Pseudo-first Order Kinetic Model Research Articles

Multi-stage batch adsorption of acephate onto cauliflower like Fe3O4-MMT: Characterization and statistical optimization using response surface methodology

Globally acephate (an organophosphate pesticide) contaminates water bodies, and detriment to the biota is cancer-causing and neurotoxic which needs to be safely removed. This study presents the synthesis and characterization of magnetic montmorillonite (Fe3O4-MMT) as an adsorbent for the adsorption of acephate. The features and characteristics of the nanocomposite were traced by XRD, SEM-EDX, gas sorption analysis, FTIR, and XRF. RSM techniques were used to identify the optimal process variables that result in the highest removal. The numerical optimization of optimum variables corresponds to an initial acephate concentration of 2 mg/L, pH 6 and material adsorbent dose of 0.5 g/L. The uptake of acephate achieved 83.18 % under optimum environs. Dual factors i.e., concentration and dosage remarked as vital parameters that affected the response from ANOVA. Results revealed that equilibrium adsorption data were best fitted with Langmuir and kinetic data were well described by pseudo-first order kinetic model. Thermodynamic parameters such as enthalpy, entropy and Gibb’s energy were evaluated and the effect of temperature on acephate adsorption was studied. Greater acephate adsorption onto on Fe3O4 serves as an excellent material for pesticide mitigation.

Exploring a surface-capping role of carboxymethyl cellulose for the synthesis of silver nanoparticles via the induction period in a catalytic hydrogenation

The present study reported a dual role as a reducing agent and a stabilizer of carboxymethyl cellulose (CMC), a natural origin biopolymer, for the synthesis of silver nanoparticles (AgNPs) via a chemical reduction method. The operating parameters were optimized and established involving pH, reaction time, reaction temperature, AgNO3 molar concentration, CMC/Ag molar ratio. The formation of monodisperse AgNPs in the assistance of a CMC surface-capping agent thanks to an electrostatic stabilization effect was evidenced by ultraviolet-visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and transmission electron microscope (TEM). The aqueous solution consisting of AgNPs in roughly spherical shape with a mean particle size of 24.3 nm was stable in ambient condition at least 2 months. The role of CMC as a surface-capping agent was also explored via the catalytic hydrogenation of methyl orange (MO) towards aromatic amines in the presence of NaBH4 at room temperature, revealing the induction period of 12 min before accelerating reaction rate in the next 18 min. At room temperature, such a catalytic hydrogenation of MO in water obeyed the pseudo first-order kinetic model with a rate constant of 0.2435 min−1 using 2.5 ppm CMC-capped AgNPs catalyst, and the reuse performance was remained in 5 consecutive cycles. To sum up, the present work shed light on a surface-capping role of carboxymethyl cellulose for the synthesis of silver nanoparticles by both physicochemical and catalytic studies.

Ni2+ removal by ion exchange resins and activated carbon: a benchtop NMR study

Heavy metal pollution in water is a critical environmental concern, demanding effective remediation techniques. Traditional methods, including ion exchange and adsorption, often rely on inductively coupled plasma (ICP) atomic emission spectroscopy/mass spectrometry (AES/MS) for the indirect and time-consuming measurement of residual metal concentrations. In contrast, this study employs innovative direct monitoring of nickel removal by benchtop NMR relaxometry using the paramagnetic properties of Ni2+. To prove the feasibility of the NMR follow-up of Ni2+ uptake, batch experiments were performed with Amberlite IR120, Amberlite IRC748, Dowex Marathon MSC, and activated carbon (AC), which were previously characterized by various techniques. The effect of contact time, pH, and Ni2+ concentration on removal efficiency were studied. Pseudo-first and pseudo-second order kinetic models were used. The Langmuir model effectively described the equilibrium isotherms. The longitudinal and transverse relaxation curves of the loaded resins were biexponential. For sulfonic resins, a strong correlation was observed between the relaxation rates of the fast-relaxing fraction and the Ni2+ content determined by ICP-AES/MS. For IRC748, the effect of Ni2+ loading on the relaxation rates was weaker because of Ni2+ complexation. The relaxation curves of loaded AC revealed multiple fractions. Centrifugation was employed to eliminate the contribution of intergranular water. The remaining intragranular water contribution was biexponential. For high Ni2+ loadings, the relaxation rates of the slow relaxing fraction increased with the AC Ni2+ content. These results mark the initial stage in developing a column experiment to monitor, in real-time, adsorbent loading by NMR relaxometry.

