Langmuir-Freundlich Isotherm Research Articles

Highly selective and reusable nano adsorbent based on Fe3O4-embedded sodium alginate-based hydrogel for cationic dye adsorption: Adsorption interpretation using multiscale modeling.

This study aims to develop a stable and efficient magnetic nanocomposite hydrogel (MNCH) for selective removal of methylene blue (MB) and crystal violet (CV). MNCHs with different Fe3O4 contents (0-9 wt%) were synthesized following graft co-polymerization method using sodium alginate, acrylamide, itaconic acid, ammonium persulfate and N,N-methylene bisacrylamide. Among them, MNCH5, with 5 wt% Fe3O4, showed highest removal efficiency (>95 %). Optimal dye removal occurred at pH 10, with 40 min for CV and 60 min for MB using 30 mg dose. MNCH was characterized using various techniques, with X-ray diffraction (XRD) revealing crystallite size of 30.5 nm, and Brunauer-Emmett-Teller (BET) indicating surface area of 59.80 m2.g-1. Adsorption kinetics followed fractal pseudo-first-order and fractal Vermeulen diffusion models, reflecting MNCH's heterogeneous nature as suggested by fractal exponent (h) ranging 0.38-0.44, significantly deviating from zero. Langmuir-Freundlich isotherm accurately described the process, demonstrating MNCH's superior affinity for MB (4216.69 mg.g-1) over CV (3730.17 mg.g-1). Thermodynamics of MB adsorption was exothermic as suggested by negative ΔH value, while CV adsorption was endothermic. Density functional theory confirmed stronger interaction between MNCH and MB (Eads = -49.29 kcal.mol-1) compared to CV (Eads = -41.30 kcal.mol-1). These findings underscore MNCH's excellent adsorption capacity, making it promising for removing dyes.

Conjugated hypercrosslinked polymers for in situ imprinting, selective sorption, and fluorescent turn-on sensing of oxalic acid.

Hypercrosslinked polymer (HCP) is a subclass of porous organic polymer possessing abundant microporosity, tailor-made functionality, and excellent stability. It features low-cost and easily direct knitting synthesis, facilitating the construction of π-conjugated frameworks with fluorescent properties by properly selecting building blocks (BBs) and linkers. Simultaneous imprinting of target molecules into the conjugated HCPs will create selective sorbents and sensors. We prepared several BBs to be polymerized with a terephthaloyl chloride (TCL) linker through Friedel-Crafts acylation in the presence of some imprinting molecules to clarify the best collocation for the advancement of imprinted polymer. With the highest increase in fluorescence intensity (F), the conjugated HCP comprised of dibenzofuran (DBF) and TCL was selected as contact with oxalic acid (OA). The OA-imprinted DBF-TCL (MICHP) was characterized by FTIR-approved structures, amorphous SEM images, TGA degradation at 390°C, blue-shift emission, prolonged lifetime, and aggregation-caused quenching. The increase in F was proportional to OA concentration (0.17-20.0μM, RSD = 1.6%, LOD = 0.03μM) in THF/H2O (pH 7.0) containing MICHP (0.2mg/3mL) and 6.0min equilibrium. The F increase arose from inhibiting the quenching of photo-induced electron transfer because of protonation and association of OA with imprinted cavities. Langmuir-Freundlich isotherm precisely modeled the imprinted cavity affinity for OA with binding sites of 114.5μmol/g and heterogeneity of 0.939. The cavities distinctly recognized OA and malonic acid interferant, presenting imprinting factor (4.76 vs. 1.35), specific sorption ratio (79.0% vs. 25.7%), and relative selectivity coefficient (3.935 vs. 0.779), which sustained the precise measurements of OA in tomato, taro, and urine. This study approved a cheap and easy strategy to implant fluorescent and imprinting functions in HCPs using as sorbent and sensor through Friedel-Crafts acylation of electrophilic crosslinker and nucleophilic BB, especially those with heterocyclics.

