Spontaneous Adsorption Research Articles

Surface sensitization of TiO2 via Pd/Rb2O cocatalysts: Mechanistic insights to the arsenic elimination from ground drinking water†

In order to abide the regulations put forth by World Health Organization (WHO), it is imperative to employ innovative technique that can eliminate arsenic from ground drinking water. The effective sorbents are desperately needed to remove arsenic from the water. In this work, rutile TiO2 surfaces were tuned with nominal ratios of palladium and rubidium oxide cocatalysts via co-precipitation method. Firstly, As (III) contents were converted to As (V) by photooxidation reaction (POR) and then As (V) contents were removed by adsorption over Pd/Rb2O@TiO2 surfaces. The morphology, optical characteristics and structural features were obtained by XRD, Raman, UV-Vis/DRS, SEM, PL and TGA analysis. The surface characteristics and chemical compositions of Pd/Rb2O@TiO2 were obtained using TEM and XPS analysis. Arsenic contaminated water samples were collected from Hasilpur Tehsil (Punjab/Pakistan). The mechanism of As (III) to As (V) conversion, adsorption kinetic for pseudo-second-order (R2꞊0.99919), and the Langmuir adsorption isotherm kinetic model (R2꞊0.98906) provided the significant clarification. Spontaneous arsenic adsorption has been determined (ΔG=−12.52 KJ/mol), which addressed the substantial columbic interactions between adsorbate and substrate. Due to non-toxic nature, dual feautres (photocatalysis and adsorption), easy accesability and low cost, the utilization of titania based sorbents appear to be viable options for arsenic removal technologies. The results of this study depict that, Pd/Rb2O@TiO2 can effectively remove 99% arsenic from contaminated water.

Benzimidazole-modified chitosan as a controller for the destruction of Al and H2 generation in the acidic environment

Benzimidazole-modified chitosan (CS-BISP) was utilized as an effective mitigator controlling the destruction of Al, and the generation of H2 in dilute HCl solutions. The techniques of gasometry, mass loss, potentiometry, galvanostatic polarization, GP, and electrochemical impedance spectroscopy, EIS, were involved. The rate of the produced H2 is found to depend on the concentration of the CS-BISP and the temperature. EIS data indicated that the existence of CS-BISP in the HCl solution increases the charge transfer resistance, Rct, and reduces the double-layer capacitance, Cdl, confirming the presence of an insulating film on the metal surface via an adsorption mechanism. GP data explained that the CS-BISP behaves as an effective inhibitor of a mixed kind. The protection efficiency was raised with increasing the CS-BISP concentration and is lowered by temperature. The protection efficiency reaches 94.2% at 300 mg L−1, at 25 °C. The free energy of adsorption, ΔGoads, varied between – 26.13 and −26.88 kJ/mol depending on the solution temperature which emphasizes the presence of physical and chemical adsorption mechanisms. The negative sign of ΔGoads proved a spontaneous adsorption process with the stability of the adsorbed film. The reduction in the Kads value with temperature signifies the desorption of a few of the CS-BISP polymeric molecules from the surface of the Al electrode. The CS-BISP molecule was theoretically examined utilizing density functional theory and Monte Carlo simulations. The theoretical parameters coincide with the experimental results.

Adsorption characteristics of magnetized biochar derived from Citrus limetta peels

Agro-industrial waste is an alarming issue that needs to be addressed. Waste valorization is an effective technique to deal with such effectively. Synthesis of biochar from fruit waste is one of the emerging approaches for adsorption, energy storage, air purification, catalysis, and biogas production trending these days. Magnetized Citrus limetta biochar (MCLB) was synthesized from Citrus limetta peels and was magnetized using iron oxide. Magnetization of biochar increases its functionalities as well as makes its separation easy. The removal of Methylene Blue (MB) dye from an aqueous solution is achieved through the use of MCLB. Methylene Blue is a prominent and widely used cationic-azo dye in the textile and printing industries. The accumulation of MB in wastewater is the major problem as MB is reported as a carcinogenic agent. The removal of MB dye with MCLB was analyzed by adsorption studies, wherein the effect of factors influencing adsorption such as initial concentration of MB dye, MCLB dosage, the effect of pH, contact time, and adsorption isotherms were studied. Characterization of MCLB was carried out using various techniques, such as FTIR, VSM, XRD, SEM, RAMAN, and Zeta potential. The adsorption isotherm mechanism was well explained with the non-linear Langmuir isotherm model resulting in a good adsorption capacity (qe = 41.57 mg/g) of MCLB when MB (co = 60 mg/L, pH ~ 6.8, T = 273K). The thermodynamics analysis revealed that MB's spontaneous and endothermic adsorption onto the MCLB surface followed pseudo-second-order kinetics. The results obtained from this study suggest that the magnetized biochar derived from Citrus limetta peels has a wide range of potential applications in the treatment of dyeing wastewater.

