Search

In this research work, the efficiency of Micellar Enhanced Ultrafiltration (MEUF) was evaluated for recovery of polyphenols from aqueous solution, using three surfactants, namely Esterquat, Dodecylbenzenesulfonic acid sodium (DBSS) and Lutensol AO 7 (cationic, anionic and non-ionic surfactants, respectively). Firstly, the critical micellar concentration (CMC) was experimentally determined for each surfactant. CMC values of DBSS was almost 4 orders of magnitude higher than Esterquat and around 200 orders higher than Lutensol A07, indicating the high efficiency of micellization for Esterquat and Lutensol A07. On the other hand, the effect on the polyphenols retention percentage of several factors in the practical application of MEUF was investigated including transmembrane pressure, nature of surfactant, feed surfactant concentration, mole fraction of non-ionic surfactant as well as initial pH value. Results showed that the permeate flux increased with increasing transmembrane pressure. It was concluded that the highest retention efficiency was obtained for the cationic surfactant during the first filtration minutes (higher than 90%). Moreover, the surfactant concentration of 5 CMC gives the best rejection percentage. There was no significant improvement with addition of non-ionic surfactant. Regarding the influence of initial pH, polyphenols rejection percentage slightly increased with an increase in the pH up to a value equal to 3 (from 93 to 95%), but higher pH values resulted in lower polyphenols retention percentage. The results demonstrate the high efficiency of MEUF system under optimal conditions for the treatment of polyphenols-contaminated wastewaters and for the concentration and recovery of these phenolic compounds. [ABSTRACT FROM AUTHOR]

An electrocoagulation (EC) process was employed to remove the Reactive Black 5 (RB5) dye from aqueous solutions using batch-stirred and recirculation flow reactor configurations. Different operating conditions, such as current density, initial pH value, initial dye concentration, sacrificial anode materials and stirring rate were tested with the synthetic wastewater in order to optimise the treatment. The best operating conditions achieved for both systems were: current density of 16 mA cm − 2 , initial pH of 6, 100 mg L − 1 of RB5 and Al anodes, as well as 800 rpm for the batch-stirred setting. These parameters, at the batch-stirred EC system, led to 76% and 97% of decolourisation after 45 and 120 min of operation, with an energy consumption of 5 and 14 kWh m − 3 , respectively. Similar colour removals were achieved for the recirculation flow system in 10 and 120 min, requiring 2 kWh m − 3 and 22 kWh m − 3 of electrical energy, respectively. The behaviours observed in each one of the EC systems (− batch and –recirculation flow) are related to the way how the liquid was mixed and the location where samples were taken. In the batch-stirred system, a real textile wastewater was also treated applying Al or Zn anode materials. Results clearly show that these two EC configurations are alternatives to depurate effluents containing dyes, since they guarantee the legal limits values so that a treated wastewater can be discharged into aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Electrochemical measurements and bulk electrolysis using individual or an assembling of flow cells in series were performed to study the anodic oxidation of amaranth dye solutions with Ti/Pt and Ti/Pt-SnSb anodes. Polarisation curves demonstrated that Ti/Pt-SnSb has high electroactivity to eliminate the pollutant. Bulk electrolysis with this material, at 30 mA cm −2 , removed 97.5% and 70.3% of colour and COD. Two cell configurations led to higher removal rates depending on the cell-electrode position. Additionally, experiments combining Ti/Pt-SnSb and Nb/BDD materials were performed to clarify the effect of non-active anodes in the system. Assembling cells revealed to be an interesting pre-treatment to degrade organic compounds. The suitable system choice will be dependent on the final target COD value, the reaction time and the energy consumption. [ABSTRACT FROM AUTHOR]

The aims of the present work were to assess the application of a chemical process to degrade a mixture of parabens and determine the influence of a natural river water matrix on toxicity. Model effluents containing either a single compound, namely methylparaben, ethylparaben, propylparaben, butylparaben, benzylparaben or p-hydroxybenzoic acid, or to mimic realistic conditions a mixture of the six compounds was used. Fenton process was applied to reduce the organic charge and toxic properties of the model effluents. The efficiency of the decontamination has been investigated using a chemical as well as a toxicological approach. The potential reduction of the effluents' toxicity after Fenton treatment was evaluated by assessing (i) Vibrio fischeri luminescence inhibition, (ii) lethal effects amongst freshwater Asian clams (Corbicula fluminea), and (iii) the impact on mammalian neuronal activity using brain slices. From the environmental point of view such a broad toxicity analysis has been performed for the first time. The results indicate that Fenton reaction is an effective method for the reduction of chemical oxygen demand of a mixture of parabens and their toxicity to V. fischeri and C. fluminea. However, no important differences were found between raw and treated samples in regard to mammalian neuronal activity. [ABSTRACT FROM AUTHOR]

The anodic oxidation of Amaranth dye has been studied by electrochemical measurements (cyclic voltammetry and polarisation curves) and bulk electrolysis employing a single or two cells in a serial mode system using active and non-active anodes (Ti/IrO 2 -Ta 2 O 5 and Nb/BDD) as electrode materials. The results of electrochemical measurements showed that, Nb/BDD had a significant oxidation power to mineralise Amaranth dye than Ti/IrO 2 -Ta 2 O 5 anode. Single cells were tested at different current densities (30, 60 and 80 mA cm −2 ). At Nb/BDD anode, total colour elimination and 49.1% of COD removal were achieved by applying 30 mA cm −2 after 60 min of treatment. Conversely, 98.5% of colour removal and 43.2% of COD decay were accomplished at 60 mA cm −2 with Ti/IrO 2 -Ta 2 O 5 electrode, after 360 min of electrolysis time. Supported on the obtained results with single cells, a system in a serial mode was further evaluated for the first time. The arrangement with Ti/IrO 2 -Ta 2 O 5 electrode at 30 mA cm −2 in the first cell followed by Nb/BDD anode at 30 mA cm −2 revealed the most interesting results. Complete decolourisation and 75.1% of COD abatement were achieved after 60 min with lower energy requirements of about 25.4 kWh m −3 (0.2 kWh gCOD −1 ). This study demonstrates the potential of a serial system to be applied as a wastewater pre-treatment approach. [ABSTRACT FROM AUTHOR]

The effect of calcination temperature on Mn-Ce-O 70/30 characteristics, activity and stability was investigated when this catalyst was applied on the catalytic ozonation of a phenolic mixture. Two crystalline phases (cubic CeO2and tetragonal Mn3O4) were observed by X-ray diffraction analysis, which also showed an increase of crystallinity with temperature. The material prepared at 300 ºC was the most efficient regarding TPh (100%), TOC (80%) and COD (62%) removal, as well as revealed to be the one leading to the lowest amount of Mn leached. The generalized kinetic model (GKM) was able to describe mineralization during this catalytic process with relative errors of ±10%. [ABSTRACT FROM PUBLISHER]

