Equilibrium Time Research Articles

The Application of Bilayer Heterogeneous MOFs in pH and Heat-Triggered Systems for Controllable Fragrance Release.

To facilitate the integration of a fragrance encapsulation system into different products to achieve effective releases, a dual-responsive release system with pH and thermal trigger control is designed in this work. A series of ZIF-8 (M) and bilayer ZIF-8-on-ZIF-8 (MM) materials are synthesized by a solvent method at room temperature. The fragrance is encapsulated into the ZIFs by dynamic adsorption or in situ encapsulation combined dynamic adsorption. The fragrance loading contributed by dynamic adsorption was as high as 80%. The fragrance loaded in the double-layer MM host was almost twice that of the monolayer host M due to the stronger electrostatic interaction between MM and vanillin. In the pH and thermal trigger response release experiments, the second MOF layer in the MM host, as a controlled entity, greatly improved the load and kinetic equilibrium time of vanillin, and realized the controlled release of guest molecules. The developed dual-responsive release system in this work exhibits great potential in daily chemical products.

Synthesis of N/P/S Co-doped porous carbons by carbonizing polyphosphazene microspheres for highly selective adsorption of Pb (II)

Heteroatom-doping has emerged as a promising approach for enhancing the properties of carbon materials, particularly in the treatment of heavy-metal wastewater. However, the simultaneous synthesis of multi-heteroatom co-doped carbon materials poses significant complexity and challenges. Consequently, there is an increasing demand for the development of non-toxic and straightforward methods to prepare such materials. In this study, we present a novel approach for the synthesis of N/P/S co-doped porous carbonaceous adsorbents using polyphosphazene as precursors. Our focus is specifically on their effectiveness in adsorbing Pb (II). The results reveal that the synthesized adsorbents, denoted as carbonized polyphosphazene or CZ-600 exhibited a high carbon content co-doped with N, P and S atoms, as well as an abundance of oxygen-containing functional groups and a porous structure. These characteristics collectively contribute to the exceptional adsorption capacity of CZ-600 for Pb (II), with a maximum adsorption capacity of 121.7 mg/g and an equilibrium time as short as 20 min. Further investigations of the adsorption process involve fitting adsorption isotherm, kinetic, and thermodynamic models, revealing chemical adsorption as the predominant mechanism, supported by contributions from micropore adsorption and electrostatic interactions. This work proposes a sustainable and efficient solution for the treatment heavy-metal wastewater, which not only advances the understanding of heteroatom-doped carbon materials but also provides valuable insights into their practical applications in environmental remediation.

Preparation of magnetic composite based on chitosan/carbon nanotubes for reactive blue 198 and lead (II) ion removal

This study involved synthesizing a magnetic composite material of chitosan and carbon nanotubes using the freeze-drying process. The composite was created by mixing chitosan (CS), carbon nanotubes (CNT), and Fe3O4 in different ratios (w/w) (1.2:0.3:0.5, 1.2:0.5:0.3, 1.2:0.6:0.2 and 1.2:0.7:0.1). Results showed that the most porous structure was achieved with a ratio of 1.2:0.5:0.3 for CS:CNT:Fe3O4 (w/w). Various analytical methods such as FT-IR, SEM, XRD, and TGA were employed to determine the characteristics of the composite. The composite material was tested for its ability to adsorb Pb2+ heavy metal ions and reactive blue 198 (RB198) at concentrations ranging from 25 to 100 ppm. The study also investigated the effects of adsorbent amount, pH, and equilibrium time on the adsorption performance of the material.

Selective adsorption and identification of penicillin G sodium in milk by molecularly imprinted polymer doped carbon dot.