Study the Corrosion Inhibition on the Iraqi Fuel Tanks using Cefoperazone Drug

Corrosion is one of the most important problems that face the petroleum industry, both production and refining, and cause damage to petroleum equipment, tanks, and transmission lines, and increasing maintenance costs. in this study , was adding six concentrations of the drug expired Cefoperzone (Exp CEF) (50, 100, 200, 300, 400, and 500 ppm) to a Simulated Oil Well Water (SOWW), the inhibitive role of (Exp CEF) drug was investigated to Reduce the corrosion risk of carbon steel. Four different temperatures were used to conduct electrochemical tests (303, 313, 323 and 333 K) to achieve the study. The study was then supported by an examination of the inhibited surface using field emission scanning electron microscopy with energy dispersive (FESEM) and (AFM). The results indicated occurring the inhibition by an anodic inhibitor that controls the dissolution of iron from steel gave the highest inhibition efficiency (IE%) by adding 500 ppm, while the calculation of polarization resistance (Rp) gave the highest resistance by 400 ppm through adsorption the added drug to show flakes shaped structures with decreasing surface roughness (Ra ) from 307.1 to 83.15 after inhibition. The calculation of adsorption isotherm confirmed the obeying of Langmuir adsorption isotherm by giving the coefficient of linear regression was about one in the range of 0.999 > R^2 > 0.995, with the spontaneous adsorption that estimated from the negative values of 〖∆H〗_ads^o and variation in the type of adsorption to be physically or chemically according to the added concentration because of the differential sign of 〖∆H〗_ads^o . The sign of 〖∆H〗_ads^o was positive that reflecting the increase in randomness at the metal/solution interface.

Porous metal-organic framework-acrylamide-chitosan composite aerogels: Preparation, characterization and adsorption mechanism of azo anionic dyes adsorbed from water

Micro- and nano-metal-organic frameworks with different adsorption properties were prepared by a time-modulation hydrothermal method. By comparing the adsorption properties, the most effective MIL-68(Fe)-12 was selected to be mixed with chitosan (CS), and porous metal-organic framework-acrylamide-chitosan composite aerogel (PMACA) was prepared by introducing acrylamide prior to glutaraldehyde crosslinking. The adsorption capacity of PMACA doped with acrylamide was as high as 2086.44 mg·g−1. The adsorption performance of PMACA was 1.48 times higher compared to the porous metal-organic framework-chitosan composite aerogel (PMCA) undoped with acrylamide. With the introduction of acrylamide, the stability of PMACA was improved, making it less prone to dispersion and decomposition. Structural characterization and adsorption properties were analyzed using methods such as XRD, FTIR, TGA, SEM, BET, and Zeta potential. The adsorption performance of PMACA was investigated further through batch tests with variables such as adsorbent dosage, pH, contact time, initial CR solution concentration, and temperature. The model fitting of PMACA was consistent with the pseudo-second-order model and the Sips model. The adsorption thermodynamics showed that high temperature promoted spontaneous adsorption behavior. PMACA showed a recovery rate of approximately 86 % after six cyclic adsorption tests. PMACA maintained a recovery rate of roughly 86 % after six cyclic adsorption tests. The combined effects of electrostatic attraction, hydrogen bonding, and π-π conjugation resulted in excellent adsorption performance, while pore filling also contributed to the efficient adsorption of Congo red (CR).

