Natural Solar Radiation Research Articles

Disparity in Discolouration of Thermally Modified Wood Exposed to Solar and Artificial Ultraviolet Irradiation

Abstract Artificial weathering is a widely used method for predicting wood behaviour during its service life. A study was carried out to compare the colour change of thermally modified aspen (Populus tremula L.) and grey alder (Alnus incana (L.) Moench) wood during natural solar and artificial ultra violet (UV) irradiation. Thermally modified wood specimens were exposed for 30 h to artificial UV irradiation at two different intensities, i.e.1.36 W m−2 at 340 nm and 0.68 W m−2 at 340 nm, as well as to solar irradiation outdoors and indoors. After 2.5, 5 and 10 h exposure, colour parameters and reflectance spectra (360–740 nm) were determined. Colour was expressed in accordance with the CIELAB colour model as colour parameters L*, a*, b*. The total colour change ΔEab was calculated from colour parameter differences ΔL*, Δa*, Δb*. The colour changes caused by solar and artificial UV irradiation had a similar pattern for both thermally modified hardwood species under study. Changes in the individual colour parameters in the course of the experiment altered their direction, which implies that discolouration of thermally modified wood is a complicated and dynamic process with various and different chemical transformations in wood chromophores. Colour and reflectance changes had similar trends for different intensities of the same type of irradiation, but they differed for various irradiation types – natural solar or artificial UV irradiation. Greater discolouration was detected for the specimens exposed to both solar irradiations - outdoors and indoors. The results suggest that the fluorescent lamps of the UVA-340 type, which only imitate well the sunlight UV spectrum from 290 nm to 365 nm, do not fully simulate the changes in thermally modified wood induced by solar radiation.

Thermal and mechanical analysis of pickled and tanned cowhide: Effect of solar radiations

ABSTRACTCowhide, a natural biopolymer of collagen, forms raw material for leather, biomaterials, and food, among others. Thermal and mechanical analysis was done using dynamic mechanical analyzer. Effect of tanning and natural solar radiations on the storage modulus, tan δ, and thermal stability of pickled and tanned cowhides has been investigated in the temperature range of 30–240°C. Tanning has been shown to enhance thermal stability and storage modulus. However, tanning decreases its dissipative capability. Thermal stability of both tanned and pickled hide decreased with time of exposure to irradiation. Storage modulus dropped drastically within the initial 6 h of natural solar radiations before rising progressively with the subsequent 12, 18, and 24 h, although still lower than that for nonirradiated sample. Thermal–mechanical analysis proved to be a useful technique for assessing effect of tanning and natural solar radiations on cowhide. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43208.

Spectral Sensitivity of Thermally Modified and Unmodified Wood

The chemical structure of wood changes significantly during thermal modification, significantly influencing the behaviour of wood during weathering. In this study, the effect of different wavelength ranges on thermally modified and unmodified aspen (Populus tremula L.) wood during solar irradiation was investigated. Irradiation was performed by exposing wood to natural solar irradiation under filters transmitting different wavelength ranges. For both woods, the magnitude of characteristic change (discolouration, changes in reflectance, and chemical composition) clearly depended on the solar wavelength bands, but the trends of the changes differed. For unmodified wood, the magnitude of the characteristic changes increased as the portion of short-wavelength radiation in the light increased. However, UV radiation was not found to be the dominant factor influencing changes in thermally modified wood during solar irradiation. The colour and chemical structure of thermally modified wood changed substantially for all studied irradiation conditions.

