Different outlet for preparing nano-TiO2 catalysts for the photodegradation of Black B dye in water

Two nano-titania catalysts were prepared using two economically varying titanium precursors: titanium tetrachloride (A) and titanium isopropoxide (B). The catalysts were calcined at temperatures of 500 °C, 600 °C and 700 °C and characterized using X-ray diffraction (XRD), electron diffraction (ED), BET surface properties and high resolution transmission microscopy (HRTEM). The calcined catalysts were found to differ markedly in their physical characters and TiO₂ phases produced as well as their photocatalytic activities. The anatase titania phase diminished from 100% to 83% in TiO₂A but from 64% to zero in TiO₂B via temperature increase from 500 °C to 700 °C, due to transforming anatase to rutile. The brookite TiO₂ phase only appeared (17%) in catalyst B500. In general, the catalyst of choice is A600 by virtue of many compositional, economical and catalytic advantages.     

Catalytic para-xylene maximization. Part X: Toluene disproportionation on HF promoted H-ZSM-5 catalysts

H-ZSM-5 zeolite catalysts were doped with 2%, 3% and 4%HF to be used for investigating their activities and selectivities for xylenes production and for para-xylene maximization at temperatures of 300–500 °C via toluene disproportionation. This doping caused pore size modification of the H-ZSM-5 catalyst. The reaction was carried out in a fixed bed flow type reactor. The ratio of produced para-xylene relative to its thermodynamic composition reached as high as 3.29 at 300 °C on the 4%HF doped H-ZSM-5 catalyst although this catalyst possessed the lowest amount of the largest pores (3.0–5.7 nm) and the smallest pores (0.4–1.7 nm). The overall activities of the catalysts were decreased with an increase in HF doping because of diffusion restriction. The kinetics of the reaction were simply treated and found to give E_a and ΔS¹ values compatible with the characterization data of the catalysts.     

Disinfecting efficacy of a plastic container covered with photocatalyst for postharvest

The simplification of the cleaning process of plastic containers used in the storage and/or distribution of fruits or vegetables is important. We coated a plastic container with an apatite-coated titanium dioxide photocatalyst (TiO₂–Ap container), and examined its disinfecting efficacy under UV irradiation from black light. The disinfecting efficacy of the TiO₂–Ap container on diluted drops evaporated from spinach (suspension) was examined. Changes in the microbial populations of the total aerobic bacteria, coliform bacteria, and moulds and yeasts in the TiO₂–Ap container were assayed at 25 °C for 24 h (UV-A intensity of 0.2 and 0.4 mW cm⁻²). The results showed that all of the microbial populations in the TiO₂–Ap container decreased with irradiation time and then reduced to uncountable levels. It was found that the increase in UV-A intensity enhanced the disinfecting efficacy.     

Operating conditions for the electrolytic disinfection of process wash water from the fresh-cut industry contaminated with E. coli o157:H7

The effect of operating conditions (current density, recirculation flow rate and electrode doping level) on the efficacy of boron-doped diamond (BDD) electrodes to inactivate microorganisms and decrease chemical oxygen demand (COD) was studied in lettuce process wash water with a COD of 725 mg/L and inoculated with a 5-strain cocktail of Escherichia coli O157:H7. Changes in pathogen population, COD, pH, temperature, redox potential, and free and total chlorine were monitored in process wash water during treatments. Considering the specific characteristics of the washing step included in the fresh-cut processing, the disinfection of process wash water should be of fast action. A biphasic with a shoulder model was used to estimate shoulder length (Sl), log-linear inactivation rates (k_max1, k_max2), lowest population (N_f) and highest log reduction (HLR). Current density clearly influenced Sl, and k_max2; recirculation flow rate influenced Sl, k_max1, k_max2 and COD depletion; and doping level influenced N_f. No relationship was observed between inactivation parameters and chlorine concentration. Conditions including high current density (180 mA/cm²), high flow rate (750 l/h) and high doping level (8 000 μmol/mol) seems to provide a disinfection efficiency suitable to decrease the chance of bacterial cross contamination in the fresh-cut industries while saving on water consumption and decreasing the amount of wastewater effluents.     