Tailoring the adsorption behaviors of flucytosine on BnNn (n = 12, 16, 20, and 24) nanocage scaffolds: A computational insight on drug delivery applications

Understanding the interactions between boron nitride-based nanocage scaffolds with drug molecules is a prerequisite for their application as drug carriers. Herein, the adsorption behaviors of the anti-fungal drug flucytosine (Fcy) on the surfaces of different zero-dimensional BnNn (n = 12, 16, 20, and 24) nanomaterials were systematically studied based on the density functional theory (DFT) and molecular dynamics (MD). An ideal complementarity between their electrostatic potential surface is witnessed for the most stable BnNn-Fcy complexes. The atoms in molecules (AIM) analysis further reveals the partially covalent B···N bond is the main force between Fcy and BnNn. And the interaction energy between the entities in both gas and aqueous phase diminishes with the increase of cage size. Meanwhile, significant reductions in the HOMO-LUMO band gap energy of BnNn-Fcy complexes were observed after Fcy adsorption. Furthermore, MD simulations demonstrate the spontaneous adsorption of Fcy molecules onto the surface of BnNn, with the adsorption capacity of BnNn decreasing as the cage sizes increase. The aforementioned findings collectively indicate the adsorption behavior of Fcy can be tailored by the selection of different BnNn, making it a potential candidate for Fcy drug delivery to meet different needs. Hopefully, the results would provide valuable theoretical guidance for the development of BnNn-based drug delivery systems.

A comparison of adsorption capacity of several synthesis methods of cellulose-based absorbent towards Pb(II) removal: Optimization with response surface methodology

The effects of various synthesis methods of a novel biodegradable magnetically recyclable cellulose-based adsorbent (a magnetized modified silica aerogel) on Pb(II) removal efficiency were studied. QSM (quince seed mucilage) was modified via hydrothermal and ultrasonic modes. Oven-drying and freeze-drying procedures were then used to obtain the final adsorbents. The adsorbents were named A1 to A4 and B1 to B4, depending on the synthesis and drying techniques. XRD, FTIR, BET, and SEM are characterization techniques for identifying the adsorbents. Average crystallite sizes of 15.5, 8.3, 10.9, and 2.7 nm were obtained for A1, A2, A3, and A4 samples (Scherrer formula). SEM image confirmed a Sticky bullets-like morphology. The pHpzc values of 3.4, 6.0, and 4.1 were also determined for Fe-silica aerogel, Fe-QSM, and Fe-silica aerogel-QSM samples. The highest adsorption efficiency of the A2 adsorbent towards Pb(II) cations was followed via the experimental design by the RSM (response surface methodology) approach. ANOVA results showed model F value 185 (>F0.05, 14, 15 = 2.42) and LOF F-value of 0.3831 (<F0.05, 10, 5 = 4.74) at a 95 % confidence interval. The center point run conditions were catalyst dose: 7 g/L, pH: 3.2; CPb: 11 mg/L, and contact time: 55 min, while the optimal run conditions were adsorbent dose: 1.0 g/L; pH: 2.6; CPb: 7 mg/L; and contact time: 80 min with about 94 % Pb(II) removal efficiency. The adsorption mechanism was studied, and correlation coefficient (R2) values of Langmuir (0.9814), Freundlich (0.9328), Temkin (0.8898), and Redlich-Peterson (0.9977). They have recommended that the adsorption process fit best with the Langmuir and Redlich-Peterson models. A kinetic study revealed that adsorption was well described by pseudo-second-order kinetics. The thermodynamic studies showed a spontaneous and endothermic adsorption process.

Experimental and Computational Study on Inhibitory Effect and Adsorption Properties of N-Acetylcysteine Amino Acid in Acid Environment.

Potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) were applied to study the inhibitory effect of N-acetylcysteine (NAC) on corrosion inhibition of carbon steel in hydrochloric acid solution. N-acetylcysteine influenced the iron dissolution to a greater extent than the hydrogen evolution reaction acting as a mixed inhibitor, predominantly anodic. The charge transfer resistance (Rct) gradually increased with the inhibitor concentration. From both methods, the inhibition efficiency (IE) reached a value of 89 ± 1% and NAC adsorption followed the Temkin isotherm. The value of adsorption Gibbs energy (ΔGadso), around -35 kJ mol-1, indicated a spontaneous adsorption and mixed action mechanism, with NAC chemical adsorption prevailing over physical one. New data will be reported by the computational study, that was performed using the density functional theory (DFT) method in aqueous phase. Quantum chemical descriptors were determined by B3LYP theory level with 6-31G+(d) basis set. Metropolis Monte Carlo atomistic simulation was used to reveal the adsorption configuration and interactions between acetylcysteine molecules and the carbon steel surface. Theoretical results were consistent with the experimental data, showing that the inhibitor action mechanism consisted of mainly chemisorption of its molecules on the carbon steel surface accompanied by van der Waals forces and electrostatic interactions.