The application of a novel fluidised photo reactor under UV–Visible and natural solar irradiation in the photocatalytic generation of hydrogen

With advancements in the development of visible light responsive catalysts for H2 production frequently being reported, photocatalytic water splitting has become an attractive method as a potential ‘solar fuel generator’. The development of novel photo reactors which can enhance the potential of such catalyst, however, is rarely reported. This is particularly important as many reactor configurations are mass transport limited, which in turn limits the efficiency of more effective photocatalysts in larger scale applications. This paper describes the performance of a novel fluidised photo reactor for the production of H2 over two catalysts under UV–Visible light and natural solar illumination. Catalysts Pt-C3N4 and NaTaO3·La were dispersed in the reactor and the rate of H2 was determined by GC-TCD analysis of the gas headspace. The unit was an annular reactor constructed from stainless steel 316 and quartz glass with a propeller located in the base to control fluidisation of powder catalysts. Reactor properties such as propeller rotational speed were found to enhance the photo activity of the system through the elimination of mass transport limitations and increasing light penetration. The optimum conditions for H2 evolution were found to be a propeller rotational speed of 1035rpm and 144W of UV–Visible irradiation, which produced a rate of 89μmolh−1g−1 over Pt-C3N4. Solar irradiation was provided by the George Ellery Hale Solar Telescope, located at the California Institute of Technology.

Disentangling the effects of solar radiation, wrack macroalgae and beach macrofauna on associated bacterial assemblages

Wrack detritus plays a significant role in shaping community dynamics and food-webs on sandy beaches. Macroalgae is the most abundant beach wrack, and it is broken down by the combination of environmental processes, macrofauna grazing, and microbial degradation before returning to the sea as nutrients. The role of solar radiation, algal species and beach macrofauna as ecological drivers for bacterial assemblages associated to wrack was investigated by experimental manipulation of Laminaria ochroleuca and Sargassum muticum. We examined the effects of changes in solar radiation on wrack-associated bacterial assemblages by using cut-off filters: PAR + UVA + UVB (280–700 nm; PAB), PAR + UVA (320–700 nm; PA), PAR (400–700 nm; P), and a control with no filter (C). Results showed that moderate changes in UVR are capable to promote substantial differences on bacterial assemblages so that wrack patches exposed to full sunlight treatments (C and PAB) showed more similar assemblages among them than compared to patches exposed to treatments that blocked part of the solar radiation (P and PA). Our findings also suggested that specific algal nutrient quality-related variables (i.e. nitrogen, C:N ratio and phlorotannins) are main determinants of bacterial dynamics on wrack deposits. We showed a positive relationship between beach macrofauna, especially the most abundant and active wrack-users, the amphipod Talitrus saltator and the coleopteran Phaleria cadaverina, and both bacterial abundance and richness. Moderate variations in natural solar radiation and shifts in the algal species entering beach ecosystems can modify the role of wrack in the energy-flow of nearshore environments with unknown ecological implications for coastal ecosystems.

Aqueous photofate of crystal violet under simulated and natural solar irradiation: Kinetics, products, and pathways

In this work photodegradation rates and pathways of an illegal veterinary drug, crystal violet, were studied under simulated and solar irradiation with the goal of assessing the potential of photolysis as a removal mechanism in the aquatic environment. Factors influencing the photodegradation process under simulated sunlight were investigated, including pH, humic acid, Fe2+, Ca2+, HCO3−, and NO3−, of which favorable conditions were optimized by the orthogonal array design.The degradation processes of crystal violet conformed to pseudo first-order kinetics, with different rate constants under different conditions. Reactive oxygen species such as hydroxyl radical, singlet oxygen, and superoxide anion participated in the indirect photolysis process, leading to much higher decolorization efficiencies than those of direct photolysis and hydrolysis. Contrasting to simulated irradiation, solar irradiation led to complete decolorization. Sixty-four products were identified by high resolution liquid chromatography-time-of-flight mass spectrometry and gas chromatography-mass spectrometry, elucidating relatively complete mineralization through photolysis.Based on the analyses of the degradation products and calculations of the frontier electron density, transformation pathways were proposed as singlet oxygen addition, N-demethylation, hydroxyl addition, decomposition of conjugated structure, the removal of benzene ring and the ring-opening reaction. As a result, small products generated as carboxylic acids, alcohols and amines, which were not likely to cause severe hazards to the environment. This study provided both a reference for photodegradation of crystal violet and future safety applications and predictions of decontamination of related triphenylmethane veterinary drug under environmental conditions.

