Initial Pollutant Concentration Research Articles

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.

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.

In situ synthesis BiOBr/Bi-TDC composite with rich oxygen vacancy to remove rhodamine B and tetracycline under ultrasound and illumination

A series of 3D hierarchical microsphere heterojunction composites combining BiOBr and Bi-MOF (Bi-TDC) supported by 2,5-thiophene dicarboxylate acid (H2TDC) was fabricated by one-step solvothermal method. Hexadecyl trimethyl bromide (CTAB) is used as the structure guide reagent and Br source to design BiOBr/Bi-TDC composites and enhance catalytic activity. The ultrasound-assisted photocatalysis effect of BiOBr/Bi-TDC for RhB and TC can reach 99.8 % and 96.1 % in 30 min, respectively. Further, the influence factor of photocatalytic degradation TC solution were explored, including pH, initial pollutant concentration, catalyst dosage and different proportions of BiOBr and Bi-TDC. The excellent catalytic activity can be attributed to the construction of heterogeneous interfaces and rich oxygen vacancies (OVs), which improve the low redox potentials and facilitate the separation of photogenerated electron-hole pairs. Radical trapping experiment is made and shown •O2− and h+ are the most active species for the photodegradation process. The EPR characteristic is also used to explore free radicals when exposed to the visible light illumination.

Natural Factors of Microplastics Distribution and Migration in Water: A Review

Microplastics are widely present worldwide and are of great concern to scientists and governments due to their toxicity and ability to serve as carriers of other environmental pollutants. The abundance of microplastics in different water bodies varied significantly, mainly attributed to the initial emission concentration of pollutants and the migration ability of pollutants. The migration process of microplastics determines the abundance, fate, and bioavailability of microplastics in water. Previous studies have proved that the physicochemical properties of water bodies and the properties of microplastics themselves are important factors affecting their migration, but the change in external environmental conditions is also one of the main factors controlling the migration of microplastics. In this paper, we focus on the effects of meteorological factors (rainfall, light, and wind) on the distribution and migration of microplastics and conclude that the influence of meteorological factors on microplastics mainly affects the inflow abundance of microplastics, the physical and chemical properties of water, and the dynamics of water. At the same time, we briefly summarized the effects of aquatic organisms, water substrates, and water topography on microplastics. It is believed that aquatic organisms can affect the physical and chemical properties of microplastics through the physical adsorption and in vivo transmission of aquatic plants, through the feeding behavior, swimming, and metabolism of animals, and through the extracellular polymers formed by microorganisms, and can change their original environmental processes in water bodies. A full understanding of the influence and mechanism of external environmental factors on the migration of microplastics is of great theoretical significance for understanding the migration law of microplastics in water and comprehensively assessing the pollution load and safety risk of microplastics in water.

Bimetal Cu/Ni-BTC@SiO2 metal-organic framework as high performance photocatalyst for degradation of azo dyes under visible light irradiation

There has been significant attention on the efficient degradation of pollutants in wastewater using metal-organic frameworks (MOFs) photocatalytic methods over the past decade. Herein, we examined the elimination of two different types of water-contaminating dyes, specifically cationic dye methylene blue (MB) and anionic dye methyl orange (MO), through the application of bimetal Cu/Ni-BTC@SiO2 MOF as high performance photocatalyst. The bimetal Cu/Ni-BTC@SiO2 photocatalyst was synthesized and characterized by XRD, FTIR, SEM, TEM, TGA, BET, DRS, and VSM techniques. The examination of the impact of different operational factors on the elimination of pollutants involved a comprehensive analysis of variables including the photocatalyst type, initial pollutant concentration, quantity of photocatalyst, and pH levels. The highest removal efficiency for MO and MB dyes by the photocatalyst was found to be 98 and 71%, respectively, within 60 min. In the fifth reaction stage, degradation efficiency for MO and MB was 76 and 56% respectively. Kinetic investigations demonstrated that, in the context of the uptake of MB and MO dyes, the interparticle diffusion, and pseudo-second-order models emerged as possessing the most robust correlation coefficients with the experimental data, registering values of 0.988 and 0.961, respectively. The examination of isotherms reveals that the isotherm models proposed by BET, and Anderson (V) demonstrate the highest level of conformity with the empirical data for the decomposition of MB and MO dyes, correspondingly. The TOC levels decreased significantly from 51 to 14 and 47 to 3 mg/L for MB and MO dyes, indicating the effective mineralization process using Cu/Ni-BTC@SiO2.

