Initial Pollutant Concentration Research Articles

Assessment and optimization of wet air oxidation for treatment of landfill leachate concentrated with reverse osmosis

Sanitary landfilling is one of the most common ways to eliminate solid municipal/urban wastes. Despite many advantages, this method leads to the generation of contaminated leachates that remains an unavoidable consequence of the waste disposal. Membrane technologies, such as reverse osmosis, are frequently used for leachate treatment as they generate good quality permeate with a high recovery rate. However, their primary drawbacks are fouling, eliminated by chemical wash, and the production of highly polluted concentrates. This paper aims to assess and optimize the use of wet air oxidation to treat reverse osmosis concentrates in terms of bio-refractory organic pollutants removal. Wet air oxidation was performed at elevated pressure and temperature using experimental design methodology with a 70% oxygen excess for 6 h in a stirred batch reactor. The effect of operating conditions was investigated with an experimental design where 3 factors (two quantitative ones: pressure and temperature and a qualitative one: seasonality of the effluent) have been considered. The chemical oxygen demand and the total organic carbon removals increased with the increase of temperature (from 200 °C to 300 °C) and no effect of the pressure was observed within the range 18 – 21 MPa. Wet air oxidation could achieve up to 99% removals for chemical oxygen demand and total organic carbon for the seasonality of October. Experiments also showed that increasing the initial pollutant concentration increased initial kinetic rates. Finally, models were established to calculate and predict pollution removal rate and its kinetic, in the domain of study.

A composite photocatalytic system based on spent alkaline Zn–Mn batteries for toluene removal under multiple conditions

The resource utilization of spent alkaline Zn–Mn batteries (S-AZMB) has always been a hot issue in the field of energy regeneration and environmental protection. The cumbersome and complicated purification process is the reason for their limited recycling. Not long ago, we proved that unpurified S-AZMB can be used directly: construct a Z-scheme photocatalytic system by combining with commercial TiO2 through high-temperature calcination. In order for this finding to be truly adopted by the application market, the high energy consumption calcination process needs to be improved urgently. In this work, we explore the temperature dependence of performance for the composite photocatalyst (TiO2@S-AZMB). A series of experimental results confirm that lowering the calcination temperature not only conducive to improving the separation efficiency of photogenerated electron-hole pairs, but also can significantly improve the environmental adaptability of the catalyst. Specifically, the catalyst synthesized by calcination temperature at 200 °C exhibits higher toluene removal efficiency than that at 500 °C under different initial concentration of pollutants, relative humidity, light intensity and oxygen content. This study not only further improves the photocatalytic performance of the composite catalyst, but also accords with the idea of energy saving and emission reduction, which provides more space for the possibility of recycling S-AZMB.

Characterization of the Adsorption of Bisphenol A and Carbamazepine from Aqueous Solution on Graphene Oxide and Partially Reduced Graphene Oxide by High-Performance Liquid Chromatography (HPLC)

Two carbonaceous materials were prepared and characterized for their effectiveness in eliminating bisphenol A (BPA) and carbamazepine (CBZ) from aqueous solution. The adsorption of these pollutants was investigated because these compounds are unregulated in water legislation and their prevalence and toxicity require special attention related to their removal. There is a global concern linked to indirect ingestion of endocrine disrupting compounds (EDCs) and pharmaceuticals due to their deleterious effects on humans and animal health. In order to determine the optimum adsorption parameters, the influence of the contact time and of the initial concentration of pollutant were investigated. According to the Langmuir model, the maximum adsorption capacity (qmax) of partially reduced graphene oxide (PRGrO) for BPA and CBZ (346.07 mg/g respectively 55.13 mg/g) was higher than qmax of graphene oxide (GO) (92.40 mg/g, respectively 32.35 mg/g). Considering these results, we suggest that partially reduced graphene oxide is a promising and effective adsorbent for the removal of bisphenol A and carbamazepine from aqueous solutions. To our knowledge, there are no other studies related to the adsorption of these pollutants on partially reduced graphene oxide.

