Pseudo-first Order Kinetic Model Research Articles

Regeneration of As(V) loaded granular activated carbon through desorption in FeCl3, CaCl2 and MgCl2 aqueous solutions

As(V) adsorption on granular activated carbon (GAC) and subsequent desorption in dH2O was modeled using the pseudo-first and pseudo-second order kinetic models. Regeneration was achieved by immersing loaded GAC in NaCl, FeCl3, CaCl2 and MgCl2 aqueous solutions. As(V) detection after desorption was highest for NaCl but subsequent adsorption was lowest. Regeneration was highest in FeCl3 solution of pH 2 followed closely by pH 3, but As(V) precipitation appeared superior at pH 3. Molar ratios of Fe, Ca and Mg to As were tested in the range of 0.75:1 to 12:1 where a logarithmic relation was found between the molar ratio and As(V) desorption as diluted in HNO3 and H2O and subsequent adsorption. Precipitation was nearly complete in FeCl3, limited in MgCl2 at a ratio of 12:1 and not observed in CaCl2. While kinetic values were lower than in previous tests, the pseudo-first and pseudo-second order models could accurately describe desorption in CaCl2 and MgCl2 but not in FeCl3 due to precipitation. Desorption in FeCl3 was most effective in precipitating As(V), being highest at a molar ratio of 6:1, but regeneration was slightly higher at a molar ratio of 12:1.

Modification of Coal Fly Ash with Dithizone for Adsorption of Ni(II) Metal Ion

Adsorption of Ni(II) ion onto adsorbent of dithizone-immobilized coal fly ash (IFA) has been investigated in batch experiments. The activated coal fly ash (AFA) and its dithizone modification were characterized by FT-IR and XRD. Several parameters influencing the adsorption of Ni (II) ions on both adsorbents including effect of pH, adsorbent dosage, contact time and initial concentration on the efficiency of the adsorption of Ni (II) ion were investigated. The optimum condition of Ni(II) adsorption was found at pH 4, adsorbent dosage of 0.02 g, contact time of 60 min and initial Ni (II) ion concentration of 80 mg L–1. The adsorption kinetics of Ni(II) ions on AFA is best described by a pseudo first-order kinetic model while that on IFA follows a pseudo-second-order kinetic model. The adsorption isotherm of Ni(II) on both adsorbents follows the Langmuir model. Kinetics and adsorption isotherm studies suggest that the capacity and affinity of the IFA in adsorbing Ni(II) ions are significantly improved compared to those of AFA, suggesting the role of dithizone in the adsorption of Ni (II) by forming chelate complexation as proved by the results of sequential desorption.

Reusable kaolin impregnated aminated chitosan composite beads for efficient removal of Congo red dye: isotherms, kinetics and thermodynamics studies

In this investigation, Kaolin (K) impregnated aminated chitosan (AM-CTS) composite beads were fabricated with multi-features including low-cost, high performance, renewable and ease of separation for adsorption of anionic Congo red (CR) dye. Characterization tools such as FTIR, XRD, SEM, TGA, BET, XPS and Zeta potential were thoroughly employed to confirm the successful formulation process. The results revealed that K@ AM-CTS composite beads displayed higher specific surface area (128.52 m2/g), while the thermal stability was prominently improved compared to pure AM-CTS. In addition, the adsorption equilibrium of CR dye was accomplished rapidly and closely gotten within 45 min. The removal efficiency was significantly enriched and reached 90.7% with increasing kaolin content up to 0.75%, compared to 20.3 and 58% for pristine kaolin and AM-CTS, respectively. Moreover, the adsorption process obeyed the pseudo-first order kinetic model, while data were agreed with the Freundlich isotherm model with a maximum adsorption capacity reached 104 mg/g at pH 6. Furthermore, D–R isotherm model demonstrated the physical adsorption process of CR dye, which includes the electrostatic interactions, ion exchange and H-bonding. Thermodynamics evidenced the spontaneous and endothermic nature of the adsorption process. Interestingly, the developed K@AM-CTS composites beads showed better reusability for eight consecutive cycles, suggesting their feasible applicability for adsorptive removal anionic dyes from polluted aquatic bodies.

Enhanced adsorption of Pb(II) by phosphorus-modified chicken manure and Chinese medicine residue co-pyrolysis biochar.

