Photochemical Degradation Rate Research Articles

Extremely interfacial bonding and photocatalytic environmental remediation on amouphous-TiO2/g-C3N4 heterojunctions by mechanochemical synthesis

TiO2/g-C3N4 composites have emerged as the most potent alternative for green photocatalysis, but are plagued by low photoactivity due to poor interfacial bonding. Herein, we report a straightforward mechanical ball milling method to fabricate an amorphous TiO2/g-C3N4 heterojunction. EPR, XPS and XAFS are used to prove that the N atoms of g-C3N4 was successfully doped into the crystal lattice of Am-TiO2 and formed typical Ti···N structure. The obtained 30-AT/CN (30 wt% g-C3N4) composites can form more heterojunction interfacial bonds and extremely improve the separation of charge carriers, showing superior photocatalytic reduction performance of perrhenate (non-radioactive chemical substitute for pertechnetate) and higher photochemical degradation rate of rhodamine B than the bulk counterpart. The material has a progressive Z-scheme heterojunction (S-scheme heterojunction), which increases the transfer ability and prolongs the lifetime of the photogenerated charge carriers. These results suggest a wide range of applications in the preparation method of heterojunction photocatalysts that are potential candidates for environmental remediation.

Risk of Brominated Flame Retardants for Aquatic Organisms

Nowadays, many experiments have detected the residues of halogenated flame retardants in organisms and even human bodies, among which the amount and type of brominated flame retardants (BFRs) are the most. Therefore, research on biological toxicity and possible harms of BFRs need to be studied to adjust the use and disposal of these chemicals to prevent irreversible consequences on the human body. This article mainly introduced the harm of BFRs to aquatic organisms and the solutions to reduce the concentration of BFRs in water. The harm of BFRs to aquatic organisms is mainly reflected in reproductive toxicity and thyroid hormone toxicity. BFRs, as toxic substances, are bio enriched and can enter the human body along the food chain, causing hormonal disorders and other problems. There are three main ways to reduce the concentration of BFRs in the environment including by using simple and easily degradable BFRs at the source, adjusting the light source conditions to enhance the photochemical degradation rate, and developing new adsorption materials.

Modelling terrigenous DOC across the north west European Shelf: Fate of riverine input and impact on air-sea CO2 fluxes

Terrigenous carbon in aquatic systems is increasingly recognised as an important part of the global carbon cycle. Despite this, the fate and distribution of terrigenous dissolved organic carbon (tDOC) in coastal and oceanic systems is poorly understood. We have implemented a theoretical framework for the degradation of tDOC across the land to ocean continuum in a 3D hydrodynamical-biogeochemical model on the North West European Shelf. A key feature of this model is that both photochemical and bacterial tDOC degradation rates are age dependant constituting an advance in our ability to describe carbon cycling in the marine environment. Over the time period 1986-2015, 182±17 Gmol yr−1 of riverine tDOC is input to the shelf. Results indicate that bacterial degradation is by far the most important process in removing tDOC on the shelf, contributing to 73±6 % (132±11 Gmol yr−1) of the total removal flux, while 21±3 % (39±6 Gmol yr−1) of riverine tDOC was advected away from the shelf and photochemical degradation removing 5±0.5 % of the riverine flux. Explicitly including tDOC in the model decreased the air-sea carbon dioxide (CO2) flux by 112±8 Gmol yr−1 (4±0.4 %), an amount approximately equivalent to the CO2 released by the UK chemical industry in 2020. The reduction is equivalent to 62 % of the riverine tDOC input to the shelf while approximately 17 % of riverine input is incorporated into the foodweb. This work can improve the assumptions of the fate of tDOC by Earth System Models and demonstrates that the inclusion of tDOC in models can impact ecosystem dynamics and change predicted global carbon budgets for the ocean.

Ultrafast Excited-State Proton Transfer in 4-Nitrocatechol: Implications for the Photochemistry of Nitrophenols.