Photocatalytic reduction of CO2 and degradation of Bisphenol-S by g-C3N4/Cu2O@Cu S-scheme heterojunction: Study on the photocatalytic performance and mechanism insight

An efficient g-C3N4/Cu2O@Cu plasmonic Step-scheme (S-scheme) heterojunction photocatalyst was successfully designed and used for the degradation of pollutants and energy generation. The removal of Bisphenol-S pollutants and catalytic reduction of CO2 for hydrocarbon fuel production experiments under the visible light irradiation showed that the catalyst displayed good stability and perfect photocatalytic performance. Among the prepared samples, g-C3N4/Cu2O@Cu-4 displayed the highest catalytic performance, which was attributed to the high light absorption capacity and the efficient interfacial charge separation in the S-scheme heterojunction. From the viewpoint of practical wastewater treatment, a series of the effects of environmental factors, such as initial pollutant concentration, inorganic salts, organic compounds and various water sources on the photocatalytic performance were investigated. Eight intermediate products formed in the photocatalytic oxidation of Bisphenol-S were confirmed by the GC-MS, and the proposed photocatalytic degradation pathway of Bisphenol-S was suggested according to the intermediate products. Importantly, the charge density difference of the interface between g-C3N4 and Cu2O (g-C3N4/Cu2O) as well as the interface between Cu and Cu2O (Cu/Cu2O heterostructures) was calculated, respectively. The calculated results verified that the built-in electric field had been established at their interface. Spatial separation of photogenerated electron-hole pairs in the S-scheme g-C3N4/Cu2O@Cu heterojunction was realized through the built-in electric field.

Structural and Adsorptive Characteristics of 2D Multilayer Nanoflakes of NiCo Phosphates for Chromium(VI) Removal: Experimental and Monte Carlo Simulations.

Metal phosphates are efficient adsorbent materials for heavy elements present in industrial effluents because of their promising properties. Hexachromium ions are among the most dangerous contaminants owing to their harmful properties and non-degradability. Accordingly, the present work offers a simplified study of the preparation of bimetallic phosphate materials from nickel cobalt phosphate (NiCo-Ph) based on the sol–gel method in an equimolar ratio. Characterization of the bulk, crystal phase, texture profile, and nanosize of NiCo-Ph was carried out using various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, nitrogen adsorption–desorption isotherm measurements, field emission scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. In this regard, the adsorption performance of NiCo-Ph was exemplified through six batch experiments, elucidating the impacts of the sorbent dose, initial concentration of pollutants, sorption time, temperature, pH, and shaking rate. According to UV/vis spectrophotometry measurements and their related calculations of NiCo-Ph, the maximum removal efficiency (RE %) of 92% and adsorption capacity (qm) of 37 mg/g were achieved at pH = 6, a dose of 5.0 g/L, 100 mg/L of [Cr(VI)], 300 rpm, adsorption time of 60 min, and 298 K. Monte Carlo simulations were also carried out to correlate the experimental data with theoretical calculations that provided a higher negative value (−911.62 kcal mol–1) for the adsorption energy of Cr(VI) in acidic medium. The adsorbent NiCo-Ph prepared by this direct method is therefore recommended for the quantification of Cr(VI) under slightly acidic solutions and at room temperature, which can maintain its efficiency even up to six cycles.

The design of praseodymium galena nanospheres: An effective photocatalyst for the remediation of carcinogenic phenothiazine and chromium contaminants

Herein, we report the synthesis of nanosphere-shaped praseodymium lead sulfide nanoparticles (PrPbS NPs) using a simple environmentally benign sonochemical technique, which have been well characterized using various spectroscopic and microscopic techniques. The nanosphere shaped PrPbS NPs were applied as a dual role photocatalyst for the degradation of hazardous methylene blue (MB) dye and the conversion of carcinogenic hexavalent chromium (Cr6+) to trivalent chromium (Cr3+) under visible light irradiation. The effective experimental parameters, such as the catalyst dosage (30 mg in 100 mL), initial concentration (30 mg/L and 20 mg/L), and pH influence (pH 7.0 and pH 3.0) of the environmental pollutant were studied. In addition, the effect of scavenging particles for the degradation of MB and Cr6+ were analyzed with help of various scavenging particles. The mechanisms for the photodegradation of MB and conversion of Cr6+ were predicted using radical scavenger measurements. Moreover, degradation efficiencies toward MB and hexavalent Cr6+ of 99.2 and 96.6%, respectively were achieved in the presence of the PrPbS NPs. These results reveal the PrPbS nanospheres are synthesized by an ecofriendly procedure and applied as photocatalyst for the effective degradation of MB and Cr6+.