Degradation of patent blue V dye using modified photocatalytic reactor based on solar and UV irradiations

The pollution effects caused by coloured wastewater streams due to the presence of biorefractory dyes are significant, directing the need for a concentrated effort for development of efficient treatment schemes. The present work reports the investigations related to the treatment of patent blue V containing wastewater using modified photocatalytic reactor providing the understanding into the effect of various process parameters and intensification using additives. Comparison of obtained results with natural (solar radiation) and artificial (fluorescent lamp, 11 W) sources confirmed the efficient treatment using the artificial source as expected though significant extent of degradation was also obtained based on the use of solar light. Modifications based on the use of glass coating at the interior of the reactor for possible enhanced utilization of the incident energy showed better degradation efficacy. The removal efficacy was also observed to be dependent on the operating parameters viz. initial concentration and pH with maximum extent of degradation being obtained at initial concentration of 10 ppm and pH of 2.5. Using optimized conditions, the maximum extent of degradation obtained in the present work for different approaches was 86.4% for UV/TiO2, 64.7% for solar/TiO2, 68.4% for UV/ZnO, 59.0% for solar/ZnO, 92.8% for UV/H2O2, 72.1% for solar/H2O2, 81.56% for UV/ferrous sulphate and 66.22% for solar/ferrous sulphate. UV irradiation with modified glass surface photoreactor has been established to be best degradation approach for the removal of patent blue V dye from the wastewater and use of different additives can help in enhancing the extent of degradation. The work has also showed the ways to improve the extent of degradation using solar-based treatment which can be very useful, especially in developing tropical countries like India.

Design improvement and performance evaluation of solar photocatalytic reactor for industrial effluent treatment

This work reports the details of the design components and materials used in a linear compound parabolic trough reactor constructed with an aim to use the photocatalyst for solar photocatalytic applications. A compound parabolic trough reactor has been designed and engineered to exploit both UV and visible part of the solar irradiation. The developed compound parabolic trough reactor could receive almost 88% of UV radiation along with a major part of visible radiation. The performance of the reactor has been evaluated in terms of degradation of a probe pollutant using the parameters such as rate constant, residence time and photonic efficiency. An attempt has been made to assess the performance in different ranges of solar spectrum. Finally the developed reactor has been employed for the photocatalytic treatment of a paper mill effluent using Degussa P25 as the photocatalyst. The paper mill effluent collected from Nagaon paper mill, Assam, India has been treated under both batch mode and continuous mode using Degussa P25 photocatalyst under artificial and natural solar radiation, respectively. The photocatalytic degradation kinetics of the paper mill effluent has been determined using the reduction in total organic carbon (TOC) values of the effluent.

Mechanistic study of the visible-light-driven photocatalytic inactivation of bacteria by graphene oxide–zinc oxide composite

The visible-light-driven (VLD) photocatalytic activity of graphene oxide–zinc oxide (GO–ZnO) composite prepared by a simple hydrothermal method was evaluated toward the inactivation of Escherichia coli K-12. The results showed that GO–ZnO composite had excellent VLD photocatalytic bacterial inactivation activity, comparing with those of ZnO and GO, which was attributed to the strong interaction between ZnO and GO in the composite. Accordingly, an interaction induced VLD photocatalytic inactivation mechanism of the strong interaction of GO with ZnO within the GO–ZnO composite was proposed. GO served as a photosensitizer and facilitated the charge separation and transfer, thus boosted the massive production of reactive oxygen species such as OHbulk, which was identified as the major reactive species from conduction band of ZnO, and resulted in a remarkable enhancement of bacterial inactivation efficiency. Moreover, GO–ZnO composite showed obviously superior photocatalytic bacterial inactivation within 10min under natural solar light irradiation, indicating that GO–ZnO composite has great potential in wastewater treatment and environmental protection.

