Superior Adsorption Properties Research Articles

A Sustainable Method for Removal of the Full Range of Liquid and Solid Hydrocarbons from Water Including Up- and Recycling.

Beyond their CO2 emittance when burned as fuels, hydrocarbons (HCs) serve as omnipresent raw materials and commodities. No matter if as liquid oil spills or the endless amounts of plastic roaming the oceans, HCs behave as persistent pollutants with water as main carrier to distribute. Even if their general chemical structure [-(CH2 )n -] is quite simple, the endless range of n leads to contaminations of different appearances and properties. A water remediation method based on superparamagnetic iron oxide nanoparticles (SPIONs) modified with self-assembled monolayers of alkyl phosphonic acid derivatives is presented. These molecules enable the SPIONs to non-covalently bind HCs, independently from the molecular weight, size and morphology. The attractive interaction is mainly based on hydrophobic and Coulomb interaction, which allows recycling of the SPIONs. The superparamagnetic core allows a simple magnetic collection and separation from the water phase which makes it a promising addition to wastewater treatment. Agglomerates of collected plastic "waste" even exhibit superior adsorption properties for crude oil, another hydrocarbon waste which gives these collected wastes a second life. This upcycling approach combined with presented recycling methods enables a complete recycling loop.

Field experiment pitting magnetite nanoparticles against microparticles: Effect of size in the rehabilitation of metalcontaminated soil

ABSTRACT A significant portion of the current knowledge regarding the use of iron nanoparticles for remediating metal-contaminated soils is derived from laboratory experiments, leaving several unanswered questions. This article presents a field experiment comparing the efficacy of magnetite nanoparticles and microparticles for the immobilization of metals and the growth of plants in metal-contaminated soils. This study aimed to investigate the effects of magnetite particle size on metal immobilization and plant growth in soils exposed to airborne pollution from the Middle-Urals Copper Smelter in the southern taiga subzone near Revda, Russia, 50 km from Ekaterinburg. Magnetite nano- and microparticles were added to forest litter at a 4 % w/w dose. The total metal contents in litter from the study plots were 1-2 orders of magnitude higher than background metal concentrations. The magnetite nanoparticle treatment was found to decrease the concentration of exchangeable copper in soil and improve the growth of red fescue (Festuca rubra L.) on polluted soil compared to the control. In contrast, magnetite microparticles did not show any statistically significant effects. These findings are in line with laboratory results that demonstrated the superior metal adsorption properties of magnetite nanoparticles compared to microparticles. However, this study was limited in duration (2 months), and longer field studies would be necessary to confirm the role of iron particle size in the rehabilitation of metal-contaminated soils.

A novel Co–CoAl2O4/exfoliated montmorillonite composite with improved nanoparticle dispersion for methyl orange removal via coupling peroxydisulfate

The degradation of refractory pollutants via the activation of peroxydisulfate (PDS) by Co-based nanostructures as catalysts has been gaining significant attention. However, most cobalt-based catalysts suffer from severe aggregation and metal ion leakage, resulting in a loss of activity and potential environmental threats. In this study, exfoliated montmorillonite (EMMT) loaded Co–CoAl2O4 composites were elaborately constructed through a facile coprecipitation-reduction method. The effects of the calcination temperature, the EMMT addition content, the pH of the precursor, and the reduction temperature on the microstructure of the Co–CoAl2O4/EMMT composites were investigated, and the optimum synthesis conditions were determined. In the optimal sample, well-crystallized CoAl2O4 nanoparticles were uniformly deposited onto the EMMT nanosheets with a considerably large specific surface area, while ultrafine metallic Co nanoparticles were homogeneously immobilized on the CoAl2O4 surface. This sample exhibited a superior activity (90% within 70 min) and reusability during methyl orange (MO) degradation. In the catalytic reaction, the superior adsorption property of EMMT facilitated the rapid transfer of MO molecules to the catalytically active sites. Moreover, CoAl2O4 acted as a transition layer which provided a cobalt source for the subsequent reduction process and regulated the growth of metallic Co nanoparticles, which increased the number of active sites for catalysis. Simultaneously, the metallic Co can not only activate PDS by being an electron donor, but also initiate the formation of Co-based redox pairs. This study offers new insights into the synthesis of efficient and cost-effective supported Co-based catalysts.