One-step hydrothermal carbonization of amine modified black liquor and lignin for efficient Cr(VI) adsorption

Amine modified black liquor (BL) and purified lignin (PL) derived biochar were successfully synthesized by facile one-step hydrothermal carbonization (HTC) with hexamethylenediamine (HMDA). A variety of analytical techniques were used to characterize the physico-chemical properties of biochar. The effects of experimental parameters (initial concentration of pollutant, contact time, solution pH and coexisting ions) on the adsorption performance of biochar were systematically investigated. The adsorption capacity of Cr(VI) on biochar prepared by BL and PL was significantly different under the optimal hydrothermal temperature. The maximum adsorption amount of BL-180 (hydrothermal temperature 180 °C) was 741.74 mg/g, while that of PL-150 (hydrothermal temperature 150 °C) was only 165.16 mg/g, as calculated by Langmuir model at 45 °C. Therefore, the preparation of biochar by direct HTC of BL showed more significant advantages and potential than PL in removing Cr(VI) from wastewater. Further, amine modification enhanced the adsorption performance of biochar, especially for PL biochar. The maximum adsorption amount of N-BL-180 was increased to 859.43 mg/g, whereas that of N-PL-150 was significantly increased to 583.77 mg/g. Moreover, the modified biochar exhibited excellent reusability. The removal mechanism of Cr(VI) was attributed to electrostatic interaction, complexation as well as redox reaction. This work provides a successful attempt of amine-modified BL biochar under mild condition, which provided a novel idea for the treatment of Cr(VI)-containing wastewater.

UVA LEDs and solar light photocatalytic oxidation/ozonation as a tertiary treatment using supported TiO2: With an eye on the photochemical properties of the secondary effluent

Photocatalytic oxidation/ozonation of a mixture of eight pharmaceuticals added to a secondary effluent, SE, of an urban wastewater treatment plant has been studied using TiO2 supported on commercial Al2O3/SiO2 ceramic foams. As radiation source UVA LEDs (365 nm) or solar radiation was used. Pharmaceuticals were added at high (1 mg L−1 each) or relatively low (50 μg L−1 each) concentration, contributing 25% and 1.5% to the initial TOC, respectively. Under both types of radiation, the photolysis of SE generated reactive species capable of degrading the contaminants (indirect photolysis), this effect being greater at lower initial concentration of pollutants. Lower concentration of contaminants also favoured their degradation and the SE mineralization by photocatalytic oxidation, whereas its effect on ozonation was low. The best results were obtained by photocatalytic ozonation, especially in terms of COD removal, without observing any synergism or antagonism between O3/Radiation and TiO2/Radiation systems. In SE, the performance of the supported catalyst resulted much better than that of suspended TiO2 P25, which showed almost no activity in this matrix. Through different cycles of reuse, the stability of the supported catalyst was confirmed.

Microwave-assisted iron oxide process for efficient removal of tetracycline

Excess tetracycline produced by livestock and poultry breeding industry not only pollute the environment, but also enter the human body with the spread of the food chain, which will produce drug-resistant genes and threaten human health. In this paper, the adsoption of tetracycline from wastewater using iron oxide under microwave oxidation condition was explored. The effect of initial pollutant concentrations, the dosage of iron oxide, pH value, and temperature on the hybrid treatment process was investigated. Under the normal iron oxide and microwave oxidation conditions, when the dosage of iron oxide was 40 g/L and 30 g/L, pH was 10 and the temperature was 318 K, the removal rate of tetracycline was significantly improved. The adsorption of tetracycline by iron oxide under the two conditions conformed to the Freundlich isotherm model and pseudo-second-order dynamics model. In addition, the associated adsorption mechanism was unveiled. Under the microwave oxidation condition, the hot spot effect generated by the microwave oxidation effect would rapidly increase its surface temperature to form the active center and the electrostatic gravity to promote the reaction. The results indicated that microwave oxidation could promote the removal of antibiotics by iron oxide in livestock and poultry breeding wastewater.

