Visible Light Driven Degradation of Terephthalic Acid: Optimization of Energy Demand by Light Modulation Techniques

2020 ◽  
Vol 01 ◽  
Author(s):  
Diana Sannino ◽  
Vincenzo Vaiano ◽  
Olga Sacco ◽  
Nicola Morante ◽  
Luca De Guglielmo ◽  
...  
Keyword(s):  
Visible Light ◽  
White Light ◽  
Terephthalic Acid ◽  
Kinetic Constant ◽  
Fixed Bed ◽  
Light Modulation ◽  
Photocatalytic Reactor ◽  
Sinusoidal Modulation ◽  
Photocatalytic System ◽  
Modulation Techniques

Aims: The aim of this work was to investigate the impact of light modulation parameters on the degradation of terephtalic acid, an organic model pollutant, within a heterogeneous photocatalytic system under visible light. For this purpose, a fixed bed photocatalytic reactor, irradiated by white-light LEDs matrix controlled by a system for light dimming, was used. The bed consisted of a nitrogen-doped titania photocatalyst deposited on polystyrene pellets. Background: Wastewater containing TPA can be treated into conventional aerobic biological units. However, the mineralization of TPA is slow and inefficient and its presence influences negatively the biodegradation efficiency because this pollutant inhibits microbial growth. Nowadays innovative technologies named advanced oxidation processes (AOPs), such as heterogeneous photocatalysis with UV and visible light, ozonation, Fenton oxidation have gained popularity for effective organic destruction of TPA from wastewater. The heterogeneous photocatalytic oxidation process of the TPA under visible light is the most advantageous process in terms of both fixed and operating costs. Objective: In this work the successful application of light modulation techniques to degradation of TPA using a photocatalytic system with supported visible active photocatalysts (N-doped TiO2) immobilized on polystyrene pellets was reported. In particular, sinusoidal lighting has been used analyzing the influence of the period of oscillation and the amplitude of the light modulation on the reaction kinetics, in such a way as to minimize the times and energy costs for the process. Methods: To evaluate the influence of light modulation on the efficiency of the TPA removal, a discontinuous system composed by a Recirculating Photocatalytic Fixed Bed Reactor (RPFBR) irradiated by a matrix of white light LEDs was used. The flat geometry of photoreactor guarantees the efficient excitation of photocatalyst. An amount of 250 mL of aqueous solution with initial TPA concentration of 12.5 ppm was applied in the photocatalytic tests lasting 180 min of irradiation fixed or sinusoidal modulated. Results: The results show that the variation of the oscillation period of the sinusoidal modulation has a relevant influence on the photodegradation of TPA and a maximum value of the apparent kinetic constant, 0.0045 min-1 is found when the period of oscillation is 0.24 s. The sinusoidal modulation with optimal amplitude is that with current between 50-200 mA, that shows the highest value of the apparent kinetic constant, equal to 0.0046 min-1. The optimal sinusoidal modulation, as a consequence is with current between 50-200 mA and period of 0.24 s. From the data collected from the tests, it is possible to evaluate the energy cost necessary to obtain the reduction of 90% of the terephthalic acid in 1 m3 of polluted water for each modulation (E E/O ), and compare these values with other tests for TPA degradation reported in the literature. The internal comparison and with the three systems of literature showed the optima sinusoidal modulation of LEDs matrix permits a strong reduction the electrical energy consumption. Conclusion: Photocatalytic tests have demonstrated the improvement of the process energy efficiency using the light modulation technique . A further confirmation of the advantage of light modulation was obtained by comparing the energy costs required for the abatement of 90% of the terephthalic acid in 1m 3 of the photocatalytic system. Finally, a mathematical model for photocatalytic degradation of terephthalic acid within the recirculating fixed bed photocatalytic reactor, irradiated by white-light LEDs was developed.

scholarly journals Comment Concerning the Effects of Light Intensity on Melatonin Suppression in the Review “Light Modulation of Human Clocks, Wake, and Sleep” by A. Prayag et al.

