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Photo-Degradation of Some Dyes using Ag-Loaded Titaniumdioxide

The photocatalytic degradation of organic dyes using TiO2 andsilver-loaded TiO2 has beenstudied. The dyes which were chosen (methyl violet, a cationicdye; Cibacron Blue FMR, areactive dye; and Maxilon Red GRL, a mono azo basic dye)represent the major structuralfamilies of organic dyes. Ag-loading dramatically reduceddegradation time. While theundoped TiO2 degraded about 63% of the total amount ofmethyl violet within 4 min,degradation rose to 95% with Ag-loaded TiO2 within the sametime period. The photo-decomposition of dyes was monitored as a function of pH anddissolved organic and inorganic matters.

Photocatalytic disinfection of Giardia intestinalis and Acanthamoeba castellani cysts in water

In this study, disinfection of water containing Giardia intestinalis and Acanthamoeba castellani cysts with TiO2 and modified catalyst silver loaded TiO2 (Ag-TiO2) was investigated. Destruction of the parasites was evaluated after UV illumination of the suspension consisting 5 x 10(8)-13.5 x 10(8)cysts/mL in the presence of 2g/L neat or modified TiO2 at neutral pH. In the initial stage, the solid photocatalyst particles penetrated the cyst wall and then oxidant species produced by TiO2/UV destroyed both cell wall and intracellular structure. In the case of G. intestinalis inactivation (disinfection) performance of TiO2/UV system reached 52.5% only after 25 min illumination and total parasite disinfection was achieved after 30 min illumination. However, silver loaded TiO2 seemed to be more effective as this loading provided better catalytic action as well as additional antimicrobial properties. Cell viability tests showed that parasite cysts, their walls in particular, were irreversibly damaged and cysts did not re-grow. Nevertheless the studied system seemed to be ineffective for the inactivation of A. castellani. Inactivation percentages of TiO2/UV and Ag-TiO2/UV systems were far lower than that of UV alone, being 50.1% and 46.1%, respectively.

Seasonal changes in antioxidant activity, total phenolic and anthocyanin constituent of the stems of two Morus species (Morus alba L. and Morus nigra L.)

Seasonal changes of antioxidant activity, total phenolic and anthocyanin constituent of Morus nigra L. and Morus alba L. stems were investigated. Stems tissues of these species exhibited different antioxidant activity. Antioxidant action as well as anthocyanin constituents of these species reached the highest value in October whereas the lowest in February. Also, total phenolic constituents showed the similar pattern.

A new nano-TiO2 immobilized biodegradable polymer with self-cleaning properties

This study concentrated on the direct immobilization of anatase nano titanium dioxide particles (TiO(2), 10nm particle size) into or onto a biodegradable polymer, polycaprolactone, by solvent-cast processes. The self-cleaning, namely photocatalytic properties of the produced materials were tested by photocatalytic removal of methylene blue as model compound and antimicrobial properties were investigated using Candida albicans as model microorganism. Produced TiO(2) immobilized polymer successfully removed methylene blue (MB, 1 × 10(-5)M) from aqueous solution without additional pH arrangement employing a UV-A light (365 nm) source. Almost 83.2% of dye was removed or decomposed by 5 wt% TiO(2) immobilized into PCL (0.08 g) and removal percentage reached to 94.2% with 5 wt% TiO(2) immobilized onto PCL after a 150 min exposure period. Although removal percentage decrease with increased ionic strength and usage of a visible light source, produced materials were still effective. TiO(2) immobilized onto PCL (5 wt%) was quite effective killing almost 54% of C. albicans (2 × 10(6)CFU/mL) after only 60 min exposure with a near visible light source. Control experiments employing PCL alone in the presence and absence of light were ineffective under the same condition.

Antioxidant and Antimicrobial Properties of the Lichens Cladonia foliacea., Dermatocarpon miniatum., Everinia divaricata., Evernia prunastri., and Neofuscella pulla.

Abstract The aim of this study was to investigate in vitro. antimicrobial and antioxidant activities of the methanol extracts of Cladonia foliacea. Willd. Hudson, Dermatocarpon miniatum.(L.) Mann., Everinia divaricata. (L.) Ach., Evernia prunastri. (L.) Ach., and Neofuscella pulla. (Ach.) Essl. Antioxidant activity was evaluated by two separate methods: scavenging of free radical DPPH and the inhibition of linoleic acid oxidation. Extracts of C. foliacea., E. divaricata., E. prunastri., and N. pulla. did not exert any activity in both assays, whereas those of D. miniatum. provided 50% inhibition at 396.1 µg/ml concentration in the former and gave 49% inhibition in the latter. Total phenolic constituents of extracts from lichen species tested (C. foliacea., D. miniatum., E. divaricata., E. prunastri., and N. pulla.) were 1.7% (w/w), 2.9% (w/w), 3.0% (w/w), 2.6% (w/w), and 1.5% (w/w), respectively (as gallic acid equivalent), implying that the observed activity could be related to the amount of polar phenolics. Extracts were also found to possess antimicrobial activity against some of the bacteria and fungi tested, but no activity was observed against the yeasts.

Photocatalytic oxidative degradation of 2-methylthiophene in suspensions of TiO2: identification of intermediates and degradation pathways

Abstract The photocatalytic oxidative degradation of 2-methylthiophene has been investigated in aqueous suspensions of TiO2. The nature of the degradation products was investigated using GC/MS. The effects of the nature of the solvent and type of radiation have also been examined. In the degradation of 2-methylthiophene several intermediates were detected including hydroxythiophenes, various dimeric and trimeric structures.

