Initial Pollutant Concentration Research Articles

Novel biocomposite (Starch/metal–organic framework /Graphene oxide): Synthesis, characterization and visible light assisted dye degradation

Herein a new efficient biocomposites containing Starch metal–organic framework (MIL88A) and graphene oxide (Starch/MIL88A/GO) with different amounts of starch (0.05 0.1 and 0.2 g denoted as SMGO-0.5 SMGO-1 and SMGO-2) was synthesized characterized and used to degrade Acid Blue 92 (AB92). Decolorization efficiency was 7.4 % for Starch 19.4 % for GO 86 % for MIL88A and 90–98.5 % for Starch/MIL88A/GO composites (90 % for SMGO-0.5 96 % for SMGO-1 and 98.5 % for SMGO-2) using visible light. SMGO-2 composite showed the highest degradation ability. The effect of catalyst dosage and contaminant concentration on decolorization percentage was investigated. The efficiency of photocatalytic decolorization using 0 4 6 8 and 10 mg of Starch/MIL88A/GO are as follow: 10 55 89 93 and 98.5 % respectively. The results indicate that the decolorization by Starch/MIL88A/GO decreases as the initial pollutant concentration increases. Different decolorization kinetics (zero-order first-order and second-order) were studied. The reaction followed the zero-order kinetics. The zero-order decolorization rate constant for 0 4 6 8 and 10 mg of Starch/MIL88A/GO were 0.0134 0.1086 0.1182 0.1308 and 0.1727 respectively. The Starch/MIL88A/GO had high reusability (95 % after five cycles). The results indicated that the synthesized biocomposite (Starch/MIL88A/GO) could be used as an efficient photocatalyst to remove dye from the colored wastewater.

Anodic oxidation of ciprofloxacin antibiotic and real pharmaceutical wastewater with Ti/PbO2 electrocatalyst: Influencing factors and degradation pathways

This study investigated the impact of operational variables including current density, solution pH, sodium sulfate electrolyte concentration, initial pollutant concentration, and reaction time on ciprofloxacin (CIP) anodic oxidation and its COD removal by Ti/PbO2 electrocatalyst. Ti/PbO2 anode was prepared by electrochemical method and its characteristics were determined using SEM, EDX-map, XRD, and linear sweep voltammetry (LSV) techniques. Under optimal conditions, the removal rate of CIP and COD at the initial concentration of 15 mg/L of the pollutant after 75 min of reaction was 92 % and 88.8 %, respectively. CIP mineralization was confirmed by evaluating its UV–vis spectra and cyclic voltammetry (CV) curves during the process. Considering the degradation intermediates identified by LC-MC analysis, the main reactions in CIP mineralization pathways were discussed in detail. Finally, the improvement of biodegradability of pharmaceutical wastewater during anodic oxidation treatment was evaluated. The results indicated that the biodegradability of wastewater significantly increased from BOD/COD = 0.18 for raw wastewater to BOD/COD = 0.42 for treated wastewater. The results showed that anodic oxidation with Ti/PbO2 electrocatalyst can be a practical method of treating wastewater that contains resistant and toxic pharmaceutical compounds.

High efficiency removal of ibuprofen in water using activated carbon derived from Radix Angelica Dahurica residue