How do defects affect hydrogen spillover on graphene-supported Pt? A DFT study

Hydrogen dissociation, adsorption, and spillover on Pt4 supported on defective graphene that contains vacancy defects, such as single and di-vacancy graphenes (SVG and DVG), have been studied using density functional theory (DFT) with dispersion correction (Grimme-D3). Vacancy defects lead to n-type doping of graphene from the Pt4 cluster, which is contrary to the p-type doping on pristine graphene. Also, the metal–support interactions increase with the presence of a vacancy defect as indicated by more negative Pt4 binding energies on the SVG, and 5-8-5, 5555-6-7777, and 555–777 DVGs of −8.60, −4.51, −4.15 and −3.63 eV, respectively, compared to that on pristine graphene (−2.16 eV). Atomic hydrogen adsorption is more stable on all defective graphenes with adsorption energies of −2.24, −0.16, 0.05, and −0.27 eV for SVG, 5-8-5, 5555-6-7777, and 555–777 DVGs, respectively, as compared to that on pristine graphene (+1.38 eV). Spontaneous hydrogen dissociative adsorption on the two-fold coordinated C site of bare SVG occurs with an adsorption energy per hydrogen atom of −1.77 eV, while those on the three types of DVGs are in the range of ∼0.03–0.29 eV; these are all more stable than those on pristine graphene that fall in the range of 0.89–1.53 eV. The energy barriers for hydrogen spillover from Pt4 to the defective graphene are 0.91, 1.09, 0.90, and 0.71 eV for SVG, 5-8-5, 5555-6-7777, and 555–777 DVGs, respectively. Ab initio molecular dynamics (AIMD) simulations show that the adsorption of up to six hydrogen molecules, with and without spillover, on the four Pt4/defective graphene systems, is stable at room temperature. This study demonstrates that the presence of vacancy defects on graphene could improve hydrogen adsorption and spillover. A trend is discovered—when the magnitude of binding energies of metal–support interaction is stronger than −3.5 eV and the adsorption energies of atomic hydrogen on the support are negative or close to zero, there is potential to facilitate the occurrence of hydrogen spillover, correlating with the hydrogen storage capacity of the materials. Thus, our findings could provide useful criteria for designing hydrogen storage materials and a fundamental understanding of the correlation between metal–support interactions and hydrogen spillover mechanisms.

Adsorption of methyl orange from aqueous solution with lignin-modified metal–organic frameworks: Selective adsorption and high adsorption capacity

The lignin-based metal–organic framework (UIO-g-NL) was prepared by a Schiff base reaction of aminated lignin and the zirconium cluster-based MOF (UIO-66-NH2) as an adsorbent of methyl orange (MO). The results showed that UIO-g-NL maintained the original crystal structure and aminated lignin was successfully introduced after functionalization. UIO-g-NL selectively adsorbed MO from a mixed solution 50 mg/L MO and 50 mg/L methylene blue (MB), with an adsorption efficiency of nearly 100%. In a mixed solution 250 mg/L MB and 250 mg/L MO, UIO-g-NL adsorbed both dyes with 1120.70 mg/g for MB and 961.54 mg/g for MO. Hydrogen bonding, π-π and NH-π interactions, and electrostatic attraction contribute to the MO adsorption by UIO-g-NL. In the MO/MB mixture, MO adsorption by UIO-g-NL follows the pseudo-second-order kinetic and Freundlich isotherm models, which is an endothermic, spontaneous, and feasible adsorption process. Furthermore, the MO adsorption efficiency of UIO-g-NL remained high (>90%) after six re-use cycles.