Adsorption and Desorption Behavior of Partially Hydrolyzed Polyacrylamide on Longmaxi Shale

Large-scale volumetric fracturing is generally used during shale gas development. The return rate of fracturing fluid is low, and a large amount of slickwater is retained in the reservoir. The adsorption and desorption of partially hydrolyzed polyacrylamide (HPAM), an additive commonly used in slickwater, on the surface of shale was studied using Longmaxi shale from the Sichuan Basin. The experimental results showed that the mass ratio of the HPAM solution to shale reached saturation adsorption at 20:1 when the concentration of HPAM solution was 1000 mg/L and 25:1 when the concentration of HPAM solution was 500 mg/L. The mass ratio of the HPAM solution to shale was fixed at 25:1, and the adsorption equilibrium was reached at a HPAM concentration of 1000 mg/L when the aqueous solution temperature was 30 °C and 800 mg/L when the aqueous solution temperature was 60 °C. The Langmuir adsorption model yielded a better fit than the Freundlich adsorption model. The adsorption equilibrium time at 30 °C was at 60 min for a HPAM concentration of 500 mg/L, while for a concentration of 1000 mg/L, it was at 90 min. The adsorption equilibrium time at 60 °C was 40 min for a HPAM concentration of 500 mg/L, whereas it was 60 min for a HPAM concentration at 1000 mg/L. The pseudo-second order (PSO) kinetics model yielded better fits than the pseudo-first order (PFO) kinetics model. The adsorption of HPAM on shale was strong, and the adsorbed HPAM resembled cobwebs adhering to the shale surface. HPAM on the surface of shale after adsorption was able to resist the desorption capacity of water. However, when the amount of adsorbed HPAM on shale increased significantly, the amount of residual HPAM on the surface of the shale decreased rapidly during desorption in deionized water. The desorption of HPAM on the shale surface followed a modified desorption model. The higher the concentration of HPAM adsorbed on the shale surface was, the easier it was to desorb and the easier it was to be removed from the shale.

Responses of Vallisneria natans and Pistia stratiotes to Cu2+ and Mn2+ stress: Occurrence of caffeic acid and its degradation kinetics during chlorination

Macrophytes are crucial in maintaining the equilibrium of aquatic ecosystems. However, the pattern of macrophyte-derived caffeic acid (CA) release under heavy metal stress is yet to be fully understood. More importantly, due to its functional groups, CA may be a precursor to the formation of disinfection by-products, posing threats to water ecology and even safety of human drinking water. This study analyzed the responses of CA released by Vallisneria natans (V. natans) and Pistia stratiotes (P. Stratiotes) when exposed to Cu2+ and Mn2+ stress. Additionally, the CA levels in two constructed wetland ponds were detected and the degradation kinetics of CA during chlorination were investigated. Results indicated that CA occurred in two constructed wetland ponds with the concentrations of 44.727 μg/L (planted with V. natans) and 61.607 μg/L (planted with P. Stratiotes). Notably, heavy metal stress could significantly affect CA release from V. natans and P. Stratiotes. In general, under Cu2+ stress, V. natans secreted far more CA than under Mn2+ stress, the level could reach up to 435.303 μg/L. However, compared to V. natans, P. Stratiotes was less affected by Cu2+ and Mn2+ stress, releasing a maximum CA content of 55.582 μg/L under 5 mg/L Mn2+ stress. Aquatic macrophytes secreted more CA in response to heavy metal stresses and protected macrophytes from harmful heavy metals. CA degradation followed the pseudo first-order kinetics model, and the chlorination of CA conformed to a second-order reaction. The reaction rate significantly accelerated as NaClO, pH, temperature and Br- concentration increased. A new pathway for CA degradation and a new DBP 2, 2, 3, 3-tetrachloropropanal were observed. These findings pointed at a new direction into the adverse effect of CA, potentially paving the way for new strategies to solve drinking water safety problems.