AbstractThe exploitation and utilization of Traditional Chinese medicine have annually produced 30 million tons of waste residues including Radix Angelica Dahurica residue (RAR), which raised environmental concerns. Meantime, the non‐steroidal anti‐inflammatory drug of ibuprofen (IBP) is an emerging contaminant in the aquatic environment, annually producing up to 9000 tons in China. After extracting the active substance, RAR is prepared as activated carbon (AC) for the purification of IBP wastewater. Two kinds AC modified without (RAR‐AC) and with phosphoric acid (M‐RAR‐AC) were characterized by FT‐IR, TG, BET and SEM. The phosphoric acid activation contributed to the high BET surface area (564.9914 m2 g−1) and large total pore volume (0.4894 cm3 g−1). M‐RAR‐AC showed 7.7 folds (15 min) and 2.7 folds (30 min) higher extent of IBP removal compared to commercial activated carbon (C‐AC). The enhancement of IBP removal with M‐RAR‐AC was investigated further by varying initial pollutant concentration, absorbent dosage, temperature, pH and rotating speed. Especially, temperature nearly has no effect on IBP removal by M‐RAR‐AC. Isotherm and kinetic studies suggested IBP was adsorbed on the heterogeneous surface in multilayer form and chemisorption played the dominant role in IBP removal. IBP removal of 93.3 ± 0.1% and 64.2 ± 2.8% was achieved for first and fifth cycle, respectively. The IBP removal on M‐RAR‐AC may be accomplished by a variety of interactions such as electrostatic attraction, pore‐filling, hydrogen bonding, and π‐π interaction. These findings provide new insights into the utilization of RAR for preparing AC and highlight the potential applications for treating industrial wastewater.

Removal of emerging micropollutants from nanofiltration retentate of municipal wastewater within biological fixed-bed reactors under nitrifying and denitrifying conditions.

Municipal water resource recovery facilities are not designed to eliminate micropollutants, leading to many pollutants entering the aquatic environment. Within this study, as part of the project MicroStop, the biological treatment of nanofiltration effluent (retentate) under pure aerobic (without nitrification) as well as nitrifying and denitrifying conditions has been investigated for micropollutant elimination. A potential of further biotransformation under increased hydraulic retention time (HRT) of 14 days was shown. Under both HRT of 7 and 14 days, eliminations below LOQ were achieved in the aerated bioreactor for gabapentin, iomeprol, and metoprolol, reaching > 95%, > 69 to > 92%, and > 72%, respectively. The reduction of diclofenac was positively influenced by longer HRT leading to an elimination of up to 67%. Sulfamethoxazole was reduced under denitrification, but accumulated under aeration, resulting in fluctuating results and an overall elimination of 78% under 14 days HRT. PRACTITIONER POINTS: The micropollutant elimination in fixed-bed bioreactors of highly concentrated nanofiltration retentate was studied. Pure aerobic (without nitrification), nitrifying, and denitrifying conditions were investigated under hydraulic retention times (HRT) of 7 and 14 days. Higher initial pollutant concentrations enhanced the biological degradability in attached growth for substances being moderately degradable in activated sludge systems. 4A potential of further biological micropollutant elimination was shown for gabapentin, iomeprol, metoprolol, and diclofenac.

Photocatalytic degradation and kinetic investigations of ZnO-SnO2 heterostructures for treatment of methyl violet using non-conventional approach

Humans and wildlife alike are threatened by the ever-increasing levels of organic pollutants exist in the world's water bodies. Nanomaterials based on metal oxides have been considered strong alternatives for the elimination of organic pollutants. In the present study, ZnO-SnO2 nanocomposites were synthesized via non-conventional microwave and ultrasonic method using fruit extract of Carissa edulis as capping agent. The synthesized nanocomposites were studied using X-ray diffraction (XRD), Diffuse reflectance spectroscopy (UV–Vis-DRS), X-ray photoelectron spectroscopy (XPS), Fourier Infrared spectroscopy (FT-IR), Photoluminescence spectroscopy (PL), and Field emission scanning electron microscope (FE-SEM). Under UV light irradiation, photo-catalytic degradation of methyl violet (MV) was investigated by examining the influence of photocatalyst dosage, initial pollutant concentration, and pH of the reaction medium. The ideal conditions for MV degradation were at initial MV concentration of 10 mg/L, a 20 mg catalyst dose, and a pH of 7. The MV degradation of the synthesised ZnO-SnO2 nanocomposite was 91 % after 120 min. Scavenging experiments demonstrated that hydroxyl radicals (.OH) acts as a key role in the photo-degradation of MV. The reusability studies demonstrate that the synthesised ZnO-SnO2 has good stability for four cycles.