The pollution of lead (Pb (II)) to water resources is becoming more and more serious. It is always a difficult problem to find efficient and low-cost adsorbents. Chicken manure (CM) and Chinese medicine residue (CMR) were modified with potassium dihydrogen phosphate (KH2 PO4 ) and pyrolyzed to obtain a modified material (PBC) for the treatment of Pb(II) in an aqueous solution. A variety of characterization analysis results could prove that KH2 PO4 was successfully introduced to PBC. By adjusting the initial pH, the zeta potential of PBC varies from -3.2 to -43.1mV, it could be seen that PBC had excellent applicability in the broad range pH value (1.0-6.0). Experimental and model results showed that R2 of the pseudo-first order kinetic model and the pseudo-second order kinetic model are greater than 0.99, indicating that that physical and chemical adsorption played a significant role in Pb(II) removal by PBC. An adsorption isotherm analysis showed that the adsorption capacity n in this study is greater than 1, confirming that PBC has a good adsorption effect on Pb (II). R2 of the Langmuir model of PBC is 0.981, and its maximum adsorption capacity of Pb(II) could reach 599.4mg/g. Environmentally friendly PBC could be used as an effective adsorbent to remove Pb(II) from aqueous systems. RESEARCH HIGHLIGHTS: Chicken manure and Chinese medicine residue were converted into biochar to improve utilization. The modified biochar exhibited extraordinary Pb(II) adsorption capacity. Adsorption mechanisms: Surface complexation, ions exchange, coprecipitation, and so on. Remained great Pb(II) removal efficiency at different pH and Pb(II) concentration.

Efficient Removal of Lead and Chromium From Aqueous Media Using Selenium Based Nanocomposite Supported by Orange Peel

This study presents the synthesis of activated orange peel, derived from bio-waste (orange peel) and its doping with selenium nano-particles to enhance the adsorption capacity. The synthesized nanocomposite orange peel/Selenium (OP/Se) was applied as adsorbents for the removal of Lead (Pb) and Chromium (Cr) from synthetic waste water as an economical water cleaning technology. Orange peel/Selenium nanocomposite was characterized by X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM). Scanning electron microscopy results showed the porous structure of OP/Se nanocomposite and distinct peaks observed in XRD and FTIR spectra depicted the successful synthesis of nanocomposite. Batch experiments were conducted to figure out the effect of different parameters on adsorption of Pb and Cr by using Atomic Absorption Spectroscopy. The maximum adsorption capacity of 99.9% was achieved for both lead and chromium at acidic pH. While at temperature of 60°C the maximum adsorption of 98.3 and 95.9% was found for Pb and Cr respectively. Furthermore the experimental data was examined with Pseudo-first order, first-order and Pseudo-second order kinetic model, as well as Morris Intraparticle diffusion model where the pseudo second order was best fitted which indicated the chemisorption mechanism in adsorption process. The adsorption process followed the Langmuir isotherm model verified that OP/Se nanocomposite was found to be favorable for the process of adsorption. The adsorption thermodynamics indicate that adsorption of heavy metals ions is spontaneous (ΔG° < 0) and the adsorption increases with increase in temperature which means that reaction was endothermic in nature. This study revealed that the synthesized bio-activated nanocomposite was an efficient adsorbent material for the removal of heavy metals from waste water.

Template- and etching-free fabrication of two-dimensional hollow bimetallic metal-organic framework hexagonal nanoplates for ammonia sensing

This work reports the template- and etching-free fabrication of hollow bimetallic nickel-cobalt benzenetricarboxylic acid (Ni-Co BTC) hexagonal nanoplates by a polyvinylpyrrolidone (PVP)-assisted approach. The incorporation of PVP can reduce the stacking of these nanoplates along the vertical direction and generate depletion forces between them to reduce aggregation. When employed for the quartz crystal microbalance (QCM) sensing of ammonia (NH3), the hollow Ni-Co BTC hexagonal nanoplates exhibit 1.6, 3.8, and 7.5 times higher sensitivity to 69.5 ppm of NH3 than non-hollow Ni-Co BTC nanoplates, Ni-BTC nanobelts, and Co-BTC microrods, respectively, and a low limit of detection (LOD) of 1.53 ppm. Additionally, they show good selectivity to NH3 in the presence of other interfering compounds and excellent stability with only a very small decrease of 2.86 % in sensitivity after 6 months. The NH3 adsorption on the hollow Ni-Co BTC hexagonal nanoplates follows a pseudo first-order kinetic model with the adsorption rate being 6.1 and 7.1 times faster than Ni-BTC nanobelts and Co-BTC microrods, respectively. The good sensing performance of the hollow Ni-Co BTC hexagonal nanoplates to NH3 is attributed to the existence of carboxyl and hydroxyl groups which can provide energetic sites for the chemisorption of NH3 molecules and the increased adsorption sites provided by the hollow two-dimensional structure and the bimetallic composition of this MOF.

