Composite Adsorbent Research Articles

Biosourced silica / Ag composite materials as a new adsorbent for the removal of mercury ions from water

In this study, the synthesis of a new composite adsorbent using rice biosourced silica, silver nanoparticles and triethoxysilane as the raw materials for removal aqueous mercury ions from water is presented. The new composite material was synthesised by modification of the surface of rice husk based silica with silane groups and farther decoration with silver nanoparticles. Characterization was carried out through, Fourier transform infrared (FT-IR) spectra analysis, N2 adsorption-desorption (Brunauer-Emmett-Teller) and thermal gravimetric analysis (TGA). Synthetic and real mercury containing water sampled from Balkyldak lake-reservoir, Kazakhstan were tested. The results demonstrated that the affinity of the composite for mercury is high and the removal mechanism is adsorption accompanied by an amalgamation reaction between silver and mercury.

Sulfur-containing adsorbent made by inverse vulcanization of sulfur/oleylamine/potato starch for efficient removal of Hg(II) ions

Mercury contamination is considered the most harmful pollutant considering its high toxicity and persistence in the environment. This study aims to design an efficient and inexpensive adsorbent to capture Hg(II) ions. Herein, a polysulfide complex material was prepared through sulfur, oleylamine, and potato starch. Initially, the potato starch was functionalized by using dimethyl sulfoxide and (3-aminopropyl) triethoxysilane. The polysulfide adsorbent was then created by copolymerizing sulfur with oleylamine and sulfhydrylation starch using the inverse vulcanization process. The composition, structure, and morphology of polysulfide adsorbent were characterized by SEM/EDS, FT-IR, TGA, and XRD. The results indicated that the adsorption capacity and removal of adsorbent reached 248.2 mg/g and 99.28%. The adsorption data were fitted with adsorption kinetics, isothermal adsorption model and adsorption thermodynamics, followed by an analysis of the possible adsorption mechanism of the adsorbent. Meanwhile, it exhibited high selectivity for Hg(II) ions and other co-existing ions, with favorable recyclability after 5 rounds of recycling. In general, a promising polysulfide for the treatment of Hg(II)-containing wastewater is reported in this study, moreover, opening a novel avenue for elemental sulfur applications.

Efficient adsorption of tetracycline from aqueous solution using copper and zinc oxides modified porous boron nitride adsorbent

It is a significant and challenging mission to explore high-efficiency adsorbents with low cost and high stability for wastewater purification treatment. In this paper, bimetallic copper and zinc oxides modified porous boron nitride (BN) was successfully obtained via an improved impregnation method. The synthesized materials were comprehensive characterized by multiple approaches including SEM, TEM, FT-IR, XRD, BET and XPS. The composite adsorbent possessed a high specific surface area and pore volume, which was conducive to the effectively adsorption of tetracycline (TC) pollutants in an aqueous solution. Notably, the optimal adsorption capacity could achieve to 623.018 mg L−1, and more than 96% of TC pollutants could be removed rapidly. The fitting results of kinetic data were stayed the same with the kinetic model of second-order (R2 ≥ 0.998). Moreover, adsorption isotherms were in accordance with the Tempkin model, indicating that the superior adsorption performance was mainly due to electrostatic interaction, π-π stacking and hydrogen bonding. The thermodynamic research illustrated that the main process of adsorption is endothermic and spontaneous. In addition, the composite adsorbent also has favorable stability and reusability. These results show that copper and zinc oxides modified BN adsorbent can exhibit a better application potential in the removal of TC.