Ultrasound-Assisted Biomimetic Synthesis of MOF-Hap Nanocomposite via 10xSBFLike for the Photocatalytic Degradation of Metformin

High levels of emerging pollutants, such as pharmaceutical compounds like metformin (MET), have been an issue for many years. The effective removal of these compounds from wastewater poses a significant challenge and has spurred interest among researchers. This study aims to integrate two of the prominent research interests in photocatalysis, Metal-Organic Frameworks (MOF), and Hydroxyapatite (HAp), and tests their effectiveness in the photocatalytic degradation of MET. The MOF-HAp was produced using a biomimetic method via 10xSBF-like solution with and without ultrasound assistance at varying biomimetic times. MOF-HAp nanocomposite’s photocatalytic degradation capabilities were tested by degrading MET, considering varying parameters – initial pollutant concentration, catalyst loading, and exposure time. Results showed that a biomimetic time of 6 h synthesized with ultrasound irradiation presented the most promising physicochemical properties for MOF-HAp, as verified by the X-ray Fluorescence (XRF), Scanning Electron Microscope (SEM), Brunauer-Emmett-Teller (BET), X-ray Diffractometer (XRD), and Fourier Transform Infrared Spectroscopy (FTIR) analyses. In the photocatalytic degradation of MET, catalyst loading, exposure time, and initial pollutant concentration were found to have significant effects on the percent degradation. The initial concentration of 8 ppm, catalyst loading of 0.25 g, and 120 min of exposure time produced the highest percent degradation with an average of 82.25%. The findings of this study prove MOF-HAp's potential to effectively degrade organic and pharmaceutical pollutants in wastewater.

Highly efficient removal of tetracycline and methyl violet 2B from aqueous solution using the bimetallic FeZn-ZIFs catalyst

Abstract Residual antibiotics and organic dyes in wastewater have gained the current challenge all over the world because of their toxicity to humans and the environment. In this study, the bimetallic porous FeZn-ZIFs materials were successfully prepared under mild conditions at room temperature and atmospheric pressure and characterized by various techniques. The FeZn-ZIFs were used as a heterogeneous catalyst to remove tetracycline antibiotics (TC) and methyl violet 2B dyes (MV) in an aqueous solution by activating peroxymonosulfate (PMS) and peroxydisulfate (PDS), respectively. The catalytic activity of FeZn-ZIFs towards TC and MV under different oxidant dosages, the catalyst dosage, the initial pollutant concentration, contact time, and reaction temperature were optimized. The results indicated that FeZn-ZIFs was an efficient catalyst for removing TC and MV based on advanced oxidant processes, having a removal capacity of 92% at TC concentration of 50 mg·L−1 and 95% MV concentration of 20 mg·L−1. More importantly, this bimetallic catalyst was identified the superior structural stability when the removal efficiency of TC and MV was maintained at approximately 90% after five cycles. In short, the FeZn-ZIFs and PMS/PDS system exhibited a promising application prospect for antibiotic and dye-containing wastewater treatment.

Zn-Al layered double hydroxide/zeolitic imidazolate framework-8 nanocomposite as a high-performance sorbent for adsorption and desorption of anticancer drugs from aqueous media

Zn-Al layered double hydroxide/zeolitic imidazolate framework-8 (Zn-Al LDH/ZIF-8) nanocomposite was synthesized through growing zeolitic imidazolate framework-8 (ZIF-8) on Zn-Al layered double hydroxide and employed as an effective pollutant adsorbent. The nanocomposite was utilized for the removal of Ifosfamide (IF) and cyclophosphamide (CK) anticancer drugs from aqueous matrices. Zn-Al LDH/ZIF-8 nanocomposite was characterized via different analyses such as Brunauer-Emmett-Teller, X-ray diffraction, X-ray photoelectron spectroscopy, Energy-dispersive X-ray spectroscopy, Elemental mapping, Fourier-transform infrared spectroscopy, Field emission scanning electron microscopy, Transmission electron microscopy, Thermogravimetric analysis, and Contact angle measurement. Batch experiments were implemented to investigate the parameters affecting the adsorption process, including adsorbent loading, pH value, ionic strength, initial pollutant concentration, temperature, and impurity. The experimental results were analyzed using various models to determine the adsorption mechanism, thermodynamics, isotherm, and kinetics. The Langmuir isotherm model presented higher consistency with the experimental data (R2 >0.990). The saturation adsorption capacity of the nanocomposite for IF and CK drugs, obtained as 929.66 and 888.94 mg/g, respectively, was found to be higher than those for ZIF-8 (759.70 and 724.53 mg/g, respectively) at a temperature of 298 ± 1 K and pH of 7.5 ± 0.1. The kinetic data had a better fit with the pseudo-second-order kinetic model (R2 >0.980). Thermodynamic studies revealed that the adsorption process was exothermic and spontaneous. The mechanism of adsorption was attributed to electrostatic interactions, hydrophobic forces, H-bonding, π-π stacking, and π-π electron-donor acceptor. Additionally, after performing four adsorption-desorption cycles, the nanocomposite indicated only a 9.3% reduction in the adsorption capacity, demonstrating the promising potential of this, for industrial applications.