Synthesis of hydrophilic sulfur-doped carbon aerogel microspheres and their mechanism of efficient removal of Sb(III) from aqueous solution

Antimony pollution is well recognized to induce cancer and deformity. By polymerization technique, a carbon aerogel microsphere (Ce@SCA) modified by Ce and S with micron size, well-developed pore structure, and large specific surface area was created. Ce@SCA exhibited the advantages of efficient selectivity and high adsorption capacity for Sb(III) in water. The highest adsorption capacity derived using the Sips isothermal model was 345.18 mg∙g−1, and the Sb (III) adsorption process was thermodynamically estimated as spontaneous, exothermic, and entropy-decreasing chemisorption. Meanwhile, Ce@SCA can convert highly toxic Sb(Ⅲ) into Sb(Ⅴ), which is suitable for the remediation of antimony-contaminated water bodies. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) were analyzed to elucidate the adsorption mechanism and to propose optimized adsorption configurations. A considerable number of –OH and -SH on the surface may increase the binding site of Sb, and the creation of S-Sb, O-Sb, and Ce-O-Sb covalent bonds was the key to Sb adsorption. This research provides a simple method for preparing cerium oxide-loaded and sulfur-doped carbon aerogel (Ce@SCA) with mild conditions and no hazardous waste, which also has superior adsorption properties for Sb (III) and high reusability.

CO2 Adsorption Behaviors of Biomass-Based Activated Carbons Prepared by a Microwave/Steam Activation Technique for Molecular Sieve.

In this study, the activated carbon was prepared with superior CO2 selective adsorption properties using walnut shells, a biomass waste, as a precursor. The activations were conducted at various times using the microwave heating technique in a steam atmosphere. The surface morphology and chemical composition of activated carbon were analyzed using a scanning electron microscope and energy-dispersive X-ray spectroscopy. The textural properties were investigated using the N2/77K isothermal method, and the structural characteristics were examined using X-ray diffraction analysis. The CO2 and H2 adsorption properties of activated carbon were analyzed using a thermogravimetric analyzer and a high-pressure isothermal adsorption apparatus, respectively, under atmospheric and high-pressure conditions. Depending on the activation time, the specific surface area and total pore volume of the activated carbon were 570-690 m2/g and 0.26-0.34 cm3/g, respectively. The adsorption behaviors of CO2 of the activated carbon were different under atmospheric and high-pressure conditions. At atmospheric pressure, a significant dependence on micropores with diameters less than 0.8 nm was observed, whereas, at high pressure, the micropores and mesopores in the range of 1.6-2.4 nm exhibited a significant dependence. However, H2 adsorption did not occur at relatively low pressures. Consequently, the prepared activated carbon exhibited superior selective adsorption properties for CO2.

Efficient Removal of Pb(II), Cr(VI), and Tetracycline Hydrochloride from Aqueous Solutions Using UiO-66-AMP@PAN: Thermodynamics, Kinetics, and Isothermal Adsorption