Catalytic performance of organically templated nano nickel incorporated-rice husk silica in hydroconversion of cyclohexene and dehydrogenation of ethanol

Rice husk silica (RHS) was extracted from local rice husk by acid digestion and burning at 650 °C. RHS-Ni catalyst was prepared by dissolving RHS in 1 N NaOH and titrating with 3 N HNO₃ containing 10 wt.% Ni²⁺. The organic modifiers, either p-amino benzoic acid (A) or p-phenylenediamine (PDA) were incorporated in 5 wt.% and reduced in H₂ flow. Investigation of the three catalysts, (RHS-Ni)_R350, (RHS-Ni–A)_R350 and (RHS-Ni–PDA)_R350, confirmed good dispersion of Ni nanoparticles; all catalysts were amorphous. The BET surface areas increased in the order: (RHS-Ni)_R350 < (RHS-Ni–A)_R350 < (RHS-Ni–PDA)_R350 with controlled pore sizes. The as-prepared catalysts were applied for both hydroconversion of cyclohexene with molecular H₂ and ethanol dehydrogenation, using a flow-type reactor, at different temperatures. The activity in cyclohexene hydroconversion and selectivity to cyclohexane depended upon the reaction temperature; at t < 150 °C, the increased hydrogenation activity was referred to the formed SiO₂–Ni–amine complex, pore regulation as a prime requirement for H₂ storage and homogeneous distribution of incorporated Ni nanoparticles. At t > 150 °C, the backward dehydrogenation pathway was more favored, due to unavailability of H₂; the process became structure-sensitive. In ethanol conversion, the prevailing dehydrogenation activity of organically modified catalyst samples was encouraged by improved homogeneous distribution of Ni nanoparticles and created micropre system.     

Catalytic performance of dealuminated H–Y zeolite supported bimetallic nanocatalysts in Hydroizomerization of n-hexane and n-heptane

A series of dealuminated Y-zeolites impregnated by 0.5 wt% Pt catalysts promoted by different amounts of Ni, Pd or Cr (0.3 and 0.6 wt%) were prepared and characterized as hydrocracking catalysts. The physicochemical and structural characterization of the solid catalysts were investigated and reported through N₂ physisorption, XRD, TGA-DSC, FT-IR and TEM techniques. Solid catalysts surface acidities were investigated through FT-IR spectroscopy aided by pyridine adsorption. The solid catalytic activities were evaluated through hydroconversion of n-hexane and n-heptane employing micro-catalytic pulse technique directly connected to a gas chromatograph analyzer. The thermal stability of the solids was also investigated up to 800 °C. Crystallinity studies using the XRD technique of all modified samples proved analogous to the parent Y-zeolite, exhibiting nearly an amorphous and microcrystalline character of the second metal oxides. Disclosure of bimetallic catalysts crystalline characterization, through XRD, was not viable. The nitrogen adsorption–desorption isotherms for all samples concluded type I adsorption isotherms, without any hysteresis loop, indicating that the entire pore system is composed of micropores. TEM micrographs of the solid catalysts demonstrate well-dispersed Pt, Ni and Cr nanoparticles having sizes of 2–4 nm and 7–8 nm, respectively. The catalytic activity results indicate that the bimetallic (0.5Pt–0.3Cr)/D18H–Y catalyst is the most active towards n-hexane and n-heptane isomerization while (0.5Pt–0.6Ni)/D18H–Y catalyst can be designed as most suitable as a cracking catalyst.     