Synthesis of AgFeO2 delafossite catalyst and its application for photo-degradation of dye present in solution

The present work highlights the physicochemical properties of a series of novel silver ferric oxide (AgFeO2) delafossite nanoparticles while employing them as photocatalysts under visible light irradiation. The first sample was synthesized by a facile co-precipitation route (AFO-0) while the second and third samples were prepared at a constant hydrothermal temperature (180 °C) with varying reaction time of 2 h (AFO-2) and 8 h (AFO-8) and all three samples were subjected to visible light irradiation to photo-degrade Malachite Green (MG) dye. The crystalline structure, morphology, functional groups, elemental analysis, and optical property was conducted by their respective characterization techniques. The size of nanocrystals increased with the hydrothermal time and the average particle size of AFO-0, AFO-2 and AFO-8 were 87.7 nm, 154 nm, and 209.3 nm respectively, with AFO-8 exhibiting prominent hexagonal flake-like morphology. The direct band gap of AFO-0, AFO-2 and AFO-8 were 2.74 eV, 2.53 eV and 2.11 eV respectively and the Urbach energy was 0.20 eV, 0.217 eV and 0.254 eV respectively. The photo generated charge isolation efficiency of the samples was conducted where charge recombination sequence was of the order: AFO-8<AFO-2<AFO-0. The sample AFO-8 exhibited the optimum performance which resulted in excellent degradation of MG under visible light irradiation based on all the batch study experiments using solution pH, comparative analysis, catalyst dose, initial pollutant concentration as parameters. Finally, the optimum conditions at which AFO-8 degraded 97 % of MG were: 80 mg catalyst dose, pH 8, 20 mg L−1 (100 mL) MG, 90 min reaction time, 30 °C temperature and 130 rpm agitation speed. As per the quenching tests, the OH° and O2°− radicals were the governing reactive species that were responsible for degrading MG.

Photocatalytic mediated destruction of 2-chlorobiphenyl by a ZnO-[10%]BiOI p-n heterojunction: effect of some process parameters

This study involved the synthesis, characterization, and application of various photocatalysts and heterojunctions using zinc oxide (ZnO), tungsten trioxide (WO3), and bismuth oxyiodide (BiOI) for the photo-abatement of 2-chlorobiphenyl (2CBP). Scanning electron microscopy revealed a variety of morphologies for all composites, while energy-dispersive X-ray spectroscopy only identified reference elements and X-ray diffraction patterns displayed crystalline patterns with no impurity peaks. The absorbance of the heterostructures exhibited slight red shifts as WO3 and BiOI were etched into ZnO. Except for ZnO-[10%]WO3, the band gaps of all composites decreased/narrowed as the doping of WO3 and BiOI into ZnO increased. Nitrogen sorption isotherms revealed that almost all the prepared materials had a Type IV isotherm, and the heterostructures showed higher surface area measurements compared to the undoped composites. The ZnO-[10%]BiOI heterojunction, which displayed the best photoactivity, was further investigated to analyze the influence of some operating conditions. Results revealed that the initial pollutant concentration influenced the degree of photodegradation, which decreased with increased initial 2CBP concentration. The optimum photocatalytic performance was detected at neutral pH. The pseudo-first order kinetic model showed that doubling the heterojunction’s weight increased the rate constant from 0.0054 to 0.0089 min−1, while increasing the pH to 11.3 resulted in an 18-fold reduction. Overall, the study demonstrated the potential application of ZnO-[10%]BiOI heterostructure as a highly effective photocatalyst for recalcitrant contaminants in water.