Reaction Mechanism of Nitrogen-Containing Heterocyclic Compounds Affecting Coal Spontaneous Combustion.

To uncover the reaction mechanism of nitrogen-containing heterocyclic compounds affecting coal self-heating, quantum chemical calculations and X-ray photoelectron spectroscopy (XPS) experiments were applied to elucidate the reaction pathways and thermodynamic characteristics of pyrrole, pyridine, indole, quinoline, and carbazole. Results show that in pyrrole, pyridine, indole, quinoline, and carbazole, the reaction with O2 captures the H atom and leads to the formation of ·OOH and pyrrolyl, pyridinyl, indolyl, quinolinyl, and carbazolyl radicals, respectively. The activation energies are 118.15, 86.642, 34.132, 21.004, and 47.259 kJ/mol, respectively. ROO· formed by spontaneous adsorption of O2 by nitrogen-containing radicals undergoes self-reaction, and the O-O bond is broken and dehydrogenated to generate ·OH. Subsequently, at room temperature, ·OH reacts with pyrrole, pyridine, indole, quinoline, and carbazole, resulting in the formation of H2O and pyrrolyl, pyridinyl, indolyl, quinolinyl, and carbazolyl radicals, respectively, thereby forming a cyclic chain reaction. The XPS analysis yielded the following findings: (i) when the temperature rises to 70 °C, the N-5 and N-6 content decrease, which is attributed to the activation energy; (ii) when the temperature reaches 200 °C, the N-5 content decreases, which can be attributed to the activation energy required for the oxidation of pyrrole (118.5 kJ/mol).

Green conversion of waste PET into magnetic Ni0·4Fe2·6O4/(Fe,Ni)@carbon nanostructure for adsorption and separation of dyes from aqueous media

A nanostructured core-shell composite (Ni0·4Fe2·6O4/(Fe,Ni)@carbon, NFC) comprising magnetic nano-cores encapsulated with graphitic shells (≈80 wt%) is prepared by facile and clean mechanochemical-molten salt processing approach using waste PET; providing a specific surface area of 201.9 m2 g−1, well-developed mesopores, and ferromagnetic behavior characterized by the coercivity value of 149 Oe. NFC is utilized as a high-performance adsorbent for the removal of organic dyes from their aqueous solutions. Moreover, the magnetic performance of NFC enables the facile collection of the exhausted adsorbent out of the purified water. Performances of NFC for the removal of crystal violet dye (CV), methyl orange (MO) and rhodamine B (Rh B) from their aqueous solutions are systematically investigated under different environmental conditions including the adsorbent dosage and dye concentration, as well as the solution pH and temperature, where an impressive CV removal capacity of 201.6–243.8 mg g−1 is recorded for a wide pH range of 2–10. Mechanism and kinetics involved in the adsorption process are investigated by studying the adsorption isotherms and thermodynamics. The dye adsorption of the nanocomposite material is confirmed to follow the pseudo-second-order kinetic model combined with the Langmuir isotherm model, exhibiting an excellent spontaneous and exothermic monolayer adsorption capacity of around 153 mg g−1 (for MO) for the fresh adsorbent and around 89 mg g−1 after three adsorption-regeneration cycles.

Electronic and structural perturbations of microporous ZIF-67 nanoparticles and Cr(VI) molecule during adsorptive water decontamination unveiled by experimental and quantum computational investigations