Trace element levels of mushroom species from East Black Sea region of Turkey

The levels of trace metals of mushroom samples collected from East Black Sea region of Turkey were determined by flame and graphite furnace atomic absorption spectrometry after microwave digestion method. The accuracy of the method was corrected by standard reference material (NIST SRM 1573a Tomato Leaves). The contents of investigated trace metals in mushroom samples were found to be in the range of 18.9–64.8 μg/g for copper, 53.5–130 μg/g for manganese, 44.7–198 μg/g for zinc, 187–985 μg/g for iron, 0.54–10.8 μg/g for selenium and 0.9–2.5 μg/g for cadmium. Mushrooms species in the highest levels of trace elements were found Entoloma sinuatum for Cu and Zn, Leucoagaricus leucothites for Mn, Amanita pantherina for Fe and Se, Agaricus arvensis for Cd.     

HPLC determination for prostaglandins from seaweed Gracilaria gigas

Seaweed (Gracilaria gigas) is an edible red alga and occasionally induces food poisoning cases. Prostaglandin E₂ (PGE₂) has been reported to be possible causative agent. In this study, a simple, sensitive, rapid and accurate HPLC method was developed for quantifying prostaglandins in seaweed. The mobile phase was gradient acetonitrile (35–60%) and 0.017 M phosphoric acid at flow rate of 1 mL/min within 30 min. The standard curves of prostaglandins were extremely linear (R² > 0.999) with low correlation coefficients (less than 4.7) in the range of 5–50 μg/mL. To obtain maximum prostaglandins amount, the optimal ratio of seaweed (wet weight) to arachidonic acid was 10 g:2 mg and oxygen was needed in reaction.     

Effect of packaging and storage conditions on quality of shelled walnuts

The present study investigated the effect of packaging and storage conditions on quality of raw shelled walnuts. Walnut kernels were packaged in: (a) low density polyethylene (LDPE), 55 μm in thickness in air, (b) polyethylene terephthalate||polyethylene (PET||PE), 70 μm in thickness under N₂, and (c) PET-SiO_x||PE pouches, 62 μm in thickness under N₂. Samples were stored either under fluorescent light or in the dark at 4 or 20 °C for a period of 12 months. Quality parameters monitored were peroxide value (PV), hexanal, 2-thiobarbituric acid (TBA), odor, and taste of product. PV ranged between 0.3 for fresh walnut kernels and 31.4 meq O₂/kg oil for walnuts packaged in PE pouches exposed to light after 12 months of storage. Respective values for hexanal were <28.5 μg/kg and 36.0 mg/kg and for TBA ca. 0.2 and 11 mg MDA/kg. Values for odor ranged between 0.2 for fresh walnut kernels and 5.7 for walnut kernels packaged in PE exposed to light after 12 months of storage at 20 °C. Respective values for taste were 0.7 and 6.8. Taste proved to be a more sensitive attribute than odor. Based on shelf life (taste) values and PV data it is proposed that the upper limit value for PV is close to 10.0 meq O₂/kg walnut oil. Respective limit values for hexanal are 1–2 mg hexanal/kg walnut and for TBA is 1–2 mg malondialdehyde/kg walnut. Walnuts retained acceptable quality for ca. 2 months in PE-air, 4–5 months in PET||PE-N₂ and at least 12 months in PET-SiO_x||PE-N₂ pouches at 20 °C, with samples stored in the dark retaining slightly higher quality than those exposed to light. The effect of parameters investigated followed the sequence: temperature > degree of O₂ barrier > lighting conditions.     

Simultaneous determination of melamine and cyanuric acid in dairy products by mixed-mode solid phase extraction and GC–MS

This report described a method for simultaneous determination of cyanuric acid (CYA) and melamine (MEL) in dairy products. The samples were extracted by a mixture of acetonitrile/water and cleaned by graphite carbon/strong cation exchange (CARB/SCX) mixed-mode solid phase extraction column. The CYA and MEL were derivatized with bis(trimethylsily1)trifluoroacetamide (BSTFA) containing 1% Trimethylchlorosilane (TMCS), and quantified with the internal standards of ¹⁵N₃-cyanuric acid and ¹³C₃-melamine by GC–MS. The results indicated that CARB/SCX mixed solid phase extraction column could be used for sample pretreatment. The fortification recoveries were 80.8–101.5%, and the relative standard deviations (RSDs) were 3.6–7.9%. The detection limits of CYA and MEL were 0.025 mg kg⁻¹ and 0.01 mg kg⁻¹ respectively.     

