Langmuir Isotherm Research Articles

Production of N–Mg doped biochars for phosphate adsorption from renewable sources

It is crucial for the environment, the economy, and society to create low-cost adsorbents from renewable resources to remove phosphate from aqueous effluents. Here, two renewablecarbon and nitrogen sources (Douglas fir and Chitosan) were used to produce engineered N-doped biochars modified with Mg for PO43− adsorption. Mg–N doped biochars were prepared using an impregnation-carbonization process. A central composite experimental design was used to select combinations of independent variables to maximize phosphate adsorption capacity. Phosphate adsorption isotherms were fitted with Langmuir and Freundlich isotherms. The biochar produced at 700 °C, 12 wt % MgCl2, and Douglas Fir/Chitosan ratio: 1/1, which has the highest PO43− adsorption capacity, was further studied. Proximate analysis, elemental composition, surface area, pore size distribution, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and Scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM-EDX) were used to characterize this biochar. This biochar has an adsorption capacity of 112.4 mg PO43−/g char. Its phosphate adsorption rate was adjusted to a pseudo-second-order kinetic model. The phosphate adsorption capacity of the biochar produced was comparable with the most effective biochar reported in the literature.

One-pot synthesis of novel polyvinylphosphonic acid hydrogels for efficient separation of low-enriched uranium in water

Uranium extraction from seawater and the treatment of radioactive wastewater has traditionally been a hot topic. Herein, p(VPA-AM)n solid hydrogels with high uranium extraction properties based on vinylphosphonic acid (VPA) were successfully prepared by one-step copolymerization for the first time. The batch adsorption experiments demonstrated that p(VPA-AM)n has strong uranium chelating ability, fast uranium adsorption kinetics (within 200 min) and high uranium adsorption capacity (644.67 mg/g), and its adsorption behavior conforms to the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model, which is a spontaneous heat-absorbing chemical monolayer adsorption process. After 15 adsorption–desorption tests, the adsorption capacity was kept above 96 % of the original capacity, and the uranium extracted from the salt lake water achieved at 3.56 mg/g, which showed superb behavior in treating complex uranium systems. Mechanism studies revealed that the strong interaction between UO22 + and −PO43- dominated the adsorption and the robust complexation might have led to the electron transfer in the structure. The maximum uranium removal rate of p(VPA-AM)n in simulated seawater reached 90 %, and the simple in situ zinc oxide-modified p(VPA-AM)n hydrogel showed good anti-biosludge properties against three common bacteria (E. coli, B. subtilis and S. aureus), which has a great potential for application in seawater uranium extraction and uranium wastewater treatment.

ZIF-67 loaded thio-groups modified chitosan hydrogel for high efficient Hg(II) removal from water

In the past few years, there has been an increasing worry about the pollution of water caused by the presence of heavy metals. To address this environmental issue, a highly effective adsorbent called ZIF-67/CS-SH was developed. This adsorbent was prepared by grafting thioglycolic acid and loading a metal-organic framework called ZIF-67 onto chitosan, to remove Hg(II) from water. Confirmation of the ZIF-67/CS-SH was achieved by employing a range of techniques including FTIR, XRD, TGA, SEM, EDS, BET, and XPS. Due to the presence of abundant active sites (-SH, O/N-containing functional groups) and ZIF-67, ZIF-67/CS-SH exhibited a high adsorption capacity (949 mg/g at 298 K) and rapid adsorption kinetics (20 min for 91 % removal). The optimal pH for the adsorption process was found to be 5. The adsorption process followed a pseudo-second-order kinetics and Langmuir isotherm, with chemisorption being the main adsorption mechanism. The adsorption process was determined to be spontaneous and endothermic. Additionally, ZIF-67/CS-SH demonstrated selective adsorption in the presence of other metal cations at concentrations of 100 mg/L. Furthermore, ZIF-67/CS-SH exhibited excellent regenerative properties, with only a 10 % decrease in adsorption capacity after ten cycles. The key adsorption sites were identified as the –SH groups, O/N-containing functional groups, and ZIF-67 in ZIF-67/CS-SH through FTIR, EDS, and XPS analyses. Considering its outstanding performance in removing Hg(II), ZIF-67/CS-SH shows promise for application in industrial wastewater treatment.