Tailoring of carboxymethyl guar gum hydrogels via gamma irradiation for remarkable removal of cationic and anionic dyes from simulated solutions

Tailoring of carboxymethyl guar gum hydrogels via gamma irradiation for remarkable removal of cationic and anionic dyes from simulated solutions

Efficient removal of Congo red from aqueous solutions using calcined and uncalcined MgZnFe ternary layered double hydroxide (LDH)

This study investigates the textile industries' dye Congo-red removal from aqueous solution using the calcined and uncalcined [Mg0.52+Zn0.252+Fe0.253+(OH)2].(CO32−)0.125.H2O ternary layered double hydroxide (LDH). XRD confirms the successful formation of the crystalline structure of LDH. FTIR analysis shows that the peak position at 1108 cm−1, which indicates the presence of S = O group. TEM analysis reveals the formation of a hexagonal shape morphology, whereas BET measurements demonstrate an improvement in surface area after calcination. This study analyzed dye adsorption, which is affected by interaction time, solution pH, and adsorbent dosage. The adsorption data is analyzed using the Langmuir isotherm and Freundlich isotherm, while the kinetics data is analyzed using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The change in enthalpy (ΔH0) being positive and the change in Gibbs free energy (ΔG0) being negative designates that the adsorption process is endothermic and occurs spontaneously. The Langmuir isotherm model analyzed the adsorption isotherm data and calculated the amount of adsorbate adsorbed by adsorbent. The maximum amount of Congo-red adsorbed by calcined and uncalcined layered double hydroxide are 205.76 and 89.76 mg g-1. These results suggested that calcined layered double hydroxide is a significant adsorbent for removing effluents from wastewater.

Kinetic investigation of dry reforming of methane reaction over Ni–Rh/ZrO2–Al2O3 catalyst using Langmuir-Freundlich isotherm

The study involved conducting kinetic measurements for the dry reforming of methane (DRM) over a Ni–Rh/Al2O3 (85%)-ZrO2(15%) catalyst under a wide range of operating conditions (temperature: 500–900 °C, total flow rate of the inlet feed: 50–100 mL/min). The support material was prepared using the sol-gel method, followed by impregnation of Ni–Rh catalyst on the incipient wetness of the Al2O3–ZrO2 support. The calcined, reduced and spent samples were characterized by X-ray diffraction (XRD), thermal gravimetric analysis (TGA), inductively coupled plasma atomic emission spectrometer (ICP-AES), N2 adsorption/desorption and CHNS analyzer, and tested for activity, yield and stability in DRM reaction. Furthermore, kinetic behavior of Ni–Rh/Al2O3–ZrO2 catalyst in DRM process was investigated by assuming DRM and reverse water-gas shift (RWGS) reactions take place on two kinds of different active sites. Experimental data were fitted using rate expressions based on the Langmuir-Freundlich (LF) isotherm for DRM and RWGS reactions. The activation energy for the DRM reaction was optimized at 43.62 kJ/mol, falling within the reported literature range of 24.73–108.9 kJ/mol. Statistical indices indicated that the kinetic model accurately predicted CO2 conversion compared to other responses, with an error of 12.054%. The computed and experimental trends for CH4 and CO2 conversions, H2 and Co yield in terms of temperature were similar with each other and the difference between the calculated and experimental trends was lower for conversions compared to yields.

Thermally Driven Catch-and-Release of CoCl2.