Transformed construction from type-II WO3/BaTiO3 heterojunction to Z-scheme WO3/Ba0.5Sr0.5TiO3 and WO3/SrTiO3 photocatalytic systems: Enhanced photocatalytic activity and mechanism insight

In this study, type-II heterojunction WO3/BaTiO3 and Z-scheme WO3/SrTiO3 or WO3/Ba0.5Sr0.5TiO3 nanocomposite photocatalysts were constructed for photodegradation of organic pollutants in wastewater under visible light. The photocatalytic performance of three WO3/titanate systems were estimated. Some influencing factors such as molar ratio of WO3 and titanates, light irradiation time, catalyst dose, and initial concentration of organic pollutants on the photocatalytic activity were investigated. The stability and reusability of three WO3/titanates systems were examined. Moreover, the production of some radicals in the three WO3/titanates photocatalytic systems was demonstrated, and the three WO3/titanates photocatalytic reaction mechanisms were compared. The results reveal that the configurations of WO3/titanates photocatalytic systems are transformed from type-II heterojunction WO3/BaTiO3 with lower activity to Z-scheme WO3/SrTiO3 and WO3/Ba0.5Sr0.5TiO3 with higher activity via the change of titanates. The WO3/titanate nanocomposites show higher photocatalytic activity at 3.0:1.0 M ratio of WO3 and titanates, and WO3/Ba0.5Sr0.5TiO3 nanoparticles have superior photocatalytic activity. The order of photocatalytic activity is as follows: WO3/Ba0.5Sr0.5TiO3 > WO3/SrTiO3 > WO3/BaTiO3. Several organic pollutants, such as rhodamine B, methyl parathion, direct brilliant yellow-4R, and methylene blue, can be efficiently degraded using WO3/Ba0.5Sr0.5TiO3 under visible light, and the RhB has higher degradation rate. After four cycles, WO3/titanate nanocomposites still have relatively high stability and reusability. •OH plays a major role in three WO3/titanates photocatalytic degradation. It is expected that the Z-scheme WO3/Ba0.5Sr0.5TiO3 photocatalytic technology creates a good foreground for disposing of dyes and pesticides in water and wastewater.

Enhancing the performance of alumina-pillared clay for phenol removal from water solutions and polyphenol removal from olive mill wastewater: Characterization, kinetics, adsorption performance, and mechanism

An alumina-pillared clay (Al-PILC) has been synthesized and tested for its ability to adsorb phenol from aqueous solutions, and polyphenols from Olive Mill Wastewater (OMW). The synthesis processes were investigated by varying parameters like the Al/clay ratio, with a molar ratio of [OH−]/[Al3+] = 2.4. Various techniques, including XRD, BET, XRF, FTIR, and SEM were used to characterize the resulting solids. The effect of key factors as pH, initial pollutant concentration, and contact time, were examined in order to evaluate the phenol adsorption capacities of raw clay (RC) and optimized Al-PILC10 materials. The specific surface areas of RC and Al-PILC10 were 40 and 127 m2/g, respectively, resulting in increasing the phenol adsorbed quantity from 14.15 mg/g for RC to 30.61 mg/g for Al-PILC10 clays, at pH 2 and 45 °C. Pseudo-second-order kinetics and Freundlich adsorption isotherm were suitable for describing phenol adsorption on both clays. Furthermore, Al-PILC10 exhibits an impressive removal efficiency of 76 % for polyphenols from OMW, in contrast to the 50 % achieved by RC at acidic pH. Furthermore, Al-PILC10 showcased a superior desorption rate and a favorable regeneration capacity of 64 % compared to RC (45 %), even after multiple adsorption-desorption cycles. These findings emphasize the potential of pillared clay as a cost-effective adsorbent for the efficient removal of phenol and polyphenols from wastewater.

Improvement strategy of citrate and biochar assisted nano-palladium/iron composite for effective dechlorination of 2,4-dichlorophenol.