Exploring the structural characteristics and dye removal capabilities of powder-, granule- and film- shaped magnetic activated carbon derived from Oleaster seed.

Dye pollution in water caused by excessive discharge of industrial effluent has become a major environmental problem in recent decades because of its irreversible effects on human health. In this study, low-cost carbon-based adsorbents synthesized from Oleaster seed (OS) were prepared in three forms of powder (PAC), film (FAC), and granule (GAC) and used for the removal of methylene blue dye. The properties of the synthesized adsorbents were characterized by SEM-EDX, BET, XPS and FTIR analyses. The maximum adsorption capacity (qmax) of PAC, FAC, and GAC adsorbents were obtained as 68.49, 32.25, and 15.10 mg/g, respectively at the optimum experimental conditions of pH = 10, adsorbent dosages of 0.5, 1, and 2 g/l, contact times of 60, 90, and 120 min, dye concentration of 10 mg/L, and temperature of 25°C. The Langmuir isotherm well described the equilibrium data for all three adsorbents. The pseudo-second-order kinetic model provided the best fit with the adsorption data obtained from all three adsorbents. Adsorption occurred spontaneously through a combination of chemical and physical mechanisms, with a thermodynamically exothermic process. The desorption experiments demonstrated that all the adsorbents have substantial potential for recovery. The novel activated carbon/alginate composite films are proposed as more promising biosorbents to remove MB dye from the aquatic environment compared to GAC adsorbents.

Fabrication of melamine formaldehyde/graphene oxide composite for efficient static and dynamic adsorption of lead ions from aqueous medium.

The present work discusses the synthesis, characterization, and environmental applications of graphene oxide (GO), melamine formaldehyde resin (MF), and melamine formaldehyde/graphene oxide composite (MGO) for the efficient removal of Pb2+ from aqueous medium via batch and column procedures. TGA, XRD, TEM, zeta potential, nitrogen adsorption/desorption, ATR-FTIR, and other characterization techniques revealed that MGO is characterized by a greater surface area (609 m2/g), total pore volume (1.0106 cm3/g), pHPZC (6.5), and the presence of various surface chemical functional groups. The synthesized solid adsorbents were used in both static and dynamic adsorption processes to remove Pb2+, with varying application parameters such as pH, starting concentration, adsorbent dosage, and shaking time in the case of static adsorption method. While through the column adsorption process the effects of column bed height, flow rate, and starting Pb2+ were taken into consideration. Results of the batch adsorption demonstrated that MGO had the highest Langmuir adsorption capacity (201.5 mg/g), and the adsorption fit the nonlinear Langmuir adsorption model and Elovich kinetic models. The adsorption of Pb2+ onto all prepared solid materials is endothermic, spontaneous, and physical in nature, as demonstrated by thermodynamic studies. Column adsorption of Pb2+ well fitted by Thomas and Yoon Nelson nonlinear adsorption models. MGO showed a maximum column adsorption capacity of 168 mg/g when applying 4 cm, 15 mL/min, and 150 mg/L as bed height, flow rate, and initial Pb2+, respectively. With only a 12.6% reduction in its adsorption capacity, column regeneration showed that MGO exhibited a high degree of reusability even after five cycles of adsorption/desorption studies.