Metal organic frameworks (MOFs) have attracted great attention due to their unique characteristics and accordingly found their way to a multitude of applications including water remediation. Co-based zeolite imidazole framework (ZIF-67) has recently shown interesting adsorptive decontamination capabilities towards metallic and organic water pollutants. Yet, ZIF-67 adsorption mechanism and stability have not been studied enough. In this study, ZIF-67 nanocrystals (∼40 nm) were synthesized and applied as an adsorbent for Cr2O72− from water. The Cr2O72−−ZIF-67 adsorption mechanism and both of Cr2O72− and ZIF-67 consequent structural changes were investigated by analyzing the elemental composition and oxidation states, the adsorption isotherms, kinetics and thermodynamics, and the optimized quantum computational models. The experimental results fitted well with pseudo-second order and Langmuir models, and gave ΔH° and ΔG° of −86.4 ± 17.6 and 12.8 ± 2.4 kJ/mol, respectively, suggesting exothermic spontaneous monolayer chemical adsorption, with maximum capacity of 370 mg/g. Kinetics also show concurrence surface adsorption with intra-particle diffusion within the micropores. XPS results reveal that both Cr6+ and the less-toxic Cr3+ co-existed in Cr2O72−−ZIF-67, whilst the Co3+/Co2+ ratio increased, referring to an oxidation–reduction reaction between Cr and Co. Computational analysis concede that the Cr2O72−−ZIF-67 high affinity is based on H-bonding between the Cr2O72− oxygens and the imidazole hydrogens, van der Waals attraction between the Cr2O72− lone pairs and the imidazole π cloud, the Cr2O72−−ZIF-67 electron transfer, and CrN coordination interaction. However, these computations show that the Cr2O72−−ZIF-67 interaction causes internal destabilization within each of Cr2O72− and ZIF-67, as Cr2O72− tends to dissociate and ZIF-67 integrity weakens.

Surface Modifications of Superparamagnetic Iron Oxide Nanoparticles with Polyvinyl Alcohol and Graphite as Methylene Blue Adsorbents

Methylene blue (MB) is one of the toxic synthetic dyes that are being discharged heavily into water supplies. Hence, MB removal is one of the most important tasks for a cleaner water supply. By using inexpensive, abundant, and easy-to-synthesize materials, superparamagnetic iron oxide nanoparticles, which were synthesized using the co-precipitation method with polyvinyl alcohol and graphite (SPION/PVA/GR), can be used to adsorb MB. The adsorbent was characterized using FE-SEM, FTIR, XRD, VSM, and BJH. The entrapment efficiency of MB on SPION/PVA/GR after 12 days was 33.96 ± 0.37–42.55 ± 0.39%, at 333.15, 310.15, and 298.15 K, and the initial concentration of MB was 0.017–0.020 mg/mL. The adsorption process can be considered spontaneous, endothermic, chemisorption, heterogeneous, or multilayer adsorption. When releasing MB at 298.15 K and a pH of 3.85 after 7 days, the release percentage ranged from 11.56 ± 0.33 to 22.93 ± 5.06 depending on the initial loading conditions and mainly the releasing temperature following the Higuchi kinetic model. Since this is a novel SPION-based MB adsorbent, optimization, and different forms of adsorbent (i.e., thin film composite) should be further researched.

Co-doped metal–organic framework MIL-125(Ti) derivate for efficient adsorption of tetracycline hydrochloride from water

Metal-organic framework (MOF) based materials have aroused much research interest owing to their unique structural features in the field of environmental purification. Herein, a MOF derivate of Co-MIL-300 was prepared by sintering the cobalt-modified MIL-125(Ti) (Co-MIL) precursor at 300 °C in an air atmosphere and used as adsorbent to remove tetracycline hydrochloride (TCH, a typical emergent pollutant) from water. The Co-MIL-300 adsorbent possesses a large specific surface area, the rich surface oxygen-containing groups, the benzene-ring structure with rich π-electrons and surface cobalt ions benefiting for TCH adsorption. The TCH adsorption on Co-MIL-300 satisfies the pseudo-second-order kinetic model and Langmuir mode well, and is found to be a spontaneous endothermic and monolayer chemical adsorption process based on covalent bonding (such as π-π conjugation interactions, hydrogen bonding, π-cation interactions, coordination bonding) adsorption mechanism. Co-MIL-300 reveals a much higher adsorption capacity than Co-MIL (2.3 times of the latter) with qmax = 321.5 mg⋅g−1 at 30 °C, and it also keeps a high adsorption capacity in a wide pH range (pH = 2–11). The coexisting CO32–, PO43-, Al3+ and Fe3+ ions can greatly inhibit TCH adsorption. Most of its adsorption capacity can be recovered in five cycles after regeneration, showing great application potential for antibiotics removal.