Preparation of Porous Composite Phase Na Super Ionic Conductor Adsorbent by In Situ Process for Ultrafast and Efficient Strontium Adsorption from Wastewater

Strontium, the main component of radioactive nuclear wastewater, is characterized by a high fission yield and an extended half-life. It is easily absorbed by the human body, thus greatly threatening the environment and the human body. In this study, a mesoporous composite phase sodium superionic conductor (NVP@NMP) was synthesized by the droplet template method, and the rapid capture of Sr2+ from wastewater was achieved by constructing a nano-heterogeneous interface to increase the ion diffusion rate. NVP@NMP showed efficient and rapid removal of strontium ions in adsorption kinetics, isothermal adsorption, solution pH, and interfering ions concentration tests, especially using the equilibrium time of 2 min for strontium absorption by NVP@NMP and a maximum theoretical adsorption capacity of 361.36 mg/g. The adsorption process was spontaneous, endothermic, and feasible. At higher concentrations of other competing ions (Na, K, Ca, Mg, and Cs), the adsorbent exhibited higher selectivity towards Sr2+.TEM, XPS, and XRD analyses revealed that ion exchange was the main mechanism for the NVP@NMP ultrafast adsorption of Sr2+. In this research, we investigated the feasibility of ultrafast strontium capture by sodium superionic conductor structured phosphates and explained the ultrafast strontium adsorption mechanism of NASICON materials through XPS.

Radiation Resistance and Adsorption Behavior of Aluminum Hexacyanoferrate for Pd.

Irradiation resistance is important for adsorbents used in radioactive environments such as high-level liquid waste. In this work, a silica-based composite adsorbent (KAlFe(CN)6/SiO2) was synthesized and γ-irradiated from 10 to 1000 kGy. The angles of the main X-ray diffraction peaks slightly decreased with the increase in irradiation dose, and a minor decomposition of CN- occurred after irradiation to 1000 kGy, indicating that the KAlFe(CN)6/SiO2 adsorbent could preserve structural integrity with a dose below 100 kGy. In 1 to 7 M HNO3, the adsorption ability of the irradiated KAlFe(CN)6/SiO2 remained performant, with a higher Kd than 1625 cm3 g-1. The adsorption equilibrium of Pd(II) in 3 M HNO3 was attained within 45 min before and after irradiation. The maximal adsorption capacity Qe of the irradiated KAlFe(CN)6/SiO2 on Pd(II) ranged from 45.1 to 48.1 mg g-1. A 1.2% relative drop in Qe was observed after 100 kGy irradiation, showing that γ-irradiation lower than 100 kGy insignificantly affected the adsorption capacity of KAlFe(CN)6/SiO2. Calculating and comparing the structures and free energies of different adsorption products via the density functional theory (DFT) method showed that KAlFe(CN)6/SiO2 was more inclined to completely adsorb Pd(II) and spontaneously generate Pd[AlFe(CN)6]2.

REMOVAL OF FLUORIDE FROM DRINKING WATER THROUGH LOW-COST TECHNIQUES

Fluoride ions (F-) from natural sources or industrial wastewater are the main cause of many pathological conditions in people living in more than 25 countries. Thus, removing F- from drinking water is pivotal for preventing serious health consequences. The WHO recommends a limit of 1,5 mg/L for fluoride in drinking. Excessive amounts of fluoride in drinking water are prevalent in Pakistan, leading to related health risks. Low-cost techniques for the defluoridation of drinking water can be used. In this study, the removal of fluoride from drinking water by an adsorption method using low-cost materials/adsorbents, such as marble chips, wheat husks, rice husks, egg shells, concrete, fuller earth, fly ash, freshly fired bricks, and charcoal, at different contact times and different bed thicknesses were investigated. A batch sampling technique was used for sample collection. On average, marble chips, wheat husks, rice husks, egg shells, concrete, fuller earth, fly ash, freshly fired bricks, and activated charcoal (rice husk) resulted in 71,99 %; 90,99 %; 66,73 %; 90,99 %; 63,30 %; 71,99 %; 22,60 %; 49,67 %; and 90,13 % fluoride removal, respectively. Therefore, defluoridation using these materials is desirable. The performance of adsorbents depends on parameters such as contact time, depth of the adsorbent media, and pH. The bed thickness of the adsorbent has a minor effect on fluoride removal. The major contributors to fluoride removal from water are contact time and adsorbent composition.

