Efficacy of ultraviolet radiation and hydrogen peroxide oxidation to eliminate large number of pharmaceutical compounds in mixed solution

Ultraviolet photolysis and ultraviolet and hydrogen peroxide oxidation of fourteen commonly used pharmaceutical compounds and two personal care products in mixed solution using low pressure ultraviolet lamp was investigated in laboratory batch experiments. Removal of the compounds followed the first-order reaction kinetic. Three distinct impacts of hydrogen peroxide on ultraviolet and hydrogen peroxide oxidation of the compounds [positive, negative and no significant effect] were observed. Removal behavior of the several tested compounds in mixed solution varied significantly than their respective behavior in absence of coexisting compounds. Clofibric acid, diclofenac, fenoprofen, isopropylantipyrine, ketoprofen, phenytoin and triclosan were removed very efficiently [> 96%] by ultraviolet photolysis alone. Residual hydrogen peroxide during ultraviolet and hydrogen peroxide oxidation was quantitated for the first time. Hydrogen peroxide addition to ultraviolet photolysis was not worthy for majority of the tested compounds as their removal did not increase significantly and very big fractions [> 85%] of the added hydrogen peroxide [0.29 - 1.47 mM] remained unused presumably due to small fluence of the lamp, very small molar absorption for hydrogen peroxide at 254 nm [27.06 /M.cm] and acidic pH of reaction solution [< 5.7]. Further exploration on ultraviolet and hydrogen peroxide oxidation with higher fluence lamp and alkaline solution pH will clarify usefulness of the method to treat pharmaceutical contaminated waters

Degradation of common pharmaceutical and personal care products in mixed solutions by advanced oxidation techniques

Widespread detection of pharmaceutical compounds in water environment has been a serious concern recently, while conventional sewage treatments are ineffective for their elimination. But, advanced oxidation techniques are very promising to remove varieties of organic contaminants in water. This research aims to elucidate oxidation potentials of sixteen commonly used pharmaceutical compounds in mixed solutions by seven advanced oxidation techniques in laboratory batch experiments. The removal profiles exhibited four distinct patterns: a] easily degradable by all seven techniques, b] not easily degradable by all seven techniques, c] easily degradable by ozone-based techniques, but not by ultraviolet radiation-based techniques and d] easily degradable by ultraviolet radiation-based techniques, but not by ozone-based techniques. Ozone-based techniques rather than ultraviolet radiation-based techniques were very powerful for simultaneous removal of the compounds efficiently. Moreover, ozonation combined with ultraviolet radiation was the most appropriate technique for simultaneous removal of the tested compounds efficiently. Increased ozone dissolution and decomposition with ozone-based techniques did not always enhance the compounds' removal. Physicochemical properties of the compounds and solution pH also presumably played an important role on the removal which merits further attention

Photocatalytic ozonation of 2, 4-dichlorophenoxyacetic acid in water with a new TiO2fiber

More effective techniques are required to mineralize the increasing number of recalcitrant organic contaminants at low concentrations in the water environment using advanced oxidation process. Though relatively new, photocatalytic ozonation [O3/UV/TiO2] is considered superior to ozonation [O3] and photocatalysis [UV/TiO2], due to synergistic effects and use of immobilized TiO2 photocatalysts is a milestone in advance oxidation process. This article aimed to elucidate 2, 4-dichlorophenoxyacetic acid [2, 4-D] mineralization characteristics in low aqueous solutions by O3/UV/TiO2 using the world's first high-strength TiO2 fiber catalyst in laboratory experiments. 2, 4-D degradation and TOC removal in O3, UV/TiO2 and O3/UV/TiO2 followed pseudo-first order reaction kinetic. The removal rates for 2, 4-D and TOC in O3/UV/TiO2 were respectively about 1.5 and 2.4-fold larger than the summation of the corresponding values in O3 and UV/TiO2. The O3/UV/TiO2 process was characterized by short-lived few aromatic intermediates, faster degradations of aliphatic intermediates and dechlorination as a major step in 2, 4-D mineralization. The significantly enhanced 2, 4-D mineralization in the process was attributed to increased ozone decomposition and reduced electron-hole recombination on TiO2 surface resulting to a large number of .OH generation. The O3/UV/TiO2 process with the TiO2 fiber catalyst was very promising with respect to the major challenges being faced in AOP involving TiO2, namely separation of powder catalyst in suspension and reduced efficiency of immobilized catalysts [e.g. TiO2 film/fiber]

Endogenous phospholipid acceptor for serine-phospholipid base-exchange reaction in rabbit platelet membranes

The endogenous phospholipid acceptor for Ca2+-dependent serine-phospholipid base-exchange reaction was explored in rabbit platelet membranes. When chasing experiments were carried out using prelabeled membranes, cold serine chased labeled serine and ethanolamine, but not labeled choline from corresponding phospholipids. This indicates that phosphatidylserine [PS] and phosphatidylethanolamine [PE] are at least utilized as phospholipid acceptors for serine base-exchange reaction, although it is not certain whether phospha-tidylcholine [PC] is utilized. For the quantitative analysis, the amounts of endogenous bases released from the membranes during serine base-exchange reaction were measured. The serine-dependent release of ethanolamine and choline was only about 10 and 3% of the amount of [3H] serine incorporated into PS, respectively. If Ca2+-dependent serine incorporation into PS occurs only through the so-called base-exchange reaction, these results suggest that the major phospholipid acceptor for serine incorporation is preexisting PS, but not PE or PC in rabbit platelet membranes