Comparative adsorption of cationic and anionic dye by using non-activated Black Plum seed biochar for aquatic phase: Isotherm, kinetic and thermodynamic studies

Industrial dye effluents play a major role in water pollution. Textile and leather industries are one of the important sectors that pollute the water by discharging many harmful cationic and anionic dyes during the dyeing process. This study aims to compare the dye removal efficiency of Black Plum seed biochar for the cationic and anionic dyes. The non-activated biochar was prepared through pyrolysis of Black Plum seed powder at 5700 C. The sample's surface chemistry was understood using various characterization techniques like Field Emission Scanning Electron Microscopy (FESEM), Energy-dispersive X-ray spectroscopy (EDS), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), Raman-Spectroscopy and Zeta-potential. The experiments were successfully performed by conducting a batch adsorption study at different parameters such as pH, concentration, contact time and temperature. The coefficients of different isotherms and kinetics models were evaluated for non-linear study and the thermodynamic model was also applied. The maximum adsorption capacity was obtained as 42.39 mg/g for Crystal Violet (CV) dye and 6.22 mg/g for Eosin Blue (EB) dye by using the Langmuir isotherm model. Hence, the Black Plum seed biochar (BPSB) has superior adsorption capacity for the cationic dye CV ( removal - 98%) as compared to the anionic dye EB ( removal - 65%) at optimum parameters. Therefore, it is concluded that the BPSB is a natural toxin-free biosorbent and it can be used for the remediation of dyes from industrial wastewater.

Aqueous removal of Cr(VI) by Citrus sinensis juice-coated multi-walled carbon nanotubes

A novel adsorbent was prepared from multi-wall carbon nanotubes (MWCNTs) and Citrus sinensis juice extract-modified MWCNTs (OJMW) and characterized using scanning electron microscopy (SEM), Fourier transform infrared spectra (FTIR), X-ray diffractometer (XRD), BET and thermogravimetric analysis. The results showed that the nanotubes exhibited good surface area, pore size, functional groups, and robust stability at elevated temperatures (308 and 313 K). The adsorbent was applied in water for the sequestration of Cr(VI). The adsorption of Cr(VI) on MWCNTs and OJMW was influenced by factors of adsorption. Optimum removal of Cr(VI) was attained at 180 min contact time, 0.05 g adsorbent dose, and solution pH 2 for MWCNTs and OJMW. The kinetic behaviour of the Cr(VI) adsorption onto MWCNTs and OJMW was governed by the pseudo-first-order and pseudo-second-order kinetic model, respectively. The equilibrium data obtained for the uptake of Cr(VI) onto MWCNTs and OJMW fitted satisfactorily with Freundlich and Langmuir isotherm models, respectively. Meanwhile, MWCNTs and OJMW exhibited monolayer adsorption capacities (qmax) of 44.72 and 12.26 g g−1, respectively, at 298 K. The adsorption process was spontaneous and feasible. The direction of energy flow in the uptake of Cr(VI) onto OJMW and MWCNTs followed endothermic and exothermic adsorption processes, respectively. The adsorption–desorption experiments showed that OJMW had good regenerative abilities.

Efficient wastewater decontamination using magnetic bentonite-alginate beads: A comprehensive study of adsorption dynamics, regeneration, and molecular interactions

This study enhances wastewater treatment methodologies by developing magnetic bentonite-alginate beads (MBent-A beads) for adsorbing methylene blue (MB) from aqueous solutions. Experimental and computational analyses were employed to evaluate the beads' adsorption efficiency, utilizing characterization techniques including Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), point of zero charge (pHpzc), Brunauer-Emmett-Teller method (BET), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) to examine the composite’s morphology and chemistry. Findings reveal a significant adsorption capacity with the beads' specific surface area at 3.94 m2/g and a maximum adsorption capacity of 774.32 mg/g. Adsorption kinetics adhered closely to the pseudo-second-order model, indicating a rapid adsorption process, while Langmuir isotherm analysis confirmed a uniform monolayer adsorption and temperature-dependent capacities. Thermodynamic analysis showed the adsorption process to be spontaneous and exothermic, reflecting a strong affinity between MB molecules and the bead surface. The beads demonstrated durability with more than 90% removal efficiency after five regeneration cycles, highlighting a minimal decrease from 98.54% to 90.60%. In-depth theoretical investigations using density functional theory (DFT), frontier molecular orbital (FMO), reduced density gradient (RDG), and quantum theory of atoms in molecules (QTAIM) analyses identified van der Waals forces and hydrogen bonding as primary interactions driving the adsorption. The synthesis of MBent-A beads and their confirmed efficacy in dye adsorption integrates experimental research with theoretical modeling, offering a robust solution for treating dye-contaminated wastewater and underlining the potential of MBent-A beads in environmental remediation.