Enhanced Cr (VI) removal with Pb (II) presence by Fe2+-activated persulfate and zero-valent iron system

ABSTRACT Combined heavy metals such as chromium (Cr (VI)) and lead (Pb (II)) in natural water have globally posed severe environmental and public health risk. Here the removal of Cr (VI) and Pb (II) mixed pollutants using Fe2+-activated persulfate (PS) with extra zero-valent iron (ZVI), which was not only a supplementary Fe2+ source, but also a high-efficiency absorbent, was investigated. During removal, pivotal factors of initial pollutant concentration, dosages of ZVI and PS, initial pH and temperatures were examined. Interestingly, generating a lot of H+ in the process of Fe (II) activating persulfate were helpful to the corrosion of ZVI over a large range of pH (1–9). Under the optimum condition, removal efficiency of Pb (II) and Cr (VI) have reached 100% and 94.26% respectively. The removal mechanism was suggested as a three-step reaction that the Pb (II) boosted the removal of Cr (VI) by co-precipitated in wastewater, and the Pb (II) and Cr (VI) were adsorbed and subsequently reduced to Pb0 and Cr3+ as Cr(OH)3 or Cr3+-Fe3+ hydroxides on ZVI surface. Cr (VI) and Pb (II) adsorption kinetics agreed with the pseudo-second-order reaction rate expression. In addition, we were surprised to found that the contribution effect of chromium and lead co-precipitation for their removal by Fe (II) – PS-ZVI has strong dependence on initial pH and concentration ratio of Cr (VI) and Pb (II). The result indicated that Fe (II)-PS-ZVI system should be a favourable removal technology for Cr (VI) and Pb (II).

Amine-amide functionalized graphene oxide sheets as bifunctional adsorbent for the removal of polar organic pollutants

Effective mitigation of polar organic impurities from industrial effluents is a global environmental challenge. Here, we describe the solvothermal synthesis of ammonia-functionalized graphene oxide (NH3GO) sheets for adsorptive removal of diverse organic pollutants, such as cationic dye basic blue 41 (BB41), anionic dye methyl orange (MO), and ionic 4-nitrophenol (4-NP), in aqueous media. Structural analysis of NH3GO suggest a potent role of surface acidic and basic binding sites in adsorption of targets through an interplay of dynamic experimental variables, e.g., contact time, pH, initial adsorbate concentration, adsorbent mass, and temperature. At an initial pollutant concentration of 20 mg/L, equilibrium adsorption capacities for BB41, MO, and 4-NP were estimated at 199.5, 64.0, and 54.1 mg/g, respectively, with corresponding partition coefficients of 4156, 79.4, and 14.3 L/g, respectively. Experimental data of all three organic pollutants are best fitted by the pseudo-second-order kinetic model. The adsorption isotherm of BB41 follows a multilayer adsorption pattern, while those of MO and 4-NP fit into a monolayer adsorption pattern. The endothermic and spontaneous nature of the adsorption processes has also been explored for the three targets on NH3GO based on thermodynamic analysis. The prepared NH3GO sheets appear to be a promising adsorbent for the removal of polar organic dyes and aromatics in the solution phase.

Development of one- and dicotyledic plants on reclaimed oil-contaminated alluvial turf soils