Degradation of Carbamazepine in Water by UV-activated Sulfite Process

In this study, the degradation efficiency and mechanism of carbamazepine (CBZ), a typical emerging contaminant in water, in the UV/sulfite process were investigated. The effects of different concentrations of dissolved oxygen [ρ(DO)] on the degradation of CBZ by UV-activated sulfite were investigated. Additionally, under a simulated natural water environment-controlled initial ρ(DO) of (8.0 ±0.2) mg·L-1, the effects of different process parameters (sulfite dosages and reaction pH) and water environmental factors (the presence of HCO3-, Cl-, and humic acids) on the degradation of CBZ were comprehensively analyzed. The results showed that the UV/sulfite process efficiently degraded CBZ with a degradation rate of 85.3% during the 30 min reaction time and followed the pseudo-first order kinetic model with the constant of 0.055 7 min-1. Using the electron spin resonance detection, reactive species quenching tests, and the competition kinetics, the sulfate radicals (SO4-·) and hydroxyl radicals (·OH) in the UV/sulfite process were determined to be the main reactive species and were responsible for the degradation of CBZ with contribution rates of 43.9% and 56.1%, respectively. In addition, the degradation efficiency of CBZ decreased with the increasing concentration of HCO3-, and the presence of Cl- had little effect on the degradation of CBZ, whereas the presence of humic acids significantly inhibited the degradation of CBZ. Moreover, the accumulation of sulfate during the reaction was significantly lower than the limit of the Standard for Drinking Water (GB5749-2022). Additionally, the sulfite consumption rate constant was 0.004 4 min-1, which was significantly lower than the degradation rate constant of CBZ, indicating that sulfite could be activated efficiently by UV light to degrade CBZ in water.

Removal and recovery of phenolic compounds from OMW by a cationic resin

Olive mill wastewater (OMW) is rich in valuable compounds such as phenolic compounds. Amberlite@HPR1100 was applied as adsorbent to recover these added-value compounds from OMW. For synthetic OMW, Langmuir isotherm and pseudo-second order kinetic model were able to predict the experimental data instead for real effluent, were the Freundlich isotherm and the pseudo-first order kinetic model the best fits. The continuous process was also studied, for real OMW the tbp, tst and tex were 1.27 min, 84.4 min and 575 min, respectively. After 645 min of adsorption, 42 % of phenolic content was adsorbed into the resin. An industrial column for recovering phenolic compounds from OMW was designed, which should have around 5 m and 0.6 m of height and diameter, respectively, filled with 112 kg of resin (dry basis). The desorption process for real OMW with acetone 80 % recovery was accomplished after 5 h of contact.

Green synthesis of NiO/ZnO nanocomposites for the adsorption of various dyes

A significant waste, including dyes in water, is generated during textile industrial processes, which causes environmental challenges. Herein, various nanocomposites (NC) of nickel oxide (NiO) and zinc oxide (ZnO) were prepared by solvothermal assisted green method where ethanolic extract of spinach leaves were used as a green source. The ultraviolet-visible (UV–vis) spectroscopy revealed that the band gap energies and absorption maxima of NiO/ZnO were 2.25 eV and 371 nm for 1:1 NC, 2.07 eV and 380 nm for 5:1 NC, and 2.02 eV and 385 nm for 1:5 NC. Ultraviolet-visible (UV–vis) spectroscopy, x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were employed to investigate the optical and structural characteristics of the NCs. The XRD patterns of NiO/ZnO NCs (i.e., 1:1, 5:1, 1:5) displayed crystallite sizes of 44.6, 52.17, and 42.5 nm, respectively. Associations of different functional groups with the surfaces of NC was confirmed by FTIR. Batch method was used to conduct the NCs-mediated adsorption of methylene blue (MB), methyl red (MR), and methyl orange (MO). Furthermore, several factors, including dye concentration, contact time, and temperature that affected the sorption, are reported. Pseudo-first order and pseudo-second order kinetic models were utilized to examine the adsorption kinetics. For all the dyes studied, pseudo-first order is the one which fitted best to the kinetic data, based on regression coefficient (R2). Indeed, experimental data were found to follow the Langmuir model. The maximum uptake capacity (qm) of MB adsorbed on NiO/ZnO NC (1:1) was 370 mg g−1 which is higher compared to that of values reported in the literature. These findings report a dual method (i.e., solvothermal-green chemistry) contribute to the development of efficient and cost-effective methods for wastewater treatment and environmental remediation.