Adsorptive removal of micron-sized polystyrene particles using magnetic iron oxide nanoparticles

Microplastics are able to pass through many filtration systems due to their small sizes, making it difficult to remove them from, for example, water. In this study, we evaluated the ability of using magnetic iron oxide (Fe3O4) nanoparticles to achieve the adsorptive removal of micron-sized polystyrene (microPS) particles. Application of a magnet for 3 min to an aqueous sample of microPS particles mixed with iron oxide nanoparticles for 1 min was able to effectively remove the microPS particles from the water. Transmission electron microscopy images of such samples showed the formation of Fe3O4-PS complexes due to the adsorption of PS particles onto iron oxide nanoparticles. This adsorption followed the pseudo-first order kinetic and Langmuir isotherm model. Hydrophobic interactions were concluded from our experiments to be the main interactions involved in the aggregation of iron oxide with PS particles. Ions present in an environmental freshwater sample inhibited the ability of iron oxide particles to become adsorbed PS particles, but the adsorption performance was improved by increasing the amount of iron oxide particles. The iron oxide particles could be recovered from the Fe3O4-PS complexes by desorption process. Our study showed the potential advantages of iron oxide particles for removing environmental pollutants of microplastics via highly efficient and environmental-friendly procedure.

Chitosan modified sugarcane bagasse biochar for the adsorption of inorganic phosphate ions from aqueous solution

Recently, a variety of bio-composites have been reported as biosorbents for nutrients removal in aqueous solutions. The preference for biosorbents in nutrient removal is based on their advantages in terms of cost-effectiveness, and biodegradability properties. Herein, sugarcane bagasse was selected as a feedstock to produce a biochar that was used as biosorbent for the removal of phosphate ions from aqueous solution. However, raw biochar possesses a surface with negative charges, which makes it less effective in the adsorption of phosphate ions. The chitosan biopolymer was employed as a modifying agent to enhance the adsorption capacity of sugarcane bagasse biochar, and epichlorohydrin was also added to increase the stability of the bio-composite. Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), Energy Dispersive X-Ray (EDX), Brunauer-Emmet-Teller (BET), and X-ray diffraction (XRD) were employed to ascertain characteristics of bio-composite in terms of functional groups, morphology, surface area and crystallinity respectively. During the experimental work, it was observed that the addition of chitosan and epichlorohydrin enhanced the adsorption capacity of the bio-composite. Experimental data best fitted to the Liu adsorption isotherm, demonstrating the surface of biosorbent was heterogeneous, and the predicted maximum adsorption was 37.2 mg/g. In addition, the experimental data best fitted to the pseudo first-order kinetic model and pseudo second-order kinetic model depending on the initial concentration of phosphate ions, indicating the mechanism of adsorption was both through the physisorption and chemisorption. Moreover, the phosphate was easily desorbed from the surface of biosorbent, and thus makes the prepared bio-composite reusable. Furthermore, the biosorbent was tested in real wastewater samples, and the removal percentage was 40.23 %, and 2.93 %, for pH 3 and pH 8, respectively. Poor removal, especially at higher pH was attributed to insufficient active sites as well as the competition from other pollutants. Therefore, these findings show that the biosorbent will have maximum performance at acidic conditions.