A carbon dot (CD) was prepared by o-phenylenediamine and water, which showed bright yellow fluorescence under ultraviolet light irradiation (λ = 580nm), and verified good fluorescence quenching effect on penicillin G sodium (Png-Na). Using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a crosslinker, and Png-Na as a template, a kind of composite microsphere combining CD and molecularly imprinted polymer (MIP) was synthesized by surface-initiated atomic transfer radical polymerization (SI-ATRP). For reasons ofcomparison, we also prepared MIP without CD and non-imprinted polymers (NIPs). Through static and dynamic adsorption experiments, the maximum adsorption capacity was 47.05mgg-1 and the equilibrium time was 30min. High-performance liquid chromatography (HPLC) was utilized to determine the content of Png-Na in the spiked milk samples. A sensitive, rapid, and simple method for determination of Png-Na in food samples was developed. The utilized approach enabled the quantification of Png-Na within theconcentration range 20-1000μg L-1 (with a limit of detection of 5μg L-1). The recoveries achieved were in the range 93.3-98.2%, with a relative standard deviation of 1.2-4.2%. The results demonstrated that CD@MIP possessed the capability of specific adsorption and fluorescence detection of Png-Na, enabling simultaneous detection and enrichment of Png-Na in real samples.

Cooling dynamics of droplets exposed to solid surface freezing and vitrification

Solid surface freezing or vitrification (SSF/SSV) can be done by depositing droplets of a sample, e.g., cells in a preservation solution, onto a pre-cooled metal surface. It is used to achieve higher cooling rates and concomitant higher cryosurvival rates compared to immersion of samples into liquid nitrogen. In this study, numerical simulations of SSF/SSV were conducted by modeling the cooling dynamics of droplets of cryoprotective agent (CPA) solutions. It was assumed that deposited droplets attain a cylindrical bottom part and half-ellipsoidal shaped upper part. Material properties for heat transfer simulations including density, heat capacity and thermal conductivity were obtained from the literature and extrapolated using polynomial fitting. The impact of CPA type, i.e., glycerol (GLY) and dimethyl sulfoxide (DMSO), CPA concentration, and droplet size on the cooling dynamics was simulated at different CPA mass fractions at temperatures ranging from −196 to 25 °C. Simulations show that glycerol solutions cool faster compared to DMSO solutions, and cooling rates increase with decreasing CPA concentration. However, we note that material property data for GLY and DMSO solutions were obtained in different temperature and concentration ranges under different conditions, which complicated making an accurate comparison. Experimental studies show that samples that freeze have a delayed cooling response early on, whereas equilibration times are similar compared to samples that vitrify. Finally, as proof of concept, droplets of human red blood cells (RBCs) were cryopreserved using SSV/SSF comparing the effect of GLY and DMSO on cryopreservation outcome. At 20% (w/w), similar hemolysis rates were found for GLY and DMSO, whereas at 40%, GLY outperformed DMSO.

الايزوثيرمات والدوال الدينميكية الحرارية لامتزاز دواء الميتوبرولول على السليكا متوسطة المسام المحضرة

في هذه الدراسة ، تم تصنيع السيليكا متوسطة المسام ((MPS) باستخدام طريقة سول-جل من مصدر رخيص ((Na2SiO3 باستخدام هيدروكسي ستيل هيدروكسي إيثيل دايمونيوم كلوريد كقالب. وتتمثل المهمة في الإزالة القائمة على الامتزاز لعقار ميتوبرولول (MP) بتراكيز تتراوح بين 10 و50 جزء في المليون. تمت دراسة المتغيرات مثل: وقت التلامس، كمية المادة المازة، التراكيز الابتدائية للمادة الممتزة، ودرجة حرارة الامتزاز، ودلت النتائج ان زمن الاتزان وكمية المادة المازة هما 40 دقيقة و 0,05 غرام على التوالي. تم تطبيق ايزوثرمات Langmuir , Freundlich ,Temkin وDubinin-Radushkevich على البيانات التي تم الحصول عليها من التجارب و قد أظهرت مقارنة النتائج أنه ، من بين نماذج الايزوثرمات الأربعة التي تم فحصها ، يمكن لنموذج معادلة Freundlich التنبؤ بهذه البيانات بدقة. وبالاعتماد على تحليل ايزوثرم الامتزاز تبين انه مع ارتفاع درجة الحرارة أن كمية الامتزاز ارتفعت وأن الامتزاز كان مفيدًا ومن النوع الفيزيائي. بالإضافة إلى ذلك، تضمنت الدراسة تقدير ∆H°, ∆S°,∆G° , كعوامل ديناميكية حرارية. ووجد ان قيمة ∆G° كانت بين -20,24 و -26,22 كيلوجول لكل مول وتقل مع ارتفاع درجة الحرارة مما يدل على ان الامتزاز يصبح اكثر تلقائية بدرجات الحرارة العالية. كانت قيمة ∆H° هي 38.10 كيلوجول لكل مول والتي دلت بان عملية الامتزاز من نوع الامتزاز الفيزيائي. اما قيمة ∆S° فكانت 199.14 جول لكل مول والتي تدل عل زيادة درجات الحرية للمادة الممتزة MP. ودلت اشارة ∆G° و ∆H° بان العملية تلقائية وماصة للحرارة.