Unleashing the potential of Cajanus cajun biochar polymer composite for Cu (II) removal: mechanism, modification, and application.

This study introduces a cost-effective approach to fabricating a porous and ionically surface-modified biochar-based alginate polymer networks composite (SBPC) through air drying. The study critically analyzes the role and concentrations of various components in the success of SBPC. Characterization techniques were employed to evaluate the microstructure and adsorption mechanism, confirming the ability of the adsorbent's carboxyl and hydroxyl groups to eliminate various heavy metal ions in water simultaneously. The SBPC demonstrated high copper binding capacities (937.4mg/g and 823.2mg/g) through response surface methodology (RSM) and column studies. It was also influential in single and natural systems, exhibiting competitive behavior and efficient removal of Cu2+. The Langmuir isotherm and pseudo-second-order kinetics strongly correlate with experimental data, with R2 values of 0.98 and 0.99, respectively. SBPC showed remarkable stability, up to 10 desorption cycles, and achieved 98% Cu2+ adsorption efficiency and 91.0% desorption. Finally, the cost analysis showed a cost of 125.68 INR/kg or 1.51 USD/kg, which is very low compared to the literature. These results highlight the potential of SPBC and show that it provides an efficient and cost-effective solution for removing Cu2+ from a real system.

Greenly synthesised novel microporous ZnO/GO for adsorption of methyl orange and malachite green

ABSTRACT This study presents a greenly synthesised novel nanocomposite composed of Zinc Oxide (ZnO) and Graphene Oxide (GO) for the adsorption of dyes from aqueous solutions. The nanocomposite was synthesised using algae thus representing a green and eco-friendly method, ensuring minimal environmental impact. The physical characterisation of zinc oxide and graphene oxide nanocomposite (ZnO/GO) was done using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FT-IR), Zeta Potential, and Particle Size Analyzer (PSA). The pore diameter of the ZnO/GO was 1.801 nm, and its total surface area was 54.062 m2/g. The nanocomposite’s adsorption performance was systematically investigated through batch adsorption experiments. With an adsorption efficiency of 296.73 mg/g and 259.74 mg/g for MO and MG, the Langmuir isotherm model outperforms the Freundlich isotherm model in terms of adsorption. The pseudo-second-order model having an R2 value of 0.99 for both MO and MG, offers a more convincing explanation of adsorption than the pseudo-first-order model. The results demonstrated rapid adsorption kinetics and high adsorption capacities for both cationic and anionic dyes. Additionally, the ZnO/GO has a high reusability without significant degradation. The sustainable nature of the nanocomposite was emphasised by its efficient dye removal, reusability, and minimal secondary waste generation.

Modified powder of Corchorus capsularis as a new adsorbent for removal of tetracycline group antibiotic from water