Removal of Reactive Black 5 by UV-C assisted peroxydisulfate process: Effect of parameters, kinetic study, and phytotoxicity assessment

ABSTRACT Photochemical removal of Reactive Black 5 (RB5) was investigated by the UV-C assisted peroxydisulfate (UV-C/PDS) process. Parameters affecting the removal of RB5 were examined. Activation of PDS by UV-C light significantly improved the removal efficiency compared to direct photolysis or PDS alone. The removal of RB5 by UV-C/PDS process fitted well with the pseudo first-order kinetic model under all tested conditions. Almost complete removal of RB5 was achieved at the end of 120 min within the pH range of 3–7, whereas 90.7 and 89.4% removal efficiency values were observed at pH = 9 and 11, respectively. An increase in PDS dosage in the range of 0.25–1 mM led to a rise in removal from 48.5 to 97.3% after 120 min, and a complete removal was observed with a dosage higher than 2 mM. Pseudo firstorder rate constant (kobs) increased linearly with PDS dosage from 0.0058 to 0.0518 min−1 in the 0.25 mM − 2.3 mM concentration range. The removal efficiency decreased with an increase in the initial concentration of RB5 from 20 to 50 mg L−1 and an exponential correlation was observed between kobs and initial concentration of RB5. Scavenging experiments conducted using t-butyl alcohol and ethyl alcohol implied that both sulphate and hydroxyl radicals were involved in the removal of RB5. Adding HCO3 − decreased the removal of RB5 within the range of 1–30 mM. The presence of CI− showed a negative impact on the removal at low concentrations (1–15 mM) and NO3 − slightly inhibited the removal of RB5. With corresponding stoichiometric PDS dosage, almost a complete mineralisation was achieved for RB5 solution and simulated dyebath effluent after 720 min of reaction time. EE/O values were determined to be 91.0, 76.8, and 41.1 kWh m−3 order−1 for UV-C/H2O2, UV-C/PMS, and UV-C/PDS processes, respectively. The phytotoxicity tests indicated that the intermediates could be more toxic than the parent compound.

Impact of (nano ZnO/multi-wall CNTs) prepared by arc discharge method on the removal efficiency of stable iodine 127I and radioactive iodine 131I from water

