroxide on 4-chlorophenol degradation rate has been considered, since the presence of iron inside SBO structure let envisage synergistic Fenton-like processes; at this purpose design of experiments (DOE) was choosen as methodologic approach to evaluate the influence of irradiation wavelength, hydrogen peroxide, substrate and SBO concentration on the degradation of 4-chlorophenol. Finally the potential of the SBO-based photochemical process to be feasibly scaled up has been evaluated using a pilot plant working under real sunlight irradiatio

Waste Cleaning Waste: Photodegradation of Monochlorophenols in the Presence of Waste-Derived Photosensitizer

Soluble bio-based substances (SBO) have been isolated from urban waste. Their structural similarity with natural organic matter suggested exploring their activity in the photodegradation of organic substrates. In this work, they are shown to promote the photodegradation of monochlorophenols. Experiments performed with 1.0 × 10-4 M substrate solutions irradiated by simulated solar light in the presence of SBO showed the progressive degradation of all the probe substrates. The experimental data were fitted to a pseudo-first-order kinetics, and the rate constant was found to decrease in the following order: 2-chlorophenol > 3-chlorophenol > 4-chlorophenol. The effect of pH and SBO concentration on chlorophenols degradation was assessed. Experiments performed in the presence of selective scavengers along with EPR measurements supported the main role of singlet oxygen in the substrate photodegradation mechanism. Toxicity assays showed that the photodegradation of chlorophenols in the presence of SBO is accompanied with a progressive up to complete detoxification of the system. Moreover, no significant contribution of SBO to the whole system toxicity was observed. The results show how urban wastes can be a resource of photosensitizing bio-based substances to be explored in wastewater treatment