AbstractThis study prepared a novel adsorbent from Corchorus capsularis modified powder for the removal of the tetracycline group (tetracycline ‐TC, oxytetracycline ‐OTC, chlortetracycline ‐CTC) in aqueous solution. Corchorus capsularis powder was pre‐treated with 15% sodium hydroxide (COC), then reformed by a mixture of 0.15 mol L−1 sodium bisulfide (SB) and 0.2 mol L−1 ammonium peroxydisulfate (APS). This adsorbent was embedded with monoacrylamide (AM) at ratio AM/COC = 1/1 at 60 °C for 2.5 h. After modification with AM (BTA), the surface area of the adsorbents increased from 1.53 to 2.79 m2 g−1, while the pore size of the adsorbents decreased from 36.95 to 11.85 nm. The study also investigated the effects of pH, adsorbent dose and temperature on the adsorptive removal process. Tetracycline concentrations were determined using liquid chromatography–tandem mass spectrometry (LC–MS/MS). The kinetics and isotherms of adsorption performance were examined using a variety of models, including pseudo‐first‐order kinetic (PFO), pseudo‐second‐order kinetic (PSO), Freundlich, Langmuir, and Dubinin–Radushkevich isotherms (DRM). The experimental data fitted very well with the pseudo‐second‐order kinetic model. The maximum adsorption bulks of TC, OTC, CTC following Langmuir isotherm model were 1.25, 0.83, 1.43 mg g−1, respectively. The adsorption constants Kp of TC, OTC, and CTC from the Freundlich isotherm model were 15.36, 21.80, and 22.08 mg1−nLng−1, respectively. The mean free energy E (kJ mol−1) of TC, OTC, and CTC from DRM was 4.35, 4.20, and 4.57, respectively. The results indicated that modified Corchorus capsularis powder had significant potential as a new adsorbent material for removing antibiotics from aqueous solutions.

A Sustainable Approach for Enhancing Cationic Dyes Adsorption in Single and Multiple Systems using Novel Nano Ferrites Modified with Walnut Shell

AbstractWalnut shell has been used in various experimental studies for different dyes removal, but it is exciting to study the adsorption behaviour of bio‐waste (walnut shell) in combination with spinel zinc ferrite which resulted in the formation of a novel material having magnetic properties and help in easy separation after the wastewater treatment. Novel magnetic walnut shell zinc ferrite (WSZF) composite has been synthesized and used to remove Malachite Green and Methylene Blue from aqueous solution in single and binary dye systems. Different techniques have been used to characterize the composite such as Fourier Transform Infrared Spectroscopy, X‐Ray Diffraction, Field Emission Scanning Electron Microscopy, Energy Dispersive Spectroscopy, Thermogravimetric Analysis and pHzpc. Adsorption of dyes were studied to see the effect of time, pH, adsorbent dose, dye concentration and temperature. The Lagergren pseudo second order model fitted well among various kinetic models employed. Langmuir adsorption isotherm best fitted with maximum adsorption capacities of 86.20 and 169.5 mg/g in single dye and 23.92 and 18 mg/g respectively in binary dye system for Malachite Green and Methylene Blue. Process was spontaneous and ΔH° were found positive, confirmed endothermic process of adsorption. The composite‘s regeneration capacity was studied for five cycles and at the end of five cycle the efficiency of the material was found to be around 80 % for both single as well as binary dye systems. It is concluded that the chosen WSZF will be the optimum solution for cationic dyes removal.

Chitin extraction from crab shells and synthesis of chitin @metakaolin composite for efficient amputation of Cr (VI) ions

The present research study combines chitin from shrimp waste with the oxide-rich metakaolin. Metakaolin is a blend of mixed oxides rich in silica and alumina with good adsorbent properties. The chitin@metakaolin (CHt@M.K.) composite was synthesized and characterized using FTIR, SEM, TGA, XRD and XPS techniques. Cr(VI) removal studies were compared for chitin and CHt@M.K. through adsorption. It was found that the adsorption capacity of CHt@M.K. is 278.88 mg/g, almost double that of chitin, at pH 5.0 in just 120 min of adsorption. Isotherm models like Langmuir, Freundlich, Temkin and Dubinin–Radushkevich were investigated to comprehend the adsorption process. It was revealed that Langmuir adsorption isotherm is most suitable to elucidate Cr(VI) adsorption on CHt@M.K. The adsorption kinetics indicate that pseudo first order was followed, indicating that the physisorption was the process that limited the sorption process rate. The positive enthalpy change (20.23 kJ/mol) and positive entropy change (0.083 kJ/mol K) showed that the adsorption process was endothermic and more random at the solid-liquid interface. The negative free energy change over entire temperature range was an indicator of spontaneity of the process. Apart from all these, the non-covalent interactions between Cr(VI) and composite were explained by quantum calculations based models.

