Concentration of phthalates in the environment has been steadily increasing due to their high utilization rate and the inability of conventional wastewater and water treatment to remove them. Electrochemical oxidation at Boron doped diamond (BDD) was effective for phthalate removal but costly and unaffordable in many situations. Hence, we carried out the electrochemical oxidation of Diethyl Phthalate (DEP) at two dimensional graphite electrodes as a low cost alternative to oxidation at BDD electrodes. Optimization studies found that high concentrations of DEP (56-112 mg/L) can be effectively removed from water with acidic pH (pH 3), 60 mA/cm 2 current density, 81 cm 2 anode surface area and 10 mM sodium sulfate with 60 min treatment time. At 56 mg/L DEP concentration, COD and TOC removal were 92.5% and 70% respectively. FTIR studies were conducted to nd out whether any adsorption or electrosorption had taken place at the electrode surface. High performance liquid chromatography-photo diode array (HPLC-PDA) analysis of 84 mg/L DEP solution treated at optimal conditions found 97.3% removal of DEP. High resolution mass spectrometry (HRMS) studies utilizing Ultra performance liquid chromatography quadrupole time of ight mass spectrometry (UPLC-Q-ToF-MS) were conducted for nding the degradation byproducts and possible degradation pathway was proposed with the degradation mechanism.
Surface-modified diatom substrates are employed for the development of immunocomplex-based optical biosensor for diagnosis of typhoid. Biosensor has been prepared by covalent immobilization of Salmonella typhi antibody onto the crosslinked diatom substrates via glutaraldehyde. Photoluminescent (PL) studies revealed good specificity and ability of conjugated diatom substrates to distinguish complementary (S. typhi) and non-complementary (Escherichia coli) antigens. The immunocomplexed biosensor showed detection limit of 10 pg. The excellent performance of biosensor is associated to its large surface-to-volume ratio, good photoluminescent property, and biocompatibility of diatom frustules, which enhances the antibody immobilization and facilitates the nucleophilic electron transfer between antibody and conjugated diatom surface. Hence, immunocomplexed diatom substrates are considered to be a suitable platform for the environmental monitoring of water-borne pathogen S. typhi.
Listeria monocytogenes is a Gram positive ubiquitous psychrotrophic bacterium responsible for foodborne infections worldwide. L. monocytogenes is capable of growing at refrigeration temperatures in high salt and acid foods. In this study a response surface methodology was used to determine the effects and interactions of pH (4 to 10), temperature (4 ºC to 40 ºC) and ozonation time (5 seconds to 60 seconds) on the inactivation of L. monocytogenes strains ATCC 19115. The models were validated on Phosphate buffered saline inoculated with L. monocytogenes (10 8 CFU/mL) using a batch reactor. According to the study, the optimum pH and the temperature for the total inactivation of L. monocytogenes falls in the range of 4.5-7.5 and 4˚C-15˚C respectively. Analysis of Variance showed that the coefficient determination value (R 2 ) of L. monocytogenes inactivation was 0.9429. The study concluded that a 7 log reduction of L. monocytogenes can be successfully achieved by ozone exposure between 33 seconds and 49 seconds.
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