The removal of heavy metal ions and medical antibiotics from wastewater is crucial for environmental protection and human health. However, the adsorption capacities and reusability of previously reported adsorbent materials have been insufficient for efficient and sustainable wastewater treatment. In this study, we present a composite material, UiO-66-AMP@PAN, synthesized from metal-organic frameworks (MOFs) and polyacrylonitrile (PAN), which exhibits superior adsorption properties and reusability. The material demonstrates excellent adsorption capacities for heavy metal ions Pb(II) and Cr(VI) as well as the antibiotic tetracycline hydrochloride (TCH), among which the maximum adsorption capacities for Pb(II)(pH=7) and Cr(VI)(pH=5) and antibiotic tetracycline hydrochloride (TCH) (pH=9) were 455.8 mg/g, 442.08 mg/g and 405.92 mg/g, respectively. The adsorption efficiency of UiO-66-AMP@PAN as an adsorbent for adsorbing Pb(II)(pH=7) and Cr(VI)(pH=5) and the antibiotic tetracycline hydrochloride (TCH) (pH=9) remained above 90% even after ten consecutive cycles. The performance of UiO-66-AMP@PAN as an adsorbent has remained unchanged across multiple adsorption-desorption cycles, demonstrating its potential for long-term use in wastewater treatment applications. This innovative approach paves the way for the development of more efficient and environmentally friendly adsorption materials to address the challenges posed by heavy metal ions in wastewater and medical antibiotics.

Preparation of W0.4Mo0.6O3 from Secondary Resources by a Simple Heat-Treatment Process and Discussion of Its Superior Selective Adsorption Properties

Preparation of W0.4Mo0.6O3 from Secondary Resources by a Simple Heat-Treatment Process and Discussion of Its Superior Selective Adsorption Properties

Hydrophilic ZnO/C nanocomposites with superior adsorption, photocatalytic, and photo-enhanced antibacterial properties for synergistic water purification

Owing to the numerous potential applications of ZnO nanomaterials, the development of ZnO-based nanocomposites has become of great scientific interest in various fields. In this paper, we are reporting the fabrication of a series of ZnO/C nanocomposites through a simple “one-pot” calcination method under three different temperatures, 500 ℃, 600 ℃, and 700 ℃, with samples labeled as ZnO/C-500, -600, and -700, respectively. All samples exhibited adsorption capabilities and photon-activated catalytic and antibacterial properties, with the ZnO/C-700 sample showing superior performance among the three. The carbonaceous material in ZnO/C is key to expanding the optical absorption range and improving the charge separation efficiency of ZnO. The remarkable adsorption property of the ZnO/C-700 sample was demonstrated using Congo red dye, and is credited to its good hydrophilicity. It was also found to exhibit the most notable photocatalysis effect due to its high charge transfer efficiency. The hydrophilic ZnO/C-700 sample was also examined for antibacterial effects both in vitro (against Escherichia coli and Staphylococcus aureus) and in vivo (against MSRA-infected rat wound model), and it was observed to exhibit synergistic killing performance under visible-light irradiation. A possible cleaning mechanism is proposed on the basis of our experimental results. Overall, this work presents a facile way of synthesizing ZnO/C nanocomposites with outstanding adsorption, photocatalysis, and antibacterial properties for the efficient treatment of organic and bacterial contaminants in wastewater.

Preparation of coal tar pitch based adsorption materials: Understanding the adsorption mechanism by combining field energy theory and statistical physics models

A coal tar pitch based adsorbent(CTPA) was prepared. The structure of the CTPA adsorbate was analyzed using FTIR, Zeta potential, SEM and BET. We investigate the adsorption mechanism of cation dye contaminants by adsorbates. It has been shown that CTPA has superior adsorption properties for MB. Thermodynamic analysis and Zeta potential analysis have shown that electrostatic forces play a particularly prominent role in adsorption. Statistical physics model studies have shown that increasing the temperature increases the trapping power and the number of adsorption sites. According to the SED theory, MB adsorption is particularly strong at elevated energy sites.