Insights into Agricultural Soil Contamination by a Veterinary Antibiotic TYLOSIN Through Continuous Run-Off Conditions

ABSTRACT Broad-spectrum veterinary antibiotic tylosin (TYL) is utilized in livestock and poultry. Due of its extensive usage and animal excretion in urine and feces, it affects the environment and human health. For determining the equilibrium time, the adsorption maximum capacity and the optimal isotherm model, adsorption batch tests have been conducted. Sips and Pseudo-second order models had R2 values of 0.9937 and 0.9764, respectively, and best matched experimental isotherm and kinetic data. The maximum TYL uptake onto soil was 2355.08 mg.kg−1. Using fixed bed adsorption experiments, the current study clarifies the issue of soil contamination in conditions that are close to natural phenomena. Fixed bed adsorption tests demonstrated that the inlet TYL concentration, soil bed height, and flow rate, influenced saturation and breakthrough times. Bohart-Adams, Thomas, and Yoon-Nelson models matched the experimental findings well in a variety of conditions. With 100 mg.L−1 concentration, 4 cm bed height, and 5 mL.min−1 flow rate, the maximal bed capacity of 1277.06 mg.kg−1 was achieved with R2 value of 0.9797. Experimental findings also indicated that the adsorption capacity in batch and dynamic tests are of the same range of magnitude. Based on this, tylosin is a probable soil contaminant.

COMPRESSION BETWEEN KAOLIN AND CORN SEED AS ADSORBENTS ON THE ADSORPTION OF METFORMIN HYDROCHLORIC FROM AQUEOUS SOLUTION UNDER DIFFERENT CONDITIONS

Metformin is currently the medicine used to treat hypoglycemia most frequently. We used kaolin and corn seed surfaces to draw out the drug metformin hydrochloride from aqueous solutions. The medicine metformin, which is currently the most frequently prescribed oral hypoglycemic, has outstanding safety profiles and is only contraindicated in people with definite medical problems, particularly chronic renal failure, congestive heart failure, chronic obstructive pulmonary disease, and liver disease. The analysis demonstrates how many factors, such as equilibrium time (5–15 min), pH (8.5) as well as for pH of small intestine, temperature (32–37°C). It is discovered that when temperature and pH increase, the amount of adsorbate present decreases, with equilibrium requiring 15 minutes. The wavelength used for the analysis of metformin HCl was (260 nm). To discover the appropriate adsorption parameters, it was chosen to apply response surface methodology (RSM). Through thorough physical characterization using techniques including FTIR it was demonstrated that the primary driving forces behind the adsorption processes are H-bonding, electrostatic attraction, and so-called (electron donor-acceptor) EDA interactions. Modeling revealed that the best explanation for the MF adsorption involved an isotherm that depended on Giles categorization, was spontaneous (ΔG = -5.9 kJ/mole), and was endothermic (ΔH = +12.14 kJ/mole).