Mn3O4 Catalysts for Advanced Oxidation of Phenolic Contaminants in Aqueous Solutions

Water-soluble organic pollutants, such as phenolic compounds, have been exposed to environments globally. They have a significant impact on groundwater and surface water quality. In this work, different Mn3O4 catalysts were prepared for metal oxide activation of peroxymonosulfate (PMS) to remove the phenolic compound from the water environment. The as-prepared catalysts were characterized using thermogravimetric-differential thermal analysis (TG-DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) surface area analysis. Furthermore, the effect of temperature and reusability of the as-prepared Mn3O4 catalysts is also investigated. The Mn3O4 nanoparticles (NPs) catalyst reveals an excellent performance for activating PMS to remove phenol compounds. Mn3O4 NPs exhibits 96.057% efficiency in removing 25 ppm within 60 min. The kinetic analysis shows that Mn3O4 NPs fitted into pseudo-first order kinetic model and exhibited relatively low energy activation of 42.6 kJ/mol. The reusability test of Mn3O4 NPs displays exceptional stability with 84.29% efficiency after three-sequential cycles. The as-prepared Mn3O4 NPs is proven suitable for phenolic remediation in aqueous solutions.

Separation of dye from aqueous solution by a new gravity compression and aeration system

ABSTRACT Filtration is one of the important technologies for separating suspended particles. Under the condition of gravity compression, the filtration density can be increased and the separation effect of suspended particles can be improved. Considering the complex composition and the difficulty in degrading dye in industrial wastewater, a gravity compression aeration system with a modified polyester fibre ball (denoted as MPFB) was evaluated for the separation of dye from water. Congo red azo dye solution (0–40 mg/L) was selected as the model treatment compound. The MPFB was prepared by adjusting the concentrations of alkali (Quality score 0–25%), β-cyclodextrin (0∼80 g/L), reaction temperature (40–90°C), and silane coupler concentration (Concentration fractions 0–0.8%). We used Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) to characterise the MPFB. The separation was affected significantly by adsorption conditions such as MPFB dose and pH. The lower the MPFB dose, the higher the expected adsorption capacity. For the treatment of a dye solution at 500 mg/L, 100% removal was achieved with 48 g/L MPFB, at pH 8 during adsorption under non-circulation aeration. For 24 h of reaction, the system could reach the maximum adsorption capacity of 11.2 mg/g, which followed the pseudo-first order kinetics model and the intraparticle diffusion model. We discovered that circulation aeration provided the best adsorption and electrostatic and hydrogen bonding were the dominant components of adsorption. Overall, the system is a promising technology and has the potential to treat large volumes of dye wastewater.

Electrochemical degradation of favipiravir (anti-viral) drug from aqueous solution: optimization of operating parameters using the response surface method

ABSTRACT The aim of the current study is to investigate the efficacy of the electro-Fenton process in the degradation of favipiravir drugs from aqueous solutions, which has increased in use as a result of the COVID-19 pandemic. The Response Surface Methodology (RSM) was developed using a Central Composite Design (CCD) in which five independent variables, including Fe2+ concentration, current density, initial FVP concentration, pH, and reaction time, were coded with high and low levels, and the maximum removal percentage of FVP (97.8%) and COD (91.65%) were determined as responses. In the EF process, 530 mg/L H2O2 was produced in-situ by cathodic reduction of O2 in aqueous solution and thus FVP has been successfully oxidized through hydroxyl radicals. The H2O2/Fe2+ ratio was determined to be 0.51 under optimum conditions. At the end of the experiment, the maximum energy consumption was found to be 2.12 kWh per g COD. The FVP was completely mineralized in a very short time by the EF process, according to the LC-MS/MS examination. The EF process followed the pseudo first-order kinetic model with the rate constants of 0.023, 0.016 and 0.006 1/min for pH 2, 3 and 4, respectively. According to the findings of this study, the electro-Fenton process is an effective method for removing FVP from aqueous solutions. To the authors’ knowledge, this is the first study to show the degradation and optimum conditions of FVP in aqueous solution using the electro-Fenton (EF) process.