Nitrophenols are a class of environmental contaminants that exhibit strong absorption at atmospherically relevant wavelengths, prompting many studies of their photochemical degradation rates and mechanisms. Despite the importance of photochemical reactions of nitrophenols in the environment, the ultrafast processes in electronically excited nitrophenols are not well understood. Here, we present an experimental study of ultrafast electron dynamics in 4-nitrocatechol (4NC), a common product of biomass burning and fossil fuel combustion. The experiments are accompanied by time-dependent quantum mechanical calculations to help assign the observed transitions in static and transient absorption spectra and to estimate the rates of singlet-to-triplet intersystem crossing. Our results suggest that electronic triplet states are not efficiently populated upon 340 nm excitation, as efficient proton transfer occurs in the excited state on a time scale of a few picoseconds in water and tens of picoseconds in 2-propanol. This suggests that triplet states do not play a significant role in the photochemical reactions of 4NC in the environment and, by extension, in nitrophenols in general. Instead, consideration should be given to the idea that this class of molecules may serve as strong photoacids.

Photochemical Fingerprinting Is a Sensitive Probe for the Detection of Synthetic Cannabinoid Receptor Agonists; toward Robust Point-of-Care Detection.

With synthetic cannabinoid receptor agonist (SCRA) use still prevalent across Europe and structurally advanced generations emerging, it is imperative that drug detection methods advance in parallel. SCRAs are a chemically diverse and evolving group, which makes rapid detection challenging. We have previously shown that fluorescence spectral fingerprinting (FSF) has the potential to provide rapid assessment of SCRA presence directly from street material with minimal processing and in saliva. Enhancing the sensitivity and discriminatory ability of this approach has high potential to accelerate the delivery of a point-of-care technology that can be used confidently by a range of stakeholders, from medical to prison staff. We demonstrate that a range of structurally distinct SCRAs are photochemically active and give rise to distinct FSFs after irradiation. To explore this in detail, we have synthesized a model series of compounds which mimic specific structural features of AM-694. Our data show that FSFs are sensitive to chemically conservative changes, with evidence that this relates to shifts in the electronic structure and cross-conjugation. Crucially, we find that the photochemical degradation rate is sensitive to individual structures and gives rise to a specific major product, the mechanism and identification of which we elucidate through density-functional theory (DFT) and time-dependent DFT. We test the potential of our hybrid "photochemical fingerprinting" approach to discriminate SCRAs by demonstrating SCRA detection from a simulated smoking apparatus in saliva. Our study shows the potential of tracking photochemical reactivity via FSFs for enhanced discrimination of SCRAs, with successful integration into a portable device.

Quantitative NMR spectroscopy reveals solvent effects in the photochemical degradation of thymoquinone

Thymoquinone, a monoterpene natural product isolated from Nigella sativa, has demonstrated potent antioxidant, cytotoxic, anticancer, and anti-inflammatory activity, making it a compound of great therapeutic potential and scientific interest. However, as a photochemically labile compound that can dimerize or decompose into other compounds upon irradiation, its clinical administration and synthetic modifications are greatly limited by its instability in the presence of light. Therefore, it is crucial to have a reliable way to quantify decreases in thymoquinone concentration as an indicator of photodegradation to provide insight into the chemical use of the compound. Here, we employed quantitative 1H nuclear magnetic resonance (NMR) spectroscopy as well as computational time-dependent density functional theory (TD-DFT) calculations to identify the effect of solvation on the photochemical degradation of thymoquinone under ultraviolet light (UV). We found that the rate of photochemical degradation of thymoquinone is highly solvent dependent, and that greatest photodegradation occurs in chloroform. The results presented here are informative for future solvent selection related to the isolation and experimental usage of the compound in solution.

Influence of seasonal variability on source characteristics of VOCs at Houston industrial area

We studied the seasonal variations of volatile organic compounds (VOCs) in the Houston metropolitan area in the summertime and wintertime of 2018. The analysis of hourly measurements obtained from the automated gas chromatograph (auto-GC) network showed the total VOC average concentrations of 28.68 ppbC in the summertime and 33.81 ppbC in the wintertime. The largest contributions came from alkane compounds, which accounted for 61% and 82% of VOCs in the summer and winter, respectively. We performed principal component analysis (PCA) and Positive Matrix Factorization (PMF) and identified seven factors in the summertime and six factors in the wintertime, among which alkane species formed three factors according to their rate of reactions in both seasons: (1) the emissions of long-lived tracers from oil and natural gas (ONG long-lived species), (2) fuel evaporation, and (3) the emissions of short-lived tracers from oil and natural gas (ONG short-lived species). Two other similar factors were (4) emissions of aromatic compounds and (5) alkene species of ethylene and propylene. Summertime factor 6 was associated with acetylene, and one extra summertime factor 7 was influenced by the biogenic emissions. The factor 6 of wintertime was affected by vehicle exhaust. Higher nighttime and lower daytime values of the ethylene/acetylene ratios indicated a stronger rate of photochemical degradation during the summertime. Higher reactivities of alkenes and aromatics with radicals make seasonal differences of these compounds less variant. Also, the exploration of the photochemical processes of the VOCs showed that the ethylene and propylene had the highest contributions to the summertime and wintertime ozone formation as well as the emissions of the isoprene, which showed a high impact on summertime ozone. Our results acknowledged that ethylene and propylene continue to be significant emissions of VOCs, and their emissions control would help the mitigation of the ozone problem in downwind areas related to emissions at the Houston Ship Channel (HSC). Based on trajectory analysis, we localized the main VOC emission sources in HSC near local industrial areas and regions south of the HSC. Ambient concentrations of VOC in both seasons revealed compounds that measured at the HSC were influenced by the emissions from the petrochemical sectors and industrial complexes, especially from the Baytown refinery and Bayport industrial district next to the HSC and Galveston Bay refineries at the south of the study area.