Rapid passivation and aggregation of nanoscale zero-valent iron (nZVI) seriously limit its performance in the remediation of different contaminants from wastewater. To overcome such issues, in the present study, nano-palladium/iron (nPd/Fe) was simultaneously improved by biochar (BC) prepared from discarded peanut shells and green complexing agent sodium citrate (SC). For this purpose, a composite (SC-nPd/Fe@BC) was successfully synthesized to remove 2,4-dichlorophenol (2,4-DCP) from wastewater. In the SC-nPd/Fe@BC, BC acts as a carrier with dispersed nPd/Fe particles to effectively prevent its agglomeration, and increased the specific surface area of the composite, thereby improving the reactivity and stability of nPd/Fe. Characterization results demonstrated that the SC-nPd/Fe@BC composites were well dispersed, and the agglomeration was weakened. The formation of the passivation layer on the surface of the particles was inhibited, and the mechanism of SC and BC improving the reactivity of nPd/Fe was clarified. Different factors were found to influence the reductive dichlorination of 2,4-DCP, including Pd loading, Fe:C, SC addition, temperature, initial pH, and initial pollutant concentration. The dechlorination results revealed that the synergistic effect of the BC and SC made the removal efficiency and dechlorination rate of 2,4-DCP by SC-nPd/Fe@BC reached to 96.0 and 95.6%, respectively, which was better than that of nPd/Fe (removal: 46.2%, dechlorination: 45.3%). Kinetic studies explained that the dechlorination reaction of 2,4-DCP and the data were better represented by the pseudo-first-order kinetic model. The reaction rate constants followed the order of SC-nPd/Fe@BC (0.0264min-1) > nPd/Fe@BC (0.0089min-1) > SC-nPd/Fe (0.0081min-1) > nPd/Fe (0.0043min-1). Thus, SC-nPd/Fe@BC was capable of efficiently reducing 2,4-DCP and the dechlorination efficiency of BC and SC synergistically assisted composite on 2,4-DCP was much better than that of SC-nPd/Fe, nPd/Fe@BC and nPd/Fe. Findings suggested that SC-nPd/Fe@BC can be promising for efficient treatment of chlorinated pollutants.

Removal of 6-methylquinoline from shale gas wastewater using electrochemical carbon nanotubes filter

6-Methylquinoline (6-MQ) is identified as a high-concentration organic compound pervasive in shale gas wastewater (SGW) and poses a significant risk of environmental pollution. In response, this study aimed to address these challenges by introducing an innovative electrochemical membrane constructed with multi-walled carbon nanotubes (CNTs) for the removal of 6-MQ. The investigation systematically explored the impact of voltage, initial pollutant concentration, and salinity on the performance of the electrochemical CNTs filter. It was found a positive correlation between removal efficiency and increasing voltage and salinity levels. Conversely, as the initial concentration of pollutants increased, the efficiency showed a diminishing trend. The electrochemical CNTs filter exhibited remarkable efficacy in both adsorption removal and electrochemical oxidation of 6-MQ. Notably, the CNTs membrane exhibited robust adsorption capabilities, evidenced by the sustained adsorption of 6-MQ for over 33 h. Furthermore, applying an electrochemical oxidation voltage of 3 V consistently maintained a removal rate exceeding 34.0% due to both direct and indirect oxidation, underscoring the sustained efficacy of the electrochemical membranes. Besides, real wastewater experiments, while displaying a reduction in removal efficiency compared to synthetic wastewater experiments, emphasized the substantial potential of the electrochemical CNTs filter for practical applications. This study underscores the significant promise of electrochemical membranes in addressing low molecular weight contaminants in SGW, contributing valuable insights for advancing SGW treatment strategies.

Treatment of emerging pyrrolizidine alkaloids in drinking water by UV/persulfate process: Kinetics, energy efficiency and degradation pathway

Pyrrolizidine alkaloids (PAs), recognized as a group of toxic secondary metabolites, have raised growing concerns in recent years due to their potential high toxicity. However, studies on the degradation of PAs in drinking water treatments have yet to be conducted. Herein, the treatment of Heliotrine (HEL) and N-oxide (HELNO), two dominant PAs detected in the treated drinking water, are analyzed for the first time. The UV/peroxydisulfate (UV/PDS) process was demonstrated to be efficient in the degradation of PAs, achieving almost complete removal of HEL and HELNO in 30 min. SO4•− plays a dominant role in the system, with second-order rate constants of 2.3 × 109 M−1 s−1 and 1.0 × 109 M−1 s−1 for HEL and HELNO, respectively. Based on the steady-state kinetic models, the effect of influence factors, including PDS dosage, initial pollutant concentration, pH, dissolved organic matter (DOM), and chloride (Cl−), were evaluated. Acidic conditions were proven to be favorable for PA degradations, primarily contributed to the minimized quenching effect of OH− and phosphate on SO4•−. The inhibitory effect of DOM on radical quenching significantly overweighted the promotion effect of the generated excited triplet DOM (3DOM*), resulting in a diminished degradation efficiency. The pronounced inhibition of Cl− could be attributed to the conversion of SO4•− to OH•, involving the formation of reactive chlorine species. The UV/PDS treatment was suggested economical in the removal of PAs as a post-filtration and before-chlorination treatment through electrical energy per order (EE/O) calculation. Finally, reasonable degradation pathways of HEL and HELNO reacted with SO4•− were proposed, involving the initial one-electron oxidation of HEL/HELNO by SO4•− radical, and further reactions (e.g., hydroxylation, pyrrolidine ring-cleavage and self-coupling) of the formed N-centered cation radicals.