Selective adsorptive removal of anionic dyes from aqueous solutions using MIL-101@GO: Effect of GO

Metal−organic framework (MOF)@graphene oxide (GO) composite materials possess the advantages of both GO and MOFs, and thus, they can be employed as effective dye adsorbents. This paper proposes a simple strategy for the preparation of MIL-101 @GO composite materials to effectively adsorb anionic dyes (Congo red, o-cresolsulfonphthalein, methyl orange, and acid chrome blue K) by adding GO to MIL-101 to form a nano-packed structure. The maximum adsorption uptakes of MIL-101 @GO were 2734.9, 484.5, and 1762.8 mg g–1 for Congo red, o-cresolsulfonphthalein, and methyl orange, respectively. These values significantly exceed the corresponding values of the original MIL-101 because of additional factors that promoted adsorption, namely hydrogen bonding and the presence of agglomerate pores. Only the maximum adsorption uptake for acid chrome blue K was lower than that of MIL-101, because of steric hindrance. Our analysis showed that the adsorption behavior of MIL-101 @GO toward Congo red, o-cresolsulfonphthalein, and methyl orange is governed by a synergistic interplay of hydrogen bonding, electrostatic interactions, π–π interactions, the adsorption space, and agglomerate pores in the composite, whereas the adsorption behavior toward acid chrome blue K is mainly limited by steric hindrance. Understanding these interactions may contribute to the development of improved sustainable composite adsorbents.

Research Progress on Synthesis and Adsorption Properties of Porous Composite Adsorbents for Adsorption Cooling and Desalination Systems: A Mini-review

The adsorption cooling and desalination system is expected to become the mainstream technology of refrigeration and desalination in the future, because it has significant advantages of low temperature driving and low carbon emission. The system based on adsorption technology merits a small environmental impact and low energy consumption, which can help solve the water and energy crises. More importantly, it can use low-grade heat energy to reduce overall carbon emissions in the working process. The adsorbent is the essential component of an adsorption system, and improving the adsorbent is a vital technological advancement for increasing system effectiveness. Porous materials, such as zeolite, silica gel, and metal–organic frameworks, are the most studied adsorption materials in adsorption cooling and desalination systems. They behave differently regarding stability, thermal conductivity, adsorption capacity, and regeneration temperature. The research status of several different adsorbents, such as zeolite, silica gel and metal–organic frameworks, was comprehensively reviewed and compared. In-depth research was done on several composite adsorption materials’ synthesis processes, characterization, and adsorption traits. The obstacles they experienced were then studied, along with the development trend of composite porous adsorbents. The purpose of this study is to provide a reference for researchers committed to developing new adsorption materials under various applications and conditions.

Application of modified graphene oxide-chitosan composite for the removal of 2-methylpyridine using fixed bed adsorption and subsequent regeneration of the adsorbent by UV photolysis

This article focuses on the development of a photolytically regenerable and practically applicable graphene oxide nanomaterial (GON) based composite adsorbent for the fixed-bed column treatment of 2-methylpyridine (2Mp). The transformation of nano-sized GON into a macro-sized adsorbent was achieved by crosslinking it with a biocompatible crosslinker, chitosan, and then coating it onto sand (abbreviated as GCS). FTIR revealed the nature of the crosslinking as amide bonding. GCS was found to interact with 2Mp via hydrogen-bonded ionic pair mechanism. Column studies of GCS with 2Mp followed Thomas kinetics at variable flow rates, bed depths and initial 2Mp concentrations. The adsorption capacity of GCS was 7.8 mg/g. The hydraulic character of flow was determined as laminar (Re < 1). Doehlert Design of experiment was used in modeling/optimization of experimental data. The polynomial model predicted an optimal column breakthrough time of 645.9 ± 10.63 min, with a regression coefficient of 0.99. Linear terms of bed depth and flow rate had the most impact on prediction. Thereafter, the regeneration of exhausted GCS was performed using direct UV photolysis, based on the SALDI mechanism. No photocatalysts/chemicals were necessary. Regeneration efficiency of 96.5 % was obtained using irradiation time of 30 min and power input of 0.96 W/cm2. GCS was reusable in 10 cycles of adsorption-regeneration, without losing significant adsorption capacity. The spent liquor obtained afterwards was remediated using batch photolysis prior to its discharge into the eco-system. Therein, the mechanism for photo-degradation of 2Mp was found, where succinic acid was detected as the eco-friendly end product. This study overcomes the practical difficulty in application of photolysis to large influent volumes by first isolating 2Mp on the GCS surface and then subjecting it to photolytic treatment in a 95.56 % smaller solution volume.