Biosorption of nickel and cadmium using Pachira aquatica Aubl. peel biochar

This study aimed to assess the value of Pachira aquatica Aubl. fruit peels by exploring their applicability in the biosorption process for the removal of Ni(II) and Cd(II) metal ions. The Pachira aquatica Aubl. fruit peel biochar (PAB) was extensively characterized through various techniques, including proximate analysis, helium pycnometer, XRD, SEM, point of zero charge determination, zeta potential measurement, and Boehm titration. Subsequently, kinetic, isotherm, and thermodynamic batch biosorption studies were conducted, followed by column biosorption tests. The characteristics of PAB, including low moisture content, a neutral point of zero charge, porosity, an irregular and heterogeneous structure, a negatively charged surface, and the presence of functional groups, indicate its remarkable capacity for efficiently binding with heavy metals. Biosorption equilibrium time was achieved at 300 min for both ions, fitting well with a pseudo second-order kinetic model and Langmuir isotherm model. These data suggest that the biosorption process occurred chemically in monolayer. The column C presented an exhaust volume of 1200 mL for Ni(II) and 1080 for Cd(II) and removal of 98% and 99% of removal for Ni(II) and Cd(II), respectively. In summary, PAB demonstrates substantial potential as a biosorbent for effectively removing heavy metals, making a valuable contribution to the valorization of this co-product and the mitigation of environmental pollution.

Efficient uptake of 85Sr and 60Co using fabricated inorganic sorbent for reducing radiation doses of simulated low-level waste

The present study investigated the sorption behavior of 85Sr and 60Co radionuclides from aqueous solutions onto tin molybdate (SnMo) sorbent. SnMo has been synthesized using the precipitation method and was characterized using four analytical techniques including FT-IR, XRD, SEM, and XRF. The sorption studies applied on 85Sr and 60Co include the effect of shaking time, pH, concentration, and saturation capacity. The experimental data revealed that the sorption process was carried out after equilibrium time (180 min). The saturation capacity for 85Sr and 60Co is measured to be 58.1 and 52.2 mg g−1, respectively. The sorption behavior of studied radionuclides is dependent on pH values. Sorption kinetic better fit with the pseudo-second-order model. Furthermore, the sorption isotherm is better represented by the model proposed by Langmuir. The results of the desorption investigations indicated that the most effective eluents for achieving full recovery of investigated radionuclides were identified. Finally, the recycling results demonstrate the suitability of SnMo for affected sorbing of 85Sr and 60Co from aqueous solutions. All the obtained data clarify that the SnMo sorbent is an effective means of removing 85Sr and 60Co from liquid waste.

The investigation of sorption-desorption performance and mechanism of copper by surfactant-modified zeolite in aqueous solutions.

As the most common filler in stormwater treatment, zeolite (NZ-Y) has good cation exchange capability and stabilization potential for the removal of heavy metal from aqueous solutions. In this study, sodium dodecyl sulfate (SDS) and NZ-Y were selected to preparing new adsorbent (SDS-NZ) by using a simple hydrothermal method. The sorption-desorption performance and mechanism of Cu(II) onto SDS-NZ were investigated. The results showed that the sorption of Cu(II) on SDS-NZ was in accordance with the pseudo-second-order kinetic model with an equilibrium time of 4h. The sorption behavior fitted Langmuir isotherm with a saturation sorption capability of 9.03mg/g, which was three times higher than that of NZ-Y. The modification of SDS increases the average pore size of NZ-Y by 3.96nm, which results in a richer internal pore structure and more useful sorption sites for Cu(II) sorption. There was a positive correlation between solution pH values and sorption capability of Cu(II) in the range of 3.0-6.0. With the ionic strength increased, the sorption capability of Cu(II) onto SDS-NZ first decreased and then increased, which may be attributed to competitive sorption and compression of the electronic layer. The desorption of Cu(II) on SDS-NZ was favored by the increase in SDS concentration and ionic strength and decrease in solution pH values. The application of SDS-NZ in runoff improved the leaching risk of Cu(II). After several cycles, the ability of reused SDS-NZ to efficiently adsorb most heavy metals was verified with removal rates above 99%.

Lotic‐SIPCO2: Adaptation of an open‐source CO2 sensor system and examination of associated emission uncertainties across a range of stream sizes and land uses