The aim of the present work was to compare the potential of iron industry wastes to enhance ozone and hydrogen peroxide action on the degradation of olive mill wastewaters (OMWs). The results attained show a higher efficiency for ozonation using a lower catalyst load. Nevertheless, Fenton's process led to a larger amount of chemical oxidation demand (COD) removed per mole of oxidant applied. It was concluded that hydroxyl radicals are responsible for the pollutant abatement. High eco-toxicity decay was observed after the treatments. Furthermore, a preliminary analysis of the iron shavings' stability was made by reusing it in two feed-batch trials. It was concluded that while activity was maintained for Fenton's, a decrease of about 20% was verified for catalytic ozonation. Comparing these results with the ones obtained for the same processes applied to an actual OMW, a lower percentage of COD abatement was achieved. However, when reporting the amount of COD removed per mole of oxidant used, the difference between effluents are not so high. This should be taken into account when deciding which process should be implemented at an industrial scale. With the outcomes of this research it was possible to conclude that integrating waste management with wastewater treatment was feasible. [ABSTRACT FROM AUTHOR]

This work aims to analyze the contribution of H2O2on ozonation of Sulfamethoxazole (SMX). A single ozonation was able to totally remove SMX. TOC and COD depletion rates after a transferred ozone dose of 60 mg/L was related to the formation and decomposition of H2O2. An increase on O3gas inlet concentration from 10 g/m3to 20 g/m3improved COD abatement from 11% to 36%. When the presence of H2O2at the beginning of ozonation was tested, it was verified that COD and TOC degradation were enhanced, attaining maximum values of 76% and 32%, respectively, when compared with 35% and 15% reached in a single ozonation. [ABSTRACT FROM PUBLISHER]

Phenoliccompounds constitute an important source of pollutioncausing severe environmental threats in countries that produce oliveoil. The efficiency of five metal anodes (Al, Cu, Fe, Pb and Zn) wastested in an electrocoagulation system, in order to purify a phenolic-simulatedeffluent. Among them, Zn anode was found to be promising, because86% of the total phenolic content and 49% of chemical oxygen demandwas removed after 180 min of treatment within the operational conditionsused (pH = 3.0, current intensity = 0.4 A, [NaCl] = 1.5 g/L, intergapdistance = 1.0 cm, effective anodic area = 33.5 cm2). Thebiodegradability of the mixture was assessed by measuring the ratioBOD5/COD before and after each treatment, as well as theecological impact through Vibrio fischeribacteria.The electrical energy consumption varied between 8–14 kWh/m3. The results also point out that during the treatment process,beyond the electrocoagulation route, the electrooxidation of organiccompounds is also expected to occur. [ABSTRACT FROM AUTHOR]

Withthe aim of selecting a low-cost catalyst to enhance ozonationon the treatment of olive mill wastewaters (OMW), volcanic rock, sepiolite,and iron shavings (zerovalent iron (ZVI)) were tested. ZVI providedthe best results; thus, its behavior was explored by analyzing theimpact of the key operating conditions. It was verified that the highestdegradation was reached when 1 gCat/L, 20 gO3/m3, pH 3, and 20 °C were used. Catalyst stabilitywas checked by reusing it in several feeding batch trials, and satisfactoryremovals were still attained after five experiments. Finally, catalyticozonation over ZVI was tested in real OMW, and the results were verysimilar to those reached for the simulated solution. Moreover, a hightoxicity removal was detected. It seems thus that iron shavings cansuccessfully be applied as a catalyst-integrating waste managementwith wastewater treatment. [ABSTRACT FROM AUTHOR]

New iron–copper based solidsprepared by coprecipitationhad their efficiency in the heterogeneous Fenton process investigatedregarding organic charge removal and biodegradability enhancement.Different molar proportions between the two metals were used to assessthe best one. Chemical oxygen demand (COD), total phenolic content(TPh), and biochemical oxygen demand in 5 days (BOD5) werethe parameters used for the evaluation. Two solutions simulated olivemill wastewaters: one comprising six phenolic acids and another containingone extra acid. The efficiency of each catalyst was compared whenfacing both mixtures, and the one containing more phenolic acids wasfurther decomposed, maybe due to a cooxidation synergistic effectrelated with the presence of more radicals. All solids proved to befit for the reaction, and the Fe–Cu–O 50/50 catalystshowed the best overall results regarding organic charge removals. [ABSTRACT FROM AUTHOR]

Abstract: The main objective of this study was to investigate the catalytic activity of three low cost materials (sepiolite, red volcanic rock and iron shavings) during the Fenton-like process on the treatment of simulated and actual olive mill wastewaters. Among the catalysts screened, iron shavings (ZVI) was the most promising, as it was the catalytic material that attained the best performance. Besides it as the advantage of being a waste of iron processing industry, not needing any modification before use. Since the Fenton's reaction efficiency is dependent on ZVI and H2O2 concentrations and as well as initial pH, the effect of these parameters was analyzed in batch tests for a synthetic phenolic effluent treatment. From the results it was concluded that the most interesting removals (94% of TPh, 54% of COD and 60% of TOC) were reached using [ZVI]=40g/L, [H2O2]=35mM and pH=3. This effectiveness was confirmed when Fenton's peroxidation under the same conditions was applied to an actual olive mill wastewater (OMW). The impact of this methodology over the effluents biodegradability and toxicity was still grasped. Furthermore, the stability of ZVI under continuous conditions was also tested when applied to both the synthetic phenolic effluent and real OMW treatments in a fixed bed reactor using the H2O2 load and pH optimized in batch reaction; high activity was still observed after 168h of operation of the column when synthetic phenolic effluent was treated, since TPh, TOC and COD removals remained about 73%, 39% and 44%, respectively. These results show that ZVI can be used as low cost catalytic material in Fenton reaction for the treatment of OWM in batch or continuous reaction with high catalytic stability. [Copyright &y& Elsevier]

This paper reports the application of flocculation, Fenton's process, and ozonation on the depuration of distillery wastewaters. The treatment processes were analyzed separately; nevertheless, integration schemes were also considered. The commercial flocculant 923PWG led to up to 84% of total suspended solids (TSS) removal even if a very low chemical oxygen demand (COD) abatement was observed (). The effect of hydrogen peroxide concentration and molar ratio were tested on the Fenton's process efficiency. Moreover, the injection mode was still analyzed. Gathering up both COD degradation and biodegradability enhancement, it was possible to select the following operating conditions: and , being the oxidant totally introduced at the beginning of the reaction. Ozonation showed poor results regarding organic matter removal; however, it seems to be an interesting methodology raising the effluent's biochemical oxygen demand ratio. In fact, in the strategies involving the integration of ozonation with Fenton's process, it was possible to conclude that ozone oxidation did not improve COD degradation; nonetheless, it was essential to improve biodegradability, particularly when conducting ozonation (at ) after Fenton's process was revealed to be an interesting approach leading to an effluent amenable to further biodegradation. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study addresses the applicability of the Fenton-like zero valent iron (ZVI) process on the remediation of several landfill leachate samples coming from different points of an existing treatment plant: initial effluent (E Raw), after biological treatment (E Post-Bio) and depurated effluent (E Treat). The effects of pH and Fe0 concentration were determined for E Raw and E Treat. It was observed that the use of low pH values enhances the treatment efficiency. Moreover, the increase on iron load leads to higher COD removals until a certain point after which the catalyst starts to show radical scavenger effect. The low efficiency attained for E Raw (COD removal always below 8%) indicates that this methodology is not suitable for this effluent. However, final E Treat within the legal limits for discharge were attained when pH=2 was used with 38% of COD removal. The utilization of iron shavings as catalyst in the Fenton-like process showed to be a suitable and economical solution on the remediation of E Treat and E Post-Bio with high COD abatements (up to 60%) leading to streams able to be released to the municipal sewage. Since the real plant often does not comply with regulatory thresholds and according to our results, it seems advisable to implement this technology after the bio-reactor for substituting the already existing physico-chemical treatment. [Copyright &y& Elsevier]