Metformin-Embedded Biocompatible Chitosan/Poly(vinyl alcohol) Beads with Superior Adsorption Properties toward Lead(II) and Levofloxacin

In this contemporary era, chitosan has gained exceptional attention as a sustainable biopolymer in the adsorption process due to its nontoxic nature, biocompatibility, accessibility, and pH-responsive active surface charge. This study developed a high-performance chitosan/poly(vinyl alcohol) adsorbent through metformin functionalization. The incorporation of poly(vinyl alcohol) (PVA), along with the metformin-activated surface, remarkably ameliorated its physiochemical properties. The abundance of inter- and intrahydrogen and chemical bonds in the porous structure enhances the specific surface area up to 83.8 m2/g. Series characterization methods are utilized to investigate the adsorbents’ characteristics in all aspects and the removal performance. Furthermore, the key factors for the adsorption process, including the influence of pH, adsorbent quantity, time intervals, and preliminary concentration, were studied and optimized. The optimal pH was observed in the neutral moiety, which is crucial from an industrial perspective. Due to the presence of countless nitrogen and oxygen atom-containing backbones, the CS/PVA-Pr-Met biocomposite has demonstrated considerable adsorption capacity toward Pb(II) ions and levofloxacin with the highest adsorption capacities of 313.162 mg/g for Pb(II) and 2872.927 mg/g for levofloxacin concerning their molecular and ionic nature and various adsorption mechanisms. In accordance with the correlation coefficient and estimated parameters, the adsorption of Pb(II) and levofloxacin onto the beads mostly follows the pseudo-second-order kinetics (R2 ≥ 0.997) and the Langmuir adsorption isotherm model (R2 ≥ 0.995). The exceptional adsorption capacity coupled with the porous structure of the modified hydrogel beads has promising applications for efficient wastewater treatment

Fast production of silica aerogel using methyltrimethoxysilane by ambient drying process for superior chemical adsorption properties

Fast production of silica aerogel using methyltrimethoxysilane by ambient drying process for superior chemical adsorption properties

Adsorption and Sensing Performance of Vented Gases from Lithium-Ion Batteries on Transition-Metal-Doped GeTe Nanosheets: A DFT Investigation

Online monitoring of vented gases released by lithium-ion batteries (LIBs) during the early stages of thermal runaway is a potential method for ensuring the operational state of LIBs. Using the density functional theory method, the adsorption and sensing performances of transition-metal (TM) (Rh, Au, Pd, and Ag)-doped GeTe monolayers toward vented gases from LIBs were analyzed by calculating the adsorption energy, charge transfer, deformation charge density, density of states, work function, sensitivity, and recovery time. Results demonstrate that TM-doped GeTe monolayers have superior adsorption properties and sensitivity for CO2, CO, C2H2, and C2H4 compared with pure GeTe. This study provides theoretical guidance for designing a new gas nanosensor to detect the vented gases emitted from LIBs during thermal runaway.

Multi-functional flame retardant coatings comprising chitosan/ gelatin and sodium phytate for rigid polyurethane foams

In this work, a renewable multi-functional composite was fabricated from the combination of chitosan, gelatin and sodium phytate by a simple and eco-friendly process. The obtained products were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and X-ray photoelectron spectrometry. The above composites were then added onto the surface of rigid polyurethane foams by a rolling procedure. The flame performance test conducted by cone calorimeter demonstrated that the surface coating could effectively reduce the value of peak heat release rate and total heat release to 115.0 kW/m2 and 3.5 MJ/m2 from 247.2 kW/m2 and 6.8 MJ/m2 of the rigid polyurethane foams, respectively. Except for foams, the coating composite also exhibited high flame-retardant efficiency in wood, plastic and fiber. Through mechanism analysis (morphology observation by scanning electron microscopy, structural analysis by X-ray photoelectron spectrometry, Fourier transform infrared spectra and pyrolysis-gas chromatography/mass spectrometry), it was suggested that the coating composite mainly took effect in condensed phase by the formation of physical barriers. Moreover, the newly prepared polyurethane foam composites also exhibited superior organic dye adsorption properties. This work provides an efficient, simple and eco-friendly route for large-scale production of multi-functional renewable materials that can be used in the fields of fire safety and environmental conservation.