A heat-driven catch-and-release strategy for CoCl2 capture is described. It is based on the use of an immobilized neutral dicyclohexylacetamide-based receptor L supported on polystyrene (PS-L). An X-ray diffraction analysis of a single crystal of L·CoCl2 revealed an ion-pair complex comprising a hexacoordinated cobalt cation [L·Co]2+ and a tetrachlorocobaltate anion [CoCl4]2-. Temperature dependent binding was seen, as inferred from UV-vis spectroscopic studies. Fits to the van't Hoff equation yielded values of ΔH° = 12.4 kJ/mol and ΔS° = 56.0 J/K·mol for L + CoCl2, and ΔH° = 16.5 kJ/mol and ΔS° = 85.0 J/K·mol for PS-L + CoCl2 in 95% ethanol. Consequently, cobalt capture and release are mediated by heating and cooling, respectively. The material PS-L exhibits a preference for binding cobalt over manganese and nickel as inferred from Langmuir-Freundlich isotherm analyses that revealed binding constants of KLF = 88.5 M-1 for CoCl2, 52.7 M-1 for MnCl2, and 49.7 M-1 for NiCl2. In a simulated ion mixture containing equimolar CoCl2, MnCl2, and NiCl2, ICP-MS analyses served to confirm that cobalt was selectively enriched to 52 mol % (from an initial level of ca. 32 mol %) after one catch-and-release cycle and 76.6% after three cycles. Our experimental results were validated by density functional theory calculations, which also show stronger binding of Co over Mn and Ni to L.

Response surface methodology optimization of sodium diclofenac adsorption using activated carbon derived from falcata tree sawdust

The presence of sodium diclofenac in water is a significant problem due to its adverse effects on terrestrial and aquatic organisms. Thus, this study investigated the Falcata tree sawdust as the precursor of activated carbon for the adsorption of diclofenac in an aqueous solution. The characterization of falcata tree sawdust-activated carbon (FTSAC) was evaluated by SEM and FTIR analysis. The activated falcata sawdust converted to activated carbon has a 30 % yield. The optimal values for the operating parameters, FTSAC dosage, initial sodium diclofenac concentration, reaction time and pH, were determined using the central composite design (CCD) of the response surface methodology (RSM). The optimal removal efficiency suggested by CCD is 93.98 % with the optimum conditions of parameters of 0.80 g FTSAC dosage, 200 ppm initial sodium diclofenac concentration, 20 min reaction time, and pH 4. These optimal values of parameters were validated by an actual experiment, and the result (average removal efficiency: 92.08 %) is within a 95 % confidence interval. On the other hand, the pseudo-second-order (R2 = 0.9991) kinetic model depicts the rate of absorption of FTSAC adsorbing SD. Moreover, the Langmuir-Freundlich isotherm or Sips isotherm model (R2 = 0.9904) is the best-fit model that describes the heterogeneous adsorption dynamics of FTSAC surfaces. This study indicates that falcata sawdust can serve as a promising and viable alternative raw material to produce activated carbon.

Linear and nonlinear regression modelling of industrial dye adsorption using nanocellulose@chitosan nanocomposite beads

Nanocellulose@chitosan (nc@ch) composite beads were prepared via coagulation technique for the elimination of malachite green dye from aqueous solution. As malachite green dye is highly used in textile industries for dyeing purpose which after usage shows fatal effects to the ecosystems and human beings also. In this study the formulated nanocellulose@chitosan composite beads were characterized by Particle size analysis (PSA), Field emission scanning electron microscopy (FESEM), Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis were done to evaluate nanoparticles size distribution, morphological behaviour, functional group entities and degree of crystallinity of prepared beads. The nanocomposite beads adsorption performance was investigated for malachite green (MG) dye and BET analysis were also recorded to know about porous behaviour of the nanocomposite beads. Maximum removal of malachite green (MG) dye was found to be 72.0 mg/g for 100 ppm initial dye concentration. For accurate observations linear and non-linear modelling was done to know about the best-fitted adsorption model during the removal mechanism of dye molecules, on evaluating it has been observed that Langmuir isotherm and Freundlich isotherm show best-fitted observation in the case of linear and non-linear isotherm respectively (R2 = 0.96 & R2 = 0.957). In the case of kinetic linear models, the data was well fitted with pseudo-second-order showing chemosorption mechanism (R2 = 0.999), and in the case of non-linear kinetic model pseudo first order showed good fit showing physisorption mechanism during adsorption (R2 = 0.999). The thermodynamic study showed positive values for ΔH° and ΔS° throughout the adsorption process respectively, implying an endothermic behaviour. In view of cost effectiveness, desorption or regeneration study was done and it was showed that after the 5th cycle, the removal tendency had decreased from 48 to 38 % for 20–100 ppm dye solution accordingly. Thus, nanocomposite beads prepared by the coagulation method seem to be a suitable candidate for dye removal from synthetic wastewater and may have potential to be used in small scale textile industries for real wastewater treatment.