Photochemical degradation of β-hexachlorocyclohexane in snow and ice.

Hexachlorocyclohexane (HCH), a typical organochloride pesticide, is one of the persistent organic pollutants. Despite the ban on technical grade HCH, it has been continuously observed at a steady level in the environment. The photochemical degradation of β-HCH in snow and ice under ultraviolet (UV) irradiation was investigated in this study. The effects of pH as well as common chemical components in snow on the degradation kinetics were investigated. In addition, the photodegradation products were determined and the reaction mechanism was hypothesized. The results showed that under UV irradiation, β-HCH can be photolyzed in snow and ice, with the photochemical degradation process conforming to the first-order kinetic equation. Changing the pH and adding Fe2+ had minimal effect on the photochemical degradation kinetics, while the presence of acetone, NO2-, NO3- and Fe3+ significantly inhibited the process. The addition of hydrogen peroxide slightly inhibited the photochemical degradation of β-HCH. Finally, the reaction rate, products and degradation mechanism of β-HCH in snow were compared with those in the ice phase. The photochemical degradation rate of β-HCH in snow was approximately 24 times faster than that in the ice phase. The photolysis product of β-HCH in snow was α-HCH, produced by the isomerization of β-HCH. However, in ice, in addition to α-HCH, pentachlorocyclohexene was produced by dechlorination. The results of this study are helpful in understanding the transformation of organochlorine pesticides in snow and ice, as well as in providing a theoretical basis for snow and ice pollution prevention and control.

A study of photocatalytic degradation of methomyl and its commercial product Lannate-90

Photocatalytic degradation of the carbamate insecticide methomyl and its commercial product Lannate-90 in aqueous suspension of TiO2 and ZnO using an Osram ultra-vitalux' lamp (315-400 nm) was investigated. The objective of the investigation was to study and compare the rates of photochemical degradation of the pure active compound and its formulated product in order to find out the impact of inert ingredients on degradation processes. The photochemical degradation of pure methomyl was found to be slower than the degradation of its commercial product Lannate-90. Photodegradation was investigated by UV-Vis spectrometry and HPLC, while mineralization was monitored using IC and TOC analyses. Light absorption capabilities of catalysts were characterized by ultraviolet-visible diffuse reflectance spectroscopy method, while the stability of catalysts was studied by infrared analyses. Degradation products of methomyl and its formulated product were identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) results and tentative photodegradation pathways were proposed.

Photochemical degradation of nitrated PAHs in snow

Nitrated polycyclic aromatic hydrocarbons (NPAHs) are derived from PAHs, which are ubiquitous in the aqueous and atmospheric environments, and whose mutagenicity and carcinogenicity are much higher than that of PAHs. Therefore, their environmental transformation has attracted a lot of attention. In the present study, direct and indirect UV photodegradation kinetics of two NPAHs (1-nitropyrene and 1,8-dinitropyrene) in snow were investigated. It was found that the kinetics followed the pseudo-first-order kinetics with the photochemical degradation rate 0.3773 h−1 for 48.98 nM 1-NP and 0.3653 h−1 for 41.00 nM 1,8-DNP. Photosensitizers (hydrogen peroxide and nitrate) promoted the photodegradation of NPAHs. Considering the lower temperature and less microorganisms in snow environment, the photodegradation can be a key factor in determining the fate of NPAHs in sunlit surface snow. To the best of our knowledge, this is the first report on the photodegradation of NPAHs in snow.