A Carbonized Zeolite/Chitosan Composite as an Adsorbent for Copper (II) and Chromium (VI) Removal from Water.

To address Cu(II) and Cr(VI) water pollution, a carbonized zeolite/chitosan (C-ZLCH) composite adsorbent was produced via pyrolysis at 500 °C for two hours. C-ZLCH was characterized using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential measurements. The batch experiments were performed by varying the initial pH, concentration, and contact time. The optimal pH values for Cu(II) and Cr(VI) were 8.1 and 9.6, respectively. The highest adsorption capacities for Cu(II) and Cr(VI) were 111.35 mg/g at 60 min and 104.75 mg/g at 90 min, respectively. The effects of chemicals such as sodium (Na+), glucose, ammonium (NH4+), and acid red 88 (AR88) were also studied. Statistical analysis showed that sodium had no significant effect on Cu(II) removal, in contrast to Cr(VI) removal. However, there was a significant effect of the presence of glucose, ammonium, and AR88 on both Cu(II) and Cr(VI) removal. The adsorption isotherm and kinetic models were fitted using Langmuir and pseudo-second-order models for Cu(II) and Cr(VI), respectively.

Phosphorylation improved the competitive U/V adsorption on chitosan-based adsorbent containing amidoxime for rapid uranium extraction from seawater

A novel chitosan-based porous composite adsorbent with multifunctional groups, such as phosphoric acid, amidoxime, and quaternary ammonium groups, was prepared to improve the adsorption rate and competitive uranium‑vanadium adsorption of amidoxime group adsorbents. The maximum uranium adsorption capacity of PACNC was 962.226 mg g−1 at 308 K and pH = 7. The maximum adsorption rate constant of PACNC for uranium was 2.83E−2 g mg−1 min−1, which is 2.38 times that of ACNC (1.19E−2 g mg−1 min−1). Moreover, the adsorption equilibrium time was shortened from 300 (ACNC) to 50 (PACNC) min. In simulated and real seawater, the Kd and adsorption capacity of PACNC for uranium were approximately 8 and 6.62 times those for vanadium, respectively. These results suggest that phosphorylation significantly improved the competitive adsorption of uranium‑vanadium and uranium adsorption rate. PACNC also exhibited good recycling performance and maintained stable adsorption capacity after five cycles. DFT calculations were used to analyze and calculate the possible co-complex structure of PACNC and uranium. The binding structure of phosphate and amidoxime is the most stable, and its synergistic effect effectively improves the competitive adsorption of uranium-vanadium of amidoxime. All the results demonstrated that PACNC has substantial application potential for uranium extraction from seawater.

Optimization and Modeling of Cyanide Removal from Cassava Waste Water Using Calcined and Activated Adsorbent Mixtures of Oyster Shell and Periwinkle Shell Ash

Cyanide, a toxic compound found in cassava wastewater which on frequent basis is discharged to the environment poses danger to the ecosystem; this research work aims to curb this menace. Temperature, pH, dosage, contact time, adsorbent mixture ratio and initial concentration were optimized using CCD on periwinkle-oyster shells composite mixtures for activated and also, calcined adsorbents on the cyanide adsorption from cassava wastewater. Three RSM models (linear, 2FI and quadratic) were applied to study, optimize and predict this adsorption process. ANOVA showed that quadratic model best predicted the processes for both the activated and calcined adsorbents having R2 values of 0.9678, CV% of 15.51% for the activated and R2 values of 0.9550, CV% of 18.54% for the calcined composite adsorbent. Surface and contour plots were generated to study the interaction between the adsorption parameters and cyanide adsorption. Results from this study also show that pH and initial cyanide concentration were the most determining factors of the adsorption process for both adsorbent samples with the highest adsorption capacity of 96.648% and 96.112% obtained for the activated and calcined composite adsorbent respectively. Numerical optimization was carried out and the confirmation test on the analyzed best-fit quadratic models yielded actual adsorption efficiency of 90.174% as against the predicted adsorption efficiency of 89.83% for the activated and actual adsorption efficiency of 82.274% as against the predicted adsorption efficiency of 83.475% for the calcined composite adsorbent hence, confirms that both activated and calcined adsorbents of oyster-periwinkle shells composite mixture is effective for cyanide adsorption from cassava wastewater and the RSM models were effective to optimize and predict the process.