Laboratory chronic experiments have determined the effect of the content of petroleum products (PP) in reclaimed alluvial turf heavy loamy and light loamy soil on the growth, yield of green mass and the development of the root system of spring wheat and seed peas. High residual PP content in reclaimed soil resulted in increased seed germination time, with no effect on germination. When growing wheat on reclaimed alluvial turf heavy loamy soil, the toxic effect was manifested only in the early stages of plant development in a variant containing 16.9 g/kg of PP. In the alluvial turf light loamy soil version containing 21.8 g/kg of pollutant, inhibition of plant growth was observed throughout the experiment. In chronic experiments for growing peas on heavy coal soil containing 16.9 g/kg of PP, on light coal soil containing 11.7 g/kg and higher, plant growth inhibition was observed, with a tendency to increase the toxic effect towards the end of the growing experience. Oil contaminants in concentration up to 11-12 g/kg in reclaimed alluvial turf heavy and light-coal soils do not affect the yield of green wheat mass, in concentration 9.7 g/kg and higher inhibit the growth of pea plants, lead to a decrease in the yield of their green mass. The oxidation efficiency of petroleum products when growing plants on reclaimed alluvial turf soil did not exceed 37% and was determined by the initial concentration of pollutant. The presence of PP in the soil led to a change in the structure of the root system of the plants being grown. Tested plants when cultivated on heavy soils are more resistant to negative PP. The findings show that sown peas are more sensitive to the presence of PP in reclaimed soil.

Multi-model Evaluation and Bayesian Model Averaging in Quantitative Air Quality Forecasting in Central China

There has been much interest in air pollution and the forecasting skill of air quality models in China since winter 2013. Different air quality models use different parameters (e.g., meteorological fields, emission sources and the initial concentrations of pollutants) and therefore their forecast results tend to have large systematic and random errors. We evaluated the concentrations of six pollutants in Henan Province predicted by three air quality models—the China Meteorological Administration Unified Atmospheric Chemistry Environment (CUACE) model, the Nested Air Quality Prediction (NAQP) model and the Community Multiscale Air Quality (CMAQ) model. We then established multi-model ensemble Bayesian model averaging (BMA). The prediction effect for PM2.5 and O3 was ranked as CUACE > CMAQ > NAQP and the prediction effect for SO2, NO2 and CO was CMAQ > NAQP > CUACE. All the models systematically underestimated O3 and heavy PM2.5 pollution events. For PM2.5 concentrations with a 24-h lead time, the root-mean-square error of BMA decreased by 35, 37, 68 and 50%, respectively, in winter, spring, summer and autumn relative to the CUACE model, whereas the normalized mean bias of BMA decreased by 67, 83, 94 and 55%, respectively, for O3 in the four seasons. Compared with the CMAQ model, the root-mean-square error of the SO2, NO2 and CO forecasts by BMA were reduced by 29, 33 and 39%, respectively. The evolution of the concentrations of the six pollutants during a heavy pollution event predicted by BMA was consistent with the observations.

Degradation of hexafluoropropylene oxide tetrameric acid (HFPO-TeA) using electrocatalytic ozone technique

Hexafluoropropylene oxide tetrameric acid (HFPO-TeA) is an alternative to perfluorooctanecarboxylic acid (PFOA) and is commonly used in the production of perfluoropolymers. In this study, the performances of ozone oxidation, electrochemical oxidation, and electrocatalytic ozone techniques in the degradation of HFPO-TeA were compared. The experimental results indicated that the electrocatalytic ozone technique was best. The effects of different current densities, ozone concentrations, electrolyte types, and initial pollutant concentrations on HFPO-TeA degradation were investigated. The results showed that the ratio of HFPO-TeA degradation reached 95.9% after electrolysis for 120 ​min for an initial HFPO-TeA concentration of 100 ​mg/L, a reaction volume of 120 ​mL, an applied current density of 10 ​mA/cm2, and an ozone concentration of 20 ​mg/L. The intermediate products detected were hexafluoropropylene oxide dimeric acid [C3F7OCF(CF3)COO−], pentafluoropropionic acid [C2F5COO−], and trifluoroacetic acid [CF3COO−]. The mechanisms involved in HFPO-TeA degradation include direct electron transfer, indirect oxidation mediated by hydroxyl radicals (·OH), and ozone oxidation.