Abstract: The efficiency of two AOPs operating at room conditions of pressure and temperature, ozonation (single and catalytic over the laboratorial Mn–Ce–O and the commercial N-150—Fe2O3/MnO x ) and Fenton''s process (homogeneous and over Fe–Ce–O), was simultaneously checked for the remediation of a phenolic mixture. Gathering up former individual results pointing out as most suitable treatments those involving solid catalysts, either for ozonation or Fenton''s, a global conclusion elects this last process as the more interesting for industrial applications. In fact, the lower retention time required by H2O2+Fe–Ce–O 70/30 to attain an easily biodegradable effluent makes this technology truly attractive for in-situ remediation of this specific wastewater. These findings were mostly driven by the comparative ability to transform the non-biodegradable raw effluent into streams more amenable to further bio-processing. In this regard, biological parameters superposed chemical COD degradation within the ultimate selection reasons. Indeed, in all cases COD limits were not reached and a subsequent biological treatment is required. Despite COD removal for catalytic ozonation showed to be higher than for heterogeneous Fenton''s (63% and 50%), BOD5/COD was contrarily favorable to Fenton''s, which immediately conducted to a biodegradable mixture in the first minutes (0.78 in 10min) while ozonation took more than 1h to impart a biodegradable character. [Copyright &y& Elsevier]

Abstract: Catalytic and non-catalytic ozonations were investigated in the depuration of simulated phenolic wastewaters. Commercial (N-150: Fe–Mn–O) and laboratory-made (Mn–Ce–O 70/30) catalysts have been used to improve the effluent biodegradability. The N-150 catalytic system followed a free radical pathway detected by means of the application of radical scavengers. After 120min of reaction, the recovered N-150 catalyst showed low carbon adsorption and negligible leaching behaviour. Moreover, the catalyst remained active after various feed-batch trials. Mn–Ce–O 70/30 led to higher mineralization levels and stronger biodegradable characteristics of the final solution measured by respirometry. Nevertheless, a lower BOD5/COD ratio of the treated effluent as well as a higher ecological impact measured by bio-luminescence techniques was detected. Further application of the N-150 catalyst seems to be preferable to enhance ozone action although its activity can be limited by the presence of radical scavengers in real effluents. [Copyright &y& Elsevier]

Abstract: In this work, the mineralization of a phenolic wastewater was investigated by several lumped kinetic models to predict the total organic carbon depletion during single ozonation of a mixture of six phenolic compounds present in olive oil mill wastewater. Firstly, the kinetic equations were developed in terms of lumped compounds representing the parent pollutants and reaction intermediates according different models: First-Order Kinetic (FOKM, with one oxidation step), Two Step First Order Kinetic (TSFOKM, including also and intermediate path), Modified First-Order Kinetic (MFOKM, adding initial non-oxidizable pollutants to the FOKM), Lumped Kinetic (LKM, accounting for non-oxidizable species production), Generalized Kinetic Model (GKM, where, besides the direct mineralization step, formation and degradation of intermediates provide a three step alternative model) and Modified Generalized Kinetic Models (MGKM, a five step proposal with the addition of two paths accounting for non-oxidizable species possible to be produced from the oxidation of raw or intermediate compounds). Secondly, the behavior of these various models was studied at different operational conditions. The FOKM failed to describe the process while TSFOKM incorporates the drawback of requiring the choice of a transition point between the two types of oxidation behaviors. MFOKM, assuming the presence of refractory compounds in the initial wastewater, was rejected since all the parent phenolic compounds were totally removed from the effluent along the treatment. LKM gave good agreement with the experimental results at low ozone inlet concentrations, due to the high recalcitrant character of the organic intermediates that were formed. Nevertheless, for higher ozone inlet concentration some by-products degradation occurs, which is not predicted by this model. Finally, the GKM fitted satisfactorily the laboratorial data with errors in the range of ±10% and, even with the shortcoming of involving a large number of parameters, MGKM was the most reliable model to describe this complex process. [Copyright &y& Elsevier]

Abstract: The depuration of a simulated wastewater comprising six phenolic acids usually present in Olive Mill Wastewaters was studied by heterogeneous Fenton''s technology. Several process parameters have been evaluated including catalyst load, hydrogen peroxide concentration and pH revealing that laboratorial Fe-Ce-O catalyst was the most active formulation with a molar ratio between Fe and Ce of 70/30. On the assessment of process efficiency, the optimum values achieved led to the selection of target values: 1.0gL−1 of Fe-Ce-O 70/30, [H2O2]=244mM and pH 3 being removed the total phenolic content and 57% mineralization after 120min of reaction time. Cutting edge environmental classification parameters such as biodegradability enhancement and toxicity reduction were considerably improved with heterogeneous Fenton''s process which enables its successful application as pre-treatment before a biological methodology. Catalytic characterization was deployed structural and morphologically whereas catalytic stability in terms of metal leaching and carbonaceous adsorption showed that used catalysts kept the oxidation efficiency in comparison with fresh ones. Finally, stability during several reuses was evaluated through the implementation of feed-batch trials reinforcing the benefits of ceria based catalysts. [Copyright &y& Elsevier]

Abstract: A mixture of six phenolic acids, corresponding to an initial TOC of 370mgC/L, was studied by Fenton''s peroxidation aiming to improve the biodegradability of agro-industrial wastewaters. Input operating variables including the concentration of pollutants, iron and hydrogen peroxide as well as the reaction time were used to assess the mineralization degree through a factorial experimental methodology. A TOC removal in the range of 15.0–58.8% was attained within the operational conditions used. A reduced model was achieved using the statistically important independent factors and interactions to predict TOC degradation. On the hydrogen peroxide injection methodology, the results showed that the continuous introduction of small volumes is advantageous when compared with one single addition of the overall volume at the zero reaction time with a mineralization improvement of 11%. The use of FeSO4·7H2O correspondent to a Fe2+ load of 271mg; [H2O2]=488.0mM, injected in twelve aliquots each 30min during 6h of reaction reached optimal efficiencies with the parent compounds (quantified by HPLC and the Folin–Ciocalteau method) quickly totally removed and TOC, COD and BOD5 final values of 123mgC/L, 180mgO2/L and 146mgO2/L, respectively. Toxicity assessment by Vibrio fischeri light inhibition revealed that Fenton''s process reduces the effluent ecological impact related with the decomposition of the toxic phenolic acids. Indeed, EC50 changed from 32.2% dilution to no-dilution needed. The analysis of BOD5/COD ratio pointed out a high improvement of the treated wastewater biodegradability from 0.30 to 0.80 meaning that the application of Fenton''s oxidation as a pre-treatment enables a further application of an efficient post-biological technology which was also confirmed by respirometry. [Copyright &y& Elsevier]