Radioactive iodine isotopes especially 131I are used for diagnosis and treatment of different types of cancer diseases. Due to the leak of radioactive iodine into the patient’s urine in turn, the wastewater would be contaminated, so it is worth preparing a novel adsorption green material to remove the radioactive iodine from wastewater efficiently. The removal of 127I and 131I contaminants from aqueous solution is a problem of interest. Therefore, this work presents a new study for removing the stable iodine 127I− and radioactive iodine 131I from aqueous solutions by using the novel nano adsorbent (Nano ZnO/MWCNTs) which is synthesized by the arc discharge method. It is an economic method for treating contaminated water from undesired dissolved iodine isotopes. The optimal conditions for maximum removal are (5 mg/100 ml) as optimum dose with shacking (200 rpm) for contact time of (60 min), at (25 °C) in an acidic medium of (pH = 5). After the adsorption process, the solution is filtrated and the residual iodide (127I−) is measured at a maximum UV wavelength absorbance of 225 nm. The maximum adsorption capacity is (15.25 mg/g); therefore the prepared nano adsorbent (Nano ZnO/MWCNTs) is suitable for treating polluted water from low iodide concentrations. The adsorption mechanism of 127I− on to the surface of (Nano ZnO/MWCNTs) is multilayer physical adsorption according to Freundlich isotherm model and obeys the Pseudo-first order kinetic model. According to Temkin isotherm model the adsorption is exothermic. The removal efficiency of Nano ZnO/MWCNTs for stable iodine (127I−) from aqueous solutions has reached 97.23%, 89.75%, and 64.78% in case of initial concentrations; 0.1843 ppm, 0.5014 ppm and 1.0331 ppm, respectively. For the prepared radio iodine (131I−) solution of radioactivity (20 µCi), the dose of nano adsorbent was (10 mg/100 ml) and the contact time was (60 min) at (pH = 5) with shacking (200 rpm) at (25 °C). The filtration process was done by using a syringe filter of a pore size (450 nm) after 2 days to equilibrate. The removal efficiency reached (34.16%) after the first cycle of treatment and the percentage of residual radio iodine was (65.86%). The removal efficiency reached (94.76%) after five cycles of treatment and the percentage of residual radio iodine was (5.24%). This last percentage was less than (42.15%) which produces due to the natural decay during 10 days.

Adsorption of Pesticides on Activated Carbons from Peach Stones

This study analyzes the adsorption of two model pesticides, namely, 2,4-dichlorophenoxyacetic acid (2,4-D) and carbofuran on activated carbons obtained by chemical activation with phosphoric acid of peach stones. The effect of the synthesis conditions on the surface area development was analyzed. The highest surface area was obtained with an impregnation time of 5 h, an impregnation ratio equal to 3.5, an activation temperature of 400 °C, and 4.5 h of activation time. Under these conditions, the maximum specific surface area was equal to 1182 m2·g−1 which confirms the high porosity of the activated carbon, predominantly in the form of micropores. The surface chemistry of this activated carbon was also characterized using pH at point of zero charge, scanning electron microscopy, and Fourier transform infrared spectroscopy. Both kinetics and equilibrium adsorption tests were performed. Adsorption kinetics confirmed that 2,4-D adsorption follows a pseudo first-order adsorption kinetic model, while carbofuran adsorption is better described by a pseudo second-order one. Regarding the equilibrium adsorption, a higher adsorption capacity is obtained for 2,4-D than carbofuran (c.a. 500 and 250 mg·g−1, respectively). The analysis of the thermodynamics and characterization after use suggest a predominantly physisorption nature of the process.

MX@MIL-125(Ti)-mediated sonocatalytic degradation for the dyes and microplastics

Organic pollution has attracted global attention for the threat to the biota. In this study, the catalyst-mediated sono-degradation was purposefully employed to remove the organic pollutants including dyes and microplastics (MPs) because it could provide a green and sustainable strategy in industrial production. Herein, the Ti-based MOFs (Ti-MOFs) was successfully prepared on the Ti3C2 MXene by the hydrothermal method, forming new plicated MX@MIL-125(Ti). The as-prepared composite had lower specific surface area than the MIL-125(Ti), but it remained porous structure, and the presence of O-Ti-O species and graphitic carbon could help to enhance the photosensitive and catalytic activity. Significantly, the MX@MIL-125(Ti) showed good catalytic removal performances under ultrasound irradiation, and could clear away over 90 % Rhodamine B (RhB) within 60 min or over 75.0 % micro-polyethylene (micro-PE) within 4 h, where the removal process obeyed the pseudo first-order kinetic reaction model and the sonocatalytic degradation was superior to the adsorption. Moreover, a degradation-dominant mechanism was proposed to administrate the MX@MIL-125(Ti)/ultrasound treatment of organic molecules. Thus, the sonocatalysis of Ti-MOFs will be attractive to apply in the degradation of organic contaminants.