Non-thermal inactivation of Escherichia coli K12 in buffered peptone water using a pilot-plant scale supercritical carbon dioxide system with a gas–liquid porous metal contactor

This study evaluated the effectiveness of a supercritical carbon dioxide (SCCO₂) system, with a gas–liquid porous metal contactor, for reducing Escherichia coli K12 in diluted buffered peptone water. 0.1% (w/v) buffered peptone water inoculated with E. coli K12 was processed using the SCCO₂ system at CO₂ concentrations of 3.1–9.5 wt%, outlet temperatures of 34, 38, and 42 °C, a system pressure of 7.6 MPa, and a flow rate of 1 L/min. Increased CO₂ concentrations and temperatures significantly (P < 0.05) enhanced microbial reduction. A maximum reduction of 5.8-log was obtained at 8.2% CO₂ and 42 °C. To achieve a 5-log reduction of E. coli K12 in 0.1% buffered peptone water, minimum CO₂ concentrations of 9.5%, 5.5%, and 5.3% were needed at 34, 38, and 42 °C, respectively. Further reductions of cells were observed after storage for 7 days at 4 °C. But storage at 25 °C increased the number of viable cells to 8-log cfu/mL after 7 days. This study showed the potential of the pilot scale SCCO₂ system with a gas–liquid porous metal contactor for microbial inactivation in liquid food.     

Aflatoxin M1 in raw milk in Croatia

In this study the levels of aflatoxin M₁ (AFM₁) of 61 milk samples delivered from small milking farms were determined in January, February, March and April (winter–spring season), and June, July and September (summer–autumn season) of 2009. The AFM₁ concentration was determined by competitive enzyme-immunoassay method. The maximum mean concentrations of AFM₁ recorded in winter–spring season were in the range of 35.8–58.6 ng/l and in summer–autumn season in the range of 11.6–14.9 ng/l. The AFM₁ levels determined in January, February, March and April were significantly higher in accordance with concentration of AFM₁ in June, July and September (P < 0.05 to P < 0.0001, respectively). Also, there was significant difference (P < 0.0001) between the mean concentrations of AFM₁ in samples taken all together in winter–spring and summer–autumn season. Only in one sample delivered in February the level of AFM₁ was higher than the maximum tolerance limit (50 ng/l). Therefore, it was concluded that in 98.4% of milk samples in Croatia the levels of AFM₁ were below maximum tolerance level accepted by the European Union.     

Some positive effects of introducing Pt4+ and Fe3+ to the MnMo-oxide anode deposited on IrO2/Ti substrate for best oxygen evolution efficiency during electrolysis in 0.5 M NaCl solution

NaCl solution (0.5 M) of pH 2 was electrolyzed at 1000 Am^?2 at room temperature. Addition of Pt⁴⁺ and Fe³⁺ to the prepared MnMo-oxide anode deposited on IrO₂/Ti substrate, significantly improves the performance of anode for the oxygen evolution reaction (OER) during NaCl electrolysis. After 2000 h of electrolysis, the oxygen evolution efficiency (OEE) is in the order of MnMoPt-oxide > MnMoFe-oxide > MnMo-oxide anodes with 100%, 99%, and 93.2% OEE, respectively. The loss in weight of MnMo-oxide is reduced from about 13% to 3.2% and 0.0% by addition of iron and platinum cations, to the deposition electrolyte. The mean average grain size of MnO₂, MnMo-, MnMoFe- and MnMoPt-oxide deposits prepared in electrolytes of pH 0.0 are in the range of 25.5, 16.22, 13.5 ～ 16.5 and 13 ～ 17.5 nm, respectively. The physicochemical properties of the deposits were characterized using X-ray diffraction spectroscopy (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and electrochemical techniques. EDX analysis illustrates that IrO₂/Ti is stable during the deposition process and behaves only as conductive substrate. SEM illustrates that, all elements constituting MnMoPt- and MnMoFe-oxide deposits are homogeneously distributed in the oxide surface.     