Abstract: Catalytic ozonation of a simulated phenolic wastewater composed by six acids: syringic, vanillic, 3,4,5-trimethoxybenzoic, veratric, protocatechuic and 4-hydroxybenzoic normally present in olive mill wastewaters was studied over a Mn–Ce–O laboratorial catalyst under different operating conditions. A high improvement in total organic carbon (TOC) degradation was observed even when low catalyst concentrations were used when compared with single ozonation. The influence of the medium pH in the performance of both single and catalytic ozonation was assessed in a wide range of pH values. An inhibitory effect in TOC removal was observed in the catalytic process performance at high pH values. The use of radical scavengers proved that this catalytic system does not follow a free radical pathway. No differences were observed between fresh and used catalyst structure and morphology by SEM and XRD. Nevertheless, a decrease on BET surface area was detected. Leaching of Mn as well as carbon adsorption due to organic intermediates deposition at the catalyst surface was analyzed for the recovered catalyst at the end of the experiments. The role of the catalyst in the catalytic ozonation pathway was discussed being concluded that the main mechanism should be developed through surface reactions involving both pollutants and ozone adsorption. A series of feed-batch trials was performed to test Mn–Ce–O activity along the time. A slight decrease on TOC removal was observed from the first to the second use, remaining the catalyst performance constant after the third run. [Copyright &y& Elsevier]

The application of TiO2 as a slurry catalyst for the degradation of contaminants of emerging concern (CEC) in liquid effluents has some drawbacks due to the difficulties in the catalyst reutilization. Thus, sophisticated and expensive separation methods are required after the reaction step. Alternatively, several types of materials have been used to support powder catalysts, so that fixed or fluidized bed reactors may be used. In this context, the objective of this work is to systematize and analyze the results of research inherent to the application of ceramic materials as support of TiO2 in the photocatalytic CEC removal from liquid effluents. Firstly, an overview is given about the treatment processes able to degrade CEC. In particular, the photocatalysts supported in ceramic materials are analyzed, namely the immobilization techniques applied to support TiO2 in these materials. Finally, a critical review of the literature dedicated to photocatalysis with supported TiO2 is presented, where the performance of the catalyst is considered as well as the main drivers and barriers for implementing this process. A focal point in the future is to investigate the possibility of depurating effluents and promote water reuse in safe conditions, and the supported TiO2 in ceramic materials may play a role in this scope. [ABSTRACT FROM AUTHOR]

Photocatalysis has been vastly applied for the removal of contaminants of emerging concern (CECs) and other micropollutants, with the aim of future water reclamation. As a process based upon photon irradiation, materials that may be activated through natural light sources are highly pursued, to facilitate their application and reduce costs. TiO2 is a reference material, and it has been greatly optimized. However, in its typical configuration, it is known to be mainly active under ultraviolet radiation. Thus, multiple alternative visible light driven (VLD) materials have been intensively studied recently. WO3 and g-C3N4 are currently attractive VLD catalysts, with WO3 possessing similarities with TiO2 as a metal oxide, allowing correlations between the knowledge regarding the reference catalyst, and g-C3N4 having an interesting and distinct non-metallic polymeric structure with the benefit of easy production. In this review, recent developments towards CECs degradation in TiO2 based photocatalysis are discussed, as reference catalyst, alongside the selected alternative materials, WO3 and g-C3N4. The aim here is to evaluate the different techniques more commonly explored to enhance catalyst photo-activity, specifically doping with multiple elements and the formation of composite materials. Moreover, the possible combination of photocatalysis and ozonation is also explored, as a promising route to potentialize their individual efficiencies and overcome typical drawbacks. [ABSTRACT FROM AUTHOR]

Nitrogen-doped TiO 2 was applied in photocatalytic ozonation reactions for the degradation of a mixture of five parabens under UVA radiation, being evaluated the influence of the reaction medium. The initial mixture parabens concentration considered in these experiments was 50 mg L−1. The parabens degradation rate was considerably enhanced under neutral pH, specially using a buffered solution, leading to a complete removal under 60 min and with transferred ozone dose (TOD) 36% lower compared to reaction under natural conditions. Isopropanol, known radical scavenger, impeded the complete contaminants removal, affecting the reaction route and by-products formation, but when KI was jointly added, total removal was achieved under 30 min and with a TOD of 25.9 mg L−1. Parabens depletion was also improved in the presence of Cl−, SO 4 2− and HCO 3 −, commonly present in wastewaters. The use of river water (RW) and a secondary wastewater (SWW) as water matrices maintained the process efficiency with lower TOD required, and treated solutions presented lower phytotoxicity towards Lepidium sativum. Unlabelled Image • Neutral pH, Cl−, SO 4 2−, HCO 3 − and KI improved the contaminants removal. • Isopropanol hindered parabens elimination and altered by-products formation. • SWW and RW demanded lower TOD, possibly due to the presence of the evaluated ions. • SWW and RW treated solution achieved lower phytotoxicity to Lepidium sativum. [ABSTRACT FROM AUTHOR]

Lead is a heavy metal of high impact for the environment as well as for human health, being cause of several diseases. Considering the importance of obtaining an effective treatment for lead removal, a new hybrid material was developed for sorption of Pb 2+ from aqueous solution. The effect of pH, temperature, liquid/solid ratio (g/cm 3 ) and lead concentration on the sorption capacity of yeasts chemically modified with cubic silsesquioxane (YS) was analyzed. Additionally, the toxicity of lead on the neuronal activity was also investigated in order to assess whether the damage caused by the Pb 2+ ion is reversible or not. The YS is highly promissory as sorbent of lead in high concentrations (100 and 500 ppm), reaching high efficiency in short contact times (15 min), and at the natural pH (4) of the Pb 2+ solution and room temperature. The best sorption obtained was 82% removal and 248 mg/g with 500 cm 3 /g sorbent, pH 4, room temperature and contact time of 15 min. Besides, such high efficiencies are obtained with low quantities of biosorbent, when compared with other similar materials. The impact of lead on neuronal function was studied by measuring autofluorescence signals, associated with changes in cellular metabolism, at the hippocampal CA3 area in brain slices. In this toxicity tests, the effect of low concentrations of lead (1 and 3 μM) on neuronal activity was evaluated. After removal of the lead, the irreversibility of the observed changes can be verified, which suggests the existence of neuronal damages. [ABSTRACT FROM AUTHOR]

