High Adsorption Efficiency Research Articles

Optimal design of silver-loaded zeolite filter structure based on porous media model

Silver zeolite filters have potential applications in nuclear power plant filtration and emission systems due to their high-efficiency adsorption properties for radioactive methyl iodide. The adsorption performance of the filter is closely related to the flow distribution characteristics. To analyze the flow distribution characteristics of the filter element, we established a reasonable numerical calculation model and verified the model through experiments. Then based on the model, the advantages and disadvantages of different filter unit structures are analyzed. We proposed two new structural forms of filters and evaluated the performance of the filters based on the pressure distribution and flow increment curve, considering the difficulty of processing and space utilization. Comparative analysis and characteristic research have been carried out under different sizes, from the cylindrical filter to the round table filter and, finally, to the square filter. Our results show that round table and square filters have significantly improved flow distribution compared to traditional cylindrical filters. However, the structure of the round table filter is irregular, and the space utilization rate is low. Finally, through optimization design, the square filter with channel spacing L of 250 mm has the best performance. Our research results have a certain guiding significance for the design of the silver zeolite filter prototype.

Tailored design of hierarchically porous metal/N-codoped carbon from soft-templated bimetallic ZIFs for the high-efficiency adsorption of tetracycline hydrochloride

Zeolitic imidazolate framework-8 (ZIF-8) is attracting considerable attention as a superior precursor to fabricate efficient carbon-based absorbents for many contaminants. However, most carbon materials still suffer from low-efficiency mass transfer and few active sites. Herein, transition metal/nitrogen-codoped hierarchically porous carbons (MNHCs) were controllably constructed by pyrolysis of soft-templated bimetallic ZIFs to enhance tetracycline hydrochloride (TCH) adsorption. Benefitting from its large specific surface area (920.73 m2 g−1), excellent hierarchical pore structure, high N content and abundant Lewis acid sites, the optimum MNHC (HC1000-Fe2Zn98) obtained at 1000 ℃ and the Fe/(Fe + Zn) molar ratio of 2 % improved the adsorption affinity for TCH and reduced the TCH diffusion resistance compared with other MNHCs, resulting in excellent adsorption of TCH. The synergistic effect of Fe and soft templates (sodium dodecyl benzene sulfonate, SDBS) added to the precursor significantly improved pore structure and enriched adsorption active sites of the derived carbon. The adsorption kinetics and isotherm data fitted well with pseudo-second-order kinetics and the Sips model (qm = 245.6 mg g−1), respectively. Adsorption experiments and characterization analyses suggested various adsorption interactions between TCH and MNHCs via pore fillings, coordination, H-bonding and π-π interactions. This study offers a facile strategy for fabricating hierarchically porous carbon for removing organic contaminants from water.

Rapid immobilization of Cr(Ⅵ) from aqueous waste through multi-functionalized surface-modified lignin-based aerogels: Dynamic and mechanism analyses

Water containing heavy metal ions can be extremely harmful to the environment and human body, thus the development of low-cost and high-efficient adsorbents has an exciting prospect. In this study, lignin/graphene aerogels modified with polydopamine and polyethyleneimine, respectively, were successfully prepared to remove Cr(VI) from aqueous waste. The physicochemical properties of graphene aerogels (GA), lignin/graphene aerogels (LGA), polydopamine-modified lignin/graphene aerogels (LGA@PDA), polyethyleneimine-modified lignin/graphene aerogels (LGA@PEI) were investigated using FT-IR, Raman spectroscopy, XRD, XPS, SEM-EDS, and BET analysis. The results demonstrate that adsorbents have a high specific surface area, an interconnected porous structure, and a large number of oxygen-containing groups, making them particularly favorable for heavy metal adsorption. The effects of GO/lignin ratio, surface modifiers, solution pH, contact time, initial concentration and temperature on the Cr(VI) removal were investigated and compared via batch experiments. Compared with GA (138.74 ± 3.93 mg/g), the adsorption capacity of LGA with GO/LA ratio 40:1 increased to 167.66 ± 4.75 mg/g. Furthermore, the maximum adsorption capacity of LGA@PEI and LGA@PDA rose up to 209.85 ± 3.25 mg/g and 240.39 ± 3.26 mg/mg, respectively. By simulating the experimental data with different kinetic models and isotherm models, the adsorption processes of different lignin-derived aerogels were further explored under various conditions. All types of aerogels fit well with the pseudo-second-order model and Langmuir model. In addition, the XPS results confirm that the chemical reduction of Cr(VI) to Cr(III) also plays a role in the removal of Cr(VI). The results demonstrated that the removal effect of lignin-derived aerogels on Cr(VI) was greatly improved through the multi-functionalized surface modification of LGA with PDA and PEI. Furthermore, the removal efficiency of LGA@PDA and LGA@PEI for Cr(VI) remained stable after repeated regeneration. Therefore, the results of this study indicate that LGA@PDA and LGA@PEI are promising Cr(VI) adsorbents for practical applications in wastewater treatment.