Electrospun Self-assembled ZnO Nanofibers Structures For Photocatalytic Activity In Natural Solar Radiations To Degrade Acid Fuchsin Dye

Zinc oxide (ZnO) nanoparticles, self-assembled in the form of one dimensional ZnO nanofibers were synthesized using electrospinning technique from solution of polyvinyl alcohol (PVA) and zinc acetate followed by calcination at 600°C in oxidizing environment. Scanning Electron Microscope (SEM) analysis demonstrates that morphology of ZnO nanofibers having rough surface and corresponding Energy Dispersive Spectrometry (EDAX) confirmed the Zn: O atomic ratio approximately in 50:50. Transmission electron microscopy (TEM) images clearly demonstrate the rough morphology is due to the self-assembling of ZnO nanoparticles having diameter approximately 50nm. X-ray Diffraction (XRD) reveals the polycrystalline structure and Raman spectra show some shifts in phonon modes. The PL graph show exceptional emission at 342nm due to band-band transition. Under solar radiations as produced ZnO nanofibers degrades the 99% of 25ppm acid fuchsine which proven through UV spectra when compared to blank dye solution. This shows that natural solar radiations are sufficient to excite theses self-assembled high surface area ZnO nanofibers to show its photocatalytic activity.

Degradation of Methyl Orange and Congo Red dyes by using TiO2 nanoparticles activated by the solar and the solar-like radiation

In this study we used TiO2 nanoparticles as semiconductor photocatalysts for the degradation of Methyl Orange (MO) and Congo Red (CR) dyes in an aqueous solution. Since TiO2 particles become photocatalytically active by UV radiation, two sources of UV-A radiation were used – natural solar radiation which contains 3–5% UV-A and artificial, solar-like radiation, created by using a lamp.The optimal doses of TiO2 of 500 mg/L for the CR and 1500 mg/L for the MO degradation were determined in experiments with the lamp and were also used in degradation experiments with natural solar light. The efficiency of each process was determined by measuring the absorbance at two visible wavelengths, 466 nm for MO and 498 nm for CR, and the total organic carbon (TOC), i.e. decolorization and mineralization, respectively. In both cases, considerable potential for the degradation of CR and MO was observed – total decolorization of the solution was achieved within 30–60 min, while the TOC removal was in the range 60–90%. CR and MO solutions irradiated without TiO2 nanoparticles showed no observable changes in either decolorization or mineralization.Three different commercially available TiO2 nanoparticles were used: pure-phase anatase, pure-phase rutile, and mixed-phase preparation named Degussa P25. In terms of degradation kinetics, P25 TiO2 exhibited a photocatalytic activity superior to that of pure-phase anatase or rutile.The electric energy consumption per gram of removed TOC was determined. For nearly the same degradation effect, the consumption in the natural solar radiation experiment was more than 60 times lower than in the artificial solar-like radiation experiment.

Sol–gel synthesis of vanadium doped titania: Effect of the synthetic routes and investigation of their photocatalytic properties in the presence of natural sunlight