Ciprofloxacin Removal via Acid-Modified Red Mud: Optimizing the Process, Analyzing the Adsorption Features, and Exploring the Underlying Mechanism.

In this study, RM (red mud) was acidified with sulfuric acid, and the acidified ARM (acidified red mud) was utilized as an innovative adsorption material for treating antibiotic-containing wastewater. The adsorption conditions, kinetics, isotherms, thermodynamics, and mechanism of ARM for CIP (ciprofloxacin) were investigated. The characterization of the ARM involved techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), X-ray fluorescence (XRF), thermogravimetric analysis (TGA), and NH3-TPD analysis. Adsorption studies employed a response surface methodology (RSM) for the experimental design. The results showed that ARM can absorb CIP effectively. The RSM optimal experiment indicated that the most significant model terms influencing adsorption capacity were solution pH, CIP initial concentration, and ARM dosage, under which the predicted maximum adsorption capacity achieved 7.30 mg/g. The adsorption kinetics adhered to a pseudo-second-order model, while equilibrium data fitted the Langmuir-Freundlich isotherm, yielding maximum capacity values of 7.35 mg/g. The adsorption process occurred spontaneously and absorbed heat, evidenced by ΔGθ values between -83.05 and -91.50 kJ/mol, ΔSθ at 281.6 J/mol/K, and ΔHθ at 0.86 kJ/mol. Analysis using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) indicated a complex reaction between the Al-O in the ARM and the ester group -COO in CIP. The C=O bond in CIP was likely to undergo a slight electrostatic interaction or be bound to the internal spherical surface of the ARM. The findings indicate that ARM is a promising and efficient adsorbent for CIP removal from wastewater.

Adsorption of arsenic and fluoride: Modeling of single and competitive adsorption systems

The elevated co-occurrence of arsenic and fluoride in surface and groundwater poses risks to human health in many parts of the world. Using single and competitive batch equilibrium adsorption studies, this research focuses on As(V) and F adsorption by activated carbon and its modeling. BET, XRD, FESEM, EDS, and FTIR analysis were used to discern the structural characteristics of activated carbon. The influence of dosage, pH, and contact time were also investigated in single and simultaneous adsorption systems. The maximum adsorption capacity of activated carbon for arsenic and fluoride were found to be 3.58 mg/g and 2.32 mg/g, respectively. Kinetics studies indicated that pseudo-second-order kinetic model fit better than pseudo-first-order, Elovich, and intraparticle diffusion kinetic models. The non-linear regression analysis of Langmuir, Freundlich, Toth, Redlich Petersons, and Modified Langmuir Freundlich models was used to determine single-component asorption model parameters. Additionally, the simultaneous adsorption was rigorously modeled and compared using the Extended Langmuir (EL), Extended Langmuir Freundlich (ELF), Modified Competitive Langmuir (MCL), and Jeppu Amrutha Manipal Multicomponent (JAMM) isotherm models, and competitive mechanisms were interpreted for the simultaneous adsorption system. Further, the model performances were evaluated by statistical error analysis using the normalized average percentage error (NAPE), root mean square errors (RMSE), and the correlation coefficient (R2). According to the modeling results, single equilibrium data fitted better with the Modified Langmuir Freundlich isotherm model, with a higher R2 of 0.99 and lower NAPE values of 3.8 % and 1.28 % for As(V) and F, than other models. For the binary adsorption, the Extended Langmuir Freundlich isotherm model demonstrated excellent fit with lowest errors. All the competitive isotherm models fit the As(V) and F simultaneous sorption systems reasonably well. Furthermore, the research unveiled a nuanced hierarchy of isotherm fitting, with ELF > EL > MCL > JAMM in varying arsenic at a constant fluoride concentration, and ELF > JAMM > EL > MCL in varying fluoride at a constant arsenic concentrations. In addition, competitive studies divulged crucial insights into selective adsorption, as As(V) exhibits a pronounced adsorption selectivity over F on activated carbon. In essence, As(V) showed a more pronounced antagonistic behavior over F, whereas F exhibited a much lesser competitive behavior in the adsorption of arsenic.