Adsorption and antibacterial studies of a novel hydrogel adsorbent based on ternary eco-polymers doped with sulfonated graphene oxide developed from upcycled plastic waste

A novel ternary blended polymer composed of cost-effective and readily available polymers was synthesized using poly (vinyl alcohol) (PVA), iota carrageenan (IC), and poly (vinyl pyrrolidone) (PVP). Sulfonated graphene oxide (SGO), prepared from recycled drinking water bottles, was utilized as a doping agent. Varying amounts (1–3 wt%) were combined into the polymer matrix. The produced hydrogel film was examined as a potential adsorbent hydrogel film for the removal of methylene blue (MB) and Gentamicin sulfate (GMS) antibiotic from an aqueous solution. The experimental results demonstrate that the presence of SGO significantly increased the adsorption efficiency of PVA/IC/PVP hydrogel film. The antimicrobial tests revealed that the PVA/IC/PVP-3% SGO hydrogel film exhibited the most potent activity against all the tested pathogenic bacteria. However, the adsorption results for MB and GMS showed that the addition of 3 wt% SGO resulted in a removal percentage that was a two fold increase in the removal percentage compared with the undoped PVA/IC/PVP hydrogel film. Furthermore, the response surface methodology (RSM) model was utilized to examine and optimize several operating parameters, including time, pH of the solution, and initial pollutant concentration. The adsorption kinetics were better characterized by the pseudo-second-order kinetics model. The composite film containing 3 wt% SGO had a maximum adsorption capacity of 606 mg g−1 for MB and 654 mg g−1 for GMS, respectively. The generated nanocomposite hydrogel film demonstrated promising potential for application in water purification systems.

Eco-friendly and efficient sulfamic acid functionalized MIL-53 (Al) nanocomposite for removal of hazardous pollutants from wastewater and catalytic synthesis of 3,4-dihydropyrimidinone pharmacological moiety

This study proposed the facile synthesis of sulfamic acid functionalized MIL-53 (Al) (SA@MIL-53(Al)) nanocomposite for dual-functional pollutant removal and catalytic synthesis. The composite was synthesized through a facile, straightforward, and one-step solvothermal process. Furthermore, different analysis techniques like XRD, SEM, XPS, FT-IR, and TGA were applied to examine the prepared composites' structure properties, confirming the successful preparation of functionalized frameworks. Several factors, including the initial concentration of pollutants, adsorbent dosage, pH, and pHpzc, have been established to optimize the suitable parameters for adsorption. 25 wt.% SA@MIL-53(Al) has the greatest adsorption capacities of 146.5, 97.7, and 35.5 mg g−1 for removing MB, CR dyes, and Pb (II), respectively. The rate-limiting steps were also discussed, and the experimental adsorption measurements obeyed the Langmuir and the pseudo-second-order kinetic models. Moreover, the fabricated composites were used as catalysts to produce 3,4-dihydropyrimidinone (3,4-DHP). 50 wt.% SA@MIL-53(Al) demonstrated the highest efficiency, nearly 92.0 %, with great durability and stability.

Insights into the generation of multiple reactive species in UV254/PMS/I− system and their roles for degradation of phenolic and non-phenolic pollutants

An innovative technology for the removal of phenolic and non-phenolic organic pollutants from aqueous solution was developed by combining UV254 irradiation, peroxymonosulfate (PMS), and iodide ions (I−). Effects of pH, ratio of [I−]/[PMS], initial concentration of pollutant, dissolved organic matter (DOM) and typical inorganic constituents of environmental water on the degradation of studied pollutants with UV254/PMS/I− system were examined. The results showed that pH and [I−]/[PMS] exhibited significant impact on the degradation of pollutants during UV254/PMS/I− process. As the ratio of [I−]/[PMS] increased from 0.1 to 10.0, the removal efficiencies of phenolic pollutants remarkably increased, but those of non-phenolic pollutants decreased. The DOM at high concentration obviously inhibited the degradation of pollutants during UV254/PMS/I− process. Meanwhile, the occurrence of NO3− can slightly enhance the degradation of pollutants, and SO42−, Cl−, and HCO4− ions had no significant effects on UV254/PMS/I− system. The abundant reactive species including OH, SO4−, and I/I2− during UV254/PMS/I− process were generated based on electron spin resonance, fluorescence spectroscopy and steady-state concentration analysis. Quenching experimental results indicated that I/I2− can selectively degrade phenolic pollutants via one-electron oxidation. This study provided a reference for the application of reactive radicals involved oxidative technique in water purification.