AbstractRiver networks play a crucial role in the global carbon cycle, as relevant sources of carbon dioxide (CO2) to the atmosphere. Advancements in high‐frequency monitoring in aquatic environments have enabled measurement of dissolved CO2 concentration at temporal resolutions essential for studying carbon variability and evasion from these dynamic ecosystems. Here, we describe the adaptation, deployment, and validation of an open‐source and relatively low‐cost in situ pCO2 sensor system for lotic ecosystems, the lotic‐SIPCO2. We tested the lotic‐SIPCO2 in 10 streams that spanned a range of land cover and basin size. Key system adaptations for lotic environments included prevention of biofouling, configuration for variable stage height, and reduction of headspace equilibration time. We then examined which input parameters contribute the most to uncertainty in estimating CO2 emission rates and found scaling factors related to the gas exchange velocity were the most influential when CO2 concentration was significantly above saturation. Near saturation, sensor measurement of pCO2 contributed most to uncertainty in estimating CO2 emissions. We also found high‐frequency measurements of pCO2 were not necessary to accurately estimate median emission rates given the CO2 regimes of our streams, but daily to weekly sampling was sufficient. High‐frequency measurements of pCO2 remain valuable for exploring in‐stream metabolic variability, source partitioning, and storm event dynamics. Our adaptations to the SIPCO2 offer a relatively affordable and robust means of monitoring dissolved CO2 in lotic ecosystems. Our findings demonstrate priorities and related considerations in the design of monitoring projects of dissolved CO2 and CO2 evasion dynamics more broadly.

Recycled gold-reduced graphene oxide nanocomposite for efficient adsorption and photocatalytic degradation of crystal violet

In this study, gold-reduced graphene oxide (Au@rGO) nanocomposite has been synthesized by repurposing electronic waste and dry batteries. This innovative approach involved utilizing the graphite rod from dry batteries to produce reduced graphene oxide (rGO), which was subsequently modified through the incorporation of gold nanoparticles obtained from recycled electronic waste. This methodology marks a significant breakthrough in electronic waste recycling, presenting a cost-effective and sustainable means of creating novel nanocomposites for applications in photocatalysis and adsorption, particularly in the removal of crystal violet (CV) from aqueous media. The synthesized Au@rGO nanocomposite was characterized using X-ray diffraction, scanning electron microscopy, energy dispersed X-ray, and N2 adsorption/desorption. Parameters that affect the adsorption and photocatalytic degradation of CV dye have been studied in detail. The optimal conditions for CV adsorption and photocatalytic degradation were pH of 10, equilibrium time of 30 min, CV concentration of 10 mg/L and adsorbent dosage of 40 mg. Furthermore, the isotherm and kinetics of CV removal were also studied. The removal of CV dye using adsorption and photocatalytic degradation techniques reached 95% and 99%, respectively. Consequently, the results showed that photocatalytic degradation of CV dye onto the mesoporous Au@rGO nanocomposite is more proper way than the adsorption technique for removing the CV dye from aqueous media. The designed photocatalyst has high efficiency and it can be reused and activated several times so it can be used in real water treatment applications.

Ultrasound-assisted removal of Imidacloprid from aqueous solutions using carboxymethyl cellulose-based bionanocomposite hydrogel beads (CMC/Fe3O4-Zeolite): Emphasis on effects Fe3O4-Zeolite nanoparticles and ultrasound

In the present work, carboxymethyl cellulose-based bionanocomposite hydrogel beads with diverse concentration ratios of Fe3O4-Zeolite were produced and used for the removal of Imidacloprid from an aqueous solution. Optimization of various factors such as Imidacloprid initial concentration, adsorbent dosage, pH solution, and sonicating time (42 kHz) affecting Imidacloprid removal was evaluated by response surface methodology (RSM). The optimum values for these parameters were obtained at 38 mg L−1, 1.9 g L−1, 7, and 19 min, respectively. The adsorption process of Imidacloprid by CMC/Fe3O4-Zeolite20 is multilayer adsorption (Jossens model) and was controlled by internal and external diffusion (double-exponential model). Additionally, the study of the ultrasonic effect on Imidacloprid removal performance showed that the ultrasound combined with adsorption significantly reduces the equilibration time. Also, the adsorption and desorption study showed that the adsorbent with high stability in adsorption performance was recycled in 6 cycles without a significant reduction in adsorption efficiency. And finally, the removal performance of CMC/Fe3O4-Zeolite20 was studied on the real wastewater samples and confirmed the feasibility of adsorbent for practical applications in industrial purposes.