Management of ibuprofen in wastewater using electrospun nanofibers developed from PET and PS wastes

Electrospinning is a promising technique for the beneficial use and recycling of plastic waste polymers using simple methodologies. In this study, plastic bottles and Styrofoam wastes have been used to develop polyethylene terephthalate (PET) and polystyrene (PS) nanofibers using electrospinning technique separately without any further purification. The effect of the concentration onto the nanofiber's morphology was studied. The fabricated nanofibers were characterized using Field Emission Scanning Electron Microscope (FE-SEM), Fourier Transformed Infrared Spectroscopy (ATR-FTIR), N2 adsorption/desorption analysis, and water contact angle (WCA). Furthermore, the prepared nanofibers were applied for the adsorption of ibuprofen (IBU) from wastewater. Some parameters that can influence the adsorption efficiency of nanofibers such as solution pH, wt.% of prepared nanofibers, drug initial concentration, and contact time were studied and optimized. The results show that the equilibrium adsorption capacity was achieved after only 10 min for 12 wt% PET nanofibers which is equivalent to 364.83 mg/g. For 12 wt% PS nanofibers, an equilibrium adsorption capacity of 328.42 mg/g was achieved in 30 min. The experimental data was fitted to five isotherm and four kinetics models to understand the complicated interaction between the nanofibers and the drug. Langmuir-Freundlich isotherm model showed the best fit for experimental data for both PET and PS nanofibers. The adsorption process was characterized by predominantly physical reaction rather than chemical adsorption for both materials. The reusability study revealed that the synthesized nanofibers maintain their ability to adsorb/desorb IBU for up to five cycles. The results obtained demonstrated that fabricated nanofibers from plastic wastes could perform promising adsorbents for the management of IBU in wastewater. However, further research is needed for the scaling-up the fabrication which is required for real-world applications.

Deciphering the mechanistic role of Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52) in bio-sorption and phyto-assimilation of Cadmium via Linum usitatissimum L. Seedlings

Three Cd2+ resistant bacterium's minimal inhibition concentrations were assessed and their percentages of Cd2+ accumulation were determined by measurements using an atomic absorption spectrophotometer (AAS). The results revealed that two isolates Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52), identified by 16S rDNA gene sequencing, showed a higher percentage of Cd2+ accumulation i.e., 83.78% and 81.79%, respectively. Moreover, both novel strains can tolerate Cd2+ levels up to 2000 mg/L isolated from district Chakwal. Amplification of the czcD, nifH, and acdS genes was also performed. Batch bio-sorption studies revealed that at pH 7.0, 1 g/L of biomass, and an initial 150 mg/L Cd2+ concentration were the ideal bio-sorption conditions for Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52). The experimental data were fit to Langmuir isotherm measurements and Freundlich isotherm model R2 values of 0.999 for each of these strains. Bio sorption processes showed pseudo-second-order kinetics. The intra-diffusion model showed Xi values for Bacillus paramycoides (PM51) and Bacillus tequilensis (PM52) of 2.26 and 2.23, respectively. Different surface ligands, was investigated through Fourier-transformation infrared spectroscopy (FTIR). The scanning electron microscope SEM images revealed that after Cd2+ adsorption, the cells of both strains became thick, adherent, and deformed. Additionally, both enhanced Linum usitatissimum plant seed germination under varied concentrations of Cd2+ (0 mg/L, 250 mg/L,350 mg/L, and 500 mg/L). Current findings suggest that the selected strains can be used as a sustainable part of bioremediation techniques.