Treatment of Mixture Pollutants with Combined Plasma Photocatalysis in Continuous Tubular Reactors with Atmospheric-Pressure Environment: Understanding Synergetic Effect Sources.

This study investigates the pilot-scale combination of nonthermal plasma and photocatalysis for removing Toluene and dimethyl sulfur (DMDS), examining the influence of plasma energy and initial pollutant concentration on the performance and by-product formation in both pure compounds and mixtures. The results indicate a consistent 15% synergy effect, improving Toluene conversion rates compared to single systems. Ozone reduction and enhanced CO2 selectivity were observed when combining plasma and photocatalysis. This process effectively treats pollutant mixtures, even those containing sulfur compounds. Furthermore, tests confirm nonthermal plasma's in-situ regeneration of the photocatalytic surface, providing a constant synergy effect.

Removal of Cr6+ ions and mordant violet 40 dye from liquid media using Pterocladia capillacea red algae derived activated carbon-iron oxides

In recent years, water pollution has become one of the most dangerous problems facing the world. Pollution of water with heavy metals and different dyes has caused many harmful effects on human health, living organisms and our environment. In this study, iron oxide nanomagnetic composite from Pterocladia Capillacea red algae-derived activated carbon (PCAC-IO) was synthesized by co-precipitation method using different iron salts and different base solutions. The synthesized nanocomposite was investigated with various characterization techniques such as FTIR, BET, SEM-EDX, TEM, XRD, and VSM. The obtained PCAC-IO adsorbent was used for Cr6+ ions and Mordant Violet 40 (MV40) dye removal. The adsorption mechanism of Cr6+ ions and MV40 dye on PCAC-IO was examined using several adsorption and kinetic isotherm models. Langmuir and Freundlich models were investigated using experimental data. Pseudo-first-order (PFO), Pseudo-second-order (PSO) and intraparticle diffusion models (IPDM) were applied to identify the adsorption mechanism. It has shown that the PSO kinetic model fits better with the experimental data obtained from PCAC-IO. This result can be interpreted as the adsorption of the adsorbate on the nanocomposite as chemical adsorption. The optimum conditions for maximum Cr6+ ions removal (96.88%) with PCAC-IO adsorbent occur at room temperature, 5 g L−1 adsorbent concentration, 100 mg L−1 initial pollutant concentration, pH 1 and at the end of 180 min, while maximum MV40 dye removal (99.76%), other conditions being the same, unlikely it occurred at pH 2.06 and after 45 min. The most suitable model for Cr6+ ions removal under the conditions of 1 L−1 g adsorbent concentration and 400 mg L−1 adsorbate concentration was Langmuir (Qmax = 151.52 mg g−1), while for MV40 removal it was Freundlich (Qmax = 303.03 mg g−1). We propose the use of activated carbon-supported iron oxide prepared from bio-waste material, especially from Pterocladia Capillacea red algae, as a promising adsorbent with high efficiency in the removal of Cr6+ ions and MV40 dye from aqueous media.