Liquid-waste derived magnetic porous carbon sphere for effective removal of tetracycline from aqueous solution

Effective removal of tetracycline (TC) from wastewater is highly important while still faces challenges especially in adsorption capacity. Herein, a novel N-doped magnetic porous graphitic carbon sphere (N-MPGCS) adsorbent was fabricated by a green strategy using tannic acid (TA) as organic ligand and stainless steel pickling wastewater as metal source. Melamine was also introduced to increase nitrogen-containing functional groups. Among the obtained carbon spheres, N-MPGCS1–800 sample shows a large specific surface area (up to 922.78 m2 g−1), appropriate O/N functional groups, suitable sp2 carbon, and good magnetic responsivity. Benefiting from these merits, this optimal material exhibits a high Langmuir adsorption capacity (1005.5 mg g−1 at 45 °C) for TC, fast adsorption kinetics (5 min for adsorption equilibration time at 50 mg L−1), and good applicability towards pH (3−10) and co-existing ions. Besides, the excellent magnetism permits the convenient and rapid recovery of adsorbent from the adsorption system. Moreover, the high TC removal ratio (92.3% after three cycles) presents its outstanding regeneration. Adsorption studies and characterizations show that H-bond, π-π stacking, metal-organic complexation interactions, and pore-filling effect contribute to the adsorption together. In addition, N-MPGCS1–800 also shows good removal on enrofloxacin, moxifloxacin, and norfloxacin. This work proves that N-MPGCS material can serve as a potential adsorbent, and more importantly, it gives a new path for mining industrial waste to produce high-effective magnetic carbon materials.

Quantitative analysis on chemical influence of modified activated carbon in TSA/PSA for methanol via alterable phosphorus functional groups and stable structure

Volatile organic compounds (VOCs) emissions cause serious health problems and environmental pollution, and modified activated carbon is widely used in the treatment of VOCs pollution. Methanol was selected as adsorbate and activated carbon with alterable phosphorus functional groups was synthesized as adsorbent. In the absence of the influence of the physical properties, the chemical functional groups influence coefficient (AC) was proposed, which can be used to analysis and predict the influence of chemical functional groups specially. The results show that the performances including adsorption capacity and enrichment ratio are positively related to the AC whether in temperature swing adsorption (TSA) or pressure swing adsorption (PSA). By comparison, the adsorption capacity of PSA is greater than that of TSA because of the higher efficiency caused by faster cycle. Further research on process showed that the curve character of TSA, including breakthrough time and equilibrium time, is highly related with AC, but the curve character of PSA is mainly depended on the state of activated carbon. Therefore, the attenuation of TSA is mainly caused by the change of chemical functional groups, while the attenuation of PSA is mainly caused by the failure of activated carbon.

Nanofiber Ion-Selective Membrane-Coated Carbon Paper All-Solid-State Sensors: One Stone, Two Birds.

Potentiometric sensors with nanostructural ion-selective membranes were prepared and tested. Electrospun nanofiber mats were applied in novel all-solid-state sensors, using carbon paper as an electronically conducting support. For the sake of simplicity, application of a solid contact layer was avoided, and redox-active impurities naturally present in the carbon paper have proven to be effective as ion-to-electron transducers. Application of a nanostructural ion-selective membrane requires an innovative approach to combine the receptor layer with the support. The nanofiber mat portion was fused with carbon paper in a hot-melt process. Applying temperature close to 120 °C for a short time (3 s) allowed binding the nanostructural ion-selective membrane with carbon paper, without significant changes in the nanofiber structure. This process was conveniently performed together with the lamination of the carbon paper support. The thus obtained, potentially disposable sensors were characterized as exhibiting highly reproducible potential readings in time as well as between sensors belonging to the same batch. The benefits of the application of nanostructural ion-selective membranes include shorter equilibration time, lower detection limit, and significantly lower material consumption. However, the nanostructural membrane is characterized by a higher electrical resistance, which is attributed to higher porosity.