The development of visible-light effective TiO2 photocatalysts allows low cost degradation of toxic non-biodegradable organic pollutants. In the present study a series of vanadium doped titania (V-TiO2) photocatalysts with V-to-Ti of 0.03, 0.06 and 0.1 were synthesized by either one-step or two-step modified sol–gel approaches. Titanium oxychloride solution was used as a titania source while vanadium pentaoxide was used as a vanadia source to form V-TiO2 in the absence of surfactants. One-step process was performed through the reaction of the TiO2 source with vanadium source. In two-step route the Ti(OH)4 gel was preformed through gelation of the TiO2 source using ammonium solution and then peptized in the acidic vanadium solution. The physicochemical properties of the samples were examined by XRF, XRD, UV–visible DRS, SEM-EDAX, TEM, DTA-TGA, XPS and nitrogen gas physisorption studies analyses. It was observed that the morphology, crystal structure and photochemical properties of the obtained samples were largely dependent on the calcination temperature, synthetic approach and V-to-Ti ratios. Calcination of the samples yielded large ultrafine and perhaps monodispersed particles with different sizes depending on the synthetic technique. The photocatalytic performance of the samples was tested in the photodegradation of methylene blue in the presence of natural sunlight. The photocatalytic activities of the samples synthesized by two-step route were higher than that of the samples yielded through one-step approach. Thus, the present report suggest systematic, convenient and cost-effective sol–gel techniques to yield V-TiO2 photocatalysts with harnessed photocatalytic performance for decolorization of toxic organic pollutants in the presence of natural solar irradiation.

Solar Radiation during Rewarming from Torpor in Elephant Shrews: Supplementation or Substitution of Endogenous Heat Production?

Many small mammals bask in the sun during rewarming from heterothermy, but the implications of this behaviour for their energy balance remain little understood. Specifically, it remains unclear whether solar radiation supplements endogenous metabolic thermogenesis (i.e., rewarming occurs through the additive effects of internally-produced and external heat), or whether solar radiation reduces the energy required to rewarm by substituting (i.e, replacing) metabolic heat production. To address this question, we examined patterns of torpor and rewarming rates in eastern rock elephant shrews (Elephantulus myurus) housed in outdoor cages with access to either natural levels of solar radiation or levels that were experimentally reduced by means of shade cloth. We also tested whether acclimation to solar radiation availability was manifested via phenotypic flexibility in basal metabolic rate (BMR), non-shivering thermogenesis (NST) capacity and/or summit metabolism (Msum). Rewarming rates varied significantly among treatments, with elephant shrews experiencing natural solar radiation levels rewarming faster than conspecifics experiencing solar radiation levels equivalent to approximately 20% or 40% of natural levels. BMR differed significantly between individuals experiencing natural levels of solar radiation and conspecifics experiencing approximately 20% of natural levels, but no between-treatment difference was evident for NST capacity or Msum. The positive relationship between solar radiation availability and rewarming rate, together with the absence of acclimation in maximum non-shivering and total heat production capacities, suggests that under the conditions of this study solar radiation supplemented rather than substituted metabolic thermogenesis as a source of heat during rewarming from heterothermy.

Effects of solar radiation on pigmentation and induction of a mycosporine-like amino acid in two cyanobacteria, Anabaena sp. and Nostoc sp. ISC26

ABSTRACTThe effect of filtered natural solar radiation, including photosynthetically active radiation (PAR) and PAR+ultraviolet radiation (UVR), on pigmentation and synthesis of a UV absorbing ‘mycosporine-like amino acid’ (MAA) in two filamentous and heterocystous cyanobacteria, Anabaena sp. and Nostoc sp. ISC26 was studied over 3 days. In Anabaena sp. and Nostoc sp. ISC26, chlorophyll a (chl a) content decreased after 72 h to 5.45 ± 0.09 and 7.01 ± 0.54 μg mg−1 DW respectively under PAR treatments; and to 4.33 ± 0.22, 6.12 ± 0.04 μg mg−1 DW in PAR+UV treatments, as did carotenoids (Car) (2.68 ± 0.01, 2.93 ± 0.01 μg mg−1 DW) (PAR), (2.53 ± 0.01, 2.57 ± 0.05 μg mg−1 DW) (PAR+UV). A considerable increase was observed in the carotenoid:chlorophyll a (Car/Chl a) ratio as a result of carotenoid accumulation in the first 24 h and reduction of chlorophyll in the following days. A single MAA was isolated, purified by high performance liquid chromatography (HPLC) and identified as shinorine. Shinorine concentration increased significantly during 72 h specifically under PAR+UV (1270.8 ± 50.42, 2208.09 ± 73.04 nmol g−1 DW) in Anabaena sp. and Nostoc sp. ISC26, respectively, indicating an adaptation strategy of cyanobacteria against harmful solar short wavelength radiation especially in natural habitats.