An integrated process by ultrasonic enhancement in the deep eutectic solvents system for extraction and separation of chlorogenic acid from Eucommia ulmoides leaves

This study established an integrated process for the extraction and enrichment of chlorogenic acid(CGA)from Eucommia ulmoides leaves in a deep eutectic solvent system via ultrasonic wave-enhanced adsorption and desorption practices utilizing macroporous resins. Although deep eutectic solvents (DESs) have the advantages of chemical stability, good dissolving capacity, and nonvolatilization, routine solvent recovery operations are not suitable for subsequent separation in this solvent system. Based on the above characteristics, this study integrated the extraction and enrichment processes, in which DESs extracts directly loaded onto the macroporous adsorption resin, avoiding the loss of target components in solvent recovery and redissolution processes. The screening results of solvents and resin types further showed that choline chloride-malic acid (1:1) was the optimal DES, and the NKA-II resin had high adsorption and elution performance for CGA. The viscosities of the DESs were much higher than those of water and conventional organic solvents; thus, the mass transfer resistance was large, which could also affect the adsorption behaviour of the macroporous resin. The thermal and mechanical effects of ultrasound could effectively enhance the efficiency of the mass transfer, adsorption, and desorption in the DES systems. When compared to no sonication treatment, the CGA adsorption at various ultrasonic powers (120–600 W) was examined. At optimal ethanol concentration (60%), the effect of the ultrasonic treatment on the recovery of the DESs (water eluting process) and the desorption capability of CGA were confirmed. The use of three volumes of water elution could recover the DESs without loss of CGA. The adsorption process significantly differed depending on the ultrasonic settings, and the absorption balance time and experimental adsorption capacity at equilibrium were enhanced. Additionally, the adsorption procedure of the NKA-II macroporous resin for CGA under ultrasonic treatment could be clarified by the pseudo second order kinetic equation and the Freundlich isotherm model. Thermodynamic and dynamic parameters indicated that physical adsorption was the main process of the entire procedure, and it was a spontaneous, exothermic, and entropy-reducing physical adsorption process. This study potentially indicates that the use of ultrasonication, as a high-efficiency, environmentally friendly method, can enhance the features of the macroporous resin to better purify target chemicals from a DES extract.

Enhanced boron recovery by a new synthesized polyvinyl alcohol anchored gallic acid moiety via ethyl carbamate linker

ABSTRACT An innovative promising Gallic acid anchored poly vinyl alcohol via ethyl carbamate linker (PVA-EC-GA), was functionalized to extract boron from a tourmaline ore sample from Sikait area in South Eastern Desert of Egypt, which assaying 10.45% boron oxide. Specifications for PVA-EC-GA composite were accomplished by employing a variety of methods including XPS, FT-IR, EDX, BET, 1 H-NMR, TGA, 13C-NMR and GC-MS analyses, which assure an equitable prepare of PVA-EC-GA. Investigational measurements, namely: pH, agitation time, initial concentration of boron, composite dose, co-ions, temp. and agents of eluting, have been improved. At 25°C, pH 10, 20 min agitation and 0.0092 mol/L boron ions, PVA-EC-GA composite has an extreme uptake capacity of 43.75 mg per gram which is equivalent to 175 mg/L boron ions. From the isotherm modeling, Langmuir’s quite fitting the practical data. Conferring to kinetic modeling, pseudo-second order kinetic model well predicted the kinetics of boron ions adsorption by PVA-EC-GA giving a theoretical retention capacity of 43.86 mg/g. Thermodynamic prospects expose that the adsorption process was expected as an exothermic, spontaneous, and preferable adsorption at low temp. Boron ions can be eluted from the loaded composite, by 0.5 M H2SO4 with a 97% effectiveness

Removal of crystal Violet From Aqueous Solutions by A Newly Developed Adsorbent: İsotherm, Kinetics, and Thermodynamics

Aim of this study, adsorption potential of modified and natural materials is investigated. The adsorbent used is watermelon peel (WP) derived from agricultural wastes to remove crystal violet (CV). The modified and raw adsorbent was characterized by Elemental analysis, Scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The studied parameters are temperature, initial metal concentration, and contact time. The most suitable kinetic (R2=0.99) and isotherm (R2=0.99) models were determined as Pseudo-second-order and Langmuir, respectively. The maximum adsorption capacity (qmax) according to Langmuir is 236.9 mg/g at 30°C. Thermodynamic analysis revealed spontaneous and endothermic adsorption of CV on modified watermelon peels. These results demonstrate that crystal violet can be removed from agricultural wastes using a low-cost adsorbent.