Predicting environmental biodegradability using initial rates: mineralization of cellulose, guar and their semisynthetic derivatives in wastewater and soil

Microplastic pollution is a growing concern, and natural materials are being increasingly sought as plastic alternatives. Semisynthetic biopolymers occupy a grey area between natural and synthetic materials and are often presented as green alternatives to conventional plastic. They can be water-soluble or insoluble, and are ubiquitous in commercial products as thickeners, films, filters, viscosity modifiers and coatings. This work compares the mineralization kinetics of cellulose, guar and several of their commercialized derivatives using a simple pseudo first-order kinetic model to extrapolate half-lives and lifetimes, while identifying the levers that influence the mineralization rates of these ubiquitous materials. Industrial composting rates were consistently faster than those of wastewater. While partially substituted biopolymers exhibited measurable degradation, kinetic analysis revealed this effect could be entirely accounted for by the fraction of unsubstituted biopolymer. Surprisingly, the initial rates of highly substituted biopolymers exhibited persistence on par with conventional plastics over the experimental durations studied.

Degradation of amoxicillin residue under visible light over TiO2 doped with Cr prepared from tannery wastewater

The degradation of amoxicillin residue has been performed using TiO2 photocatalyst doped with Cr prepared from tannery wastewater under visible light exposure. The incorporation of Cr metal into TiO2 structure was conducted via hydrothermal method. From the characterization results, it is found that doping Cr from the tannery wastewater into TiO2 structure has been successfully shifted the light absorption into visible region. Among the various Cr content in the TiO2-Cr photocatalyst, TiO2-0.33Cr (medium level) shows the highest ability in the visible light absorption, suggesting it to be the best photocatalyst. It is also clearly proven that in the presence of TiO2-0.33Cr photocatalyst, the degradation of amoxicillin can reach almost 100 % after the third cycles. Furthermore, this study also investigated the optimum condition for photodegradation of amoxicillin as the prevalent antibiotic residue in batch technique. The concentration of amoxicillin after the photodegradation process was determined using a UV–visible spectrophotometer. The result identifies the optimal condition for the amoxicillin photodegradation is reached at pH 6, with 10 mg of the photocatalyst mass per 30 mL of the sample solution, and an irradiation time at 90 min. The photodegradation of amoxicillin using TiO2-0.33Cr follows the pseudo-first order kinetic model with kinetic constant (k) is high as 0.004 min−1.

Valorisation of energy plant Arundo donax cultivated in Serbia for biosorption of cobalt ions from an aqueous solution: Kinetic aspect

Metal ions can be eliminated from aqueous solutions using biosorbent, a substance made from plant biomass. This study investigated the potential use of Arundo donax stems as a cheap, natural biosorbent to remove cobalt ions (Co2+) from an aqueous solution. The biosorbent was characterized by the chemical composition analysis (cellulose, hemicellulose, and lignin), the point of zero charge (pHPZC), by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analysis, and Fourier-transform infrared spectroscopy. According to the experimental data of kinetic studies, the equilibrium condition of Co2+ adsorption was attained 360 min after the biosorption started. The pseudo-first, pseudo-second, Elovich, and intra-particle diffusion models were used to model the kinetic experimental data. The best compliance was obtained with the pseudo-first order kinetic model, considering the highest value of the coefficient of determination R2 (0.996) and the lowest chi-square (?2) value (0.757). The findings of this study can be applied to the design of batch biosorption systems for the removal of Co2+ ions in real industrial systems.

Effect of copper doping on the photocatalytic performance of Ni2O3@PC membrane composites in norfloxacin degradation.