Polymer-grade propylene production through temperature swing adsorption: Molecular simulation and techno-economic analysis

Producing polymer-grade propylene from the propylene-rich mixtures can be quite challenging since the most commonly employed technology, distillation, requires high-energy input and is expensive. Therefore, identifying less-costly, efficient, and environmentally friendly methods, such as the use of the adsorptive process, is highly desirable. In this regard, six pure silica zeolites (AFV, AST, AVL, IFR, LEV, and SWY) as propane selective adsorbents are investigated for the separation of 10 mol.% propane and 90 mol.% propylene mixture. Molecular simulation Monte Carlo (MC) is used to calculate framework structure parameters such as pore volume, surface area, and framework density of pure silica zeolites. Also, adsorption isotherms, propane selectivity, and working capacity are presented using MC calculations. The Langmuir-Freundlich isotherm model is utilized to calculate isotherm parameters. A system model is implemented in Aspen Adsorption software (version 11) and breakthrough curves are achieved. The Temperature Swing Adsorption (TSA) cycle is simulated and key performance parameters such as propylene purity, recovery, and productivity for all six silica zeolites are calculated. Finally, economic analysis of the TSA process is performed using the Aspen Capital Cost Estimator (version 11) and Aspen Process Economic Analyzer (version 11) and compared with the cost of the conventional distillation process. Results showed that the capital cost and operating cost of temperature swing adsorption are 42.3 % and 91.37 % less than those of distillation, respectively.

Facilely tuning the morphologies of tertiary amine-functionalized SBA-15 for optimizing selective SO2 capture

The amine-based materials pose high potential for the adsorption of sulfur dioxide (SO2). This work is aimed at modulating the morphologies of SBA-15 adsorbents by controlling the precursor self-assembly processes, for the sake of optimizing the utilization efficiency of amine species in the polytertiary amine (PTA)-functionalized SBA-15. It results that worm-like SBA-15 (WLS) material shows a better particle aspect ratio and well-defined pore structure, which helps to optimize the adsorption sites invoked by the preferable dispersion and exposure of PTA, thus amplifying the chemisorption of SO2 on the adsorbent. Consequently, the functionalized WLS-PTA adsorbent exhibits remarkable SO2 adsorption performance (15.43 mmol/g), exceptionally high selectivities of SO2/N2 (27522) and SO2/CO2 (652). Surprisingly, the desulfurization capacity can be further enhanced by the positive effect of the water vapor co-fed. It is unveiled that the whole SO2 adsorption process mainly follows the dual site Langmuir-Freundlich isotherm model and Bangham model. This work sheds light on the design of polymer-solid composite adsorbents for selective capture of SO2.

Treatment of acidic electroplating effluent from small scale industries using batch and continuous flow adsorption reactor

If electroplating effluent discharges aren’t properly treated, they have a detrimental effect on the aquatic ecology. The effluent characteristics comprise heavy metals that were toxic and causes carcinogenic effects. Among the conventional methods, adsorption being the most economically viable and technically straightforward. This study focuses on the removal of hexavalent chromium ion from the electroplating effluent using commercial activated carbon in both batch and continuous flow experiments. In column studies, various grades of commercial activated carbon were tested, with 80 × 200 mesh size yields complete Cr6+ removal. The batch study revealed that 83% removal was achieved at 5g of 80 × 200 mesh size activated carbon. The isotherm studies indicated a better fit with the Langmuir model and kinetics studies indicated pseudo-second order kinetics. Continuous flow experiments with an 80 × 200 mesh size activated carbon bed showed an upward trend in pH. However, Cr6+ removal efficiency decreased over time. UV–vis spectroscopy using the Diphenyl carbazide method confirmed Cr6+ concentrations. Morphological and elemental analyses were conducted using SEM and Edax, revealing significant changes before and after treatment. These findings underscore the effectiveness of activated carbon in mitigating the environmental impact of electroplating effluents, particularly in Cr6+ removal.