Synthesis of molecularly imprinted polymer by precipitation polymerization for the removal of ametryn

Ametryn (AME) is a triazine herbicide which is mainly used to kill unwanted herbs in crops. Despite its importance in agriculture, the usage of AME also poses a risk to humans and the ecosystem due to its toxicity. Hence, it is important to develop a method for the effective removal of AME from various water sources which is in the form of molecular imprinting polymer (MIP). In this study, MIP of AME was synthesized via precipitation polymerization using AME as the template molecule with three different functional monomers including methacrylic acid (MAA), acrylamide (AAm) and 2-vinylpyridine (2VP). The three different synthesized polymers namely MIP (MAA), MIP (AAm) and MIP (2VP) were characterized using Fourier Infra-red spectroscopy (FTIR) and Field Emission Electron Microscopy (FESEM). Then, the batch binding study was carried out using all three MIPs in which MIP (MAA) attained the highest rebinding efficiency (93.73%) among the synthesized polymers. The Energy-Dispersive X-ray spectroscopy (EDX) analysis, Brunauer–Emmett–Teller (BET) analysis and thermogravimetric analysis (TGA) were also conducted on the selected MIP (MAA). Adsorption studies including initial concentration, pH and polymer dosage were also conducted on MIP (MAA). In this study, the highest adsorption efficiency was attained at the optimum condition of 6 ppm of AME solution at pH 7 with 0.1 g of MIP (MAA). MIP (MAA) was successfully applied to remove AME from spiked distilled water, tap water and river water samples with removal efficiencies of 95.01%, 90.24% and 88.37%, respectively.Graphical

A novel ZIF-8@IL-MXene/poly (N-isopropylacrylamide) nanocomposite hydrogel toward multifunctional adsorption

Phenols, dyes, and metal ions present in industrial wastewater can adversely affect the environment and leach biological carcinogens. Given that the current research focuses only on the removal of one or two of those categories. Herein, this work reports a novel ZIF-8@IL-MXene/Poly(N-isopropylacrylamide) (NIPAM) nanocomposite hydrogel that can efficiently and conveniently absorb and separate multiple pollutants from industrial wastewater. Ionic liquid (IL) was grafted onto MXene surfaces using a one-step method, and then incorporated into NIPAM monomer solutions to obtain the IL-MXene/PNIPAM composite hydrogel via in-situ polymerization. ZIF-8@IL-MXene/PNIPAM nanocomposite hydrogels were obtained by in-situ growth of ZIF-8 on the pore walls of composite hydrogels. As-prepared nanocomposite hydrogel showed excellent mechanical properties and can withstand ten repeated compressions without any damage, the specific surface area increased by 100 times, and the maximum adsorption capacities for p-nitrophenol (4-NP), crystal violet (CV), and copper ion (Cu2+) were 198.40, 325.03, and 285.65 mg g−1, respectively, at room temperature. The VPTTs of all hydrogels ranged from 33 to 35 °C, so the desorption process can be achieved in deionized water at 35–40 °C, and its adsorption capacities after five adsorption-desorption cycles decreased to 79%, 91%, and 29% for 4-NP, CV, and Cu2+, respectively. The adsorption data fitting results follow pseudo-second-order kinetics and Freundlich models, which is based on multiple interactions between the functional groups contained in hydrogels and adsorbent molecules. The hydrogel is the first to realize the high-efficiency adsorption of phenols, dyes and metal ions in industrial wastewater simultaneously, and the preparation process of hydrogels is environmentally friendly. Also, giving hydrogel multifunctional adsorption is beneficial to promote the development of multifunctional adsorption materials.