In this study, copper (Cu) and nickel oxide (Ni2O3) microtubes (MTs) were synthesized using an electroless template deposition technique within porous polycarbonate (PC) track-etched membranes (TeMs) to obtain Cu@PC and Ni2O3@PC composite membranes, respectively. The pristine PC TeMs featured nanochannels with a pore density of 4 × 107 pores per cm2 and an average pore diameter of 400 ± 13 nm. The synthesis of a mixed composite, combining Cu and Ni2O3 within the PC matrix, was achieved through a two-step deposition process using a Ni2O3@PC template. An analysis of the resultant composite structure (Cu/Ni2O3@PC) confirmed the existence of CuNi (97.3%) and CuO (2.7%) crystalline phases. The synthesized catalysts were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) analysis, and atomic force microscopy (AFM). In photodegradation assessments, the Cu/Ni2O3@PC mixed composite demonstrated higher photocatalytic activity, achieving a substantial 59% degradation of norfloxacin (NOR) under UV light irradiation. This performance surpassed that of both Ni2O3@PC and Cu@PC composites. The optimal pH for maximum NOR removal from the aqueous solution was determined to be pH 5, with a reaction time of 180 min. The degradation of NOR in the presence of these composites adhered to the Langmuir-Hinshelwood mechanism and a pseudo-first order kinetic model. The reusability of the catalysts was also investigated for 10 consecutive runs, without any activation or regeneration treatments. The Cu@PC membrane catalyst demonstrated a marked decline in degradation efficiency after the 2nd test cycle, ultimately catalyzing only 10% of NOR after the 10th cycle. In contrast, the Ni2O3@PC based catalyst demonstrated a more stable NOR degradation efficiency throughout all 10 runs, with 27% NOR removal observed during the final test. Remarkably, the catalytic performance of the Cu/Ni2O3@PC mixed composite remained highly active even after being recycled 4 times. The degradation efficiency exhibited a gradual reduction, with a 17% decrease after the 6th run and a cumulative 35% removal of NOR achieved by the 10th cycle. Overall, the findings indicate that Cu/Ni2O3@PC mixed composite membranes may represent an advancement in the quest to mitigate the adverse effects of antibiotic pollution in aquatic environments and hold significant promise for sustainable water treatment practices.

An Effective Sol-Gel-Functionalized Polyurethane Foams Solid Platform Packed Minicolumns for Complete Extraction of Chromium (VI) from Water: Kinetic, Sorption Isotherms, Thermodynamic Study, and Analytical Utility.

In the modern era, sol-gel plays a key role in the progress of a new generation of dispersive solid-phase microextractors (d-µ SPMEs) for the removal of organic and inorganic pollutants in complex matrices. Thus, the current study reports the use of sol-gel-functionalized polyurethane foams (PUFs) as a novel solid platform for complete extraction of chromium (VI) species from aqueous media. The planned protocol was based upon the complete extraction of the formed binary complex ion associates between the protonated ether and/or urethane groups of PUFs and chlorochromate anion [CrO3Cl]- aq in aqueous HCl (≥1M) medium in addition to H-bonding and the electrostatic π-π interaction that resulted between the CrO3Cl- and the silanol group (Si/ZrO2, Si-O-Zr) and siloxane (Si-O-Si) groups of the sol-gel. The impact of the analytical parameters (solution pH, natural mineral acids, shaking time, temperature, and chromium (VI) concentrations) was critically studied. At the optimal conditions, the uptake capacity of the established extractor (9.9 mg·g-1) was in agreement with the Langmuir adsorption capacity (12.08 mg·g-1) of the monolayer. The sorption data fitted well with the pseudo first-order kinetic model (R 2 = 0.9961) with an overall rate constant (k 1) of 0.081 min-1 and an equilibrium capacity (q e ) of 8.6 mg·g-1, which is in a good agreement with the experimental value (9.9 mg·g-1). The sorption of the oxyion [CrO3Cl]- aq onto the solid sorbent is an endothermic and spontaneous process as reflected from the values of ΔH (6.99 kJ·mol-1) and ΔG (-8.14 kJ·mol-1 at 293 K), respectively. The ΔS value (15.13 kJ·mol-1·K-1) reflects that the [CrO3Cl]- aq retention onto the sol-gel-treated PUFs sorbent proceeded in a more unplanned fashion. Sol-gel-treated PUFs sorbent-packed minicolumns were successfully used for the complete removal of trace levels of chromium (VI) species from water samples. Sorbed chromium (VI) species were recovered with NaOH (0.5 M) and analysed by spectrophotometry, which supports the utility of the sol-gel-treated PUFs as a low-cost solid extractor for water treatment.