ОБ ОЦЕНКЕ ЭФФЕКТИВНОСТИ ПРОЦЕССА ВЫСОКОИНТЕНСИВНОГО ОКИСЛЕНИЯ

The EEO parameter is commonly used as a figure-of-merit of ultraviolet-based advanced oxidation processes (UV AOPs). It represents the energy input into the UV AOPs that can achieve an order of magnitude decrease in the target contaminant concentration in a unit volume. This paper focuses on factors, that influence on the EEO parameter and should be reported with it to compare the efficiency of different reactors or UV AOPs: the identity and concentration of the target pollutant, as well as the concentration of scavengers; the amount of hydrogen peroxide or other oxidizing agent, source of UV radiation etc. Decays of phenol, sodium dodecyl sulfate and petroleum products in UV AOP were used to show how various conditions affect on the EEO parameter. The studies were carried out on model solutions with an initial concentration of pollutants of 10 mg/l. As a source of ultraviolet radiation, a pulsed xenon lamp was used. It has a continuous emission spectrum in the range of 200 – 1000 nm, the average energy consumption was about 200 W, the radiation energy in the range of 200–300 nm was 2.7 J. Hydrogen peroxide was used as an oxidizing agent, it concentration varied from 10 to 340 mg/L. The modified parameter of UV AOP efficiency is proposed. It considers electrical energy input with reagents consumption. It is proposed to express the costs of the oxidant in physical values and include them in the modified parameter with a weighting factor.

Kinetic modeling of removal of aromatic hydrocarbons from petroleum wastewaters by UiO-66-NH2/TiO2/ZnO nanocomposite

In this study, the UiO66-NH2/TiO2/ZnO (UTZ) nanocomposite was synthesized using the sol-gel method. The mean particle size of UTZ nanocomposite was about 33.63 nm. The present work investigates the applicability of a photocatalytic oxidation process for benzene, toluene and xylene (BTX) degradation. The response surface modeling (RSM) was utilized to optimize important parameters, i.e. catalyst content (g/L), lamp power (W), initial contaminant concentrations and pH. The optimized values of these parameters involved UTZ concentration of 0.11 g/L, lamp power of 15 W, the initial pollutant concentration of 50 ppm and pH= 7. The BTX degradation and total organic carbon (TOC) removal efficiencies were 90.03% and 85.16%, respectively, under optimal conditions. Ultimately, a new kinetic reaction rate model was developed in the form of Langmuir- Hinshelwood equation based on the intrinsic-element reactions in the form of−r=0.102I0.5[UTZ]0.5[BTX]/1+1.9298[BTX]0+1.6059I0.5[UTZ]0.5. The first-order kinetic constant determined by this model was 0.133 min-1. It was observed that the model for the photocatalysis reaction rate was well fitted with the experimental data at minimal mean absolute relative residual (14.18%).

Remediation of emerging metal pollutants using environment friendly biochar- Review on applications and mechanism

Bioremediation of heavy metals has become a major environmental concern due to their bio resistant nature and tendency to accumulate. Application of various technologies, involving physical and chemical working principles are applied and passive uptake using sorption involving eco-friendly substrates gained significant attention. Biochar, a cheaper and efficient material, offers good potential due to the greater ease of production, treatment and disposal. This review focuses on the effective application of biochar to treat water contaminated by three specific heavy metals: chromium, lead and arsenic. The on-field applications like soil amendment, industrial wastewater treatment and groundwater treatment using biochar are highlighted. The review article describes the feedstock available for biochar production, various production processes and the importance of optimum conditions like pyrolysis temperature, rate and retention time for various feedstocks reported in literature. The energy requirement of the production process can be supplied by its own energy output. Various modifications that are suitable for the biochar from distinct feedstocks are also discussed. The removal performance of biochar at different working conditions like pH, initial concentration of pollutant and adsorbent dose are consolidated. The highest removal efficiencies reported were by coconut shell biochar (Cr – 99.9%), canola straw biochar (Pb – 100%) and perilla leaf biochar (As – 100%). The adsorption mechanism is explained with reference to kinetics, isotherms, and molecular dynamics. Adsorption mechanism of most of the biochars was found to fit either Freundlich or Langmuir isotherm.