Photodegradation of salicylic acid in aqueous phase by TiO2 / UV System

Man uses the background where he lives and transforms it; he becomes the factor controlling the ecosystem conditions and the main reason of degradation of environment especially by industrialization and rejecting wastewaters. Water pollution can be soluble or not. The main categories of the water soluble pollution are represented by: inorganic pollutants, biological pollutants and organic pollutants. There are numerous methods to treat wastewaters; they depend on the characteristics of pollution. This study aims to examine the application of the advanced oxidation process, particularly heterogeneous photocatalysis. This process has been applied for degradation of salicylic acid dissolved in water; its degradation occurs in a photocatalytic reactor made up of a titanium dioxide (TiO2) as a semiconductor supported on a glass plate placed at the middle of the reactor and subjected to the U.V irradiation. The assessment of the parameters influence related to the reactor such as recirculation flow and initial concentration of pollutant has shown that at low recirculation flow, the photodegradation of pollutant was accelerated about 98 % of salicylic acid was degraded after 3 hours of irradiation, in addition the heterogeneous photocatalysis process is applied even at low concentration. Kinetic analyses indicated that the photodegradation of pollutant can be described by a pseudo-first-order reaction. The Langmuir Hinshelwood model was used to assess the kinetics of the heterogeneous photocatalytic process, the rate constant, kapp for the photocatalytic degradation was determined at different concentrations.

Nanocomposite from tannery sludge-derived biochar and Zinc oxide nanoparticles for photocatalytic degradation of Bisphenol A toward dual environmental benefits

The growing concern over the presence of pollutants like Bisphenol A (BPA) in water sources has led to the growth of novel treatment technologies for its removal. This research work investigates the development of a novel biochar-metal oxide nanocomposite derived from tannery sludge and Zinc oxide (ZnO) nanoparticles for the photodegradation of BPA. The biochar was obtained by pyrolysis process, followed by impregnation of ZnO nanoparticles using a hydrothermal technique. The critical properties of as-prepared nanocomposite were evaluated by FT-IR, BET surface area, XRD, FE-SEM, HR-TEM, XPS, PL, EPR, and Raman Spectroscopy. In addition, the photocatalytic activity of nanocomposites was evaluated by measuring the degradation of BPA in visible light irradiation. The outcomes revealed that ZnO-loaded chemically activated biochar exhibited higher photocatalytic activity for the degradation of BPA than the pristine and non-chemically activated biochar. At pH 5, 0.2 g/L of photocatalyst dosage, 20 ppm of initial pollutant concentration, and 150 min of contact time, the maximum degradation efficiency of BPA was observed as 94.50 %. Also, nanocomposites showed good stability and reusability, with only a slight decrease in photocatalytic activity after multiple cycles of use. More importantly, the degradation mechanisms of BPA using as-prepared nanocomposites were analyzed in detail, indicating that the observed photocatalytic activity could be attributed to the synergistic effect between the biochar and ZnO, which provided a large surface area for the adsorption of BPA and promoted the generation of reactive oxygen species for its degradation. Overall, this study highlighted the potential of using nanocomposites from tannery sludge-derived biochar and ZnO nanoparticles for the degradation of BPA from polluted water sources using a photocatalytic process toward the dual environmental benefits.

Removal of chromium from aqueous solution using a nanocomposite of nickel ferrite and polyaniline doped with 2-naphthalene sulfonic acid

Chromium is a highly toxic, highly mobile heavy metal commonly found in industrial effluents. This study investigated the efficacy of a nickel ferrite/polyaniline/2-naphthalene sulfonic acid nanocomposite (PANI-NSA/NiFe2O4) in removing Cr(VI) from solution. NSA doping led to the formation of tubular-shaped rods, enhancing the material's surface area. Key adsorption parameters (pH, adsorbent dosage, agitation time, and initial pollutant concentration) were thoroughly examined and optimized. The adsorption process was notably pH-dependent, with maximal adsorption occurring at pH 2. The findings indicated a remarkable 99.9% removal of Cr(VI) from a 50 mg/L solution with a 25 mg adsorbent dose. Freundlich, Langmuir, and Two-Surface Langmuir isotherm models were tested, with the Two-Surface Langmuir model best describing the experimental results. Kinetics studies revealed rapid adsorption within the initial 30 min, followed by a slower rate, reaching maximum Cr(VI) removal within 24 h. Temperature studies revealed and enhanced adsorption capacity at higher temperatures, with a maximum adsorption capacity of 420.0 mg/g at 45 °C. Thermodynamic analysis indicated an endothermic and spontaneous adsorption process. The mechanism of Cr(VI) removal involved electrostatic attraction, reduction, and surface complexation. PANI-NSA/NiFe2O4 could be reused for up to five cycles, achieving 99% Cr(VI) removal from a 50 mg/L Cr(VI) solution in the first two cycles. Furthermore, tests on authentic chromium wastewater showed that a 40 mg dose in 50 mL liquid fully removed 50 mg/L Cr(VI). This study underscores the potential of PANI-NSA/NiFe2O4 for industrial applications in Cr(VI) removal, offering a promising solution for addressing the pressing issue of chromium pollution.

Metal organic framework-based photocatalyst-assisted peroxone process for formaldehyde and acetaldehyde removal from waste air stream: intermediates and mineralization

ABSTRACT Formaldehyde (FA) and acetaldehyde (AA) are known as the two major pollutants used at industrial processes. The BiOI@NH2-MIL-125 (Ti)@Zeolite heterostructures combined with UV-assisted peroxone process were investigated for oxidative degradation of the aldehydes in a continuous waste air stream. Different characterisation methods including XRD, FTIR, FESEM, EDS, EDS elemental mapping, BET, TEM and XPS were used to characterise the photocatalyst. This study focuses on optimising the parameters selected for removal of FA and AA using the one-factor-at-a-time (OFAT) technique. Therefore, the effects of operational parameters: air flow rate, ozone feeding rate, hydrogen peroxide (H2O2) concentration, relative humidity (RH), and initial concentrations on FA and AA removal efficiency were investigated and optimised using the OFAT procedure. The results showed the complete degradation of FA and AA were achieved at optimal conditions (air flow rate: 0.2 L/min, O3 dosage: 0.3 and 0.4 mg/min for FA and AA, respectively, H2O2 concentration: 150 and 200 ppm for FA and AA, respectively, RH of 35%, and an initial pollutant concentration of 5 ppm). In addition, kinetic models revealed that the FA and AA degradation process are fitted with first-order kinetic (R2 = 0.85). Mineralisation analysis revealed that the complete degradation of FA and AA were obtained at CO2 levels of 4.3 and 3.9 ppm, respectively. Overall, it could be concluded that the suggested treatment method has the capability to efficiently eliminate the aldehydes of interest from waste gases.

Efficient removal of Cu2+ and methylene blue pollutants from an aqueous solution by applying a new hybrid adsorbent based on alginate-chitosan and HAP derived from Moroccan rock phosphate.

Alginate-chitosan/hydroxyapatite (Alg-Cs/HAP) beads were prepared as adsorbent to remove methylene blue (MB) and copper ions from an aqueous solution using a batch system. FTIR, TGA, point of zero charge (pHpzc), SEM, XRD, and BET analysis were used to characterize the elaborated material. The effect of several parameters such as initial pH value, adsorbent dose, temperature, contact time, and initial pollutant concentration were also investigated. The obtained results showed that Alg-Cs/HAP exhibit excellent adsorption properties for Cu (II) and MB removal, with high adsorption capacities of copper ions (208.34mg/g) and methylene blue (454.54mg/g). The kinetic of the adsorption process is correlated with the pseudo-first-order for methylene blue and the pseudo-second-order for copper ions. The equilibrium data for MB dye fitted the Freundlich isotherm model, thus implying that the adsorption process consists of multilayer adsorption as well as interactions between the adsorbate and the adsorbent. The equilibrium data for copper ions corresponds closely with the Langmuir model which suggests that the adsorbed molecules occur over a monolayer. Various thermodynamic parameters such as the standard Gibbs energy (ΔG°), standard enthalpy (ΔH°), and standard entropy (ΔS°) were calculated. All results indicated that Alg-Cs/HAP material has a good potential for the treatment of wastewater.