The main objective of this work is to evaluate the phytotoxicity of olive mill solid wastes (OMW) produced in two different centrifugation technologies and also the toxicity associated with specific phenolic compounds. Two samples of waste were collected in two-phase (2P-OMW) and three-phase (3P-OMW) centrifugation olive oil production processes, and cress bioassays with Lepidium sativum L. were employed to evaluate phytotoxicity. Although both OMW have similar total phenolic content (TPh), results confirmed that 2P-OMW is more phytotoxic than 3P-OMW. When extracts from 2P-OMW at liquid to solid ratio of 10 L kg −1 were applied none of the seeds germinated, i.e. germination index ( G I ) was 0%, while for 3P-OMW GI was 94.3%. Growth tests in soil and mixtures with OMW also led to more favorable results for 3P-OMW, whereas worse results than those obtained in the control experiments were observed. In order to discriminate the individual influence of eleven phenolic compounds, gallic acid, protocatechuic acid, cinnamic acid, syringic acid, 3,4,5-trimethoxybenzoic acid, 4-hydroxybenzoic acid, vanillic acid, p -coumaric acid, caffeic acid, veratric acid and phenol were tested in the concentration range of 5–500 mg L −1 . Results showed that cinnamic acid is the most phytotoxic, with EC 50 of 60 mg L −1 , which is related with its hydrophobicity. Moreover, increasing -OH and -OCH 3 groups in these molecules seem to reduce phytotoxicity. Tests with a mixture of six phenolic compounds demonstrated there are neither synergistic nor additive effects. The phytotoxicity appears to be determined by the presence of the most lipophilic phenolic molecule. [ABSTRACT FROM AUTHOR]

A new sludge free Fenton's process for wastewater treatment is proposed. Fenton's reagent is an interesting oxidation treatment for organic matter removal from liquid effluents. However, its main drawback is the iron sludge produced at the end of the reaction. An integrated methodology is recommended involving the application of ion exchange resins that recover dissolved iron without the need of sludge production. The results reveal high iron removal efficiencies (~ 100%). On the other hand, this strategy is able to fulfill iron removal requirements even if some iron precipitation occurs during Fenton's peroxidation. In fact, sludge dissolution is promoted and the resulting dissolved iron is then adsorbed by the resin. Langmuir model was able to satisfactorily describe the experimental results leading to a q m = 56 mg/g. A design of experiments approach allowed concluding that pH is a key parameter for ion-exchange. This combined strategy overcomes Fenton's main shortcoming and will boost the industrial application of this interesting wastewater treatment approach. [ABSTRACT FROM AUTHOR]

OpenCL is an open standard for parallel programming of heterogeneous compute devices, such as GPUs, CPUs, DSPs or FPGAs. However, the verbosity of its C host API can hinder application development. In this paper we present cf4ocl, a software library for rapid development of OpenCL programs in pure C. It aims to reduce the verbosity of the OpenCL API, offering straightforward memory management, integrated profiling of events (e.g., kernel execution and data transfers), simple but extensible device selection mechanism and user-friendly error management. We compare two versions of a conceptual application example, one based on cf4ocl, the other developed directly with the OpenCL host API. Results show that the former is simpler to implement and offers more features, at the cost of an effectively negligible computational overhead. Additionally, the tools provided with cf4ocl allowed for a quick analysis on how to optimize the application. [ABSTRACT FROM AUTHOR]

Computational models of complex systems are usually elaborate and sensitive to implementation details, characteristics which often affect their verification and validation. Model replication is a possible solution to this issue. It avoids biases associated with the language or toolkit used to develop the original model, not only promoting its verification and validation, but also fostering the credibility of the underlying conceptual model. However, different model implementations must be compared to assess their equivalence. The problem is, given two or more implementations of a stochastic model, how to prove that they display similar behavior? In this paper, we present a model comparison technique, which uses principal component analysis to convert simulation output into a set of linearly uncorrelated statistical measures, analyzable in a consistent, model-independent fashion. It is appropriate for ascertaining distributional equivalence of a model replication with its original implementation. Besides model-independence, this technique has three other desirable properties: a) it automatically selects output features that best explain implementation differences; b) it does not depend on the distributional properties of simulation output; and, c) it simplifies the modelers’ work, as it can be used directly on simulation outputs. The proposed technique is shown to produce similar results to the manual or empirical selection of output features when applied to a well-studied reference model. [ABSTRACT FROM AUTHOR]

An electrochemical oxidation (EO) process with Ti/RuO 2 anodes was applied to treat phenolic wastewaters. In order to optimise the system, different operating conditions were tested. The nature of the electrolyte and the applied current density greatly affected the process, while the concentration of the electrolyte as well as the initial pH had a sparingly impact. The optimum operating conditions attained, 10 g L − 1 of NaCl, 119 mA cm − 2 and initial pH 3.4, allowed the complete removal of the total phenolic content (TPh) and chemical oxygen demand (COD) when applied to a simulated phenolic mixture. SEM analysis revealed no morphological differences on the surface of the anode before and after it being used in EO. Neuronal studies were performed to verify the impact of the synthetic phenolic effluent, before and after the EO treatment, in the formation of neuronal reactive oxygen species (ROS). The treated effluent had a milder effect, compared to the raw one, but neuronal activity became enhanced after its removal. Regarding the depuration of an undiluted real olive mill wastewater (OMW) under the optimised parameters, the treatment achieved 100% of TPh removal and 17.2% of COD removal. Thus, the EO can be considered a satisfactory pre-treatment process to real wastewaters, since all phenolic content can be removed in 180 min. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4) is a promising catalyst for contaminants of emerging concern removal applications, especially as a visible-light-driven material. In this study, g-C3N4 catalysts were effectively synthesized through a simple thermal polymerization method, using melamine, urea, and thiourea as precursors to elucidate the influence of these compounds on the final product's photocatalytic performance. The degradation of a mixture of three parabens was investigated under different types of radiation: two artificial, ultraviolet-A (UVA) and visible LED, and natural sunlight. The urea-based catalyst (UCN) presented better results under all radiation sources, followed by thiourea, and finally, melamine. Among the artificial light sources, the degradation of parabens under UVA was considerably higher than visible—up to 51% and 21%, respectively—using UCN; however, the broader spectrum of natural sunlight was able to achieve the highest removals, up to 92%, using UCN. Comparing artificial radiation sources, UVA lamps presented 45% lower energy consumption and associated costs. Photocatalytic ozonation was tested using UCN and MCN, with UCN once more possessing superior performance and a synergetic effect between photocatalysis and ozonation, with complete removal under 12 min. The use of g-C3N4 was then successfully tested in initial screening and found to be an efficient alternative in more low-cost and feasible solar photocatalysis water treatment. [ABSTRACT FROM AUTHOR]

Esters of p-hydroxybenzoic acid, commonly known as parabens are preservatives used in a variety of personal care products, cosmetics, pharmaceutical and food products. This paper presents the results of studies on photochemical degradation of hazardous water contaminants – methyl- (MP), ethyl- (EP), propyl- (PP), butyl- (BuP), benzylparaben (BeP) and p-hydroxybenzoic acid (p-HBA) (individually or in mixture) using ultraviolet C lamps in the presence and absence of hydrogen peroxide. Both systems were very efficient on the degradation of the single parent compounds. Total removal of individual pollutant was achieved after 2 h or 6 min for UVC and UVC/H 2 O 2 , respectively. The kinetic constants of hydroxyl radicals reaction and the photolysis quantum yields were obtained for each pollutant. The decomposition of the mixture of the six compounds with the H 2 O 2 /UVC system ensures a complete degradation after 30 min with a degree of mineralization of 25%. Whereas only 10% of mineralization was observed after the same time for photolysis. The pseudo-first-order fluence-based rate constants (for UVC and H 2 O 2 /UVC) for each paraben in the mixture reaction were calculated for the first time. The analysis using UHPLC/MS/MS technique shows that hydroxylation is the main pathway of the reaction with hydroxyl radicals. In fact, p-hydroxybenzoic acid, 2,4-dihydroxybenzoic acid and 3,4-dihydroxybenzoic acid were identified as a major transformation products. Moreover the mono, di and tri derivatives of parabens were detected as the main intermediates formed during oxidation. The fluence-based experimental data and cost analysis showed that the H 2 O 2 /UVC treatment was effective in mineralizing of the parabens mixture. [ABSTRACT FROM AUTHOR]