Adsorption Kinetics of Banana Stem Activated Carbon in Reducing Phosphate Levels

Introduction: High levels of phosphate in water are caused by wastewater pollution such as laundry waste water causing eutrophication. Adsorption is a method that can be used to reduce phosphate level. Banana stem that contains high levels of cellulose can be used as the main ingredient for making activated carbon. The aims of this study were to analyze the adsorption capacity and adsorption kinetics of banana stem activateld carbon in relducing phosphatel lelvells. Methods: The design of this research was true experiment with a pretest-posttest controlled group. Adsorption process was carried out with batch method that used three variations of adsorbate concentration and four variations of mixing time. Adsorption took place at pH 3 and 30 rpm of mixing time. Adsorption capacity was analyzed using the Langmuir isotherm and Freundlich isotherm models. Adsorption kinetic was analyzed using pseudo-first-order and pseudo-second-order kinetic models. Results and Discussion: The X-Ray Diffraction (XRD) difactogram and Scanning Electron Microscopy (SEM) results prove that the activateld carbon was successfully made. The iodine number of banana stelm activateld carbon was 698.12 mg/g. The results showed that activated carbon from banana stem successfully reduced phosphate levels in water with adsorption capacity 0.10708 mg/g and following the Langmuir isotherm model. The kinetics adsorption of banana stem activated carbon was validated by the pseludo-selcond-ordelr kinetics model with a kinetics constant of 0.17137 g/mg.min. Conclusion: The Langmuir models indicated that adsorption of phosphate occurred in monolayer. Modifications of activated carbon were needed based on characterization results.

Integrating DFT and machine learning for the design and optimization of sodium alginate-based hydrogel adsorbents: Efficient removal of pollutants from wastewater

This study presents a novel approach to design and optimize a sodium alginate-based hydrogel (SAH) for efficient adsorption of the model water pollutant methylene blue (MB) dye. Utilizing density functional theory (DFT) calculations, sodium alginate-g-poly (acrylamide-co-itaconic acid) was identified with the lowest adsorption energy (Eads) for MB dye among 14 different clusters. SAHs were prepared using selected monomers and sodium alginate combinations through graft co-polymerization, and swelling studies were conducted to optimize grafting conditions. Advanced characterization techniques, including FTIR, XRD, XPS, SEM, EDS, and TGA, were employed, and the process was optimized using statistical and machine learning tools. Screening tests demonstrated that Eads serves as an effective predicting indicator for adsorption capacity (qe) and MB removal efficiency (RRMB,%), with reasonable agreement between Eads and both responses under given conditions. Process modeling and optimization revealed that 5 mg of selected SAH achieves a maximum qe of 3244 mg g−1 at 84.4% RRMB under pH 8.05, 98.8 min, and MB concentration of 383.3 mg L−1, as identified by the desirability function approach. Moreover, SAH effectively eliminated various contaminants from aqueous solutions, including sulfasalazine (SFZ) and dibenzothiophene (DBT). MB adsorption onto selected SAH was exothermic, spontaneous, and followed the pseudo-first-order and Langmuir-Freundlich isotherm models. The remarkable ability of SAH to adsorb MB is attributed to its well-designed structure predicted through DFT and optimal operational conditions achieved by AI-based parametric optimization. By integrating DFT-based computations and machine-learning tools, this study contributes to the efficient design of adsorbent materials and optimization of adsorption processes, also showcasing the potential of SAH as an efficient adsorbent for the abatement of aqueous pollution.

Ag-Co ferrite-based magnetic polymeric composite film: a breakthrough in cationic dye remediation for sustainable environment.

The deployment of magnetically responsive and polymeric materials to remove dyes that are hazardous in aquatic environments has profoundly revolutionized environmental sustainability. This study focuses on removing the hazardous cationic Malachite Green (MG) dye from solutions, employing a novel magnetic composite film as an adsorbent, designated as Ag0.2Co0.8 Fe2O4 (ACFCeP). The composite was synthesized via solvent casting, incorporating Ag0.2Co0.8 Fe2O4 nanoparticles and CeO2 into a cellulose acetate/polyvinylpyrrolidone (CA/PVP) polymer matrix. The Ag0.2Co0.8Fe2O4 nanoparticles were synthesized by a co-precipitation method. Comprehensive characterization of the synthesized composite was conducted using techniques, such as Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM), and vibrating sample magnetometer (VSM). The Ag-doped cobalt ferrite component retained a strong hysteresis loop within the final composite, even when blended with the CA/PVP polymer, preserving the robust magnetic properties that facilitate the easy removal of the composite post-treatment without secondary pollution. Additionally, the mesoporous structure of the composite effectively aids in the adsorption mechanism. The isothermal study shows that both linear Langmuir isotherm and Freundlich isotherm are well fitted with R 2 values of 0.99 and 0.97, respectively. The linear Langmuir maximum adsorption capacity, q max, is 45.66 mg g-1 at pH 7. The kinetic studies of the composite resemble the pseudo-second-order kinetic model, reaching adsorption equilibrium within 70 min for a 100 ppm MG dye concentration. The composite film exhibits excellent reusability, maintaining high removal efficiency over three cycles. Overall, the ACFCeP composite film showcases excellent dye removal capabilities, a fast adsorption rate, and satisfactory magnetic properties and offers a sustainable solution for environmental pollution, thus contributing to ecosystem preservation through efficient recycling and reuse in dye adsorption applications.

Study of Suregada Multiflora Leaves Extract as a Green Corrosion Inhibitor on Iron in HCl Medium

Suregada multiflora leaves extract (SMLE) was prepared and used as a new eco-friendly green inhibitor for acid induced corrosion of mild steel(MS) in 1M HCl solution. The aqueous extract of leaves of Suregada multiflora was tested by dipping MS coupons in 1M HCl with and without SMLE solution at 303 k, 313 k, 333k and 343k using gravimetric method. The data obtained by weight loss measurement revealed that the SMLE has good inhibiton effect and mitigates the rate of corrosion. The inhibition efficiency (IE) increases with an increase in inhibitor concentration and with the exposure time. The adsorption study showed that the use of SMLE obeyed the Langmuir isotherm with regression co-efficient value nearly equal to unity. A part from this, Flory-Huggins isotherm and Langmuir-Freundlich isotherm were also used to study the interaction between the inhibitors and the mild steel surface, and mechanism of electrochemical reaction. At last the free energy of adsorption and activation energy were calculated and discussed.

Bio-adsorption of heavy metals from aqueous solution using the ZnO-modified date pits

The bio-adsorption of heavy metals (including Cu2+, Ni2+, and Zn2+) in aqueous solution and also in an industry wastewater using the ZnO-modified date pits (MDP) as the bio-adsorbent are investigated. The fresh and used bio-adsorbents were characterized by FT-IR, SEM, BET, and XRD. The bio-adsorption parameters (including the pH of solution, the particle size of MDP, the shaking speed, the initial concentration of heavy metals, the dosing of MDP, the adsorption time, and the adsorption temperature) were screened and the data were used to optimize the bio-adsorption process and to study the bio-adsorption isotherms, kinetics, and thermodynamics. Two adsorption models (Langmuir isotherm model and Freundlich isotherm model) and three kinetic models (pseudo-first-order model, pseudo-second-order model, and intra-particle diffusion model) were applied to model the experimental data. Results show that the maximum adsorption amount of Cu2+, Ni2+, and Zn2+ on a complete monolayer of MDP are 82.4, 71.9, and 66.3 mg g−1, which are over 4 times of those of date pits-based bio-adsorbents reported in literature. The bio-adsorption of heavy metals on MDP is spontaneous and exothermic, and is regulated by chemical adsorption on the homogeneous and heterogeneous adsorption sites of MDP surface. This work demonstrates an effective modification protocol for improved bio-adsorption performance of the date pits-based bio-adsorbent, which is cheap and originally from a waste.