Synthesis and characterization of KOH@Graphene oxide-Fe3O4 as a magnetic composite adsorbent for CO2 capture

In this study, Fe3O4 nanoparticles were incorporated on graphene oxide (GO) layers to maintain the surface area of GO, while GO-Fe3O4 maintained their nanostructure. In order to enhance the alkaline natural of GO-Fe3O4, a 0.1 N KOH solution was added using an impregnation method. Brunauer-Emmett-Teller analysis showed that the adsorbent with a pore diameter of 15.05 nm was in the mesoporous range. The KOH@GO-Fe3O4 was tested for CO2 adsorption at temperature in range of 298–338 K and pressure range of 1–9 bar. The highest CO2 adsorption capacity of 6.812 mmol/g was obtained using 0.5 g of adsorbent at 298 K and 9 bar. The isotherm results showed that the Sips model gives the best fit to the experimental data obtained at 298 K and 9 bar. The adsorption mechanism between the KOH@GO-Fe3O4 active sites and CO2 molecules was physisorption. The best kinetic model was the Elovich model, which demonstrated a good fit of these associations to the linear function at 308 K. The thermodynamic results show that the highest capacity of CO2 capture was 6.812 mmol/g, which was achieved at low temperature when compared to other GO-based adsorbents. The thermodynamic parameters confirmed that CO2 adsorption was exothermic and physical. Thermogravimetric analysis and regeneration studies showed that KOH@GO-Fe3O4 has high thermal stability and regenerability.

Effect of Dolomite Addition on The Performance of Palm Oil Mill Fly Ash for Methylene Blue Adsorption

The use of palm oil mill fly ash (FA) as a low-cost adsorbent is one of the solutions for handling FA waste. In this study, the addition of dolomite is expected to improve the adsorbent performance. The aim of this study was to investigate the optimum FA-dolomite adsorbent composition and operating conditions for methylene blue adsorption. Different parameters were studied to optimize adsorption process such as the amount of dolomite, methylene blue flow rate, bed height and number of trays. FA-dolomite was converted into nano-adsorbent by sol-gel method which was coated on zeolite surface. Nano-adsorbents were characterized by XRF, FTIR, XRD and SEM. The adsorption capacity was tested by Spectrophotometer UV-Vis. XRF characterization showed that FA had the highest SiO2 content of 58.15%, while dolomite contained CaO of 52.72%. FTIR characterization detected the groups of Si-O-Si, Si-O-Al, Ca-O and Si-O. XRD characterization showed the average crystalline size of FA-dolomite 2% adsorbent was 28.56 nm and SEM characterization showed fine pores on the adsorbent surface. The highest adsorption efficiency obtained at FA-dolomite 2% was 97.364% and the lowest obtained at FA-dolomite 8% was 13.16% with a flow rate of 500 ml/h, adsorbent height of 9 cm and 3 trays. The greater the amount of dolomite added, the absorption efficiency decreases.