Simultaneous Removal of Heavy Metals and Ciprofloxacin Micropollutants from Wastewater Using Ethylenediaminetetraacetic Acid-Functionalized β-Cyclodextrin-Chitosan Adsorbent

The current study pertains to the synthesis of an EDTA-functionalized β-cyclodextrin-chitosan (β-CD-CS-EDTA) composite via a two-step process for the adsorptive removal of toxic heavy metallic ions (i.e., Pb(II), Cu(II), and Ni(II)) and antibiotic micropollutant, i.e., ciprofloxacin (CIP), from water. Different batch adsorption experiments such as pH, reaction time and initial pollutant concentration effects were carried out to identify the adsorption condition to attain the maximum removal efficiency. Kinetics results fit well with the pseudo-second order (PSO) kinetics model for both inorganic and organic pollutants. However, adsorption of heavy metal ions to the adsorbent was faster than that of CIP. Isotherms results showed excellent monolayer adsorption capacities of 330.90, 161, and 118.90 mg g–1 for Pb(II), Cu(II), and Ni(II), respectively, with a heterogeneous adsorption capacity of 25.40 mg g–1 for CIP. The adsorption mechanism was investigated using energy dispersive X-ray (EDX), elemental mapping, and Fourier transform infrared (FTIR) techniques. More significantly, the synthesized adsorbent gave good removal efficiencies when it was applied to simultaneously adsorb metal ions and CIP from real wastewater. Furthermore, excellent reusability could be obtained, making it a viable alternative to remove the inorganic and organic micropollutants for wastewater treatment.

Cephalexin removal by persulfate activation using simulated sunlight and ferrous ions.

This study presents the main results related to the use of activated persulfate (PS) in the elimination of the beta-lactam antibiotic cephalexin (CPX). Experiments were done using K2S2O8 and simulated sunlight. A face-centered central composite experimental design was used to analyze the effects of the solution pH and the PS concentration on the reaction, and to determine the optimized conditions that favor the CPX elimination. The results indicated that the removal of CPX is promoted by an acidic pH and under the higher evaluated PS dose (7.5 mg L-1). CPX total removal was achieved in 30 min. The analysis of the effect of the pollutant initial concentration indicated that a pseudo-first-order kinetics model can be used to describe the reaction. Likewise, the use of Fe2+ ions for PS activation (in the dark) was evaluated and established that a higher concentration of ions favors the pollutant removal. Control tests and under the presence of scavenger agents indicated that both HO• and SO4-• radicals would be present in the solution and promote the CPX elimination. The assessment of the solution dissolved organic carbon, nitrates and sulfates was also carried out, and indicated that a portion of the organic matter was mineralized.

Photocatalytic performance and interaction mechanism of reverse micelle synthesized Cu-TiO2 nanomaterials towards levofloxacin under visible LED light

The degradation performance of Cu-TiO2 nanomaterials towards levofloxacin (LFX) antibiotic was investigated under an environmentally benign visible LED light source. Cu-TiO2 nanomaterials were prepared using the reverse micelle sol-gel method with different copper content ranging from 0.25 to 1.0 wt% concerning titania. Characterization of Cu-TiO2 samples was performed by XRD, TEM, UV-Vis, BET, ICP-MS, FTIR and XPS techniques. 0.5 wt% Cu-TiO2 showed crystallite size below 6 nm, surface area (69.85 m2/g) and significant visible light absorption capacity. Both Cu1+ and Cu2+ are formed in lower Cu-doped TiO2 samples, whereas only Cu2+ is present in higher Cu-doped TiO2 samples as evident in XPS analysis. 0.5 wt% Cu-TiO2 has shown the optimum photocatalytic degradation of 75.5% under 6 h. of a visible light source. FTIR analysis of LFX adsorbed Cu-TiO2 materials indicated the pollutant-catalyst interaction, where the declining trend was observed in photocatalytic degradation efficiency for higher Cu-doped TiO2 samples due to copper-LFX complex formation. Copper-LFX complexes are formed due to the presence of Cu2+ in higher Cu-doped TiO2 nanomaterials, which might have hindered the photocatalytic activity under visible light. Effects of initial pollutant concentration, catalyst loading and visible light intensity on the degradation of LFX are studied. Photocatalytic degradation pathways of LFX using best performing Cu-TiO2 material were also proposed based on the LC-MS analysis.