Electrocoagulation using a Zn anode was applied for the first time to remove the organic load of a liquid effluent. Different operating conditions (pH, current density, distance between electrodes, nature of electrolyte and kind of cathode) were tested with synthetic phenolic wastewater, in order to optimise the process. Both the medium pH and the type of electrolyte that were used greatly affected the efficiency of the system, followed by the influence of the current density and the cathode material, in a lesser extent. The effect of the distance between electrodes was quite negligible. Furthermore, a sequence of fed-batch trials involving the electrodes reuse showed almost constant activity during the operation time. The optimum operating conditions achieved were initial pH of the effluent equal to 3.2, current density of 250 A/m 2 , distance between electrodes of 1.0 cm and 1.5 g/L of NaCl. Moreover, the Zn anode/stainless steel cathode pair revealed the most interesting results. These parameters led to 84.2% and 40.3% of total phenolic (TPh) content and chemical oxygen demand (COD) removal, respectively. In addition, the depuration of a filtered real olive mill effluent without NaCl addition achieved the abatement of up to 72.3% of TPh and 20.9% of COD. An energy consumption of 40 kW h/m 3 and 34 kW h/m 3 was observed for the treatment of the simulated and the real wastewater, respectively. Furthermore, the ecological impact of the treated effluent was detected by bio-luminescence techniques. This study shows the potentiality of the electrocoagulation process as a pre-treatment of other methods, namely the electrochemical oxidation, to ensure the legal limits values of the wastewater to be discharged into the aquatic environment regarding their organic load. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amberlite HPR1100 can remove phenolic compounds from real olive mill wastewater. • Different adsorption behaviours for real and synthetic olive mill wastewater. • Acetone was the solvent that led to higher recovery efficiencies. • Adsorption is a feasible technology for phenolics recovery. Olive mill wastewater (OMW) is rich in valuable compounds such as phenolic compounds. Amberlite@HPR1100 was applied as adsorbent to recover these added-value compounds from OMW. For synthetic OMW, Langmuir isotherm and pseudo-second order kinetic model were able to predict the experimental data instead for real effluent, were the Freundlich isotherm and the pseudo-first order kinetic model the best fits. The continuous process was also studied, for real OMW the t bp , t st and t ex were 1.27 min, 84.4 min and 575 min, respectively. After 645 min of adsorption, 42 % of phenolic content was adsorbed into the resin. An industrial column for recovering phenolic compounds from OMW was designed, which should have around 5 m and 0.6 m of height and diameter, respectively, filled with 112 kg of resin (dry basis). The desorption process for real OMW with acetone 80 % recovery was accomplished after 5 h of contact. [ABSTRACT FROM AUTHOR]

Wastewater from the olive oil industry is an environmental problem which is growing in the Mediterranean region. Presence of phenolic compounds and high organic matter load are characteristics of this effluent that make it difficult to treat. In this study, the applicability of sulfate radical based advanced oxidation processes (SRbAOPs), using peroxymonosulfate (PMS) as oxidant, was evaluated in the treatment of synthetic olive mill wastewater (OMW). Different procedures for PMS activation were studied such as activation by Fe(II), radiation (visible and UV-A) and ultrasounds. The operation conditions were optimized by testing pH values, Fe(II) and PMS loads. At optimal conditions ([PMS] = 1600 mg/L, [Fe2+] = 700 mg/L and pH = 5) 60 ± 2% COD removal was achieved. This process shows to be selective since complete degradation of 3,4,5-trimetoxybenzoic acid was obtained after 3 min of reaction. The addition of light, PMS/LED/Fe(II) and PMS/UV-A/Fe(II), did not increase the efficiency of organic matter removal, with 56 ± 2% and 58 ± 1% of COD removal, respectively, comparatively to PMS/Fe(II) (60 ± 2%). PMS activated by ultrasounds led to 52 ± 3% and 23 ± 2% removal of phenolic compounds and COD, respectively, after 60 min. Toxicity tests using Lepidium sativum showed that treatment with PMS/UV-A led to a treated sample with mild inhibition of plant growth. [ABSTRACT FROM AUTHOR]

Composting is one of the technologies recommended for pre-treating industrial eggshells (ES) before its application in soils, for calcium recycling. However, due to the high inorganic content of ES, a mixture of biodegradable materials is required to assure a successful procedure. In this study, an adequate organic blend composition containing potato peel (PP), grass clippings (GC) and wheat straw (WS) was determined by applying the simplex-centroid mixture design method to achieve a desired moisture content, carbon: nitrogen ratio and free air space for effective composting of ES. A blend of 56% PP, 37% GC and 7% WS was selected and tested in a self heating reactor, where 10% (w/w) of ES was incorporated. After 29 days of reactor operation, a dry matter reduction of 46% was achieved and thermophilic temperatures were maintained during 15 days, indicating that the blend selected by statistical approach was adequate for composting of ES. [ABSTRACT FROM AUTHOR]

Abstract: The need of more efficient solid catalysts for the heterogeneous slurry Fenton process led many investigators to research new compounds activities. Ceria based iron catalysts have proved their good performance enhancing the removal of organic compounds, reducing toxicity and improving biodegradability in the depuration of phenolic wastewaters. This work evaluates the calcination temperature (300°C, 600°C and 1000°C) during the preparation of the catalysts—co-precipitation of the precursors salts, while the same previously optimized conditions were adopted (pH 3.0, 1.0gL−1 of Fe–Ce–O 70/30 as the catalyst, [H2O2]=244mM and 120min of room temperature reaction) to treat a simulated wastewater comprising 0.1gL−1 of each of the six common phenolic acids found in Olive Mills wastewaters. The three obtained solids were characterized regarding superficial area, average pore diameter, FT-IR and XRD. Catalysts calcinated at 300°C, 600°C and 1000°C presented superficial areas of 188, 86 and 2m2/g, respectively, and their average pore diameter are 66, 87 and 151Å, correspondingly. As showed in the XRD, the increase of the calcination temperature promotes the crystallinity of the obtained solid—higher amount of prominent peaks, meaning that the catalysts have different states of valence for iron (Fe2+ or Fe3+) and ceria (Ce2+ to Ce4+), what would explain their singular behaviours during the reaction. As expected, the solids with higher superficial areas had better performances in every aspect: more COD, TOC and phenolic acids removal, pointing the lowest calcination temperature as leading to a more efficient solid to enhance hydrogen peroxidation, involving, however, more metal leaching. The higher the calcination temperature is, the more oxidized the solid will become because the calcination occurs without atmospheric control and so the oxygen contained in the air will interfere on the valence of iron ions at the solid''s surface. This means that a solid calcinated at a higher temperature will have increased Fe3+ content and, as one can find in the literature, Fe2+ is more effective than Fe3+ at hydrogen peroxidation, explaining the better efficiency of the catalyst calcinated at the lowest temperature. Toxicological and biodegradability studies were still performed and showed enhancement in all cases. [Copyright &y& Elsevier]