Behavior of a thermoelectric power generation device based on solar irradiation and the earth’s surface-air temperature difference

Motivated by the limited power supply of wireless sensors used to monitor the natural environment, for example, in forests, this study presents a technical solution by recycling solar irradiation heat using thermoelectric generators. Based on solar irradiation and the earth’s surface-air temperature difference, a new type of thermoelectric power generation device has been devised, the distinguishing features of which include the application of an all-glass heat-tube-type vacuum solar heat collection pipe to absorb and transfer solar energy without a water medium and the use of a thin heat dissipation tube to cool the earth surface air temperature. The effects of key parameters such as solar illumination, air temperature, load resistance, the proportional coefficient, output power and power generation efficiency for thermoelectric energy conversion are analyzed. The results of realistic outdoor experiments show that under a state of regular illumination at 3.75×104lx, using one TEG module, the thermoelectric device is able to boost the voltage obtained from the natural solar irradiation from 221mV to 4.41V, with an output power of 4.7mW. This means that the electrical energy generated can provide the power supply for low power consumption components, such as low power wireless sensors, ZigBee modules and other low power loads.

Photolytic and thin TiO₂ film assisted photocatalytic degradation of sulfamethazine in aqueous solution.

This paper deals with the photolytic and the photocatalytic degradation of sulfonamide antibiotic sulfamethazine (SMT) dissolved in Milli-Q water and in synthetic wastewater. Besides the direct photolysis, oxidation processes including UV/H2O2, UV/TiO2, and UV/TiO2/H2O2 using UV-A and UV-C radiation were investigated. Pseudo-first-order kinetics was observed for the degradation of SMT in all investigated processes. Additions of an electron acceptor (H2O2) and a catalyst (TiO2 film) accelerated the photolytic degradation of SMT for both the UV-A- and the UV-C-based processes. The most efficient process was UV-C/TiO2/H2O2 with complete degradation of SMT obtained in 10 min. The UV-A-based processes have been less efficient in terms of irradiation time required to totally degrade SMT than the UV-C-based processes. It was also confirmed that different wastewater components can significantly reduce the degradation rate of SMT. An almost ninefold reduction in the rate constant of SMT was observed for the specific synthetic wastewater. Although UV-A radiation experiments need more time and energy (2.7 times more electrical energy was consumed per gram of demineralized SMT) than UV-C experiments, they have a potential for practical use since natural UV-A solar radiation could be used here, which lowers the overall cost of the treatment. Five degradation products were detected during the degradation processes, and their structural formulae are presented. The structural formulae were elucidated based on mass spectra fragmentation pattern obtained using the tandem mass spectrometry (MS/MS) and NMR analysis.

Enhanced biodiesel production in Neochloris oleoabundans by a semi-continuous process in two stage photobioreactors.

Under autotrophic conditions, highly productive biodiesel production was achieved using a semi-continuous culture system in Neochloris oleoabundans. In particular, the flue gas generated by combustion of liquefied natural gas and natural solar radiation were used for cost-effective microalgal culture system. In semi-continuous culture, the greater part (~80%) of the culture volume containing vegetative cells grown under nitrogen-replete conditions in a first photobioreactor (PBR) was directly transferred to a second PBR and cultured sequentially under nitrogen-deplete conditions for accelerating oil accumulation. As a result, in semi-continuous culture, the productivities of biomass and biodiesel in the cells were increased by 58% (growth phase) and 51% (induction phase) compared to the cells in batch culture, respectively. The semi-continuous culture system using two stage photobioreactors is a very efficient strategy to further improve biodiesel production from microalgae under photoautotrophic conditions.