Effect of ozonation combined with heterogeneous catalysts and ultraviolet radiation on recycling of gas-station wastewater

Ozonation is extensively applied in the treatment of drinking water and wastewater due to the powerful oxidation potential of ozone. Heterogeneous catalytic ozonation (HCO) of wastewater proceeds through hydroxyl radicals as the oxidation species. The effect of ozonation alone and combined with catalysts in the presence and absence of UV-radiation was investigated to reuse the biologically pretreated gas-station wastewater instead of fresh water. Two types of catalysts: titanium dioxide (TiO₂) and activated carbon (AC) were studied. The concentration of catalyst, dark adsorption, reaction time and the improvement of biodegradability were studied. The combination of catalysts and ozonation reveals a significant improvement in the removal of contaminants present in wastewater by using the ozonation, adsorption or photocatalysis systems. Maximum dissolved organic carbon (DOC) removal of 91% was achieved by the combination of ozone, TiO₂ and the UV-radiation system. But, an increase in biodegradability from 0.12 to 0.33 was realised with ozone and the TiO₂ system. Furthermore, the biodegradability was increased with increasing catalyst concentration combined with ozone up to 1 g/L with TiO₂ and 0.5 g/L with AC.     

Mycotoxin occurrence in corn meal and flour traded in São Paulo,Brazil

In the present study, 60 samples of corn meal and flour traded in São Paulo were analysed for determination of aflatoxins and fumonisins B₁ (FB₁) and B₂ (FB₂). No aflatoxin was found in samples of both products. In corn meal, the concentrations of FB₁ and FB₂ ranged from 1.1 to 15.3 mg kg⁻¹ (mean: 5.2 mg kg⁻¹) and 0.2 to 3.9 mg kg⁻¹ (mean: 1.0 mg kg⁻¹), respectively. Corn flour presented lower levels of FB₁ (0.5–7.2 mg kg⁻¹; mean: 2.1 mg kg⁻¹) and FB₂ (0.1–1.8 mg kg⁻¹; mean: 0.7 mg kg⁻¹). Considering the average values of FB₁ found in corn meal samples, as well as food consumption estimates in Brazil, the worst case of FB₁ consumption would be 2.9 μg kg body weight⁻¹ per day. Results indicate the need for the adoption of practices to control the occurrence of fumonisins by manufacturers of corn products, mainly in corn meal.     

Characterization and catalytic activity of NiO/mesoporous aluminosilicate AlSBA-15 in conversion of some hydrocarbons

Mesoporous aluminosilicate AlSBA-15 was synthesized and adopted as a support for NiO with 3, 6 and 9 wt.% loadings. Characterization of various samples was performed through XRD, FTIR, DSC-TGA, TPR, SEM and TEM techniques. Textural and morphological characteristics were examined using N₂ adsorption–desorption isotherms. Catalytic activities were measured in cumene cracking for parent AlSBA-15 and in n-hexane and toluene cracking and cyclohexane dehydrogenation for supported NiO samples. Uniformity of the ordered 2D-hexagonal structure of AlSBA-15 was evident even after loading with NiO. NiO and NiOOH phases could be detected particularly in the sample containing 9 wt.% NiO. TPR profile of solid loaded with 3 wt.% NiO sample showed negative peaks at 400 and 600 °C, related to hydrogen spillover on reduced sample. Selectivity towards n-hexane and toluene cracking increased with both temperature and metal oxide loading, achieving 100% at 350 °C. In cyclohexane dehydrogenation, the sample loaded with 3 wt.% NiO was the most active and selective one towards benzene formation.     