Obtaining an organosorbent based on Apis Mellifera chitosan and bentonite for cleaning textile wastewater from dyes and metals

This article presents the results of studying the sorption of Cu2+ ions in artificial solutions to ionite obtained on the basis of the PPD brand of Navbakhor bentonite at temperatures of 303, 313 and 323 K, the duration of sorption up to the equilibrium state (between 1-24 hours) and at different concentrations. The kinetics of the processes were studied, Langmuir and Freundlich isotherm models were used to express the adsorption mechanism in the equilibrium state. Based on the obtained results, it was found that the value of isotherm parameters R2 (0,9973) was consistent in all isotherm models. According to the Langmuir isotherm model, 𝑞𝑚𝑎𝑥= 212,7 mg/g, and n=0,2456 according to the Freundlich isotherm model. This indicates the sorption of Cu2+ ions to bentonite-based ionite. Based on scientific research, pseudo-first and pseudo-second order kinetic models of sorption of metal ions to ionite were also studied. It was determined that the obtained kinetic parameters of the process obey the pseudo-second-order model and the sorption of Cu2+ ions to the obtained ionite.

Adsorption of Metaldehyde by Oil Palm Kernel Biochar and Rice Husk Biochar: A Comparative Study

Metaldehyde is a toxic molluscicide that has the potential to contaminate water supplies and damage aquatic life. Existing water treatment methods are ineffective at removing it from water bodies. In this study, oil palm kernel biochar (OPKB) and rice husk biochar (RHB) were utilized to assess metaldehyde adsorption. Using a batch adsorption approach, the physicochemical parameters of biochar and their metaldehyde adsorption capacities were investigated. The results indicated that the metaldehyde adsorption capacities of both varieties of biochar are significant. Considering the initial concentration of metaldehyde, contact time, and adsorbent dosages, OPKB demonstrated a higher metaldehyde adsorption capacity than RHB. The study examined metaldehyde’s effects on OPKB and RHB using Langmuir and Freundlich isotherms. Both models provided a good fit, with the Freundlich model slightly better fitting. The study also used pseudo-first and second order kinetic models, revealing that the adsorption process follows pseudo-second-order kinetics for both biochar. This information can aid in developing efficient and successful metaldehyde removal technologies from contaminated water sources. This study showed that oil palm biochar has the potential to be an effective adsorbent for removing metaldehyde from contaminated water.

Sorption Kinetics and Equilibrium Isotherms of Phosphine Gas into Wheat Kernels

Highlights The pseudo-first order kinetic model fits well with the experimental data of sorbed phosphine versus time. Sorption isotherm curves were developed using Langmuir, Freundlich, and Redlich-Peterson models. Phosphine adsorption capacity of wheat kernels increased with increase in applied concentration (400-2400 ppm). Abstract. Phosphine (PH3) is the most used fumigant in the U.S. due to its low price, ease of use, and wide accessibility. With the growing concerns of phosphine-resistant insect pests, the sustainability of PH3 as an effective fumigant has been put at risk. Sorption equilibrium data is critical for improving the accuracy of modeling studies for phosphine-wheat fumigation systems and would clarify the PH3 uptake and sorption capacity of wheat. The objectives of this study were to determine the effect of initial concentration (from 400 to 2400 ppm) on the equilibrium concentration for PH3 in wheat kernels and on cumulative and daily PH3 sorption through time. Kinetic data showed the sorption process was time-dependent and occurred in two phases: an initial faster adsorption phase, followed by a phase with a slower sorption rate as the grain and PH3 reached equilibrium. Pseudo-first and pseudo-second order models were fit to PH3 concentrations versus time experimental data. The pseudo-first order model provided better equilibrium estimates and was used for the sorption isotherm analysis. Langmuir, Freundlich, and Redlich-Peterson sorption isotherm models were fit to the plot of equilibrium headspace gas concentration versus sorbed PH3 quantity. All three models had low standard errors of prediction (0.46-0.47). These PH3 sorption kinetics and values of total sorbed quantity at equilibrium are valuable for modeling the rate and maximum quantity of PH3 uptake in wheat. Keywords: Fumigation, Kinetics, Phosphine, Sorption Isotherm, Wheat.