The Photochemical Degradation (PCD) of Nitrobenzene (NB) using UV Light and Fenton Reagent Under Various Conditions

Photochemical degradation contributes to the environmental fate of many pesticides, chemicals, and industrial waste in surface waters. Photochemical degradation (PCD) of Nitrobenzene (NB) has been studied using a UV light source and Fenton reagent under different experimental conditions. The effect of concentration on PCD of NB was monitored and recorded in the range 0.5 x10-4M to 3.0x10-4M. The concentration of H2O2 was performed from 5.0 x10-4M to 2.5 x10-4M and Fe(II) from 1.0 x10-4M to 5.0 x10-4M respectively.In terms of concentration, the absorbance increases with increasing the concentration of the solution of NB, H2O2 and Fe(II). The initial rate of PCD was recorded at fixed pH 2.42 of solution. Two optimums for pH were found for PCD of Nitrobenzene ranging from pH 2.42 to 4.20. The intermediates formed during PCD of NB were identified, by which a mechanism was then suggested that PCD is actually found to follow pseudo first order kinetics.

The photocatalytic degradation of carbofuran and Furadan 35-ST: the influence of inert ingredients.

A comparative study on photocatalytic degradation of the pesticide carbofuran and its commercial product Furadan 35-ST in an aqueous suspension of ZnO, irradiated by long-wave light (315-400nm), is presented in this study. In order to assess the effects of inert ingredients present in the commercial product Furadan 35-ST, non-competitive and competitive adsorption and kinetic studies of carbofuran degradation processes were conducted. A higher photochemical degradation rate was found for pure carbofuran in comparison to a two-component system, carbofuran and single addition of ingredients at appropriate concentrations, and the commercial product Furadan 35-ST. The overall effect of inert ingredients was evaluated from a competitive study using the model system of Furadan 35-ST. The results of a mineralization study, obtained by ion chromatography (IC) and total organic carbon (TOC) analyses, revealed the formation of acetate, oxalate, and formate ions. Photodegradation products of carbofuran, three of them detected for the first time, were identified based on high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) and gas chromatography-mass spectrometry (GC-MS) results, and their photodegradation pathways were proposed.

Determination of the thermal, oxidative and photochemical degradation rates of scintillator liquid by fluorescence EEM spectroscopy.

The thermal, oxidative and photochemical stability of the scintillator liquid proposed for the SNO+ experiment has been tested experimentally using accelerated aging methods. The stability of the scintillator constituents was determined through fluorescence excitation emission matrix (EEM) spectroscopy and absorption spectroscopy, using parallel factor analysis (PARAFAC) as an multivariate analysis tool. By exposing the scintillator liquid to a well-known photon flux at 365 nm and by measuring the decay rate of the fluorescence shifters and the formation rate of their photochemical degradation products, we can place an upper limit on the acceptable photon flux as 1.38 ± 0.09 × 10-11 photon mol L-1. Similarly, the oxidative stability of the scintillator liquid was determined by exposure to air at several elevated temperatures. Through measurement of the corresponding activation energy it was determined that the average oxygen concentration would have to be kept below 4.3-7.1 ppbw (headspace partial pressure below 24 ppmv). On the other hand, the thermal stability of the scintillator cocktail in the absence of light and oxygen was remarkable and poses no concern to the SNO+ experiment.

Photochemical Degradation of Disazo Dyes, R-Salt Derivatives, on Dyed Cotton

ABSTRACTDirect disazo dyes, R-salt derivatives, were synthesized and examined. The dyes were prepared by coupling of appropriate components with tetrazotized diacyl derivatives of aromatic diamines. Derivatives of dicarboxylic acids with the general formula HOOC―(CH2)n―COOH (n = 0 ÷ 4) were used as acylating agents. Photochemical degradation rates of dyes on dyed cotton fabric were studied. Compositions of azo-hydrazone tautomers, their aggregates, and their decay rates in UV-Vis light were determined. It was assumed that the length of aliphatic chain in the molecule affects the rate of its photochemical degradation T1/2, tautomeric composition, and dyes aggregation in azo and hydrazo forms.