Mussel inspired synthesis of polydopamine/polyethyleneimine-grafted fly ash composite adsorbent for the effective separation of U(VI)

Polydopamine/polyethyleneimine-grafted fly ash composite (PDA/PEI/FA), an efficient multifunctional adsorbent for U(VI) with excellent separation efficiency (94.5 %) and capacity (422.5 mg/g), was synthesized by grafting PDA and PEI on FA via Mussel inspiration and Michael addition reaction. The introduction of PDA and PEI had brought numerous functional groups with fine affinities to uranium, like catechol, amino and imino, causing good U(VI) separation performances. Langmuir and Pseudo-second-order models were well matched with experimental data, illustrating the U(VI) separation on PDA/PEI/FA was a homogeneous chemical adsorption process. After five cycles, the U(VI) adsorption efficiency for PDA/PEI/FA was still up to 90.2 %, implying that PDA/PEI/FA possessed good stability and reusability. Besides, the good dynamic adsorption performances of PDA/PEI/FA further demonstrated that PDA/PEI/FA was an ideal adsorbent for the practical wastewater treatment. According to the characterization results, U(VI) was absorbed by PAD/PEI/FA through complexation, redox reaction, electrostatic attraction and hydrogen bonding. Given the above, PDA/PEI/FA showed good practical application prospect in U(VI) separation.

Recoverable cellulose composite adsorbents for anionic/cationic dyes removal

GO/HEC/PGDE/Fe3O4 materials were successfully fabricated using environmentally-friendly hydroxyethyl cellulose (HEC), poly(ethylene glycol) diglycidyl ether (PGDE), graphene oxide (GO) and magnetic Fe3O4. Systematic investigations were completed to explore the influences of GO content in GO/HEC/PGDE/Fe3O4 and adsorption conditions on the adsorptions of cationic dyes (methylene blue (MB), crystal violet (CV)) and anionic dye acid blue 25 (AB-25). The increase of GO content can remarkably improve the adsorption capacity of GO/HEC/PGDE/Fe3O4 for the dyes. The three kinetic, four isothermic and three thermodynamic models were investigated to reveal the adsorption behaviors of the dyes. The formation of HEC/PGDE/Fe3O4 and adsorption mechanisms of the dyes by GO/HEC/PGDE/Fe3O4 were suggested. The GO/HEC/PGDE/Fe3O4 endowed with easy-fabrication, eco-friendly feature, efficient adsorption capacity of anionic/cationic dyes, convenient separation and reusability has potential applications in wastewater purification industry.

Synthesis of activated carbon composited with Egyptian black sand for enhanced adsorption performance toward methylene blue dye

The present study reports the feasibility of the synthesis of a novel porous composite adsorbent, prepared from olive stone activated carbon (OS400) and garnet (GA) mineral impregnations (referred to as OSMG). This composite (OSMG) was applied for its ability to adsorb a macromolecular organic dye. The composite’s structural characteristics were evaluated using various techniques such as Brunauer–Emmett–Teller (BET), Scanning Electron Microscopy equipped with Energy Dispersive X-ray spectroscopy (SEM–EDX), X-ray diffraction (XRD), and a Fourier transform infrared spectrometer (FT-IR). The specific surface area of the garnet (GA), (OS400), and (OSMG) were found to be 5.157 mg⋅g−1, 1489.598 mg⋅g−1, and 546.392 mg⋅g−1, respectively. The specific surface area of the new composite (OSMG) was promoted to enhance the adsorption of methylene blue (MB). Experiments were conducted under various conditions, including contact time, initial dye concentration, adsorbent dosage, pH, and temperatures. Data from these experiments were analyzed using several adsorption models including Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R). The results indicated that, the adsorption fit best with the Freundlich model and that the adsorption process followed a pseudo-second-order kinetic mechanism. Additionally, the thermodynamic analysis indicated the adsorption of MB onto garnet(GA) adsorbents is endothermic, while the sorption onto (OS400) and (OSMG) is an exothermic and non-spontaneous process. The OSMG composite can be used for at least five cycles without significant loss of adsorptive performance, and can easily be separated from the water after treatment.

