Comparison of adsorption and photo-Fenton processes for phenol and paracetamol removing from aqueous solutions: single and binary systems

Recent trends in magnetic spinel ferrites and their composites as heterogeneous Fenton-like catalysts: A review

In recent years, there has been a growing interest in utilizing spinel ferrite and their nanocomposites as Fenton-like catalysts. The use of these materials offers numerous advantages, including ability to efficiently degrade pollutants and potential for long-term and repeated use facilitated by their magnetic properties that make them easily recoverable. The remarkable catalytic properties, stability, and reusability of these materials make them highly attractive for researchers. This paper encompasses a comprehensive review of various aspects related to the Fenton process and the utilization of spinel ferrite and their composites in catalytic applications. Firstly, it provides an overview of the background, principles, mechanisms, and key parameters governing the Fenton reaction, along with the role of physical field assistance in enhancing the process. Secondly, it delves into the advantages and mechanisms of H2O2 activation induced by different spinel ferrite and their composites for the removal of organic pollutants, shedding light on their efficacy in environmental remediation. Thirdly, the paper explores the application of these materials in various Fenton-like processes, including Fenon-like, photo-Fenton-like, sono-Fenton-like, and electro-Fenton-like, for the effective removal of different types of contaminants. Furthermore, it addresses important considerations such as the toxicity, recovery, and reuse of these materials. Finally, the paper presents the challenges associated with H2O2 activation by these materials, along with proposed directions for future improvements.

Corchorus Olitorius-Mediated Green Synthesis and Characterization of Nickel and Manganese Ferrite Nanoparticles

Developing a method for preparing Ni and Mn ferrites was the main objective of this study due to the importance of these materials in high-frequency applications. These ferrites were made by assisting combustion with dried leaves of Corchorus olitorius and then heating them to 700 °C. Several methods, including FTIR, XRD, TEM, and SEM/EDX, were used to characterize these ferrites. The thermal behavior, surface and magnetic properties of the as-prepared materials were determined. The results revealed that the method used is cheap, economical, environmentally friendly and makes it easy to produce the studied ferrites. FTIR, XRD, TEM, and SEM/EDX analyses show the formation of nanocrystalline ferrites with brittle, spongy and spinel-type structures, having two main vibration bands located around 400 cm−1 and 600 cm−1. However, TG-DTG results display the thermal behavior of different materials which consisted of unreacted oxides, carbon and the corresponding ferrites in the range of 300 °C to 600 °C. Moreover, complete conversion of the unreacted oxides to the equivalent ferrite was achieved by increasing heat treatment from 600 °C to 1000 °C. Ferrites are heated at 700 °C, which reduces their surface area. The magnetic properties of different ferrites calcined at 700 °C were estimated using the VSM technique. The magnetism of Fe-based materials containing Ni and Mn is 12.189 emu/g and 25.988 emu/g, respectively. Moreover, the squareness and coercivity of Ni ferrite are greater than for Mn ferrite.

Phosphate removal using dolomite modified with ultrasound: mathematical and experimental analysis

We studied the dolomite modified using an ultrasound bath and its application in phosphate removal. The modification was applied to improve the physicochemical properties of the dolomite and then to enhance its suitability as an adsorbent solid. The settings for analyzing the adsorbent modification were bath temperature and sonication time. The modified dolomite was characterized by electron microscopy, N₂ adsorption/desorption, pore size, and X-ray diffraction. To grasp the pollutant's adsorption mechanism more precisely, we used experimental research and mathematical model analysis. Design of Experiments was conducted to determine the ideal circumstances. In addition, the Bayesian method of Markov Chain Monte Carlo was used to estimate the isotherm and kinetic model parameters. A thermodynamic study was done to investigate the adsorption mechanism. Results show that the surface area of the modified dolomite was greater, enhancing its adsorption properties. To remove more than 90% of the phosphate, the optimal operational parameters for the adsorption were pH 9, 1.77 g of adsorbent mass, and 55 minutes of contact time. The pseudo-first-order, Redlich-Peterson and Sips models presented a good fit to the experimental data. Thermodynamics suggested a spontaneous and endothermic process. The mechanism suggested that physisorption and chemisorption could be involved in phosphate removal.

A critical review on paracetamol removal from different aqueous matrices by Fenton and Fenton-based processes, and their combined methods

Paracetamol (PCT), also known as acetaminophen, is a drug used to treat fever and mild to moderate pain. After consumption by animals and humans, it is excreted through the urine to the sewer systems, wastewater treatment plants, and other aquatic/natural environments. It has been detected in trace amounts in effluents of wastewater plant treatments, sewage sludge, hospital wastewaters, surface waters, and drinking water. PCT can cause genetic code damage, oxidative degradation of lipids, and denaturation of protein in cells, and its toxicity has been well-proven in bacteria, algae, macrophytes, protozoan, and fishes. To avoid its harmful health problems over living beings, powerful Fenton and Fenton-based treatments as pre-eminent advanced oxidation processes (AOPs) have been developed because of the inefficient treatment by conventional treatments. This paper presents a comprehensive and critical review over the application of such Fenton technologies to remove PCT from natural waters, synthetic wastewaters, and real wastewaters. The characteristics and main results obtained using Fenton, photo-Fenton, electro-Fenton, and photoelectro-Fenton are described, making special emphasis in the oxidative action of the generated reactive oxygen species. Hybrid processes based on the coupling with ultrasounds, gamma radiation, photocatalysis, photoelectrocatalysis, zero-valent iron-activated persulfate, adsorption, and microbial fuel cells, are analyzed. Sequential treatments involving the initiation with plasma gliding arc discharge and post-biological process are detailed. Comparative results with other available AOPs are also described and discussed. Finally, 13 aromatic by-products and 9 short-linear aliphatic carboxylic acid detected during the PCT removal by Fenton and Fenton-based processes are reported, with the proposal of three parallel pathways for its initial degradation.

Fabrication of Polyaniline@β-cyclodextrin Nanocomposite for Adsorption of Carcinogenic Phenol from Wastewater

We synthesized a stable, eco-friendly, and low-cost polyaniline@β-cyclodextrin (PANI@β-CD) nanocomposite via oxidative polymerization for phenol adsorption from water waste since phenol pollution is a global danger to human and animal health and the environment. The production of the composite and synergistic alteration of PANI with β-CD resulted in 66% reduction in particle size from 59 nm (PANI) to 20 nm (PANI@β-CD) as well as better phenol adsorption. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscope (SEM), and thermogravimetric analysis (TGA) were used to analyze the produced PANI@β-CD nanocomposite. Our results show the optimum conditions for phenol adsorption: time (50 min), pH (8.0), nanosorbent dose (0.5 g), and the sorption isotherm fitted with Langmuir model; the monolayer adsorption capacity of the prepared PANI@β-CD for phenol was determined to be 8.56 mg g-1. The average pore size, total pore volume, and surface area of PANI/βCD nanocomposite are 15.62 nm, 0.1586 cm3/g, and 90.901 m2/g, respectively, for the pseudo second order model. Finally, modifying PANI nanoparticles with βCD allowed reusability up to four cycles with superior adsorption performance of ∼95% using (0.01 N) HNO3.

Reaction kinetics formulation with explicit radiation absorption effects of the photo-Fenton degradation of paracetamol under natural pH conditions

The degradation of paracetamol (PCT) in an aqueous medium using the Fenton and photo-Fenton reactions was investigated. The aim of this research was the development of a kinetic model based on a reaction mechanism, which includes two main intermediates of PCT degradation and the local volumetric rate of photon absorption (LVRPA). Ferrioxalate was used as a catalyst and the working pH was adjusted to 5.5 (natural pH). Experimental work was planned through a D-optimal experimental design and performed in a flat plate reactor irradiated by a solar simulator. Hydrogen peroxide (HP) concentration, reaction temperature, and radiation level were the operating parameters. The photo-Fenton reaction allowed to reach a minimum relative PCT concentration of 2.01% compared to 5.04% achieved with Fenton reaction. Moreover, the photo-Fenton system required a 50% shorter reaction time and lower HP concentration than in dark conditions (90 min and 189 mg L^-1 vs. 180 min and 334 mg L^-1, respectively). The experimental results were used to estimate the kinetic parameters of the proposed kinetic model employing a nonlinear, multi-parameter regression method. The values obtained from the normalized root-mean-square error (14.52, 1.96, 4.36, 13.16, and 8.72 % for PCT, benzoquinone, hydroquinone, HP, and oxalate, respectively) showed a good agreement between the predicted and experimental data.

Photocatalytic and biodegradation treatments of paracetamol: investigation of the in vivo toxicity

Medicines and drugs consumption by all populations of the world can be expected to result in the contamination of the environment since 30-90% of residual drugs will be found into wastewaters. In this study, we investigate the degradation of acetaminophen, selected as a xenobiotic model molecule, via two separate procedures, the TiO₂ impregnated on cellulosic paper photocatalysis, and specific bacterial biodegradation process. Results showed that for initial drug content of 400 mg/L and after 5 hours of processing, around 85% of paracetamol was photocatalytically degraded. The use of Pseudomonas putida E1.21 isolate allowed an abatement of around 92% after 32 h of processing. The acetaminophen toxicity conducted in vivo on laboratory mice showed a net decrease of the creatinine release and enzymes activities like ALP, ALT, AST, and LDH decreased significantly (p < 0.05) when mice were treated distinctly by acetaminophen treated with UV/TiO₂ and the Pseudomonas putida E1.21 strain compared with the control experiments. CAT, MDA, and AchE serum level disruption measurement indicated a serious affection of the mice antioxidant system. These results were found to be in correlation with the ones of the histological analysis of the liver and kidney.

Removal of paracetamol from aqueous solution by activated carbon and silica. Experimental and computational study

The presence of pharmaceutical residues in the aquatic environment is a known problem worldwide. Paracetamol is widely used as an analgesic and antipyretic. Its high consumption implies a continuous discharge in aqueous environments through industrial and domestic wastewater that requires mitigation and remediation strategies. The aim of the present study was to analyse the removal of the paracetamol from aqueous solutions using the adsorption technique. For this, three commercial adsorbents with different textural properties were used: two activated carbons (CAT and CARBOPAL) and silica gel. A series of batch adsorption experiments were conducted at different values of pH (3.0, 7.0 and 10.5) and ionic strength (0.01, 0.5 and 1 M) to investigate the effects on the removal of paracetamol from the aqueous solution. In addition, we investigated the adsorption mechanism using the density functional theory. Adsorption was found to be higher in the acidic pH range, as varying pH showed significant influence on the surface charge of the adsorbents and degree of ionization of the paracetamol. Adsorption capacity of the adsorbents increased with an increase in the ionic strength of solution. At 25 °C, pH 3, ionic strength 1 M, 167 mg L^-1 of adsorbent and initial concentrations of paracetamol between 25 and 150 mg L^-1, the maximum adsorption capacity was 560 mg g^-1, 450 mg g^-1 and 95 mg g^-1, for CAT, CARBOPAL and silica respectively. The experimental kinetic data fitted well the pseudo-second order model and the equilibrium isotherm data the Langmuir model. The functional density theory methods provided atomistic details about paracetamol adsorbed on the surface of carbon and silica through molecular modeling.

Study on Treatment of Salicylhydroxamic Acid Wastewater from Tungsten Molybdenum Mineral Processing

Salicylhydroxamic acid is an excellent collector of oxidizing ore, and it has an efficient collection performance for tungsten molybdenum ore. However, the utilization ratio of salicylhydroxamic acid is relatively low in the flotation process, and a large amount of flotation wastewater discharged might cause damage to the water environment. This study mainly compared the effects of natural sunlight degradation, ozonation, and Fenton oxidation processes on the treatment of salicylchydroxamic acid wastewater from W–Mo mineral processing. The results showed after 30 hours degradation by natural sunlight, the CODcr removal rate of wastewater was only 25.99%. When the initial pH was 8, the dosage of O3 was 1.3 mg/L and the reaction time was 60 minutes; O3 oxidation could remove 40.37% CODcr from wastewater, and the BOD5/CODcr value increased to higher than 0.3 after 15 min reaction. Under the Fenton oxidation conditions such as initial pH 3, H2O2 dosage 0.96 g/L, and the molar ratio of H2O2 to Fe2+ 2 : 1, 90.43% CODcr could be removed from flotation wastewater after 90 min reaction, and the BOD5/CODcr value was obviously improved. Fenton oxidation was a high efficient processing technology for salicylhydroxamic acid wastewater, and the effluent could meet the discharge and reuse emission standard requirements in China.

Spectrophotometric determination of hydrogen peroxide in water by oxidative decolorization of azo dyes using Fenton system

In this study, based on the oxidative decolorization of three azo dyes (Orange G (OG), Acid Orange 7 (AO7) and Reactive Black 5 (RB5)) with hydroxyl radicals generated in Fenton system, we have successfully established three types of azo dyes spectrophotometric methods for measuring aqueous hydrogen peroxide (H₂O₂) concentration. The decolorization extent of OG, AO7 and RB5 at the corresponding characteristic wavelengths of 478 nm, 484 nm and 597 nm are proportion to the concentration of H₂O₂ in aqueous solutions. Under the selected reaction conditions, three well linear correlations between the depletion of azo dyes and the H₂O₂ concentration are established in the range of 0.45-175 μmol L^-1 of OG, 0.36-120 μmol L^-1 of AO7 and 0.44-175 μmol L^-1 of RB5, respectively. These proposed spectrophotometric methods are enough accurate to measure low concentrations of H₂O₂ in practical water samples and monitor the variations of H₂O₂ concentration during the phenol degradation in the Cu(II)/HCO₃^-/H₂O₂ process.

KOH-super activated carbon from biomass waste: Insights into the paracetamol adsorption mechanism and thermal regeneration cycles

A super activated carbon (SAC) was produced by KOH-activation of a biomass waste for paracetamol (PCT) adsorption from aqueous solution and for adsorption-thermal regeneration cycles. The SAC and the regenerated SAC after five adsorption-regeneration cycles (RSAC-5th) were fully characterized by several techniques. The N₂ physisorption showed that the S_BET values of the SAC and RSAC-5th are remarkably different, being 2794 m² g^-1 and 889 m² g^-1, respectively. The XPS analysis demonstrated that the SAC surface is composed by oxygen containing-groups, whilst the RSAC-5th also presents nitrogen ones, provenient from the PCT molecules. The adsorption studies revealed that the maximum adsorption capacity (Q_m) for the SAC (356.22 mg g^-1) is higher than that for RSAC-5th (113.69 mg g^-1). Also, the results demonstrated that the PCT adsorption is governed by both physisorption and chemisorption and the ab initio calculations showed the chemisorption mainly occurs in carboxylic groups.

Simultaneous removal of pollutants from water using nanoparticles: A shift from single pollutant control to multiple pollutant control

The steady increase in population, coupled with the rapid utilization of resources and continuous development of industry and agriculture has led to excess amounts of wastewater with changes in its composition, texture, complexity and toxicity due to the diverse range of pollutants being present in wastewater. The challenges faced by wastewater treatment today are mainly with the complexity of the wastewater as it complicates treatment processes by requiring a combination of technologies, thus resulting in longer treatment times and higher operational costs. Nanotechnology opens up a novel platform that is free from secondary pollution, inexpensive and an effective way to simultaneously remove multiple pollutants from wastewater. Currently, there are a number of studies that have presented a myriad of multi-purpose/multifunctional nanoparticles that simultaneously remove multiple pollutants in water. However, these studies have not been collated to review the direction that nanoparticle assisted wastewater treatment is heading towards. Hence, this critical review explores the feasibility and efficiency of simultaneous removal of co-existing/multiple pollutants in water using nanomaterials. The discussion begins with an introduction of different classes of pollutants and their toxicity followed by an overview and highlights of current research on multipollutant control in water using different nanomaterials as adsorbents, photocatalysts, disinfectants and microbicides. The analysis is concluded with a look at the current attempts being made towards commercialization of multipollutant control/multifunctional nanotechnology inventions. The review presents evidence of simultaneous removal of pathogenic microorganisms, inorganic and organic compound chemical pollutants using nanoparticles. Accordingly, not only is nanotechnology showcased as a promising and an environmentally-friendly way to solve the limitations of current and conventional centralised water and wastewater treatment facilities but is also presented as a good substitute or supplement in areas without those facilities.

Degradation of pharmaceuticals in different water matrices by a solar homo/heterogeneous photo-Fenton process over modified alginate spheres

A solar homo/heterogeneous photo-Fenton process using five materials (Fe(II), Fe(III), mining waste, Fe(II)/mining waste, and Fe(III)/mining waste) supported on sodium alginate was used as a strategy to iron dosage for the degradation of eight pharmaceuticals in three different water matrices (distilled water, simulated wastewater, and hospital wastewater). Experiments were carried out in a photoreactor with a capacity of 1 L, using 3 g of iron-alginate spheres and an initial hydrogen peroxide concentration of 25 mg L^-1, at pH 5.0. All the materials prepared were characterized by different techniques. The Fe(III)-alginate spheres presented the best pharmaceutical degradation after a treatment time of 116 min. Nineteen transformation products generated during the solar photo-Fenton process were identified by liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, using a purpose-built database developed for detecting these transformation products. Finally, the transformation products identified were classified according to their toxicity and predicted biodegradability.

Comparison of Fenton process and adsorption method for treatment of industrial container and drum cleaning industry wastewater

The present study aims to explore the characterization of industrial container and drum cleaning (ICDC) industry wastewater and treatment alternatives of this wastewater using Fenton and adsorption processes. Wastewater derived from ICDC industry is usually treated by chemical coagulation and biological treatment in Turkey and then discharged in a centralized wastewater treatment facility. It is required that the wastewater COD is below 1500 mg/L to treat in a centralized wastewater treatment facility. The wastewater samples were characterized for parameters of pH, conductivity, COD, BOD₅, TSS, NH₃-N, TN, TOC, TP, Cd, Cr, Cu, Fe, Ni, Pb, Zn, and Hg. Initial COD values were in the range of 11,300-14,200 mg/L. The optimum conditions for Fenton treatment were 35-40 g/L for H₂O₂, 2-5 g/L for Fe²⁺, and 13-36 for H₂O₂/Fe²⁺ molar ratio. The optimum conditions of PAC doses and contact times in adsorption studies were 20-30 g/L and 5-12 h, respectively. Removal efficiencies of characterized parameters for the three samples were compared for both Fenton and adsorption processes under optimum conditions. The results suggest that these wastewaters are suitable for discharge to a centralized wastewater treatment plant.

Removal of pharmaceuticals from water by homo/heterogonous Fenton-type processes - A review

The presence of emerging contaminants such as pharmaceuticals in natural waters has raised increasing concern due to their frequent appearance and persistence in the aquatic ecosystem and the threat to health and safety of aquatic life, even at trace concentrations. Conventional water treatment processes are known to be generally inadequate for the elimination of these persistent contaminants. Therefore, the use of advanced oxidation processes (AOPs) which are able to efficiently oxidize organic pollutants has attracted a great amount of attention. The main limitation of AOPs lies in their high operating costs associated with the consumption of energy and chemicals. Fenton-based processes, which utilize nontoxic and common reagents and potentially can exploit solar energy, will considerably reduce the removal cost of recalcitrant contaminants. The disadvantages of homogeneous Fenton processes, such as the generation of high amounts of iron-containing sludge and limited operational range of pH, have prompted much attention to the use of heterogeneous Fenton processes. In this review, the impacts of some controlling parameters including the H₂O₂ and catalyst dosage, solution pH, initial contaminants concentrations, temperature, type of catalyst, intensity of irradiation, reaction time and feeding mode on the removal efficiencies of hetero/homogeneous Fenton processes are discussed. In addition, the combination of Fenton-type processes with biological systems as the pre/post treatment stages in pilot-scale operations is considered. The reported experimental results obtained by using Fenton and photo-Fenton processes for the elimination of pharmaceutical contaminants are also compiled and evaluated.

Biological hazard evaluation of a pharmaceutical effluent before and after a photo-Fenton treatment

The aim of this study was to evaluate the biological hazard of a pharmaceutical effluent before and after treatment. For the former, the determined 96h-LC50 value was 1.2%. The photo-Fenton treatment catalyzed with an iron-pillared clay reduced this parameter by 341.7%. Statistically significant increases with respect to the control group (P<0.05) were observed at 12, 24, 48 and 72h in HPC (50.2, 30.4, 66.9 and 43.3%), LPX (22, 83.2, 62.7 and 59.5%) and PCC (14.6, 23.6, 24.4 and 25.6%) and antioxidant enzymes SOD (29.4, 38.5, 32.7 and 49.5%) and CAT (48.4, 50.3, 38.8 and 46.1%) in Hyalella azteca before treatment. Also increases in damage index were observed before treatment of 53.1, 59.9, 66.6 and 72.1% at 12, 24, 48 and 72h, respectively. After treatment the same biomarkers of oxidative stress decreased with respect to before treatment being to HPC (29.3, 22.5, 41.6 and 31.7%); LPX (14.2, 43.1, 30.7 and 35.5%); PCC (12.6, 21.3, 24.2 and 23.9%); SOD (39.2, 33.9, 49.5 and 37.9%) and CAT (28.6, 35.8, 33.7 and 31.7) at 12, 24, 48 and 72h, respectively (P<0.05). The damage index were decreased at 12, 24, 48 and 72h in 48.9, 57.8, 67.3 and 72.1%, respectively. In conclusion, the obtained results demonstrate the need of performing bioassays in order to characterize an effluent before discharge and not base such a decision only upon current normativity. In addition, it was also concluded that the heterogeneous photo-Fenton process decreases the presence of PCT, oxidative stress, genotoxic damage and LC50 in Hyalella azteca.

Effective adsorption of phenolic pollutants from water using β-cyclodextrin polymer functionalized Fe3O4 magnetic nanoparticles

β-Cyclodextrin polymer functionalized magnetic nanoparticles possess adsorption properties favorable for the purpose of removing phenolic pollutants.

Albumin matrix assisted wet chemical synthesis of nanocrystalline MFe2O4 (M = Cu, Co and Zn) ferrites for visible light driven degradation of methylene blue by hydrogen peroxide

Nanocrystallite MFe₂O₄ (M = Cu, Co and Zn) ferrites synthesized via a facile wet chemical process assisted by albumin matrix are reported to exhibit significant photodegradation of methylene blue (MB) in the presence of H₂O₂ under visible light.