Presence of aflatoxin M1 in milk and infant milk products in Tehran,Iran

Aflatoxins are highly toxic, mutagenic, teratogenic and carcinogenic compounds. The purpose of this survey was to determine natural occurrence and level of AFM₁ in pasteurized liquid milk, infant formula and milk-based cereal weaning food consumed in Tehran, Iran.A total of 328 branded milk products and liquid milk samples were collected and investigated by Enzyme Linked Immuno Sorbent Assay (ELISA).The samples of pasteurized liquid milk (n = 128), infant formula (n = 120) and milk-based cereal weaning food (n = 80) showed that the incidence of contamination with AFM₁ is 96.3%, the presence of AFM₁ in each group was 72.2 ± 23.5, 7.3 ± 3.9 and 16.8 ± 12.5 ng/kg, ranging between 31–113, 1–14 and 3–35 ng/kg, respectively.In general, the amount of AFM₁ in 100 (78%) of liquid milk samples and 24 (33%) of milk-based weaning food was higher than the maximum tolerance limit accepted by European Union, but in all of the infant formula samples was lower (European Communities and Codex Alimentarius has prescribed a limit of 50 ng/kg for AFM₁ in milk and 25 ng/kg in infant milk products).     

A rapid FT-NIR method for estimation of aflatoxin B1 in red chili powder

The feasibility of measuring Aflatoxin B₁ (AFB₁) in red chili powder was investigated by using Fourier transform near-infrared (FT-NIR) spectroscopy in diffuse reflectance mode combined with appropriate chemometric techniques. Aflatoxin free chili powder samples were spiked with known amount of AFB₁ ranging from 15 to 500 μg/kg and used for calibration model building based on partial least squares (PLS) regression algorithm. Different spectral preprocessing methods were investigated and optimized based on the lowest values of root mean square error of cross validation (RMSECV). Spectral wavenumber range of 6900.3–4998.8 and 4902.3–3999.8 cm^?1 and straight line subtraction preprocessing technique predicted AFB₁ content with best accuracy with lowest RMSECV = 0.654% and maximum correlation coefficient for validation plots (R² = 96.7). The overall results demonstrate that FT-NIR spectroscopy can be used for rapid, non destructive quantification of Aflatoxin B₁ in red chili powder.     

Upgrading of coker distillate under variable hydrotreating operating conditions

Studies on hydrotreating coker distillates, produced from a delayed coker unit were done using a commercially available CoMo/γ-Al₂O₃ catalyst, on which 0.2 wt% P₂O₅ was added in order to improve its characteristics. The experimental studies were conducted in a fixed-bed continuous-reactor (cata-test unit) at temperatures (300–400 °C) and total hydrogen pressure (40–65 bar). These conditions have affected the feedstock characteristics and great reduction of sulfur, aromatics and boiling ranges. Other improvements were obtained in diesel index (DI) due to hydrogenation reaction of aromatics and desulfurization of its sulfur contents.     

In vitro control of growth and ochratoxin A production by butylated hydroxyanisole in Aspergillus section Nigri species

This study was carried out to determine the efficacy of phenolic antioxidant butylated hydroxyanisole (BHA) under different interacting water activity (a_W) and temperature regimes on the lag phase and growth rate by Aspergillus section Nigri strains. In this experiment four A. section Nigri strains were used. Peanut meal extract agar (PMEA) was prepared at 2%. The a_W of the medium was adjusted to 0.995, 0.980 and 0.930, BHA at 1, 5, 10 and 20 mmol l^?1 was added to the basic medium. The plates were inoculated and incubated for 30 days at 18 and 25 °C. Radial growth rates (mm d^?1) and lag phase (h) were calculated. In control treatments, the growth rate decreased as water activity reduced in all strains assayed. At all a_W levels tested, BHA at 20 mmol l^?1 completely inhibited growth. In general, at 10 mmol l^?1 and 0.995 and 0.980a_W level, a significant reduction respect to control was observed. This antioxidant completely inhibited OTA production, at concentrations of 20 mmol l^?1, regardless of a_W used by all the strains evaluated.