Synthesis of a novel microplastic trap with abundant oxime groups based on MOF-545 post-engineering for the environmental pollution control and water remediation

The elimination of microplastics (MPs) from aquatic systems is a great challenge because of its miniature dimension and exorbitant stability. Hence, a novel MP trap with abundant oxime groups (MOF-545-oxime) was triumphantly synthesized based on MOF-545 post-engineering. The supreme MP adsorption capacity of MOF-545-oxime was 294.6 mg/g, which also manifested excellent selectivity and reusability for MP adsorption. Moreover, the kinetic, isothermal and thermodynamic models were used to inquiry the MP adsorption mechanism, which was governed by electrostatic attraction, coordination, and π–π interactions. The XPS spectra and adsorption energy calculations upheld the CN–OH and CN groups executed a pivotal part in the MP adsorption process of MOF-545-oxime. MOF-545-oxime also possessed splendid anti-biofouling activity and environmental safety, which efficaciously diminished the pessimistic influences of Halamphora upon the MP adsorption capacity and complied with the requirements for non-toxicity and innocuousness in the adsorbent application. The superb anti-biofouling activity and environmental safety of MOF-545-oxime might be due to the abundant functional groups and stable chemical structure. Indubitably, the development of efficacious adsorbents is crucial for the MP removal from aquatic systems. The originally proposed MOF-545-oxime has a great potential to remove MPs from aquatic systems, which also offers an inspiration for perfect high-efficiency adsorbents.

Scalable production of wood carbon microspheres for high-efficiency carbon dioxide capture

Utilizing abundantly available biomass materials to prepare adsorbent substances is a simple and cost-effective method for CO2 adsorption, which, however, is often hampered by low adsorption capacity. Here, we demonstrate near-spherical active carbon (C-DWP/Zn) with high CO2 adsorption ability, employing delignification combination with ZnCl2 activation of natural wood powder. Removing lignin from wood cell walls facilitates easy absorption of Zn ions by the cellulose nanofibers (CNFs), thereby promoting micro/nano pores formation. Moreover, rapid dehydration of cellulose molecular chains alters the morphology of activated carbon, resulting in a transition from a granular to a near-spherical shape. Consequently, C-DWP/Zn with high specific surface area of 1769 m2 g−1, shows a significantly higher microporous volume than that of a control sample without delignification. The CO2 adsorption capacity of C-DWP/Zn, with values of 3.51 mmol g−1 and 5.12 mmol g−1 at 1 bar, 25 °C and 0 °C, respectively, is superior to that of commercial activated carbon. Attributable to its optimal micropore structure, C-DWP/Zn exhibits high CO2/N2 selectivity. Furthermore, the high carbon dioxide adsorption efficiency of C-DWP/Zn was maintained and the substance could be reused at least 20 times. Near-spherical active carbon adsorbents prepared from low-value wood powders, all featuring high CO2 adsorption performances, reasonable CO2/N2 selectivity, good recoverability, suitable heat of adsorption, and fast adsorption kinetics, which are promising candidates for practical CO2 adsorption.

Facile in-situ growth of ZIF-67 nanoparticles and in-situ polymerization of polyacrylamide on chitosan aerogel spheres and their high-efficient adsorption of tetracycline

A compressible ZIF-67/polyacrylamide/chitosan composite aerogel (named as ZIF-67/PAM/CSA) is prepared by two-step method with in-situ polymerization and growth, which exhibits excellent compressible property and efficient adsorption performance of tetracycline. The loading capacity of ZIF-67 in ZIF-67/PAM/CSA can reach 42.7%, making the increased specific surface area up to 491.95 m2 g−1 for composite aerogel. For tetracycline adsorption, ZIF-67/PAM/CSA presents high capacity of 260.09 mg g−1 as well as stable enough recycling availability. The composite aerogel synthesized here with high specific surface area and compressibility, offers a promising method to branch out compressible adsorbents with benefits for the adsorption regeneration process in pollutant treatment applications.

