Diego H. Quiñones-Murillo, Universidad del Atlántico
Authors: Diego H. Quiñones-Murillo, Angélica A. Ariza-Reyes, Luis J. Ardila-Vélez

The degradation of a synthetic azo dye known as Ponceau 4R, widely used in several chemical processes is assessed through a series of solar UV-mediated advanced oxidation processes (AOP). Experiments were carried out in different surface water samples. A magnetic iron oxide/activated carbon composite was synthetized and applied as a Fenton catalyst. This catalyst was characterized by FTIR, XRD and VSM. Experiments were performed at bench scale using a cylindrical reactor containing a 0,5 L of the solution of Ponceau 4R. This reactor was placed under solar radiation and constantly bubbled with air (or a mixture of ozone-air to feed 200 mg/h of O3). Experimental conditions were as follows: [H2O2] = 33 mM, [catalyst] = 500 ppm, average incident solar UV radiation = 3.54 mW/sq-cm. In the first stage, several oxidation systems such as hydrogen peroxide photolysis, photo Fenton and photocatalytc ozonation were applied in a matrix of deionized water at pH 5.7 (the natural pH of a 50 ppm Ponceau 4R solution) and pH 3 (the optimum pH for Fenton processes). At pH 5.7 the dye was partially degraded through UV-hydrogen peroxide photolysis and photo-Fenton (reaching, respectively, 11 and 58 % colour removal in 90 min of treatment). The application of photocatalytc ozonation led to a complete colour removal before 60 min of treatment. At pH 3, an enhanced efficiency was observed in all cases because at acidic conditions the generation of oxidizing species is improved. Finally, photocatalytic ozonation process was applied to domestic wastewater and seawater samples doped with Ponceau 4R at the natural pH of the samples (8 and 8.7, respectively) and pH 3. It was observed that Ponceau 4R can be completely removed in less than 60 min independently of the water matrix if applied at pH 3. In contrast, not more than 80% of colour removal (after 90 min of treatment) was reached when the process was applied at the natural pH of the samples.

Jiangyong Hu, National University of Singapore
Authors: Lu Xing, Say Leong Ong, Jiangyong Hu

Both natural and anthropogenic processes may bring in various inorganic ions into natural water systems. The appearance of some of the ions could play a significant role in the treatment process of the target compounds. The degradation of taste and odor compounds: 2-MIB and geosmin was investigated in this study applying a VUV involved ozone/UV device in which ozone was generated by a VUV lamp in the absence/presence of , and . The results show that nitrate alone and bicarbonate alone accelerated and decelerated the degradation, respectively, by producing more reactive radicals ( , ), or scavenging hydroxyl radicals. When the two ions were added together, combined effects of inner filter, reactive radical generation and hydroxyl radical scavenging were founded. Nitrite and bromate are the by-products during UV related and ozone related processes, respectively. At the meantime, ozone addition can reduce nitrite formation and UV photolysis is also one of the methods to minimize bromate. However, it is more complex for VUV related ozone/UV process as hydroxyl radicals which will generate bromate are also produced as a result of water homolysis under VUV photolysis. By combining UV and ozone, both nitrite and bromate generation were reduced whereas more complex mechanism was disclosed. Surprisingly, rather than ozone, hydroxyl radicals were the primary influencing factor for bromate formation in the VUV involved ozone/UV combined process.

Nicole Braun, DermaTronnier, Experimental Institute of Dermatology
Authors: Braun N., Garbe B., Werner M., Theek C. Tronnier H., Heinrich U.

Sunscreen products aim to help protect the skin against UV-rays and consequently reduce the risk of early skin ageing and skin cancer. But it is well known that some sunscreens ingredients are photounstable, but this usually refers to irradiation with UV light. Under practical conditions, the sunscreen product is not only exposed to UVA/B-light, but also to visible light (VIS) and infrared light (IR). In fact, the spectrum of solar radiation is composed of 6.8 % UV, 38.9 % VIS and 54.3 % IR. This raises the question whether laboratory SPF testing should include (pre)irradiation with an artificial light source that mimics the total solar spectrum. To help address this issue we analyzed different sunscreens including the reference sunscreen formula S2 after UV irradiation compared to UV+VIS+IR radiation. Irradiation was performed with the Suntest CPS+ that is considered to closely mimic natural light. The following transmission measurements were performed with Labsphere’s UV-2000s device. The filter UG11, which absorbs much of visible and IR-light and the glass filter WG320 which effectively absorbs radiation of wavelengths less than 300 nm were used individually and in combination. Thus, in the latter case it complies with the latest ISO spectral irradiance standards for SPF in vivo testing. After Suntest CPS+ irradiation, the reference sunscreen formula S2 had a 95 % CL of 16.2 – 17.4, after IR+VIS-blocking the 95 % CL was 17.0 – 18.2, and after blocking short-wave radiation the 95 % CL was 18.3 – 19.9. BY filtering with UG11 and WG320 filter in combination a 95 % CL of 18.2 – 20.2 was achieved. The other tested sunscreens showed similar tendencies. Based on these data we can speculate that both short-waves and IR+VIS have an influence on the measured SPF. The influence of VIS and IR alone and the impact on the measured SPF in vivo should be object further investigations.

Semir Loncarevic, Norwegian Veterinary Institute
Authors: Loncarevic, S.; Hytterød S.; Wennberg A.C.; Delacroix, S.

The aim of the study was to establish dose response curves of the effect of disinfection by ultraviolet (UV) irradiance and chlorination towards P. perurans. Amoebae were exposed to UV radiation with both a low and a medium pressure UV lamps in collimated beam set-up and chlorination with different concentrations for varying periods of time. The subsequent morphology and growth characteristics of the amoebae cultures were monitored using visual observation and MPN methods. UV appeared to have significant effects showing both changes in morphology and the ability to reproduce. The experiments were done with different concentrations of amoebae cultures, a different UV-t and different temperatures. The experiments showed that amoebae were highly susceptible to UV treatment, and especially from medium pressure UV lamps. Some amoebae reduce their ability to reproduce even at the shortest UV exposure time (5 sec), both with low and medium pressure UV lamps (UV 254-doses of 4 and 2 mJ/cm2, respectively). The cells were destroyed at doses higher than 48 mJ/cm2 with medium pressure lamps. Furthermore, experiments showed that UV exposure induce acute damage and possibly kill the amoeba. However, surviving amoebae that were not killed by the low UV doses entered a viable, cultivable state, beginning to reproduce.