Influence of distillates (petroleum) on microcrystalline cellulose pyrolysis

Porous materials have received extensive attention due to their superior adsorption properties, but there are few studies on oil adsorption. In this paper, a new self-design high-temperature reactor carried out MCC adsorption experiments, and a complete test system was used to study the adsorption characteristics, pyrolysis kinetics and pyrolysis products. The results of SEM and XRD showed that G3H gradually wetted the surface of MCC and the crystallinity increased. In addition, the pyrolysis parameters of MCC-adsorption-G3H (MAG) were measured by DSC and STA. The results showed that MCC was pyrolyzed in one step while MAG was in two. Meanwhile, thermodynamic model fitting indicated that the first stage was Fn and the second was Cnm autocatalytic. Notably, the variation of pyrolysis activation energy in the first stage was similar to that of adsorption capacity. Pyrolysis products of G3H were measured by Py-GC-MS, and pyrolysis residues of MAG were tested by FTIR. Combined with the volatiles determined by TG-IR, the influence of G3H on the pyrolysis characteristics was obtained, and the pyrolysis path of MAG was summarized. The results showed that porous materials can recycle oil and provided a guideline for industrial production.

Enhanced selectivity and ultra-fast detection of NO2 gas sensor via Ag modified WO3 nanostructures for gas sensing applications

Recently, nanostructured tungsten oxide-based materials have received much attention in the field of the gas sensor due to their superior size-dependent gas adsorption and catalytic properties. Herewith, we have successfully prepared pure and Ag-doped WO3 nanostructures via a hydrothermal method. The effect of doping (Ag) in WO3 and their gas sensing properties was systematically studied. Interestingly, the Ag-2 sensor revealed the enhanced gas sensing response of 52404% @1000 ppb, which is 5-fold higher than that of the pure WO3 sample at 150 ℃. Moreover, Ag-2 sensor possessed an ultra-fast response and recovery time of 1 s and 3.5 s. Further, as-prepared sensors exhibit excellent selectivity, repeatability, and long-term stability. In addition, the DFT calculations were performed to evaluate the adsorption and charge transfer dynamics of NH3, H2S, and NO2 gas molecules on pure and Ag-doped WO3 surfaces. These results pave the new pathway to developing real-time metal oxide-based gas sensors at lower operating temperatures.

Modified red clays as adsorbents in the removal of cationic dyes from aqueous solutions

Thermal and thermo-chemical modification methods were applied to a red clay mineral and the resulted products were comparatively studied. The modified clays were characterized by XRD, XRF, UV-vis and FTIR spectroscopy. The adsorption properties towards two cationic dyes, namely methylene blue and crystal violet, were investigated and the effect of initial concentration and contact time was analyzed, revealing superior adsorption properties for the thermo-chemical modified clay. The values of dye removal rate are very high, over 85%, with better adsorption of methylene blue and a competition between dyes as demonstrated by using binary solutions. The best match with the experimental results was obtained for the pseudo-second-order kinetic model.

Heterostructured Mo and Co-based phosphides as high-performance bifunctional electrocatalysts for overall water splitting.

Transitional metal phosphides are efficient and durable electrocatalysts for water splitting. In this work, Mo-CoP/Co2P/NF heterostructures are reported to exhibit bifunctional electrocatalyst properties in various electrolytes. The Co phosphides were found to be possessing a hydrogenase-like structure in these heterostructures with P as the proton-acceptor site and Co as the hydride-acceptor site, making them highly active during the HER process. Moreover, the electronic structure of Co ions could be modified, or the transfer of electrons could be accelerated due to the different valence states of Mo. Additionally, the Mo centers possessed superior adsorption properties toward hydrogen. Consequently, excellent performance for the electrocatalytic HER was exhibited by the Mo-CoP/Co2P/NF-300 heterostructure with small overpotentials of 86.6 mV and 48 mV at a current density of 10 mA cm-2 in 1.0 M KOH and 0.5 M H2SO4 solutions, respectively. Furthermore, it also exhibited efficient OER activity in an alkaline solution with a low overpotential of 245 mV at 30 mA cm-2. Post-analysis revealed the changes in the surface and the formation of Co oxyhydroxide during the OER process, and the formation of Co-P-O during the HER process. The high HER and OER performances are attributed to these transformations of morphologies and compositions. Consequently, a two-electrode electrolyzer based on Mo-CoP/Co2P/NF-300 required voltages of 1.59 V and 1.703 V at 20 mA cm-2 and 100 mA cm-2, respectively, and maintained long-term stability.