Evaluation of inhibition performance of methylimidazolium ionic liquids on surface of mild steel in sulfuric acid

In the present study, the microwave irradiation approach was used to synthesize two methylimidazolium-based ionic liquids (MImILs), specifically 1-Heptyl-3-methylimidazolium bromide [HMImBr] and 1-Benzyl-3-methylimidazolium bromide [BzMImBr]. Several spectroscopic methods have been used to characterize the produced compounds. Gravimetric and electrochemical techniques were employed to examine their ability to prevent corrosion of the mild steel in a 0.5 M sulfuric acid solution. Amongst all the evaluated ionic liquids, [BzMImBr] having an aromatic ring instead of hexyl ((–CH2)5–CH3) hydrocarbon of [HMImBr] manifests better inhibition efficiency of 95.49 % at 1000 ppm concentration. The experimental ionic liquids negatively impact both the anodic and cathodic Tafel reactions, exhibiting mixed-type inhibition properties, as demonstrated by the findings of the potentiodynamic polarization investigations. Through their adsorption employing their electron-rich centres, the examined ionic liquids create a corrosion-protective covering, and their adsorption follows the Langmuir isotherm model. Negative values of ΔGads indicate the spontaneous nature of [HMImBr] and [BzMImBr] adsorption, whereas values between −20 and −40 KJ mol−1 indicate the physio-chemisorption mode of adsorption. Energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and field emission-scanning electron microscopy (FE-SEM) techniques were used to assess and evaluate surface morphology. The DFT-based analysis indicates that aromatic rings played a significant role in the charge sharing (donation and acceptance) in [BzMImBr].

Advanced Pyrene Copolymer/rGO Hydrogels for Efficient Congo Red Removal from Aqueous Systems

AbstractThis study investigates the use of hydrogel semi‐interpenetrating polymer networks (semi IPN) as efficient adsorbents for removing the dye congo red (CR) from aqueous solutions. Specifically, three hydrogel semi IPN, namely AH0–AH2, were synthesized through redox polymerization of acrylamide, polyethylenimine, polyhydroxylethylmethacrylate and (pyren‐1‐yl)methyl methacrylate/2‐acrylamido‐2‐methylpropane‐1‐sulfonic acid copolymer (pyrene−AMPS) using a reduced graphene oxide (RGO)‐N,N’‐methylene‐bis(acrylamide) (MBA)‐based crosslinker (GABC). Results indicated that these hydrogels were efficient in removing CR at pH 6.73, with the adsorption behaviour conforming to the Langmuir isotherm. This suggests a monolayer adsorption pattern, indicating a chemical nature. Thermodynamic analysis supports the practical feasibility of this process. The negative Gibbs free energy of adsorption (ΔG̊) indicates that adsorption is spontaneous and favorable. Conversely, the positive standard entropy of adsorption (ΔS̊) suggests an increase in molecular randomness during the process. Additionally, the standard enthalpy change (ΔH̊) suggests an endothermic activation energy for the binding process. Response Surface Methodology (RSM), utilizing four variables was employed to optimize the removal of CR. The model demonstrated high R2‐values and strong agreement between experimental and projected results, affirming its reliability. AH1 and AH2 showed significant efficacy in removing CR dye from aqueous solutions, underscoring their potential application in wastewater remediation.

Adsorption of Diclofenac Sodium and Tetracycline From Aqueous Solution Using PVA Films Prepared with Modal/Cotton Fiber Wastes