Removal of neonicotinoid pesticides by adsorption on modified Tenebrio molitor frass biochar: Kinetics and mechanism

Neonicotinoid pesticides (NEOs) are the most widely used insecticides in the world and pose a serious threat to ecological systems. Thus, the development of an efficient and sustainable technique for their removal is urgently needed. In this study, a novel biochar was prepared by pyrolysis of Tenebrio molitor frass and activated with KOH at 650 (TMFBC-650A), 750 (TMFBC-750A) and 850 °C (TMFBC-850A). Among them, TMFBC-750A showed the best adsorption performance, and the adsorption capacities for thiacloprid (THI), nitenpyram (NIT) and dinotefuran (DIN) were 155.08 mg·g−1, 195.86 mg·g−1, 325.81 mg·g−1, respectively. The isotherms for the adsorption of NIT and THI fit the Langmuir model quite well, while DIN fits the Freundlich model. Moreover, the adsorption of THI, NIT and DIN was well fitted by the pseudofirst-order kinetic model. The physicochemical characterization analysis demonstrated that the adsorption process of NEOs by TMFBC might be mainly controlled by micropore filling, π-π electron donor–acceptor interactions and functional group interactions (H-bonding, covalent bonding and hydrophobic interactions). Additionally, the thermodynamic parameters suggested that NEO adsorption in this work was a spontaneous, endothermic and randomly increasing process. TMFBC also exhibited a high selective adsorption capacity regardless of solution pH and inorganic ion strength concentrations. The regenerated TMFBC (via synergistic ultrasound/ethanol) could sustainably and efficiently absorb NEOs in reuse cycles, suggesting that TMFBC has excellent reusability and stability. These results indicated that TMFBC can be a potential and sustainable adsorbent for neonicotinoid pesticide removal.

Bio-Sorbent Derived from Annona Squamosa for the Removal of Methyl Red Dye in Polluted Waters: A Study on Adsorption Potential

Sorbent got from leaves and barks of Annona squamosa has been investigated for its sorption capacity towards Methyl Red (MR) utilizing artificially arranged recreated squander waters. Different components influencing adsorption, viz., initial color concentration, contact time, adsorbent dosage, along with the impact of temperature were assessed. The equilibrium of adsorption was demonstrated by Freundlich; Langmuir, Temkin, and Dubinin-Radushkevich isotherms. Pseudo-first order, pseudo-second order, Weber and Morrish intraparticle diffusion, Bangham's pore dispersion and Elovich equations were applied in order to distinguish the rate and kinetics of adsorption progression. Interference of a five-fold abundance of regular anions and cations present in common waters, have been examined. Cation like Ca2+, Mg2+ and Cu2+ have showed some impedance, however, Fe2+ and Zn2+ have synergistically maintained the greatest extraction of the MR. The methods developed were effectively applied to some effluent. The results of experimental data were found appropriate to the pseudo-first order kinetic model. Correlation coefficient (R2) and dimensionless division or separation factor (RL) values have affirmed that adsorption obeys Langmuir adsorption showing monolayer development.

Removal of diethyltoluamide, paracetamol, caffeine and triclosan from natural water by photo-Fenton process using powdered zero-valent iron

The removal of four pharmaceuticals and personal care products (PPCPs), namely diethyltoluamide (DEET), paracetamol (PAR), caffeine (CAF) and triclosan (TCS) (at a spiked concentration of 25 μg/L), from natural water using the photo (UVC)-Fenton (powdered zero-valent iron, pZVI) process was investigated. The results show that a molar ratio of H2O2/pZVI of 2.0, pZVI concentration of 22.4 mg/L and pH of 3.0 maximised the removal of the target compounds at 71.1%, 100%, 64.2% and 87.1%, for DEET, PAR, CAF and TCS, respectively, after 30 min in Fenton (pZVI) process. When this process was coupled with UVC radiation, 29.6%, 80.3%, 3.1% and 88.4% of DEET, PAR, CAF and TCS, respectively, were removed within the first minute, and 99.0%, 100%, 99.5% and 100%, respectively, were removed after 30 min. The pseudo first-order kinetic model best fitted the degradation data of DEET, PAR and CAF (1–20 min); and because 80% of TCS and PAR degraded within the first minutes, it is suggested to explore the kinetics during the initial period. Characterisations of pZVI after the photo-Fenton (pZVI) process indicated the corrosion of the surface of iron powder and the presence of iron oxides and iron hydroxides. Lower removals of nitrate (35–50%), phosphate (<35%) and total organic carbon (TOC, <18%) were observed, which may be attributed to the small H2O2/pZVI dosage used. Results of this investigation show that the photo-Fenton (pZVI) process has potential for efficient and cost-effective removal of PPCPs.