Enhanced autotrophic astaxanthin production from Haematococcus pluvialis under high temperature via heat stress-driven Haber–Weiss reaction

High temperatures (30-36 °C) inhibited astaxanthin accumulation in Haematococcus pluvialis under photoautotrophic conditions. The depression of carotenogenesis was primarily attributed to excess intracellular less reactive oxygen species (LROS; O2 (-) and H2O2) levels generated under high temperature conditions. Here, we show that the heat stress-driven inefficient astaxanthin production was improved by accelerating the iron-catalyzed Haber-Weiss reaction to convert LROS into more reactive oxygen species (MROS; O2 and OH·), thereby facilitating lipid peroxidation. As a result, during 18 days of photoautotrophic induction, the astaxanthin concentration of cells cultured in high temperatures in the presence of iron (450 μM) was dramatically increased by 75 % (30 °C) and 133 % (36 °C) compared to that of cells exposed to heat stress alone. The heat stress-driven Haber-Weiss reaction will be useful for economically producing astaxanthin by reducing energy cost and enhancing photoautotrophic astaxanthin production, particularly outdoors utilizing natural solar radiation including heat and light for photo-induction of H. pluvialis.

Optimization of operating parameters for photocatalytic degradation of tetracycline using In2S3 under natural solar radiation

Batch tests were employed to estimate the optimal conditions for photocatalytic degradation of tetracycline using In2S3 under natural solar radiation by response surface methodology. Three key operating parameters, such as dosages of In2S3, initial concentration of tetracycline and an initial pH value, were selected, and their interrelationships were studied by the Box–Behnken design. The experimental data and ANOVA analysis showed that the coefficient of determination (R2) was 0.9998, which demonstrated that the model was significant. The optimum conditions were predicted to give a maximal removal efficiency of 100% at the In2S3 dosage of 2.5g/L, an initial tetracycline concentration of 20mg/L and pH of 7.0. The prediction was tested by triplicate experiments, where a removal efficiency of 100% was achieved under the chosen optimal conditions. This excellent correlation between the predicted and measured values provided confidence in the model.

Insights into solar photo-Fenton process using iron(III)–organic ligand complexes applied to real textile wastewater treatment

The treatment of a real textile wastewater was accomplished using a conventional photo-Fenton reaction and mediated by different ferric–organic ligand complexes, performed in lab and pilot scale photoreactors irradiated by simulated and natural solar radiation, respectively. The textile wastewater presents a dark-blue colour, alkaline pH, a high organic content (COD=1239mgO2L−1; DOC=408mgCL−1) and moderate biodegradability (BOD5/COD=0.16). The conventional solar-photo-Fenton reaction showed limited efficiency in the mineralization of the textile wastewater, which is characterized by a fast initial dissolved organic carbon decay in the absence of light, mainly attributed to the formation of iron–organic pollutants complexes with a low solubility at acidic pH values, leading to iron precipitation, followed by a very slow reaction rate under UV–visible light associated to (i) low amounts of dissolved iron and (ii) low photoactivity of the iron precipitates. The addition of the organic ligands, such as oxalic acid, citric acid and EDDS, enhanced significantly the photo-Fenton reaction, avoiding the formation of iron–organic pollutants complexes, and consequently increase of the quantum yield for ferrous ions production through the photodecarboxylation of ferric–organic ligands complexes. The catalytic activity of the iron–organic ligand complexes increased in the following order: Fe(III)–EDDS<Fe(III)–citrate<Fe(III)–oxalate. All the tested processes mediated by ferric–organic ligands complexes contributed to an effective decolourization and mineralization, but the most efficient system was the photo-Fenton-ferrioxalate reaction with an optimum catalyst concentration of 100mgFe3+L−1, pH 2.8, temperature of 30°C leading to complete decolourization and 69.1% mineralization after less than 8.8kJUVL−1. An enhancement of the wastewater biodegradability was observed during the photo-Fenton-ferrioxalate reaction.