Ultrasonic Leaching of Bio-Collectors for Heavy Metal Analysis

Abstract A Bio Collector - Ultrasonic Leaching Method (BC-ULM) was developed for the analysis of heavy metals (Pb, Cd,Cr, Ni, Cu, Fe and Al) on plant sprouts for the assessment of environmental pollution. Fabaceae Rabinia Pseudoacacia L. and Pinaceae Pinus Sylvertris L. sprouts were chosen as bio-collectors. The bio-collector sprouts were leached using 1% HNO3 solution under ultrasonic effect and the obtained leachate samples were analysed by atomic absorption spectrometry (AAS). The accuracy of BC-ULM was tested by comparing obtained results with those of deposition plate (DPM) and ashing (AM) methods which both are of practical use. Our findings show that BC-ULM and AM results are in agreement. Average heavy metal pollution factors of BC-ULM and DPM are well comparable with each other. Maximum and minimum heavy metal polluted stations were determined with no difference at all for all three methods. The average RSD % of BC-ULM varied between 5.5–8.4 % for n=13, depending on the analyte and the nature of the sample. Again, average RSD % was obtained between 1.7–8.0 % (n=9) and 3.4–9.8 % (n=11) for AM and DPM, respectively. The precision variance between BC-ULM and AM was not significant at 0.05 probability for all metals except copper.

Antitumoral and antioxidant effect of essential oils and in vitro antioxidant properties of essential oils and aqueous extracts from Salvia pisidica

The aim of the work was to investigate antitumoral effect of essential oils on cancer cells and their possible protective (antioxidant) effects against hydrogen peroxide-induced cytotoxicity. Also, in vitro antioxidant properties of essential oils and aqueous extracts from wild form and cultivated form of Salvia pisidica were compared.We found out that essential oils from wild form (IC50 128, and 85.17 μg /mL) and cultivated form (IC50 115.00 and 74.83 μg/mL) differed in their antitumoral effects on Hep G2 and H1299 cells respectively. As a very important we consider the finding that both essentials oils significantly reduced the cytotoxicity induced by the strong oxidant in cancer cells. We assume that protective effect of essential oils on cancer cells against H2O2 cytotoxicity can be accompanied by their antioxidant action.Antioxidant properties of essential oils and aqueous extract from wild and cultivated S. pisidica were determined by different test systems. In DPPH assay, the weakest radical scavenging activity was exhibited by the aqueous extract from wild form (66.55 ± 1.15 μg/mL). Similarly inhibition of linoleic acid oxidation of aqueous extract from wild and cultivated form (50.93% and 59.66%) was lower than essential oils. In the case of reducing power assay and hydroxyl radical scavenging activity, a similar activity pattern was observed as given in the first two systems. Essential oils from wild and cultivated form had higher reducing power activity (EC50; 100.99 ± 3.0 and 96.87 ± 3.15 μg/mL) and hydroxyl radical scavenging activity (EC50; 15.99 ± 0.95 and 13.01 ± 1.35 μg/mL) than aqueous extracts.

Phenolic Contents and Antioxidant Potential of Crataegus Fruits Grown in Tunisia as Determined by DPPH, FRAP, and β-Carotene/Linoleic Acid Assay

Crataegus fruit is one of most important fruits in Tunisian flora. Some fruits of this genus are edible. This study was undertaken in order to examine the benefits of these fruits in human health and their composition of antioxidants including total polyphenol, flavonoids, proanthocyanidins content, and total anthocyanins. The antioxidative properties of the ultrasonic methanolic extract were assessed by different in vitro methods such as the FRAP, DPPH, and β-carotene/linoleic acid assay. We concluded that peel fraction of red fruits possessed relatively high antioxidant activity and might be a rich source of natural antioxidants in comparison with the pulp and seed fruit extract. The results also showed that hawthorn yellow fruit presents lower amounts of phenolic content, absence of anthocyanins, and less antioxidant capacity. Most of peel and seed fractions were stronger than the pulp fractions in antioxidant activity based on their DPPH IC50, FRAP values, and results of β-carotene/linoleic acid. The total phenolic compounds contents were also highly correlated with the DPPH method and the FRAP assay.

Evaluation of the Chemical Composition and Antioxidant Activity of the Peel Oil of Citrus nobilis

Peel oil of Citrus nobilis (Lour) was analyzed for determining its chemical composition. Fourteen identified components accounted for 99.1% (GC) and 100.0% (FID) of the total oil. Major component of the oil was limonene (76.8%-GC and 86.2%-FID). Essential oil was also evaluated for its antioxidant activity in four complementary test systems namely; β-carotene/linoleic acid, DPPH radical scavenging, reducing power and metal chelating activities. In the first system, antioxidant activity increased with the increasing concentration. At 20.0 mg.ml−1 concentration, antioxidant property of the oil was 96.8% ± 0.2 and as strong as the positive controls BHT and α-tocopherol. Scavenging effect of the oil was superior to the positive controls BHT and α-tocopherol at 1.5 mg.ml−1 concentration (96.4% ± 0.1). Reducing power and chelating effect of the essential oil increased with the increasing concentration.