2021 ◽  
Vol 3 (1) ◽  
pp. 181-188
Author(s):  
Peter Bracke ◽  
Eowyn Van de Putte ◽  
Wouter R. Ryckaert
Keyword(s):  
Phase Shift ◽  
Light Intensity ◽  
Dose Response ◽  
Light Modulation ◽  
Response Curves ◽  
Practical Applications ◽  
Circadian Phase ◽  
Melatonin Suppression ◽  
Dose Response Curves ◽  
Circadian Phase Shift

Dose-response curves for circadian phase shift and melatonin suppression in relation to white or monochromatic nighttime illumination can be scaled to melanopic weighed illumination for normally constricted pupils, which makes them easier to interpret and compare. This is helpful for a practical applications.

scholarly journals Atom guiding along high order Laguerre–Gaussian light beams formed by spatial light modulation

2006 ◽  
Vol 53 (4) ◽  
pp. 547-556 ◽  
Author(s):  
D. P. Rhodes ◽  
D. M. Gherardi ◽  
J. Livesey ◽  
D. McGloin ◽  
H. Melville ◽  
...  
Keyword(s):  
High Order ◽  
Light Modulation ◽  
Spatial Light Modulation ◽  
Light Beams

Coupled mode analysis of light modulation in dielectric waveguides

1975 ◽  
Vol 5 (4) ◽  
pp. 307-315 ◽  
Author(s):  
Masayuki Izutsu ◽  
Tadasi Sueta
Keyword(s):  
Mode Analysis ◽  
Dielectric Waveguides ◽  
Light Modulation ◽  
Coupled Mode

Light-modulation of nitrate reductase activity in leaves and roots of maize

1995 ◽  
Vol 94 (2) ◽  
pp. 305-311 ◽  
Author(s):  
Lucia Merlo ◽  
Massimo Ferretti ◽  
Calvino Passera ◽  
Rossella Ghisi
Keyword(s):  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Light Modulation ◽  
Leaves And Roots

Field‐Effect Light Modulation in Germanium

1963 ◽  
Vol 34 (6) ◽  
pp. 1743-1748 ◽  
Author(s):  
B. O. Seraphin ◽  
D. A. Orton
Keyword(s):  
Field Effect ◽  
Light Modulation

Exploring Nature's plasticity with a flexible probing tool, and finding new ways for its electronic distribution

2002 ◽  
Vol 30 (2) ◽  
pp. 78-82 ◽  
Author(s):  
M. Beier ◽  
M. Baum ◽  
H. Rebscher ◽  
R. Mauritz ◽  
A. Wixmerten ◽  
...  
Keyword(s):  
Three Dimensional ◽  
In Situ Synthesis ◽  
Light Modulation ◽  
Genomic Assays ◽  
Electronic Distribution ◽  
Spatial Light Modulation ◽  
Microarray Fabrication ◽  
Set Up ◽  
Microarray Format

Concepts and results are described for the use of a single, but extremely flexible, probing tool to address a wide variety of genomic questions. This is achieved by transforming genomic questions into a software file that is used as the design scheme for potentially any genomic assay in a microarray format. Microarray fabrication takes place in three-dimensional microchannel reaction carriers by in situ synthesis based on spatial light modulation. This set-up allows for maximum flexibility in design and realization of genomic assays. Flexibility is achieved at the molecular, genomic and assay levels. We have applied this technology to expression profiling and genotyping experiments.

scholarly journals Light modulation of the activity of protochlorophyllide reductase

1980 ◽  
Vol 189 (1) ◽  
pp. 125-133 ◽  
Author(s):  
R E Mapleston ◽  
W T Griffiths
Keyword(s):  
Light Modulation ◽  
Protochlorophyllide Oxidoreductase ◽  
Constant Illumination ◽  
Protochlorophyllide Reductase ◽  
Etiolated Plants

Illumination of etiolated plants effects the activity of protochlorophyllide reductase (NADPH-protochlorophyllide oxidoreductase) in the plastids. Constant illumination or a 2-min light-triggering of etiolated plants leads to an approx. 80% decrease in activity of the enzyme, a change that can be reversed by returning the plants to darkness. The change in activity results from an alteration of the Vmax. rather than Km. Despite the fact that exogenous pigments effect the activity of the enzyme in vitro, no correlation could be drawn between the concentrations of pigments in vivo and activity of the enzyme.

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