Monitoring and Recovery of Chromium (III) from Inorganic Waste Industrial Solution

Using Solvent Extraction Calixe arene diluted in toluene at pH 6.5 extracts Chromium (III) from aqueous medium well. The equilibrium time has been calculated to be between 20 and 25 minutes. The degree of extraction increases with increasing Chromium (III) concentration in the aqueous phase, whereas the extraction ratio decreases with increasing Chromium (III) concentration. The extraction rate increases as the pH and concentration of Calixe arene rise. The results of batch equilibrium tests showed that the Langmuir isotherm accurately reflects the adsorption process; the impact of numerous analytical parameters such as pH, equilibrium time, temperature, stripping agent, and diluents was rigorously investigated. The findings showed that 99.5%. The recovered solvent could be utilized in subsequent extractions. The results of batch equilibrium tests showed that the Langmuir isotherm accurately reflects the adsorption process; the impact of numerous analytical parameters such as pH, equilibrium time, temperature, stripping agent, and diluents was rigorously investigated. The findings showed that 99.5%. The regenerated solvent might be reused in further chromium (III) extractions. Finally, the process was used to extract Cr (III) from waste solutions from electroplating and leather tanning.

Nitrogen and sulfur-doped biochar supported magnetic CuZnFe2O4 as a sustainable adsorbent for efficient reactive black dye 5 removal from industrial wastewater

AbstractThe shortage of clean and safe water resources, due to the growing pollution and the high cost of water treatment techniques, has become a real threat. Herein, CuZnFe2O4@N,S-doped biochar (CZF@N,S-BC), a novel magnetic, cleaner, and completely green-based composite, was fabricated using the aqueous extract of Beta vulgaris (sugar beet) leaves for the efficient removal of reactive black dye 5 (RB5) from industrial wastewater discharge. With the aid of numerous techniques, including Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Spectroscopy (SEM), Vibrating Sample Magnetometer (VSM), and zeta potential analyses, CZF@N,S-BC was well-characterized. The results revealed the successful fabrication of CZF@N,S-BC with good magnetic saturation of 12 emu/g and a highly positively charged surface of 32 mV at pH 2. The removal efficiency of RB5 was reached 96.5% at equilibrium time 60 min, and adsorbent dose of 80 mg. The equilibrium data fitted well with the Freundlich isotherm model, while the adsorption kinetics followed a pseudo-second-order model (PSO), with a maximum adsorption capacity of 276.57 mg/g. The thermodynamics results confirmed the physical interaction between the composite and RB5. Additionally, the composite also demonstrated exceptional reusability, maintaining a removal efficiency of 57.27% even after six consecutive cycles. To evaluate the performance of CZF@N,S-BC composite in a real water matrix, the composite was subjected to remove RB5 from a real wastewater sample obtained from an industrial discharge of a textile dyeing industry. Also, a plausible mechanism of RB5 removal by the composite was intensively discussed using XPS before and after adsorption.

Application of a novel polymer cross-linked with magnetite for efficient norfloxacin adsorption at a wide pH range

Nowadays, NOR-containing wastewater has placed huge pressure on global ecology. In this study, a chemically-modified chitosan-based polymer was cross-linked with magnetite to prepare a novel magnetic composite adsorbent named Fe3O4/CS-P(AM-SSS) for norfloxacin (NOR) removal. The preparation conditions were optimized by single factor experiments and response surface methodology. A series of characterization analyses were carried out on the morphology, structure, and properties of Fe3O4/CS-P(AM-SSS), verifying that Fe3O4/CS-P(AM-SSS) was successfully prepared. Batch adsorption experiments showed that NOR was efficiently removed by Fe3O4/CS-P(AM-SSS), with a broad pH applicability of 3–10, short adsorption equilibrium time of 60 min, maximum adsorption capacity of 268.79 mg/g, and high regeneration rate of 86% after eight adsorption-desorption cycles. Due to the three-dimensional network structure and abundant functional groups provided by modified chitosan polymer, the superior adsorption capability of Fe3O4/CS-P(AM-SSS) was achieved through electrostatic interaction, π-π stacking, hydrophobic interaction, and hydrogen bonding. Adsorption process was exothermic and well fitted by the pseudo-second-order kinetic model and the Langmuir isothermal model. The presence of cations had a slight inhibitory effect on NOR adsorption, while humic acid nearly had no effect. In model swine wastewater, 90.3% NOR was removed by Fe3O4/CS-P(AM-SSS). Therefore, with these superior characteristics, Fe3O4/CS-P(AM-SSS) was expected to be an ideal material for treating NOR-containing wastewater in the future.