AbstractIn this study, fiber‐polymer composite films were prepared by adding 0.5 g, 1.0 g, and 1.5 g of modal/cotton (50 : 50) waste to 10 % PVA film, and the properties of the films were revealed by SEM, FTIR analyzes and swelling percentage. It is observed that the strength of the bonds in the FTIR analysis decreases when modal/cotton fibers are added to the PVA film. While a 406 % swelling is achieved in the PVA film, the swelling percentages of the films decrease when modal/cotton fibers are added to the PVA film, and a greater swelling is observed at pH 9 compared to pH 5. The adsorption efficiency of tetracycline and diclofenac sodium on the films was researched at different pH levels and film doses. Tetracycline removal reached its highest value at pH 9, while diclofenac sodium removal reached its highest value at pH 5. Langmuir and Freundlich isotherm models were determined for tetracycline and diclofenac sodium adsorption. Tetracycline removal is better described by the Freundlich isotherm model, whereas diclofenac sodium removal fits the Langmuir isotherm model better. As a result, films prepared with modal/cotton waste not only provide tetracycline and diclofenac sodium removal but also contribute to waste recycling by utilizing waste fiber materials.

Consecutive high-performance removal of Cu2+ metal ions and Deltamethrin using multifunctional pyrolysis cuttlebone/cotton fabric nanocomposite

A simple technique was developed for the modification of cotton materials that is inexpensive, environmentally friendly, and very effective. Waste Cotton fabrics (WCFs) are loaded with propolis extract (PE) for Cu2+ removal. Then, Cu2+ underwent a pyrolysis process with modified cuttlebone (CB) at 900 °C for 5 h. The surface of the prepared materials was characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray (SEM-EDX), Fourier transform infrared (FTIR), BET, particle sizes, thermogravimetric analysis (TGA) and zeta potential analysis. The Cu2+ metal ions from an aqueous solution were removed using WCFs/PE, and DLM was subsequently removed using pyro WCFs/PE/Cu/CB. The as-prepared NPs exhibited the face-centered cubic structure of WCFs/PE/Cu/CB with crystallite sizes ranging from 386.70 to 653.10 nm. FTIR spectra revealed that CB was present on the surface of the resulting WCFs/PE/Cu. SEM revealed the dispersion of a uniformly flower-like morphology over a large area. Sorption studies were performed based on parameters that included pH, dose, contact time, and initial concentration. The adsorption isotherm and the kinetic studies of the DLM adsorption process were applied at a pH of 5.0 and a temperature of 25 °C using several isotherms and kinetic models. The results revealed qmax (20.51 mg/g) with R2 = 0.97, the Langmuir isotherm that best matches the experimental data. Hence, the Langmuir isotherm suggests that it is the model that best describes sorption on homogenous surfaces or surface-supporting sites with various affinities. The correlation coefficient R2, χ2, adjusted correlation coefficient, and error functions like root mean square (RMSE), normalized root mean square error (NRMES), and mean absolute error (MAE) were used to evaluate the best-fit models to the experimental adsorption data. Moreover, cost estimation for the prepared adsorbent WCFs/PE/Cu showed that it costs approximately 3 USD/g, which is a cheap adsorbent compared to other similar adsorbents reported in the literature. The examined WCFs/PE have significant applicability potential for Cu2+-laden wastewater treatment due to their superior Cu2+ metal ions adsorption capability and reusability.The cytotoxicity and safety study showed that at higher concentrations, it resulted in much less cell viability. Additionally, the removal efficiency of Cu2+ metal ions from synthetic, realistic industrial wastewater using WCFs/PE reached up to 96.29 %, demonstrating good adsorption capability. Thus, there is a huge possibility of accomplishing this and performing well. This study paves the way for the reuse and valorization of selected adsorbents following circular economy principles.Two green metrics were applied, the Analytical Eco-scale and the Analytical GREEnness Calculator (AGREE).

Synthesis of MgZnAl Layered Triple Hydroxide Nanoplates as an Efficient Adsorbent for Removing the Acid Yellow 76 Azo Dye