In Situ Confined Synthesis of a Copper-Encapsulated Silicalite-1 Zeolite for Highly Efficient Iodine Capture.

Effective capture of radioactive iodine is highly desirable for decontamination purposes in spent fuel reprocessing. Cu-based adsorbents with a low cost and high chemical affinity for I2 molecules act as a decent candidate for iodine elimination, but the low utilization and stability remain a significant challenge. Herein, a facile in situ confined synthesis strategy is developed to design and synthesize a copper-encapsulated flaky silicalite-1 (Cu@FSL-1) zeolite with a thickness of ≤300 nm. The maximum iodine uptake capacity of Cu@FSL-1 can reach 625 mg g-1 within 45 min, which is 2 times higher than that of a commercial silver-exchanged zeolite even after nitric acid and NOX treatment. The Cu nanoparticles (NPs) confined within the zeolite exert superior iodine adsorption and immobilization properties as well as high stability and fast adsorption kinetics endowed by the all-silica zeolite matrix. This study provides new insight into the design and controlled synthesis of zeolite-confined metal adsorbents for efficient iodine capture from gaseous radioactive streams.

The performance and mechanism of Cr(VI) adsorption by biochar derived from Potamogeton crispus at different pyrolysis temperatures

To evaluate the impact of preparation temperature on the structure characteristics and Cr(VI) adsorption capability of Potamogeton crispus biochar (PCB), PCB was prepared at 300, 500, and 700 °C, respectively. Characterization results based on BET, XRD, SEM-EDS, Raman, and FTIR measurements showed that the physicochemical features of PCB were dictated by the pyrolysis temperature, which had a substantial impact on the surface morphology and functional group composition of biochar. The specific surface area and pore volume of PCB increased with the increase of pyrolysis temperature, while more oxygen-containing groups were existent on the surface of biochar produced by low temperature pyrolysis. The pseudo-second-order model and the Freundlich model were used to explain the Cr(VI) adsorption process by PCB, inferring that multilayer chemisorption occurred on the heterogeneous surface of biochar. PCB had superior adsorption properties, being 34.37, 5.99, and 2.51 mg/g, respectively, under the addition of PCB300, PCB500 and PCB700. In addition, pH value had a strong impact on the disposal of Cr(VI) with the best removal effect at pH 2.0. The process of Cr(VI) adsorption through SEM-EDS, XRD, FTIR, and XPS included physical adsorption, electrostatic interaction, complexation and reductive adsorption and so on. Therefore, PCB may have been a promising application prospect for removing Cr(VI) from aqueous solutions due to its high performance and economical characteristics.

Properties and adsorptive performance of candlenut shell and its porous charcoals for aqueous mercury(II) removal

The present work investigated the functional properties of candlenut shell particles (CSP), candlenut shell charcoal (CSC), and candlenut shell activated charcoal (CSAC) for Hg2+ removal. The highest Brunauer-Emmet-Teller (BET) surface area of 1183 m2/g and total pore volume of 0.674 cm3/g were achieved from the CSAC. The aqueous Hg2+ removal performance was evaluated via a continuous flow experiment at 25 °C. Although the CSP and CSC showed a relatively good adsorption performance, the CSAC presented superior adsorption properties to remove Hg2+ from water. Its pristine mineral constituents and large surface area corresponded to the highest adsorption capacity of 214.36 mg/g. These findings were confirmed by the energy-dispersive X-ray spectroscopy analysis (EDX) which was lineal substantiation for the Hg2+ adsorption onto the CSAC film. It appears feasible to use candlenut shell (CS) waste as an economical precursor for the high-grade bioadsorbent production and augmentation of agro-industrial waste management.