Synthesis of Photocatalytic Nanocomposite Biomaterials for Enhanced Water Filtration Application

Clean and drinkable water is a critical necessity for all human and economic development; unfortunately, millions of people do not have access to potable water, resulting in the death of over 2 million children every year. Over the past decade, emphasis has been placed on the synthesis and design of photocatalytic nanocomposites to enhance the chemical degradation of organic pollutants as a cost effective vehicle for clean water production. Amongst the many semiconducting nanoparticles explored in literature, TiO2has stood out for its favorable physiochemical properties, low toxicity, easy availability, high stability, and low cost. When TiO2is irradiated by ultraviolet light, there is creation an electron-hole pair which provides sites for effective reduction or oxidization of the pollutant, converting the pollutant to carbon dioxide, water, and mineral acids. One major shortcoming of TiO2 is related to the efficiency of these systems to harness the entire solar spectrum; therefore, a main focus of this work is the modification of the TiO2 nanoparticles to increase the photon capture efficiency in the visible light region. Of the various possible functionalization pathways, this work focuses on dye sensitization, noble metal deposition, and silane functionalization as well as understanding the synergy between all three. When looking at the rate of remediation of a organic dye pollutant in a simulated sunlight environment, the functionalized particles completely remediated an organic dye pollutant. These functionalized nanoparticles were then deposited into a cellulose matrix of highly absorbent beads in order to prepare a nanocomposite. Results show there is a decrease in the chemical degradation of the pollutant when in the nanocomposite, but a significant increase in a physio-absorption capacity, thus maintaining the rate of total remediation. In addition, the binding interaction between the dye and the particle is a major component in chemical degradation; an aminosilane can be covalently added to the surface of the nanoparticle, and increase the ability of various dyes to adhere to the surface of the TiO2. The incorporation of Ag-functionalized nanocomposites resulted in a synergistic antimicrobial effect, which eliminated both E. coli and S. aureus from the water sample, in addition to increasing the photochemical degradation rate. The specific aim of this work was to create functionalized TiO2 particles with silane groups, organic dyes, and Ag, for the incorporation into a photocatalytic biomimetic nanocomposite membrane which utilizes sunlight to degrade pollutants and inhibit the growth of deadly bacteria.

The Influence of Conjugated Polymer Side Chain Manipulation on the Efficiency and Stability of Polymer Solar Cells.

The stability of polymer solar cells (PSCs) can be influenced by the introduction of particular moieties on the conjugated polymer side chains. In this study, two series of donor-acceptor copolymers, based on bis(thienyl)dialkoxybenzene donor and benzo[c][1,2,5]thiadiazole (BT) or thiazolo[5,4-d]thiazole (TzTz) acceptor units, were selected toward effective device scalability by roll-coating. The influence of the partial exchange (5% or 10%) of the solubilizing 2-hexyldecyloxy by alternative 2-phenylethoxy groups on efficiency and stability was investigated. With an increasing 2-phenylethoxy ratio, a decrease in solar cell efficiency was observed for the BT-based series, whereas the efficiencies for the devices based on the TzTz polymers remained approximately the same. The photochemical degradation rate for PSCs based on the TzTz polymers decreased with an increasing 2-phenylethoxy ratio. Lifetime studies under constant sun irradiance showed a diminishing initial degradation rate for the BT-based devices upon including the alternative side chains, whereas the (more stable) TzTz-based devices degraded at a faster rate from the start of the experiment upon partly exchanging the side chains. No clear trends in the degradation behavior, linked to the copolymer structural changes, could be established at this point, evidencing the complex interplay of events determining PSCs’ lifetime.

FATE OF METRONIDAZOLE UNDER SOLAR IRRADIATION

Photodegradation caused by sun irradiation may be of major significance in the natural elimination process of pharmaceuticals and personal care products (PPCPs). The fate of metronidazole (MET) in surface water under solar irradiation was investigated. Several parameters affecting the photochemical degradation rate of MET were investigated, including the initial pharmaceutical concentration, continuous input and the presence of other pharmaceuticals like tinidazole (TNZ) with similar structure to MET as the analogue or amoxicillin (AMX) as non-analogue. The focus of the study was to evaluate the effect of the coexisting pharmaceuticals and continuous input on the photodegradation of PPCPs. The results showed that the photodegradation rate of MET became lower in the presence of TNZ. At the same time, the presence of AMX showed no effect on the photodegradation rate of MET. Besides, to elucidate the effects of continuous input on the photodegradation, a high concentration solution of MET with calculated volume of MET was added repetitively to the reaction solution under solar irradiation for 60 minutes. After 5 times of recovering concentration, the removal of MET decreased from 32.9% to 9.6%. The fact shows that the coexisting pharmaceuticals and continuous input effect on the photodegradation of MET obviously. Therefore, these factors must be taken into account in assessing the fate of PPCPs in the environment. In addition, the kinetic parameters such as quantum yields and rate constants were also determined.