Synthesis of pectin hydrogel /Fe3O4/Bentonite and its use for the adsorption of Pb (II), Cu (II), and Cd (II) heavy metals from aqueous solutions

The magnetic nano adsorbent was prepared by adding Fe3O4 magnetic nanoparticles and bentonite clay into the three-dimensional (3D) cross-linked pectin hydrogel substrate. To determine optimum adsorption conditions, effective factors on the adsorption efficiency of the Pb (II), Cu (II), and Cd (II), including solution pH, adsorbent dosage, contact time, and initial concentration of pollutants, have been experimentally investigated. Thus, in optimum conditions, i.e., contact time (60 min), pH 7, adsorbent dosage (0.03 g), and initial concentration (100 mg/L), the adsorption efficiency of Pb (II), Cu (II), and Cd (II) was obtained at 95.2 %, 92.8 %, and 87.6 %, respectively. The results of the adsorption isotherm studies exhibit a good fit of the data with the Langmuir adsorption isotherm. The obtained kinetic and thermodynamics parameters illustrated that the pseudo-second-order equations, the spontaneous process and endothermic, control the adsorption process.

Construction of Z-scheme FeTiO3/g-C3N4 heterojunction system: Characterization and statistical optimization of photocatalytic behavior under visible light irradiation

Construction of low-cost and green photocatalysts is an emerging subject in wastewater treatment processes. In the present study, FeTiO3/g-C3N4 (FTO/CN) photocatalytic system was constructed via ultrasonication followed by thermal mixing method. The synthesized FTO/CN hybrids with different CN ratios were characterized by SEM-EDX, TEM, XRD, XPS, XRF, UV–vis DRS, PL techniques. The photodegradation efficiencies of the hybrid materials were systematically examined towards decolorization of tartrazine dye under visible light irradiation. Using the FTO/CN hybrid catalyst, the photocatalytic efficiency of the pristine FeTiO3 greatly enhanced from 39.8% to 90.5%, which was attributed to appropriate band alignment and heterojunction transfer mechanism to hinder the recombination rate of photo-excited charge carriers. The effects of initial pollutant concentration (10–30 mg/L), catalyst dosage (0.1–0.5 g/L) and peroxymonosulfate (PMS) concentration (1–3 mM), as independent variables on the degradation efficiency were investigated by response surface methodology with Box-Behnken design model. Under optimized conditions (R2 = 0.99, R2adj = 0.98), the highest removal efficiency (100 %) was obtained with 0.5 g/L catalyst, 10 mg/L initial dye concentration and 3 mM PMS. The photodegradation efficiency of the hybrid system was investigated towards other pollutants (Sunset yellow, orange II, tetracycline and ciprofloxacin) and recyclability of the catalyst was also explored. The obtained results demonstrated that the hybridization of FeTiO3 particles with g-C3N4 sheets greatly enhanced the photocatalytic properties of FeTiO3 under different conditions.

Enhancing the efficiency of Ni(II), Cd(II), and Cu(II) adsorption from aqueous solution using schist/alginate composite: batch and continuous studies.

The main aim of this research is focused on the synthesis of schist/alginate composite (SC/AL) adsorbent and its utilization for the removal of Ni(II), Cu(II), and Cd(II) from waste streams using batch and column processes. The characterization of developed adsorbent was performed by X-ray fluorescence, X-ray diffraction, FTIR, and BET analyses. The most influential operating parameters (pH, contact time, temperature and initial adsorbate concentration) on the adsorption capacity of pollutants were examined to evaluate the performance of developed adsorbent. The kinetic and equilibrium adsorption results at pH 5.0 indicated that SC/AL composite had good adsorption capacity (qmax) for Ni(II), Cu(II), and Cd(II) estimated at 124.79 mg/g, 111.78 mg/g, and 119.78 mg/g, respectively. From the kinetic viewpoint, the good fit of pseudo-first-order kinetic model to the kinetic adsorption data indicated that dominant interaction of heavy metals with SC/AL composite was physisorption. The results of thermodynamic studies indicated that the adsorption of heavy metals onto SC/AL composite was endothermic and spontaneous in nature. The adsorption capacity of developed adsorbent could still reach relatively 85% of the original one after completing fifth cycle. Therefore, the reusability results of SC/AL composite were quite satisfied, making the developed adsorbent a commercially attractive and green method. Finally, in column studies, the effect of initial concentration of pollutants at pH 5.0 on the removal of heavy metal ions was investigated. The Thomas and Yoon-Nelson models provided a satisfactory explanation for the results of column data.