Abstract: The inactivation of Escherichia coli using moderate electric fields (MEF) below 25°C, was investigated. Keeping the temperature always below 25°C demonstrated that electric fields are involved in the inactivation of E. coli, without possible synergistic temperature effects. Electric fields above 220Vcm−1 promoted death rates of 3log10 cycles of E. coli in less than 6min, and even higher rates at greater electric fields, while presumably overcoming the thermal degradation caused by conventional high temperature treatments. A non-thermal model was proposed that successfully describes the E. coli death kinetics under this treatment. SEM observations of E. coli cells after the exposure to the MEF treatment, revealed changes at the cell membrane level, indicating a possible cause for the cell death rates. These results show that this treatment holds potential for sterilization of thermolabile products (e.g. serum and other physiological fluids, food products), by itself or as a complement of the traditional heat-dependent techniques. [Copyright &y& Elsevier]

Abstract: Fifty-one quince jams from several different brands, commercialised in three consecutive years, traditionally prepared and industrially manufactured, were studied. Principal component analysis (PCA) was performed, in order to assess the correlations between the different components of quince jam phenolics, organic acids and free amino acids. Phenolics determination was the most interesting. The differences between phenolic profiles of traditional and industrial quince jams were emphasised during PCA. Two main PC characterise the quince jam phenolic composition (54.4% of all variance): PC1 (37.4%) and PC2 (17.0%). The PC1 describes the differences between the contents of 3-O- and 5-O-caffeoylquinic acids and all flavonoids and the PC2 relates the contents of 4-O- and 5-O-caffeoylquinic acids against 3-O-caffeoylquinic and 3,5-dicaffeoylquinic acids. The results indicate that many industrial manufacturers usually use unpeeled fruits in the preparation of the jams. The PCA of phenolic compounds enabled clear discrimination between quince jams prepared with peeled and unpeeled fruits. [Copyright &y& Elsevier]

However, despite the efficient degradation of dye solutions in the presence of TiO SB 2 sb -catalysts, the application of TiO SB 2 sb catalysts for industrial textile wastewater treatment was not satisfactory, even when it was enhanced by the presence of ozone [[23]]. In the experiments with a TiO SB 2 sb -pillared catalyst that was hydrothermally treated and activated, complete removal was obtained after almost 2 h, whereas dielectric barrier discharge plasma in the presence of photocatalysts was used and complete degradation was achieved after only 8 s [[22]]. Butman's group demonstrated the photocatalytic degradation of Rhodamine B using two forms of TiO SB 2 sb , namely, biomorphic fibrous TiO SB 2 sb ([[21]]) and TiO SB 2 sb -pillared montmorillonite ([[22]]) under UVA irradiation. Methylene blue degradation was investigated in the presence of polyaniline-wrapped, manganese-doped titanium oxide (PANi/Mn-TiO SB 2 sb ) [[16]] as well as Au-Ag co-decorated TiO SB 2 sb (Au SB x sb Ag SB (1-x) sb /TiO SB 2 sb ) [[15]] under visible light. [Extracted from the article]

The evolution of the analytical techniques allowed the detection of pollutants so called contaminants of emerging concern (CEC). Water scarcity is a reality lived by some populations. Thus, water reuse is mandatory to minimize this problematic. This implies that wastewater treatments must be improved. The Advanced Oxidation Processes (AOP) such as photocatalysis and ozonation can be suitable solutions for CECs abatement. Also, TiO 2 powder catalyst is an important material in this field. However, its powder form presents a huge obstacle for industrial application, and the solution may be to support this material. This work studies the degradation of a mixture of 3 parabens by photocatalysis, catalytic and photocatalytic ozonation using TiO 2 nanotube arrays (NTs). The studied catalysts were produced using electrolyte solutions with different ages, so the nanotubes growth ocurred at 5 (NTs_5) and 20 (NTs_20) anodization cycles. The toxicological assessment for the initial mixture, final samples and along the reaction time was performed using the cress seeds Lepidium sativum and the bacteria Aliivibrio fischeri. The photocatalysis with UVA radiation led to 50 % and 35 % parabens removal for NTs_5 and NTs_20 catalysts. This can be related to the different dimensional characteristics of the nanotubes. Ozone technologies led to total parabens degradation with an improvement when catalytic ozonation was applied. The use of NTs as catalysts in ozonation also reduced the transferred ozone dose (TOD) required for total parabens abatement when compared to single ozonation. The main parabens degradation mechanism seems to be via direct pathway by molecular ozone. Regarding the toxicity assessment, the toxicity did not change significatively, which can be explained by the intermediate's formation. [ABSTRACT FROM AUTHOR]

This study explores the physicochemical capacities of solid wastes from olive oil mills (olive stone, OS, and olive pomace, OP), in obtaining catalysts to be applied in heterogeneous Fenton and persulfate processes. Through physicochemical treatments and the impregnation of iron by hydrothermal deposition and wetness impregnation (WI) different catalysts were produced, tested and characterized. The olive mill wastewater (OMW) studied in this work is a synthetic solution with five phenolic compounds to mimic the real effluent. The removal efficiency of phenolic acids and organic load (COD) present in this type of effluent was evaluated. In the treatment of synthetic wastewater, almost 100% COD was removed using OS and OP-FeWI as catalysts in the heterogeneous Fenton process. In the sulfate radical-based reaction, the 3,4–Dihydroxybenzoic acid was slightly more degradable than other phenolic acids which confirms the selectivity of sulfate radicals. The materials subject to thermal processes revealed an interesting adsorption capacity. This procedure not only reduces the environmental impact of OMW, but also promotes the implementation of new circular economy approaches. [Display omitted] • Olive mill waste can be suitable used for the preparation of iron catalysts. • Incipient wetness and hydrothermal impregnation were used for Fe catalyst preparation. • Fenton process almost reduces all initial chemical oxygen demand from simulated olive mill wastewater. • Olive mill waste biochar with incipient wetness Fe impregnation is the better adsorbent. [ABSTRACT FROM AUTHOR]

The complexity of water contaminants, both chemical and biological requires an efficient and feasible treatment alternative. Herein, the photocatalytic ozonation treatment using graphitic carbon nitride catalysts was effectively applied for the elimination of a mixture of targeted chemical contaminants, and both Escherichia coli bacteria and Human polyomavirus JC (JC virus) in real secondary wastewater. The exfoliation treatment was compared in catalysts prepared using urea and melamine as precursors. The physical treatment provided no significant enhancement in the urea-based catalyst, while the improvement in the structure of the melamine-based (36MCN) material and formation of melem heterojunction increased its catalytic properties. In both sets of contaminants, the photocatalytic ozonation systems were superior to photolytic ozonation, especially regarding ozone consumption. The best catalyst, 36MCN, resulted in a decrease of 57.5%, 33.0% and 29.0% in the ozone dose required to eliminate chemical, bacteria and virus contaminants, respectively. The hydroxyl radicals were also shown as a key responsible for the pollutant's elimination. The higher radical production and decomposition of ozone are possible indications of the better performance of graphitic carbon nitride photocatalytic ozonation, as an efficient tertiary wastewater alternative. [Display omitted] • Exfoliation treatment for urea-based g-C3N4 provided no significant benefits. • Photocatalytic ozonation using had a faster removal of all 6 pollutants and using a lower ozone dose. • Exfoliated melamine-based g-C3N4 reaction had the lowest ozone usage, 57.5% less than single ozonation. • The melamine-based g-C3N4 fully eliminated all pathogens analyzed under 30 min. • ·OH was indicated as a key radical in bacteria inactivation. [ABSTRACT FROM AUTHOR]