Integrated study of antiretroviral drug adsorption onto calcined layered double hydroxide clay: experimental and computational analysis

This study focused on the efficacy of a calcined layered double hydroxide (CLDH) clay in adsorbing two antiretroviral drugs (ARVDs), namely efavirenz (EFV) and nevirapine (NVP), from wastewater. The clay was synthesized using the co-precipitation method, followed by subsequent calcination in a muffle furnace at 500 °C for 4 h. The neat and calcined clay samples were subjected to various characterization techniques to elucidate their physical and chemical properties. Response surface modelling (RSM) was used to evaluate the interactions between the solution’s initial pH, adsorbent loading, reaction temperature, and initial pollutant concentration. Additionally, the adsorption kinetics, thermodynamics, and reusability of the adsorbent were evaluated. The results demonstrated that NVP exhibited a faster adsorption rate than EFV, with both reaching equilibrium within 20–24 h. The pseudo-second order (PSO) model provided a good fit for the kinetics data. Thermodynamics analysis revealed that the adsorption process was spontaneous and exothermic, predominantly governed by physisorption interactions. The adsorption isotherms followed the Freundlich model, and the maximum adsorption capacities for EFV and NVP were established to be 2.73 mg/g and 2.93 mg/g, respectively. Evaluation of the adsorption mechanism through computational analysis demonstrated that both NVP and EFV formed stable complexes with CLDH, with NVP exhibiting a higher affinity. The associated adsorption energies were established to be −731.78 kcal/mol for NVP and −512.6 kcal/mol for EFV. Visualized non-covalent interaction (NCI) graphs indicated that hydrogen bonding played a significant role in ARVDs-CLDH interactions, further emphasizing physisorption as the dominant adsorption mechanism.

Green synthesis of manganese ferrite magnetic nanoparticle and its modification with metallic-organic frameworks for the tetracycline adsorption from aqueous solutions: A mathematical study of kinetics, isotherms, and thermodynamics

In the current investigation, MnFe2O4/ZIF-8 nanocomposite was generated as a magnetic nanoadsorber using the extract of Dracocephalum plant and characterized by XRD, FTIR, VSM, BET, FESEM, EDS-mapping, TEM, XPS, TPD-NH3, and TGA analyses. Also, to determine its efficiency in the adsorption process of tetracycline, the effect of pH (3–9), nanocomposite dose (0.025–2 g/L), initial pollutant concentration (5–100 mg/L), contact time (5–200 min), and temperature (5–50 °C) were studied. The results of the morphological properties of the magnetic nanocomposite confirmed the spherical shape of this nanoadsorber with an average size of 54 ± 31 nm. BET analysis showed that modification of MnFe2O4 material with ZIF-8 as a new nanoadsorber leads to excellent modification of SBET (143.8 m2/g) and VTotal (0.44 cm3/g). The highest removal efficiency of tetracycline in optimal conditions (pH = 7, contact time = 120 min, nanocomposite dose = 1.5 g/L, and temperature = 20 °C for a tetracycline concentration of 20 mg/L) was 90.11%. As the temperature increased, the removal efficiency increased from 40.46% to 95.06% during 120 min, which indicates that the adsorption reaction is endothermic. In addition, the data obtained from the isotherms of Langmuir (R2 = 0.958), Freundlich (R2 = 0.534), and Temkin (R2 = 0.747) showed that the tetracycline adsorption is monolayer and on the homogeneous surface of the synthesized magnetic nanoadsorber. The elimination process of tetracycline by nanoadsorber followed the pseudo-second order model (R2 = 0.998). Investigating the effect of interfering ions also confirmed the decrease in the adsorption efficiency. Also, the investigation of the reusability of the synthesized magnetic nanoadsorber in tetracycline adsorption indicates that after eight cycles, the efficiency decreases by %16.51. According to the results, the magnetic nanocomposite synthesized in this work can be a suitable and economical adsorber for the removal of tetracycline from aqueous environments.