AbstractA simple hydrothermal method was employed for synthesizing MgZnAl layered triple hydroxide nanoplates (MgZnAl LTH) as an efficient adsorbent for removing the Acid Yellow 76 (AY76) azo dye. A batch process was used to perform adsorptions were and investigate the effects of experimental parameters including temperature, adsorbent dosage, solution pH. The best adsorption conditions obtained were pH of 4, MgZnAl LTH dosage of 20 mg and temperature of 55 °C. The kinetics of adsorption was studied using pseudo‐first‐order, pseudo‐second‐order, Elovich, and intraparticle diffusion models. To obtain equilibrium absorption data, Freundlich, Langmuir, and Temkin isotherms were utilized. The findings showed that the adsorption data based on the experiment had a good agreement with the Freundlich model. The highest capacity of adsorption equal to 277.8 mg/g was obtained for the MgZnAl LTH nanoplates toward AY76. Thermodynamic results showed that the process of adsorption of AY76 onto MgZnAl LTH nanoplates had a spontaneous and endothermic nature.

Synthesis and characterization of selenium-polyvinyl alcohol nanoparticles as eco-friendly corrosion inhibitor for carbon steel in 1.0 M H2SO4

Selenium nanoparticles capped with polyvinyl alcohol (Se-PVA NPs) have been synthesized by chemical reduction using ascorbic acid as a reducing agent. The synthesized nanoparticles were characterized using XRD, DLS, zeta potential, FT-IR, and TEM analysis and found to be stable. The solution of Se-PVA NPs was used as a carbon steel corrosion inhibitor in 1.0 M H2SO4. The effect of the presence of Se-PVA NPs in the corrosion medium was studied by potentiodynamic polarization and gravimetric analyses In the presence of Se-PVA NPs with a concentration of 600 ppm at 303 K, corrosion inhibition efficiency values of 92.86 % and 92.3 % were recorded by potentiodynamic polarization and gravimetric analysis methods, respectively. Over the Se-PVA NPs concentration range 100–600 ppm, it was found that increasing the concentration increases the inhibition efficiency, while the temperature has an adverse effect, inhibition efficiency values of 80.0 % was recorded at 323 K for the 600 ppm Se-PVA NPs solution. The potentiodynamic polarization measurements suggested that Se-PVA NPs work as a mixed-type inhibitor. The corrosion inhibition process was confirmed by testing the used specimens’ metal surface using SEM and AFM techniques, which showed that the acidic medium’s negative impact (distortion and roughness) on the carbon steel surface was reduced significantly in the presence of Se-PVA NPs. The inhibitor’s adsorption on the metal surface was studied. It obeys the Langmuir isotherm with a mixed-type adsorption process. The related kinetic and thermodynamic parameters were investigated.

Adsorption Efficiency of Cadmium (II) by Different Alkali-Activated Materials.

The objective of this study was to demonstrate the potential utilization of fly ash (FA), wood ash (WA), and metakaolin (MK) in developing new alkali-activated materials (AAMs) for the removal of cadmium ions from waste water. The synthesis of AAMs involved the dissolution of solid precursors, FA, WA, and MK, by a liquid activator (Na2SiO3 and NaOH). In concentrated solutions of the activator, the formation of an aluminosilicate gel structure occurred. DRIFT spectroscopy of the AAMs indicated main vibration bands between 1036 cm-1 and 996 cm-1, corresponding to Si-O-Si/Si-O-Al bands. Shifting vibration bands were seen at 1028 cm-1 to 1021 cm-1, indicating that the Si-O-Si/Si-O-Al bond is elongating, and the bond angle is decreasing. Based on the X-ray diffraction results, alkali-activated samples consist of an amorphous phase and residual mineral phases. The characteristic "hump" of an amorphous phase in the range from 20 to 40° 2θ was observed in FA and in all AWAFA samples. By the XRD patterns of the AAMs obtained by the activation of a solid three-component system, a new crystalline phase, gehlenite, was identified. The efficiency of AAMs in removing cadmium ions from aqueous solutions was tested under various conditions. The highest values of adsorption capacity, 64.76 mg/g (AWAFA6), 67.02 mg/g (AWAFAMK6), and 72.84 mg/g mg/g (AWAMK6), were obtained for materials activated with a 6 M NaOH solution in the alkali activator. The Langmuir adsorption isotherm and pseudo-second kinetic order provided the best fit for all investigated AAMs.