Unveil the quantum chemical descriptors determining direct photodegradation of antibiotics under simulated sunlight: Batch experiments and model development

The massive use of antibiotics has led to their omnipresence in aquatic environments, and the photodegradation was found to be the dominant transformation process for antibiotics in the natural river system. Herein, we investigated the photodegradation kinetics of 77 antibiotics in 7 classes in water under simulated sunlight. Using the quantum chemical descriptors predicted by the density functional theory calculation, the quantitative structure-activity relationship (QSAR) models were established to explore the main chemical descriptors determining the photodegradation of antibiotics. The results showed that the photodegradation kinetics of antibiotics conformed to the pseudo-first order kinetic model. The photodegradation rate constants of different antibiotics varied 4 orders of magnitude, and the photodegradation rate constants of quinolones were significantly higher than those for other classes of antibiotics due to the F atoms in their molecular structures. The developed QSAR models revealed that the energy gap (Egap) between ELUMO and EHOMO was the main chemical descriptor determining the photodegradation of antibiotics, and it was negatively correlated with lgk. In addition, the number of F atom was also included in the QSAR models due to the great contribution of F atom to the direct photolysis of quinolones. This study ordered the photodegradation rate constants of 77 antibiotics, and revealed the major chemical descriptors determining the photodegradation of antibiotics. The results provide the basic information for the photolysis of antibiotics, which is significant for predicting the environmental behaviors and evaluating the ecological risks of antibiotics in aquatic environments.

Photocatalytic antifouling nanohybrid polysulfone membrane using the synergetic effect of graphene oxide and SiO2 for effective treatment of natural rubber-laden wastewater

This study investigates the effects of graphene oxide (GO) and SiO2 composite as nano-photocatalysts in the polysulfone (PSf) membrane to treat natural rubber-laden wastewater (NRW) treatment under UV irradiation. The membranes were fabricated using the phase inversion process. Characterization results showed that the incorporation of GO and SiO2 nanoparticles as a composite successfully changed the properties of the membranes. Optical analysis tests revealed that the composite enhanced the photocatalytic activity and possessed bandgap energy of 3.25 eV, which made the SiO2 more active under UV light exposure after incorporating the GO. The addition of GO/SiO2 to the membrane resulted in more hydrophilic properties with contact angle of 60.34° and water uptake ability of 52.78%. Conducting filtration under UV irradiation using PSf/GO/SiO2 membrane exhibited a remarkable improvement in permeate flux by 129% from 9.85 L m−2 h−1 to 22.55 L m−2 h−1 and maintained 85.4% of permeate flux stability. With respect to removal performance, under the photo-filtration process, chemical oxygen demand (COD) removal increased from 73 to 84%, and ammonia-nitrogen (NH3–N) removal improved from 78 to 92%. The photocatalytic kinetic evaluation suggested that the pseudo-first order kinetic model had a better fit than the zero-order kinetic. Regeneration tests showed that the PSf/GO/SiO2 membrane has outstanding durability. The resistance during filtration and antifouling potential evaluations revealed that the GO/SiO2 composite under UV light irradiation during filtration remarkably reduced the fouling formation and generated a high flux recovery ratio. This implies that this PSf/GO/SiO2 membrane is promising for advanced treatment of NRW.

A Novel Cu2O/ZnO@PET Composite Membrane for the Photocatalytic Degradation of Carbendazim.

The extremely high levels of water pollution caused by various industrial activities represent one of the most important environmental problems. Efficient techniques and advanced materials have been extensively developed for the removal of highly toxic organic pollutants, including pesticides. This study investigated the photocatalytic degradation of the fungicide carbendazim (Czm) using composite track-etched membranes (TeMs) in an aqueous solution. Copper(I) oxide (Cu2O) and zinc oxide (ZnO) microtubes (MTs) were prepared using an electroless template deposition technique in porous poly(ethylene terephthalate) (PET) TeMs with nanochannels with a density of 4 × 107 pores/cm−2 and diameter of 385 ± 9 nm to yield Cu2O@PET and ZnO@PET composite membranes, respectively. A mixed Cu2O/ZnO@PET composite was prepared via a two-step deposition process, containing ZnO (87%) and CuZ (13%) as crystalline phases. The structure and composition of all composite membranes were elucidated using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) techniques. Under UV–visible light irradiation, the Cu2O/ZnO@PET composite displayed enhanced photocatalytic activity, reaching 98% Czm degradation, higher than Cu2O@PET and ZnO@PET composites. The maximum Czm degradation efficiency from aqueous solution was obtained at an optimal pH of 6 and contact time of 140 min. The effects of various parameters such as temperature, catalyst dosage and sample exposure time on the photocatalytic degradation process were studied. The degradation reaction of Czm was found to follow the Langmuir–Hinshelwood mechanism and a pseudo-first order kinetic model. The degradation kinetics of Czm accelerated with increasing temperature, and the activation energy (Ea) levels were calculated as 11.9 kJ/mol, 14.22 kJ/mol and 15.82 kJ/mol for Cu2O/ZnO@PET, ZnO@PET and Cu2O@PET composite membranes, respectively. The reusability of the Cu2O/ZnO@PET catalyst was also investigated at different temperatures for 10 consecutive runs, without any activation or regeneration processes. The Cu2O/ZnO@PET composite exhibited degradation efficiency levels of over 50% at 14 °C and over 30% at 52 °C after 5 consecutive uses.