Facile fabrication of superior Pd and Ce containing SiO2 aerogel composite adsorbents for deep desulfurization of model fuels and aromatics

A series of PdO/CeO2/SiO2-z aerogel composites with different molar ratio of Si/Ce were facilely fabricated via sol-gel method combined with atmospheric drying technology, where a major of Ce3+ species could be oxidized to Ce4+ species by adding hydrogen peroxide. They were used to remove thiophenics from model fuels and aromatics, compared with PdO/SiO2 and CeO2/SiO2 aerogel composites. Adding Ce and Pd led to an appearance of weak Lewis acid centers on the surface of adsorbents. Compared with PdO/SiO2 and CeO2/SiO2, the adsorption capacity of PdO/CeO2/SiO2-z significantly increased, in which PdO/CeO2/SiO2-100 performed best and the adsorption capacity for thiophene was 15.0 mg-S/gads, which was about the sum of PdO/SiO2-636 and CeO2/SiO2-100. The case was attributed to π-complexation of Pd2+ and S-M (Pd, Ce, acted as Lewis acid centers) bond (σ) with thiophenics, where the adsorption process was dominated by S–Ce bond. Combined with the same chemical state of Pd and Ce in single metal and bimetal adsorbents verified by XPS, it can be deduced that no synergistic interaction between Pd and Ce species was formed in the adsorption process. PdO/CeO2/SiO2-100 exhibited a higher resistance for competitive adsorption of aromatics and a good solvent washing regeneration performance. The adsorption process of PdO/CeO2/SiO2-100 for thiophene was well fitted by Langmuir isothermal and pseudo-secound-order model and were spontaneous and endothermic. The solvents (n-heptane, benzene and p-xylene) have no obvious effect on the adsorption thermodynamics and kinetics of PdO/CeO2/SiO2-100.

The synthesis, application and mechanism of a novel Zr-based magnetic MOFs adsorption material

In the current study, a novel material Fe3O4@PDA@UiO-67 was synthesized by combining magnetic polydopamine (PDA) and zirconium-based metal-organic framework UiO-67 as well as applied as an adsorbent to remove azole fungicides in environmental water. The morphology and structure of this synthesized material were confirmed through a series of characterization. Modifying of UiO-67 on magnetic PDA could dramatically expand the surface area, enlarge the porosity and pore volume, and therefore improving the adsorption of pesticides. In addition, the effects of adsorbent dosage, solution pH, ionic strength and material composition on adsorption capability were evaluated and optimized. Under optimal conditions, the removal efficiencies were more than 90%. Furthermore, the adsorption mechanism was revealed by Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy (XPS) analysis and density functional theory calculations. Hydrogen bonds were considered as the major intermolecular interaction between the MOF backbones and the target pollutants. The binding energy ∆Ebof epoxiconazole and flusilazole are − 18.63 kJ/mol and − 28.54 kJ/mol, respectively, which are in consist with the maximum adsorption value for flusilazole (43.54 mg g−1) and flusilazole (54.60 mg g−1). In general, the synthesized Fe3O4@PDA@UiO-67 shows great potential in removing the environmental pollutants.

Compression-assisted adsorption thermal battery based on composite sorbent for heat supply in alpine cold region

Adsorption thermal battery (ATB) has drawn burgeoning attention since it could address the problem of heat loss for long-term or seasonal thermal energy storage. However, poor energy storage efficiency of ATB cannot be avoided at low ambient temperature in cold regions. This paper aims to explore the potential of compression-assisted adsorption thermal battery (CATB) at low ambient temperature in winter. Composite adsorbents with expanded natural graphite and carbon coated metal are developed. Heat and mass transfer as well as adsorption characteristics are investigated, which are used to further analyse thermal performance. Results indicate that thermal conductivities of composite manganese chloride and strontium chloride with carbon coated copper (Cu@C) range from 0.59 W·m−1·K−1 to 3.2 W·m−1·K−1, respectively, while permeabilities range at a magnitude of 10−9–10−13 m2. The increment of global conversion rate is up to 17 % through pressurisation process. Besides, energy storage density and power density of CATB with Cu@C increase from 956 kJ·kg−1 to 1336 kJ·kg−1 and from 531 Wh·kg−1 to 742 Wh·kg−1, respectively, which are increased by up to 7.6 % and 13.7 % when compared with those not using Cu@C. It reveals that CATB could be a promising solution to heat supply issues in cold regions.