UV emitting glass: A promising strategy for biofilm inhibition on transparent surfaces.

Marine biofouling causes serious environmental problems and has adverse impacts on the maritime industry. Biofouling on windows and optical equipment reduces surface transparency, limiting their application for on-site monitoring or continuous measurement. This work illustrates that UV emitting glasses (UEGs) can prevent the establishment and growth of biofilm on the illuminated surfaces. Specifically, this paper describes how UEGs are enabled by innovatively modifying the surfaces of the glass with light scattering particles. Modification of glass surface with silica nanoparticles at a concentration 26.5 µg/cm2 resulted in over ten-fold increase in UV irradiance, while maintaining satisfactory visible and IR transparency metrics of over 99 %. The UEG reduced visible biological growth by 98 % and resulted in a decrease of 1.79 log in detected colony forming units when compared to the control during a 20 day submersion at Port Canaveral, Florida, United States. These findings serve as strong evidence that UV emitting glass should be explored as a promising approach for biofilm inhibition on transparent surfaces.

CrVI reductive transformation process by humic acid extracted from bog peat: Effect of variables and multi-response modeling.

The present paper reports the efficiency of bog peat-derived humic acid (HA) in the reductive removal of hexavalent chromium (CrVI) from aqueous solution as affected by solution pH, the dose of FeIII and reaction time (numeric variables) and light irradiation (categorical variable). A three-level Box-Behnken design (BBD) applied to design experimental matrix, model the effects and interactions of variables on four determined responses (residual concentration of dissolved CrVI, dissolved CrIII, dissolved FeII and total CrVI) and optimize the experimental conditions for highest CrVI removal efficiency (CrVI RE). Reaction mechanisms are also well discussed. Regression models were developed and analyzed by the ANOVA test and models determination coefficient R2. Obtained models were significant (F values > 13) and an excellent relationship between experimental and predicted responses (R2: 98.1-99.6%) was observed. The optimum conditions were established corresponding to the residual concentration of dissolved CrVI as an index for CrVI removal efficiency (RE). In the dark system, the highest CrVI RE (98.1%) was obtained under the following conditions: pH = 1, reaction time = 7 d and FeIII dosage = 0.110 mM. In the light-irradiated system, the optimal CrVI RE of 98.3% was observed in pH = 1, reaction time = 5 d and FeIII dosage = 0.075 mM. Almost all reduced CrIII remained in the solution even at high pH value. No adsorption or precipitation of CrIII on the HA surface at pH 5 was confirmed by surface analyses of HA using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM).