Initial Pollutant Concentration Research Articles

Response Surface Methodology: A Review on Optimization of Adsorption Studies

Herein, we reviewed response surface methodology (RSM), a powerful statistical tool widely used in optimizing adsorption processes to remove synthetic dyes, toxic heavy metals, and phenols from wastewater. The widely used RSM models during optimization are the central composite design and Box-Behnken, which are second-order polynomial models. The models give a predictive insight into the number of experimental runs to be carried out. Furthermore, an in-depth overview of RSM and its application in optimizing various adsorption parameters, such as adsorbent dosage, initial pollutant concentration, contact time, and pH is discussed. In addition, RSM enables researchers to efficiently determine the optimal conditions for maximum pollutant removal. Lastly, the findings of this research highlight the potential of RSM as a valuable tool for optimizing adsorption processes and contributing to sustainable water treatment technologies.

Simultaneous electrochemical removal of three microcystin congeners and sulfamethoxazole in natural water

Microcystins (MCs), frequently detected in freshwater ecosystems, have raised significant human health and ecological concerns. New approaches are being developed to control and remove MCs. In this study, we examined factors influencing the efficacy of electrochemical oxidation as a means of control. Anode material (Pt/Ti, Ta2O5-IrO2/Ti, SnO2-SbO2/Ti, boron-doped diamond (BDD)/Si), anode surface area ratios and solution volumes, initial pollutant concentrations, and the co-existing antibiotic sulfamethoxazole (SMX) were investigated. MCs and SMX were dissolved in filtered Taihu Lake water to simulate the natural aquatic environment. The results showed that non-active anodes, lower initial concentration of MC, larger surface area ratio of anode to cathode, and smaller ratio of reaction solution volume to anode surface area could promote the degradation target pollutants. Under optimal conditions in this study, the degradation rates of MC-LR, MC-YR, MC-RR, and SMX each reached more than 90% within 6 hours, and the removal efficiency of MC-YR was the highest among three congeners. The effect of SMX on the degradation of MC congeners depended mainly on their concentration differences, such that when the initial concentration of SMX was one to two orders of magnitude lower than microcystin, the presence of SMX would promote the degradation of MCs. In contrast, when the initial concentration of SMX was higher than that of microcystin by approximately an order of magnitude, sulfamethoxazole would inhibit the degradation of MCs by between 4.6% and 24.5%. Ultra-high-performance liquid chromatography tandem mass spectrometry analysis revealed that the three MC congeners were electrochemically degraded through aromatic ring oxidation, alkene oxidation, and bond cleavage on the ADDA (3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid) side chain. Notably, the removal of MCs was accompanied by a decline in the hardness of the reaction water. This study provided insights into electrochemical degradation of microcystins and antibiotics in natural water, offering suggestions for its practical application.

Sustainable Activated Carbon from Agricultural Waste: A Study on Adsorption Efficiency for Humic Acid and Methyl Orange Dyes

In this study, porous activated carbon was produced from coffee waste and used as an effective adsorbent for the removal of humic acid (HA) from seawater and methyl orange (MO) dye from aqueous solutions. Phosphoric acid H3PO4 was used as an activating agent for the chemical activation of these agricultural wastes. The characterization of the activated carbon obtained using a scanning electron microscope (SEM), Fourier-transform infrared (FTIR) spectroscopy analysis, X-ray diffraction (XRD) and the Brunauer–Emmett–Teller (BET) method revealed that the activated carbon products exhibited high porosity and the formation of various functional groups. The effects of different parameters were examined using batch adsorption experiments, such as the adsorbent masses, pH, initial pollutant concentration and contact time. The results show that the performance increased with an increased adsorbent mass (up to 0.25 g/L) and decreased initial concentration of the adsorbent tested. On the other hand, this study clearly showed that the adsorption efficiency of the MO on the raw spent coffee grounds (SCGs) waste was around 43%, while no removal was observed for the humic acid. The experiments demonstrated that the activated carbon synthesized from the used coffee grounds (the efficiency was compared with commercial activated carbon (CAC) with a difference of 13%) was a promising alternative to commercially available adsorbents for the removal of humic acid from seawater. To understand and elucidate the adsorption mechanism, various isothermal and kinetic models were studied. The adsorption capacity was analyzed by fitting experimental data to these models. The experimental data for methyl orange dyes were analyzed using Langmuir and Freundlich isothermal models. The Freundlich isotherm model provided a superior fit to the equilibrium data, as indicated by a higher correlation coefficient (R2) than that of the Langmuir model. The maximum adsorption was observed at pH 3. The Freundlich adsorption capacity was found to be 333 mg/g adsorbent. The PAC showed a high adsorption capacity for the MO and HA. The PAC showed the highest adsorption capacities for the HA and MO compared with the other adsorbents used (SCGs and CAC) and would be a good material to increase the adsorption efficiency for humic acid removal in the seawater pretreatment process. In addition, the prepared AC BET surface area was 520.40 m2/g, suggesting a high adsorption capacity. This makes the material potentially suitable for various applications that require a high surface area. These results indicate that high-quality sustainable activated carbon can be efficiently produced from coffee waste, making it suitable for a wide range of adsorbent applications targeting various pollutants.

Modification of steel slag and its application for phosphate and ammonia removal in aquatic products processing wastewater

ABSTRACT This study aims to modify different types of steel slag by heating, characterise the material and test its ability for adsorption of phosphate and ammonia from aquatic products processing wastewater. The materials were characterised by SEM, EDS, BET and FT-IR analyses. The effects of the type of steel slag, calcination temperature in steel slag modification, pH, contact time, adsorbent mass and initial pollutant concentration were investigated using the one-factor-at-a-time approach. The results show that the adsorption kinetic of the samples followed the pseudo-second-order model, whereas their adsorption isotherm fitted well with the monomolecular adsorptive Langmuir with a maximum phosphate adsorption capacity of 45.045 mgPO43-/g. Optimisation using Response Surface Methodology was conducted with the independent factors (adsorbent doses, contact time and calcination temperature of steel slag) and response (removal efficiency of phosphate). The temperature and dosage of the material significantly affected phosphate removal efficiency and optimisation conditions were suggested. Validation of one optimum condition at the calcination temperature of 801°C, the adsorbent dosage of 11.9 g/L and the contact time of 72 min using real aquatic products processing wastewater resulted in the removal efficiencies of 86.93, 87.59, 7.76 and 7.58% for phosphate, total phosphorus, ammonia and total nitrogen, respectively.

Novel tempo oxidized polyvinyl alcohol/ cellulose nanocrystal-based nanocomposite membrane for malachite green dye removal.

In this study, in-situ modification by TEMPO oxidation was performed after nanocomposite synthesis to improve its properties toward dye molecule removal. The unoxidized and oxidized polymeric-based nanocomposite was denoted as PNC6 and PNC6O respectively. The nanocomposites were characterized using FESEM, FTIR, contact angle, XRD and BET analysis. Measurements of swelling ratio and chemical stability were also performed to provide insight into the durability of the nanocomposites. The effects of changing variables included contact duration, pH of aqueous solution, initial pollutant concentration, and temperature were observed. The kinetic study showed that the experimental data is best fitted with pseudo-second-order kinetics (R2 = 0.988 and 0.997 respectively), whereas on observing isotherm data, in both unoxidized and oxidized nanocomposite it fits well with Langmuir isotherm (R2 = 0.951 and 0.993 respectively). In addition, the effects on Gibb's free energy, Enthalpy, and Entropy were measured in terms of thermodynamic characteristics, it was established that dye molecules adsorption mechanism is endothermic and spontaneous in behaviour. To check regeneration tendency of the nanocomposite seven consecutive adsorption desorption cycles were run and about 90% and 80%, regeneration ability could be seen in an unoxidized state (PNC6) and an oxidized state (PNC6O) respectively upto 5th cycle after that the tendency get reduced. This study suggests that this novel polymeric nanocomposite can be employed as an efficient and relatively inexpensive adsorbent for dye removal from aqueous solutions.

Continuous Fixed Bed Bioreactor for the Degradation of Textile Dyes: Phytotoxicity Assessment

This study explores a novel bioremediation approach using a continuous upflow fixed bed bioreactor with date pedicels as a biosupport material. Date pedicels offer a dual advantage: providing microbial support and potentially acting as a biostimulant due to their inherent nutrients. This research is divided into two phases: with and without microbial introduction. The bioreactor’s efficiency in removing two common textile dyes, RB19 and DR227, was evaluated under various conditions: fixed bed high, the effect of the initial concentration of the pollutant, and recycling the RB19 solution within the bioreactor. Optimization studies revealed an 83% removal yield of RB19 dye with an initial pollutant concentration of 100 mg·L−1 using activated sludge as inoculum. The bioreactor developed its own bacterial consortium without initial inoculation. Microscopic analysis confirmed the presence of a diverse microbial community, including protozoa (Aspidisca and Paramecium), nematodes, and diatoms. The bioreactor exhibited efficient removal of RB19 across a range of initial concentrations (20–100 mg/L) with similar removal efficiencies (around 65%). Interestingly, the removal efficiency for DR227 was concentration-dependent. The bioreactor demonstrated the ability to enhance the biodegradability of treated RB19 solutions. Phytotoxicity tests using watercress and lettuce seeds revealed no negative impacts on plant growth. SEM and FTIR analyses were conducted to examine the biosupport material before and after biotreatment.

Ciprofloxacin removal as an emerging contaminant using electrochemical advanced reduction process: Mechanism, degradation pathway and reaction kinetic

The introduction of emerging contaminants (ECs), particularly antibiotics to the water resources has grown in recent years. Due to its widespread application and their toxicity, the ECs are one of the major environmental concerns. The present study is to evaluate the electrochemical removal of ciprofloxacin (CIP) as an emerging contaminant through the advanced reduction process (ARP). Moreover, the degradation pathway, mechanism and its kinetics have provided. In this study, the impacts of main operating variables were evaluated including pH, current density, initial pollutant concentration, sodium sulfite (Na2SO3) concentration, and time on the CIP removal through electrochemical process based-ARP. The obtained results revealed the 94.15 % CIP degradation rate under optimal conditions, at the concentration of 20 mg/L and pH 5 during 60 min. The CIP reduction followed the first-order kinetics with the rate of 0.99. In addition, the ARP along with electrochemical systems as a novel process were suggested as suitable and high efficiency technique for the CIP removal.

Magnetic recyclable carboxymethyl cellulose/gelatin/citrate@Fe3O4 photo-nanocomposite beads for ciprofloxacin removal via hybrid adsorption/photocatalysis process under solar light as a renewable energy source

Magnetically separable cross-linked carboxymethyl cellulose/gelatin/citrate-functionalized magnetite nanoparticles (Cit-Fe3O4) photo-nanocomposite beads (mCMC/Ge) were synthesized and applied in synergistic adsorption/photocatalytic degradation of ciprofloxacin (Cipro) pharmaceutical pollutant under sunlight irradiation. Various analytical techniques were employed to characterize their structural, textural, magnetic, thermal, and optical properties. The removal efficiency of mCMC/Ge beads was investigated considering different influencing parameters (pH, beads dosage, contact time, Cipro concentration, and temperature). Experimental data modeling indicated that the adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models, with a maximum Langmuir adsorption capacity (qm) of 50 mg g−1 for mCMC/Ge, twice that of the matrix. Photocatalytic activity results showed prominent enhancement in Cipro removal using 1 g L−1 of mCMC/Ge at pH 7, as compared to Cit-Fe3O4, reaching 96 %, 85 %, and 63 % after 180 min of adsorption and 120 min of irradiation for initial pollutant concentrations of 10, 20, and 60 mg L−1, respectively. Furthermore, mCMC/Ge demonstrated efficient removal even in real water sample.The excellent removal performance of mCMC/Ge highlighted the synergy between polymeric matrix template and encapsulated Cit-Fe3O4 in improving Cipro adsorption and photodegradation. Furthermore, facile recyclability and sustained activity over five cycles identify mCMC/Ge photo-nanocomposite as a promising material for removing organic pollutants from contaminated waters.

Photocatalytic Luminous Textiles for the Treatment of Wastewater Issued from Petroleum Activity: Photocatalytic Process Extrapolation

In this study, the degradation of naphthalene in water was performed via photocatalysis with two different configurations: UV-irradiated TiO2 deposited on cellulosic tissue and photocatalytic luminous textiles. The photocatalytic performance of these configurations was evaluated in terms of pollutant removal and mineralization yield. Moreover, the influence of key operating parameters, such as the initial pollutant concentration, solution turbidity, the number of tissues, and the type of irradiation, was investigated. The results showed a complete removal of 8 mg/L of naphthalene with photocatalytic luminous textiles after 4 h of UV irradiation, with a mineralization yield of 80%. The impact of the turbidity shows that at 90 NTU, reductions in photocatalytic activity of 30% and 10% were recorded for the UV-irradiated TiO2 deposed on cellulosic tissue and photocatalytic luminous textiles, respectively. The reactive oxygen species (ROS) concentrations were monitored during photocatalysis to better understand the contribution of each active species in the mechanism reaction of naphthalene oxidation. The results show that the hydroxyl radical (•OH) is responsible for 70% of pollutant oxidation. A scaling up of the water treatment with photocatalytic luminous textiles was performed. The extrapolation confirmed the same trends observed at the laboratory scale in terms of degradation and mineralization.

Catalytic Ozonation Treatment of Coal Chemical Reverse Osmosis Concentrate: Water Quality Analysis, Parameter Optimization, and Catalyst Deactivation Investigation.

Catalytic ozone oxidation, which is characterized by strong oxidizing properties and environmental friendliness, has been widely used in organic wastewater treatments. However, problems such as a low organic pollutant removal efficiency and unstable operation during the catalytic ozone treatment process for wastewater remain. To address these disadvantages, in this study, the treatment efficacy of catalytic ozone oxidation on a coal chemical reverse osmosis concentrate was investigated. The basic water quality indicators of the chemical reverse osmosis concentrate were analyzed. The effects of initial pollutant concentration, pH, ozone concentration, and catalyst concentration on the COD removal rate from the coal chemical reverse osmosis concentrate were explored. Water quality indicators of the chemical reverse osmosis concentrate before and after the catalytic ozone treatment were studied using spectroscopic analysis methods. The RO concentrate demonstrated large water quality fluctuations, and the catalytic ozonation process removed most of the pollutants from the treated wastewater. A possible deactivation mechanism of the ozone catalyst was also proposed. This study provides a theoretical reference and technical support for the long-term, efficient, and stable removal of organic pollutants from coal chemical reverse osmosis concentrate using a catalytic ozone oxidation process in practical engineering applications.

Novel synthesis organic–inorganic heterojunctions of protonated g-C3N4/Fe3O4/AgBr/AgCl/AgI quinary magnetic photocatalyst with enhanced visible-light photocatalytic degradation of methylene blue in water

A novel magnetic quinary nanocomposite, protonated g-C3N4/Fe3O4/AgBr/AgCl/AgI, was synthesized using a wet chemical method. The multi-heterojunction photocatalyst with multi-carrier source and multi-channel carrier transport is constructed to enhance the photocatalytic degradation performance of pure g-C3N4. The design of the quinary nanocomposite is also an effective approach to solve the chemical stability problem of silver halides. The photocatalytic degradation efficiency under visible light irradiation was analyzed for methylene blue (MB) as the target organic pollutant. The quinary nanocomposite with 10 % g-C3N4 displayed high photocatalytic performance, with 83 % of MB degraded under 6 h LED white light irradiation. The effective quinary nanocomposite has good magnetic properties and can be magnetically separated to prevent secondary pollution of the photocatalyst in water. Parameters such as initial concentration of pollutant, initial solution pH, and light source were studied. Zeta potential results showed that the quinary nanocomposite could disperse homogenously to decrease aggregation in the solution. The photocatalytic degradation mechanism was investigated, and the mineralization results were analyzed based on liquid chromatography-mass spectroscopy (LC-MS) and total organic carbon (TOC). It was found that the hydroxyl and superoxide radicals were major reactive species by scavenging experiments. Additionally, protonated g-C3N4/Fe3O4/AgBr/AgCl/AgI nanocomposite showed excellent reusability after magnetic separation and regeneration, thus suggesting it to be a promising photocatalyst for treating wastewater containing organic contaminants.

Utilization of photocatalytic degradation and efficiency of engineered geopolymer composite tile doped with nano-particles under ultraviolet light

This study investigates the impact of nano-zinc oxide (ZnO) on the self-cleaning and microstructural performance of engineered geopolymer composites (EGC) for urban cleanliness enhancement. The research focuses on achieving homogeneous dispersion of nano-ZnO through ultrasonication to prevent agglomeration and assess its effects on workability, setting time, mechanical, and microstructural properties of EGC. Results show that incorporating ZnO nanoparticles at 5 % and 10 % concentrations as a surface coating on engineered geopolymer composite creates a highly effective photocatalytic material. This enhanced composite demonstrates significant capability in degrading Rhodamine B (RhB) under UV light exposure over a 15-day period, breaking down organic pollutants into simpler, potentially less toxic substances. The efficiency of degradation depends on factors such as nano-ZnO concentration, UV radiation intensity, and initial pollutant concentration. The optimal dosage of nano-ZnO in EGC is found to be 0.5 %, which enhances hydration and pozzolanic activity, promoting a densified microstructure at the nanoscale. This innovative composite material shows promise as a self-cleaning finishing material for urban buildings, offering potential improvements in both aesthetics and environmental sustainability.

PW12/Fe3O4/biochar nanocomposite as an efficient adsorbent for metronidazole removal from aqueous solution: Synthesis and optimization

The growing occurrence of antibiotics in aquatic environments has emerged as a notable environmental issue given their potential detrimental impacts on ecosystems and the well-being of individuals. Therefore, there is a pressing need to develop effective strategies for removing antibiotics from wastewater. Herein, PW12/Fe3O4/biochar nanocomposite as a highly efficient adsorbent was synthesized to remove metronidazole (MNZ) antibiotic from wastewater through a sustainable and environmentally friendly approach. Simple surface modifications, such as chemical and physical modification with acid and base, as well as adding polyoxometalate were employed to enhance the adsorption of MNZ. The physical and chemical characteristics of the adsorbent were extensively analyzed using several techniques as follows, Fourier transform infrared (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) coupled with energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET), and transmission electron microscopy (TEM). Experimental results demonstrated a significant increase in the efficacy of MNZ removal when the adsorbent surface was modified with polyoxometalate (H3PW12O40) compared to magnetic biochar (MBC). This improvement favors the pore-filling mechanism, electrostatic, H-bonds, and π-π interactions. To optimize the operating parameters for MNZ removal, response surface methodology (RSM) was employed using Design Expert software, considering the pH of a solution, initial pollutant concentration, adsorbent amount, and contact time. The results revealed that when the conditions were ideal (pH ∼1, initial concentration of MNZ at 5 mg/L, adsorbent amount of 0.6 g/L, and contact time of 60 minutes), the removal efficiency and the adsorption capacity reached 94.28 % and 78.45 mg/g, respectively. The analysis of isotherm and kinetic experiments revealed that the adsorption mechanism followed the Freundlich isotherm and pseudo-second order kinetic models, respectively. Furthermore, the adsorbent demonstrated excellent efficiency and reusability, with a removal efficiency of over 90 % even after four cycles, highlighting its potential and economic viability as an adsorbent for metronidazole removal.

Copper Ion Removal by Adsorption Using Fly Ash-Based Geopolymers: Process Optimization Insights from Taguchi and ANOVA Statistical Methods.

The present study aimed to use geopolymer materials synthesized from different fly ashes, which are promising for the adsorption of copper ions from aqueous solutions. The characterization of fly ashes and prepared adsorbents was performed by energy-dispersive X-ray spectroscopy (EDS) analysis, Brunauer-Emmett-Teller (BET) surface area analysis, and Scanning Electron Microscopy (SEM). Taguchi and ANOVA methods were used to predict the effect of different working parameters on copper ion removal by prepared geopolymers. Based on data obtained by the Taguchi method, it was found that the factor most influencing the adsorption process is the type of adsorbent used, followed by the solution pH, the reaction time, the adsorbent dose, and the initial copper ion concentration. The ANOVA results agree with the Taguchi method. The optimal conditions of the adsorption process were: fly ash C modified by direct activation with 2 M NaOH, at 70 °C for 4 h, solution pH of 5, initial pollutant concentration of 300 mg/L, 40 g/L adsorbent dose, and 120 min of reaction time. Copper ion removal efficiency was determined experimentally under optimal conditions, achieving a value of 99.71%.

A multi-task stations cooperative air quality prediction system for sustainable development

In recent years, A series of environmental problems caused by air pollution have attracted widespread attention. Air quality forecasting has become an indispensable part of people’s daily life. However, the traditional air quality prediction (AQP) model WRF-CMAQ simulation system faces several challenges: (1) the fuzziness of pollutant formation mechanism; (2) the hardness of integrating the features of meteorological conditions; (3) the difficulty of cooperating among monitoring stations. To deal with these challenges, we propose a multi-task station cooperative air quality prediction (MTSC-AQP) system for sustainable development. The MTSC-AQP system contains three modules: air quality analysis, a WRF-LSTM module for initial pollutant prediction, and multi-station cooperative AQP. Through air quality analysis, it can calculate the air quality index (AQI) and analyze the correlation between pollutants and meteorological conditions. Then, the WRF-LSTM module integrates spatio-temporal multi-source data to forecast the initial concentration of pollutants. Finally, the system incorporates the gravity model to predict the final AQI. Extensive experiments conducted on real-world datasets show the effectiveness of forecasting the AQI by using the MTSC-AQP system.

Removal of methylene blue from aqueous solutions by adsorption onto Carpobrotus edulis biomass

The aim of this work is to investigate the influence of an alkaline pretreatment of the Mediterranean plant Carpobrotus edulis on the adsorption capacity toward the dye methylene blue and to estimate the content of soluble organic matter that can be released into the aqueous solution by this biomaterial. The biomaterial used was characterized by SEM-EDX, SS, FT-IR, pHZ, COD and BOD5. Removal of methylene blue (MB) dye by this biomaterial was carried out and the effects of physicochemical factors such as initial pollutant concentration, adsorbent dose, contact time, pH and temperature were investigated. After adsorbent treatment, the soluble organic matter was reduced by 97%, 96%, and 96% for biological oxygen demand, chemical oxygen demand, and organic matter, respectively. Kinetics and equilibrium studies of MB adsorption on the bioadsorbents were fitted with a pseudo-second order kinetic model and a Langmuir model, respectively. The maximum adsorption amount of the modified C. edulis plant was 153.9 mg/g at 298°K. The thermodynamic parameters show that the adsorption process was possible and spontaneous in nature. The adsorption mechanism of MB on the surface of biomaterials was attributed to the electrostatic interaction and H-bonding. The prepared biomaterial (0.016 U$ per gram) was easily regenerated with aqueous HNO3 solution, with a slight decrease in adsorption capacity up to five cycles. The results of Taguchi experimental design and analysis of variance showed that contact time, adsorbent mass and initial concentration are the most important factors affecting the removal efficiency with a contribution of 43.91%, 32.68%, and 22.95%, respectively. The maximum removal capacity of MB dye in optimal operating conditions was 99.39%, which was obtained at the optimum conditions of m = 1 g, pH 4, T = 35 °C, Ci = 1000 mg/L, tc = 5 min. These results confirm previous results obtained with the batch system and show that this absorbent is also promising for the removal of cationic dyes from wastewater.

Stabilized Hf-doped Ti/Sb-SnO2 electrode for efficient degradation of tetracycline.

The electrochemical advanced oxidation process (EAOP) has shown significant promise in the field of refractory organic wastewater treatment due to its high efficiency and environmentally friendly nature. In this study, Ti/Sb-SnO2 electrodes with varying proportions of Hf were prepared using the sol-gel method. The addition of Hf transformed the original collapsing and broken surface into a flat and regular surface. The results demonstrated that Ti/Sb-SnO2-Hf electrode doped with 6% Hf exhibited a higher oxygen evolution potential (OEP) and excellent stability. The OEP increased from 2.315 V without Hf-doping to 2.482 V, and the corresponding actual life was 321.05% higher than that without Hf. The current density (5-40 mA·cm-2), electrolyte concentration (0.02-0.2 mol·L-1), pH (3-11), and initial pollutant concentration (5-80 mg·L-1) were evaluated to confirm the tetracycline (TC) degradation characterization of Ti/Sb-SnO2-6%Hf electrodes. It was concluded that under the optimal degradation conditions, the removal rate of TC could reach 99.66% within 2 h. The degradation of TC follows first-order reaction kinetics. The oxidative degradation of TC was achieved through indirect oxidation, with ·OH playing a dominant role. TC's electrochemical oxidation degradation pathway has been proposed: Based on LC-MS results, three main pathways are speculated. During the electrocatalytic oxidation process, decarboxylation, deamidation, and ring-opening reactions occur under ·OH attack, producing intermediate compounds with m/z values of 427, 433, 350, 246, 461, 424, 330, 352, 309, 263, and 233. These intermediates are further oxidized to intermediate compounds with an m/z value of 218. This work introduces a new efficient anode electrochemical catalyst for the degradation of TC, providing a strategy for industrial applications.

Sustainable removal of tetracycline and paracetamol from water using magnetic activated carbon derived from pine fruit waste

This work presents highly porous magnetic activated carbon nanoparticles (MPFRC-A) derived from pine fruit residue. The MPFRC-A were produced through a three-step process: physical activation (carbonization temperature: 110–550 °C), chemical activation (H2SO4 (0.1 N, 96%)), and co-precipitation. These nanoparticles were then used to remove tetracycline (TC) and paracetamol (PC) from water. Functionalization with Fe3O4 nanoparticles on the surface of the pine fruit residue-derived activated carbon (PFRC-A) resulted in high saturation magnetization, allowing for separation from aqueous solution using an external magnet. The MPFRC-A adsorbent was characterized by Brunauer–Emmett–Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX) analyses, In the experimental section, the effects of various factors on the adsorption process were investigated, including pH, contact time, initial pollutant concentrations, adsorbent dosage, and temperature. Based on these investigations, adsorption isotherm models and kinetics were studied and determined. The results showed that MPFRC-A exhibited a large specific surface area (182.5 m2/g) and a high total pore volume (0.33 cm3/g). The maximum adsorption capacity was achieved at pH 6 and 5 for PC and TC drugs with an adsorbent dose of 400 mg and an initial concentration of 20 mg/L at 25 °C. The study revealed that the experimental data were well-fitted by the Langmuir isotherm model (R2 > 0.98), with maximum uptake capacities of 43.75 mg/g for TC and 41.7 mg/g for PC. Outcomes of the adsorption thermodynamics shows non-spontaneity of the reaction and the adsorption process by all adsorbents was endothermic.

Activation of H2O2-HCO3- by Ca2Co2O5 for pollutant degradation.

The bicarbonate-activated hydrogen peroxide (BAP) system is widely studied for organic pollutant degradation in wastewater treatment. Ca2Co2O5, a heterogeneous catalyst containing multivalent cobalt including Co(II) and Co(III), was herein investigated as a BAP activator, and Acid Orange 7 (AO7) was used as a model pollutant. Ca2Co2O5 exhibited good activation performance. The degradation rate and the initial rate constant of the Ca2Co2O5-activated BAP system were 5.4 and 11.2 times as high as the BAP system, respectively. The removal rate of AO7 reached 90.9% in 30min under optimal conditions (AO7 20mg/L, Ca2Co2O5 0.2g/L, H2O2 1mM, NaHCO3 5mM, pH 8.5, 25℃). The Ca2Co2O5 catalyst exhibited good stability and recyclability, retaining 85% of AO7 removal rate in the fifth run. Compared to the BAP system, a lower dosage of H2O2 was required and a higher initial concentration of pollutants allowed for effective degradation in the Ca2Co2O5-BAP system. X-ray photoelectron spectroscopy was used to analyze the catalytic mechanism. The analysis showed that the good catalytic performance of Ca2Co2O5 attributes to its high proportion of oxygen vacancies and Co(III) species, and the presence of Ca. The active species O2•-, •OH, and 1O2 are responsible for the degradation, as indicated by the quenching experiments. The degradation mechanism of AO7 was speculated based on UV-Vis spectral analysis and the identification of degradation intermediates. The azo form, naphthalene and benzoic rings in the AO7 structure are destroyed in the decomposition. This research provides a feasible approach to designing effective and reusable BAP activators for pollutant degradation in wastewater treatment.

Green and environmentally friendly architecture of starch-based ternary magnetic biocomposite (Starch/MIL100/CoFe2O4): Synthesis and photocatalytic degradation of tetracycline and dye

The presence of tetracycline and dye as organic contaminants has led to the poisoning of wastewater. The aim of this study is to synthesize a novel biocomposite material by decorating natural starch polymer granules with metal-organic framework (MIL100) and cobalt ferrite magnetic (CoFe2O4) nanoparticles. The synthesized ternary magnetic biocomposite (Starch/MIL100/CoFe2O4) was used for the photocatalytic degradation of methylene blue (MB) and tetracycline (TCN) using LED visible light. The synthesis of the biocomposite was confirmed through comprehensive analyses (XRD, SEM, FTIR, BET, EDX, MAP, DRS, pHzpc, TGA, and Raman). The evaluation examined the influence of initial pollutant concentration, catalyst dosage, pH, and the impact of anions on pollutant removal. The results show that the pollutant degradation ability of biocomposite has been significantly improved, so that the base biopolymer, starch, achieved 18% tetracycline degradation, but when decorated with MIL100 and cobalt ferrite, it increased to 91.2%. It was observed that the degradation for methylene blue improved from 12% for starch to 96.6% for the magnetic biocomposite. The tetracycline degradation decreased by more than 20% in the presence of NaCl, NaNO3, and Na2SO4. The finding shows that the biocomposite adheres to first-order kinetics for both pollutants. The scavengers test identified hydroxyl radicals as the most effective active species in the degradation process. High stability, even after passing 5 cycles of recycling was observed for the biocomposite. The results indicated that the facile and green synthesized Starch/MIL100/CoFe2O4 magnetic biocomposite could be used as an effective photocatalyst for the degradation of Tetracycline and dye at room temperature.