Enhanced removal of RB5 pollutant via sono-catalytic activation of potassium peroxydisulfate using Porous/ZIF-8

In recent years, the proper integration of various advanced oxidation processes has posed a new challenge. As synergy plays a critical role in integrated processes, it is highly essential to develop an integrated process that is not only effective but also economically feasible. In this study, the integration of sonochemical process for efficient activation of potassium peroxydisulfate (PDS) was used with ZIF-8 and Porous/ZIF-8 catalysts, resulting in the creation of an indirect photocatalytic process assisted by ultrasonic waves. The Porous/ZIF-8 sample with higher porosity (233.67 m2/g) than ZIF-8 (183.61 m2/g) was prepared using a polystyrene template. The created porosity leads to an increase in active reaction sites, which is effective in improving the efficiency of pollutant removal. A comprehensive investigation was conducted to analyze the effects of various operational parameters, namely pH, catalyst concentration, and initial pollutant concentration, on the removal efficiency (RE), pseudo-first-order kinetic rate constant (kapp), and synergistic factor (SF) of reactive black 5 (RB5). The optimum operational conditions were determined as pH = 5, 0.6 g/L [Porous/ZIF-8], and 10 mg/L [RB5]. The integrated process proposed in this study demonstrates a high level of acceptability and environmental friendliness, owing to its remarkable SF and novel characteristics.

Application of iron-manganese oxide fillers in bioretention facility: Enhanced removal of antibiotics and conventional contaminants

Bioretention facilities are common source reduction facilities, but traditional fillers are not effective in reducing emerging contaminants such as antibiotics. Although Fe-Mn oxides have been extensively explored, their removal of emerging contaminants and application in the sponge city have not yet been addressed. Therefore, this study aims to address this limitation by developing Fe-Mn oxide fillers. In this research, the optimal preparation conditions (Fe/Mn mole ratio, polyvinyl alcohol (PVA) concentration, and filler particle size) and influencing factors (filler dosage, initial pollutant concentration, pH, temperature, and co-existing ions) were investigated using a typical antibiotic, norfloxacin (NOR), as the target contaminant. The removal mechanism of NOR was investigated by SEM, FTIR, and XPS characterizations. Subsequently, the fillers were applied to bioretention facilities with different filling modes (layered and mixed) to evaluate their effectiveness in removing NOR and conventional pollutants at different recurrence periods, drought periods, and pollutant influent concentrations. The study indicated that Fe-Mn oxide filler (Fe/Mn mole ratio of 4:1, PVA concentration of 7 %, particle size of 4 mm) could remove more than 70 % of NOR (1–20 mg/L). The NOR removal by Fe-Mn oxide filler involved adsorption and redox reactions. Notably, bioretention facilities using Fe-Mn oxide fillers have shown varying degrees of improvement in the removal of NOR and conventional pollutants compared to conventional ones. This study contributes to the application of Fe-Mn oxide filler in bioretention facilities, thus playing a crucial role in mitigating antibiotic pollution in stormwater runoff.

Adsorption of Zinc(II) Ion by Spent and Raw Agaricus bisporus in Aqueous Solution

A significant environmental concern globally is the pollution of water bodies as a result of heavy metals. To date, various attempts have been made to effectively remove heavy metals, such as those that use synthetic and biogenic materials to abate and control water pollution. The biological removal of pollutants from water is an efficient and environmentally friendly technique. In this study, we evaluated the biosorption characteristics of Zn2+ ions from aqueous solution by spent composed of raw Agaricus biosporium (RAB) and A. biosporium (SCAB). We added different biosorption doses, metal ions, and initial concentrations of pollutants to explore the adsorption of Zn2+ by RAB and SCAB. We applied pseudo-first- and second-order models to investigate the biosorption kinetics. According to our results, the rate of Zn2+ removal from the aqueous solution using raw biomass was significantly lower than that using sodium citrate-treated biomass of SCAB. When the Zn2+ concentration increased from 10 mg L−1 to 200 mg L−1, the rate of removal of RAB decreased from 73.9% to 38.4%, and that of Zn2+ by SCAB decreased from 99.9% to 75.9%. As we increased the biosorbent dose, the rate of Zn2+ removal by SCAB increased. Interestingly, Zn2 biosorption was inhibited by heavy co ions (Cu2+ and Pb2+) and light metals (e.g., Na+, Mg2+, K+, and Ca2+). When treating wastewater polluted with Zn2+, Pb2+, and Cu2+, SCAB showed good potential. The results of this study provide a scientific basis for an environmentally sound approach to controlling water pollution.