Photochemical degradation of Corexit components in ocean water

Due to the large quantities of dispersants used during the Deepwater Horizon spill in 2010, there were immediate concerns with regards to the fate and transport of the mixture in ocean waters. Direct and sensitized photolysis experiments were carried out for two compounds chosen as surrogates for the Corexit mixture (9500 and 9527) that were applied to surface waters during the oil spill in the Gulf of Mexico. The results showed that direct photolysis did not contribute significantly to the overall degradation (max ∼30%), therefore the focus shifted to sensitized photolysis, specifically the degradation stemming from the reaction rate with hydroxyl radical (HO). The direct photochemical degradation rates for two of the compounds, dioctyl sulfosuccinate (DOSS) and dipropylene glycol butyl ether (DGBE) were measured as 4.29×10−6s−1 and 5.95×10−6s−1, respectively; whereas the overall degradation rate in ocean water was 1.56×10−5s−1 and 2.23×10−5s−1. The formation rates and apparent quantum yields for HO formation were determined for six ocean water samples. The values ranged from 1.81×10−5 near shore to 0.061×10−5 for the open ocean. These degradation rates suggest the possibility for photolysis to play a role in the overall fate of Corexit.

Origin, concentration, availability and fate of dissolved organic carbon in coastal lagoons of the Rio de Janeiro State

The coastal lagoons in the northern Rio de Janeiro State (Brazil) present a wide gradient of dissolved organic carbon (DOC) and water color, with the highest DOC concentrations reported in the literature for aquatic ecosystems. Thus, they represent a peculiar set of ecosystems for the study of the origin, processing and fate of DOC in inland waters. We reviewed data from 2 decades of studies on the carbon cycle in these coastal lagoons and discussed the fluctuations in the concentration and quality of DOC, factors affecting DOC microbial and photochemical degradation, CO2 emission, as well as the role of humic and non-humic carbon to the energy flow through the trophic chains. We show that DOC quality, not its quantity, determines the rates of photochemical and microbial degradation both seasonally (within system) and spatially (among systems), with the exception of DOC photo-oxidation among lagoons, which is partially explained by DOC concentration at regional scale. In humic lagoons, there is a fairly predictable pattern of seasonal variation in DOC concentration associated to rainfall-induced inputs of allochthonous C. However, little is known about the exact timing of these allochthonous inputs and how they relate to the seasonal variation of DOC chemical properties (i.e. its quality). Depth-integrated photo-oxidation rates were less representative in highly humic lagoons, due to strong light attenuation in the water column. Nevertheless, the potential contribution of photo-oxidation and bacterial respiration to total CO2 efflux (~11%) did not differ significantly when all lagoons were pooled together. Contrary to prevailing paradigms for humic waters, microalgae seem to be the main C source in humic lagoons, sustaining pelagic food webs through zooplankton, in spite of some contribution of allochthonous C. Thus, the predominant role of the microbial loop in the DOC recovery to food webs in such systems is to be questioned.

EFFECT OF SURFACTANTS ON KINETICS OF β-CAROTENE PHOTODEGRADATION IN EMULSIONS

The effect of surfactant type on photodegradation kinetics of β-carotene in oil-in-water emulsions has been investigated. The stabilized emulsions of lecithin, sodium stearoyl 2-lactylate (SSL), and polyoxyethylene sorbitan monolaurate (Tween-20) together with a β-carotene solution in corn oil were exposed to illumination. The rate of photochemical degradation was mathematically modeled by regression fitting. The lecithin-stabilized emulsion showed higher light fastness than the other samples. β-carotene photodegradation reaction followed a zero-order kinetic model for oil-based systems and lecithin emulsions, while β-carotene degraded by a first-order reaction in SSL and Tween-20 emulsions. Thermodynamic parameters revealed that water-based samples are more heat sensitive than oil-based samples. An isokinetic relationship was observed between the samples. Moreover, results indicated mixing of SSL and Tween-20 with lecithin leads to better protection of β-carotene than emulsions stabilized with SSL or Tween-20, separately.