Composite hydrogel based on chemically modified gelatin and PVA containing graphene oxide nanoparticles (CHGP-GOn)

The increased consumption of medications such as Chloroquine (CQN) during the Covid-19 pandemic, the excretion of this drug leading to an overload of CQN and its metabolites in sewage treatment plants, increased the necessity to adequate treatment for their removal. Water treatment using advanced processes can be enhanced through the utilization of adsorbent and absorbent materials, facilitating the removal of hard-to-treat compounds and enabling material reusability. The use of nanoparticles offers desirable attributes responsible for the adsorption process, maximising the feature of water treatment materials. In this context, graphene oxide exhibits high surface area and significant adsorption capacity due to its abundance of desirable functional groups for adsorbing contaminant molecules. However, the lixiviation from these materials represents an environmental problem. The functionalization of adsorbent materials with nanoparticles has been used to minimise the loss of nano-compounds. In this way, composite hydrogels synthesized with graphene oxide have demonstrated adsorption and absorption properties for emerging contaminants, including pharmaceuticals. Therefore, a composite hydrogel based on chemically modified gelatin and PVA containing graphene nanoparticles, with resistant reticulation and non-toxic compounds, synthesized for the first time, was employed for the removal of CQN from aqueous media. This hydrogel superabsorbent with morphological rough shows 175% capacity of swelling, positive tendency of charge on natural pH due to diverse functional groups, as well as point of zero charges at pH 9.1, amorphous features. The batch removal tests demonstrated a superabsorbent material (175% swelling), showing the best removal in Qe of 13.20 mg g −1 of Chloroquine, as well as a superior performance at natural pH. The adsorption kinetics were best described by the Elovich model, indicating multi-step resistance with intraparticle diffusion as the rate-limiting step, equilibrium in 240 min and a maximum adsorption capacity of 13.31 mg g−1. Furthermore, the isotherm exhibited spontaneous and exothermic adsorption, with low reversibility and randomness in the adsorption system. Besides, the maximum experimental adsorption capacity was 52.98 mg L-1 in 288 K. The material demonstrated promising reusability, retaining its adsorption capacity over three adsorption cycles and values of 14.26 followed by 4.830 and 2.280 mg g- 1, respectively. In conclusion, the composite hydrogel based on graphene oxide shows great potential as an efficient and eco-friendly approach for removing emerging contaminants, particularly pharmaceuticals like CQN, from aqueous environments.

Facile surface-controlled synthesis of phytic acid-facilitated calcium carbonate composites for highly efficient ferric ion adsorption and recovery from rust

This work presents a simple synthesis of calcium carbonate (CaCO3)-based composites designed for the efficient adsorption of ferric ions (Fe3+) from solution, and specifically applied for Fe3+ recovery from rust. The strategy involves coordinating phytic acid (PA) with calcium ions (Ca2+) and coprecipitation with carbonate ions (CO32−) at room temperature to form phytate-CaCO3 (Ph-CC) composites. The obtained composites exhibited a robust mesoporous crystal structure with numerous phosphate groups of phytate functionalized on CaCO3 microparticles. The surface properties of the composites were optimized by adjusting the molar ratio (x) of PA:Ca2+ in synthesis. The Ph-CC0.10 composite (x = 0.10), with the highest specific surface area (99.56 m2/g), demonstrated exceptional Fe3+ adsorption (>99% efficiency in 80 min). The adsorption process followed the pseudo-second-order and Langmuir isotherm models, indicating monolayer coverage. Impressively, the maximum adsorption capacity reached 1385.85 mg/g, surpassing that of previously reported adsorbents. Thermodynamic studies confirmed a spontaneous and exothermic adsorption process. The superior Fe3+ adsorption of the composite was attributed to electrostatic and chelation interactions, with partial ion exchange. Furthermore, the Ph-CC0.10 composite effectively captured Fe3+ from rust dissolution in an acidic solution (pH 3) under sonication at 35 kHz for 60 min. These results highlight the potential use of the developed composites in mitigating environmental pollution and transforming waste materials into valuable sources. Therefore, Ph-CC composites are promising alternatives for wastewater treatment and metallurgical applications.