Synthesis of Silica-Based Quaternized Adsorption Material and Study on Its Adsorption Behavior for Pu(IV).

In this research, we explored the synthesis optimization of the silica-based quaternized adsorption material (SG-VTS-VPQ) and its adsorption behavior for Pu(IV). By optimizing the synthesis process, the grafting amount of 4-vinylpyridine reached 1.25 mmol·g−1. According to the analysis of NMR and XPS, the quaternization rate of pyridine groups reached 91.13%. In the adsorption experiments, the thermodynamic experiment results show that the adsorption of Pu(IV) by SG-VTS-VPQ is more in line with the Langmuir adsorption model and the adsorption type is a typical chemical adsorption; the kinetic results show that adsorption process is more in line with the pseudo first-order kinetic model, and the larger specific surface area of SG-VTS-VPQ plays an important role in the adsorption. The results of the adsorption mechanism show that the adsorption of Pu(IV) by SG-VTS-VPQ is mainly complex anion Pu(NO3)62− and Pu(NO3)5−. This research provides in-depth and detailed ideas for the surface modification and application of porous silica gel, and at the same time provides a new way to develop the direction of the analysis of pretreatment materials in the spent fuel reprocessing field.

Adsorption of chromium from aqueous solution using Chitosan-g-Graphene /Hydroxyapatite composite

The preparation and characterisation of a polymeric composite incorporating graphene, hydroxyapatite, and chitosan as an adsorbent to remove chromium (VI) from wastewater. The FTIR and XRD studies supported the composite's production. Analysis of surface morphology and heat stability involved TGA and SEM studies. A batch adsorption was run to determine the efficacy of the adsorbent by varying contact time, adsorbent dose, and pH. The kinetics of the adsorption process were examined using pseudo-first and second order kinetic models after the equilibrium data had been fitted with the Langmuir and Freundlich isotherms. The findings showed that pseudo second order kinetics was utilised for the adsorption of Cr(VI) onto chitosan-grafted graphene/hydroxyapatite (CS-g-Gr/HA) composite.

Flower-like FeMoO4@1T-MoS2 micro-sphere for effectively cleaning binary dyes via photo-Fenton oxidation

Right here, flower-like FeMoO4@1T-MoS2 composites were prepared by modifying FeMoO4 microspheres with two-dimensional lamellar 1T-MoS2 as co-catalyst, which was used for photo-Fenton catalysis degradation of binary dyes mixed with methylene blue (MB) and rhodamine B (RhB). Then various parameters affecting the generation of ·OH in the system were investigated. Systematic research shows that the degradation efficiency of MB and RhB can reach 99.8% in 18 min when the Mo/Fe molar ratio of the composite is 1:1. Furthermore, these experiments data were fitted by pseudo-first order kinetics model and pseudo-second order kinetics model. Subsequently the density functional theory (DFT) simulation results showed that FeMoO4 exhibited excellent adsorption for H2O2, and the introduction of 1T-MoS2 played a certain role in the adsorption and activation of H2O2. Finally, the degradation pathways of MB and RhB were proposed to determine intermediates during photo-Fenton process by LC-MS and the reaction mechanism was detailed investigated by quenching experiment of active free radicals. FeMoO4@1T-MoS2 has also excellent stability and highlights the potential and prospect of the composite for dye wastewater treatment.