Polydimethylsiloxane is a suitable photocatalyst support for wastewater treatment. However, as polydimethylsiloxane is hydrophobic it must be modified, to become hydrophilic prior to its application. Unfortunately, this modification is not permanent and polydimethylsiloxane materials can recover part of their original characteristics. Therefore, even though photocatalytic polydimethylsiloxane-based membranes exhibit a satisfactory performance in the abatement of pollutants, they present a low performance when reused. The main objective of this study was to develop methodologies that may improve the surface wettability of P25/polydimethylsiloxane materials to enhance their reusability. Thus, the following strategies were implemented to delay the hydrophobic recovery or decrease the water contact angle stabilization values of both polydimethylsiloxane and P25/polydimethylsiloxane membranes: increased amount of photocatalyst particles added to the matrix, prolongated curing process and finally storage/application of the material at low temperatures. According to the results, the followed approaches were effective in this regard. However, (i) the first two mentioned strategies led to the formation of photocatalysts agglomerates and, as such, the membranes exhibited a low photocatalytic activity compared to previous studies, and (ii) the last-mentioned strategy led to the inactivation of the photocatalyst. Therefore, it was concluded that an improvement in the surface wettability does not necessarily translate in an improvement of the materials performance, since it may affect other crucial characteristics. It was also concluded that the best results were achieved when P25 was attached to the surface of polydimethylsiloxane but no photocatalyst particles were added to the polymer bulk, when the curing process took four hours, and also when the photocatalytic process was conducted at 25 °C. With these conditions, the material exhibited a performance on the degradation of a mixture of three pollutants of, approximately, 55% in the first cycle, 35% in the second cycle and 30% in the third and fourth cycles. [Display omitted] • PDMS was successfully used a polymeric support for P25. • PMDS is hydrophobic but its surface wettability may be improved by plasma treatment. • The applied strategies delayed hydrophobic recovery and WCA stabilization values. • Distribution of P25 on surfaces was affected and agglomerates were sometimes formed. • Results show removals of 55% in the 1st, 35% in the 2nd and 30% in the 3rd. [ABSTRACT FROM AUTHOR]

• Photocatalytic ozonation totally degraded the parabens mixture over 120 min reactions. • 10 % N-TiO 2 (ammonia) had the best result for parabens degradation and TOC and COD removal. • Low amount of urea on TiO 2 enhances cress seeds growth and reduces the mortality of clams. • Treated solutions presented lower toxicities to bacteria, cress and clams. Degradation of a mixture of five parabens was evaluated using photocatalytic oxidation, photolytic ozonation and photocatalytic ozonation, being applied UVA radiation and N-TiO2 doped catalysts. Photocatalytic oxidation was not able to eliminate parabens, achieving less than 10 % of removal. The use of ozone and UVA radiation resulted in total contaminants abatement with a transferred ozone dose (TOD) of 46.2 mg L−1. Photocatalytic ozonation also totally removed parabens but with a considerable reduction of TOD required along with higher COD and TOC removals, up to 35.7 % and 34.1 %, respectively, for the best catalyst (ammonia-doped 10 % N-TiO 2). Toxicity tests were conducted using three different species. Lepidium sativum seeds had higher growth indexes (GIs) when exposed to solutions treated by photocatalytic ozonation reactions. Nevertheless, Allivibrio fischeri and Corbicula fluminea demonstrated lower toxic responses to photolytic ozonation treated solution which may be related with the different by-products formed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solar photocatalysis presented higher degradation than UVA photocatalysis. • Pt- and Pd- TiO 2 nanotubes led to better results than pristine TiO 2 for UVA radiation. • Catalytic-based ozone experiments led to lower ozone consumption than single ozone. • Modified photocatalysts improved the catalytic ozonation process. • Pristine TiO 2 nanotubes led the lowest ozone consumption in photocatalytic ozonation. The role of modified TiO 2 nanotubes (TNTs) with noble metals was studied for photocatalysis, catalytic and photocatalytic ozonation of a paraben's mixture. The TNTs were obtained by anodization and were modified by photodeposition with 0.25 mol% of Au, Pt or Pd. Results showed that solar photocatalysis led to higher degradation than UVA radiation, and under UVA radiation, the use of 3 Pt-TNTs (3 TNTs plates modified with Pt) and 3 Pd-TNTs present the same effect as the use of 5 and 7 pristine-TNTs plates, respectively. The best parabens removal was achieved for Pd-TNTs under UVA radiation and pristine TNTs under solar radiation, with 43% and 81% removal in 120 min, respectively. All the catalytic and photocatalytic ozonation experiments led to less ozone consumption than single ozonation (transferred ozone dose (TOD) = 5.27 mgO 3 /L) with total parabens abatement. Catalytic ozonation experiments suggest that the presence of metals can promote the formation of oxidative radicals, with the Au-TNTs presenting best performance (TOD ≈ 3.59 mgO 3 /L) while pristine TNTs led to TOD = 4.98 mgO 3 /L. For photocatalytic ozonation, the pristine TNTs led to the lowest ozone consumption (TOD = 3.74 mgO 3 /L). Moreover, the use of hydroxyl radical scavenger showed that hydroxyl radical is formed during single and photocatalytic ozonation mechanism, which should be related to the natural and surface catalytic ozone decomposition. [ABSTRACT FROM AUTHOR]

Application of solar photocatalysis for water treatment is intensively studied. In this work, we investigated TiO2 modified with platinum (Pt/TiO2) and palladium (Pd/TiO2) using sulfamethoxazole (SMX) as the model contaminant. We considered the following parameters: (i) level of TiO2 modification with Pt/Pd, (ii) initial concentration of photocatalysts, (iii) geographic location where processes were conducted, and (iv) natural water matrix. The catalysts characterized by SEM, EDX, DRS, and XRD techniques showed successful deposition of Pd and Pt atoms on TiO2 surface that enabled light absorption in the visible (Vis) range, and therefore caused efficient SMX removal in all tested conditions. A comparison of the rate constants of SMX degradation in various conditions revealed that modification with Pd gave better results than modification with Pt, which was explained by the better optical properties of Pd/TiO2. The removal of SMX was higher with Pd/TiO2 than with Pt/TiO2, independent of the modification level. In the experiments with the same modification level, similar rate constants were achieved when four times the lower concentration of Pd/TiO2 was used as compared with Pt/TiO2. Formation of four SMX transformation products was confirmed, in which both amine groups are involved in photocatalytic oxidation. No toxic effect of post-reaction solutions towards Lepidium sativum was observed. [ABSTRACT FROM AUTHOR]