Adsorption of uranium (VI) from aqueous solutions using boron nitride/polyindole composite adsorbent

AbstractTurbostratic boron nitride (tBN) surface is modified with polyindole (PIn) by a facile polymerization technique and the uranyl adsorption efficiency of this mesoporous hybrid is investigated. The successful surface modification is confirmed by FT‐IR, Raman, XRD, TEM, SEM, EDX, EDS mapping XPS, BET, and zeta potential techniques. The batch experiments are performed in various temperatures (T), contact times (t), pH, and initial solution concentrations (C0) to evaluate its adsorption performance. The optimum adsorption performance is achieved at pH = 5.0–5.5, T = 307 K, t = 10 min, C0 = 18 mg L−1. These experimental results are evaluated using Freundlich, Redlich–Peterson, and Langmuir isotherm models, which presents equivalent regression coefficients. Maximum adsorption capacity (qm) of the nanoadsorbent (tBN/PIn), determined by the Langmuir isotherm, is 315.29 mg g−1. The adsorption kinetics of uranyl ions on tBN/PIn are in harmony with the pseudo‐second order model. tBN/PIn nanoadsorbent provides high adsorption efficiency even at exceptionally low UO22+ concentration range (4–40 mg L−1) and low adsorbent mass (0.005 g). XPS analysis results show that 0.05% of uranium is adsorbed on tBN/PIn via mainly U‐O coordination. The results of present study demonstrate that tBN/PIn can a potential adsorbent for removing uranium from aqueous solutions.

Magnetic porous carbon material derived from imine-linked covalent organic frameworks for magnetic solid phase extraction of trace chlorine-containing herbicides in soil

Here, imine-linked covalent organic frameworks coated Fe3O4 microspheres were fabricated and employed as the self-template to prepare magnetic porous carbon material. The magnetic solid phase extraction (MSPE) performance of such magnetic covalent organic frameworks derived porous carbons (CMCOFs) were studied for the first time, and the improved MSPE performance was verified. The variations of chemical and material properties in the carbonization processes were studied, and it was found that the CMCOFs carbonated at 400°C exhibited highest adsorption efficiencies for chlorine-containing herbicides due to the formation of nitrile components at this stage. The CMCOFs retained high adsorption efficiencies (above 90 %) to chlorine-containing herbicides at wide pH range (3–12) and high salt concentration. The CMCOFs-based MSPE coupled with HPLC technique was in good potential for analysis of trace chlorine-containing herbicides in soil samples. Under the optimized conditions, this approach displayed short extraction and elution time (5 and 8 min) and low limits of detection (0.35–5.5 ng/mL) for chlorine-containing herbicides. The recoveries of spiked analytes and the relative standard deviations in real soil samples were 81.86 %–110.9 % and less than 5.92 %, respectively. This study provides an efficient method for the analysis of trace chlorine-containing herbicides in complex samples, as well as give some inspiration on material modulation by controlled carbonization to achieve improved sorption performances.

Myrica esculenta Leaf Extract-Assisted Green Synthesis of Porous Magnetic Chitosan Composites for Fast Removal of Cd (II) from Water: Kinetics and Thermodynamics of Adsorption.

Heavy metal contamination in water resources is a major issue worldwide. Metals released into the environment endanger human health, owing to their persistence and absorption into the food chain. Cadmium is a highly toxic heavy metal, which causes severe health hazards in human beings as well as in animals. To overcome the issue, current research focused on cadmium ion removal from the polluted water by using porous magnetic chitosan composite produced from Kaphal (Myrica esculenta) leaves. The synthesized composite was characterized by BET, XRD, FT-IR, FE-SEM with EDX, and VSM to understand the structural, textural, surface functional, morphological-compositional, and magnetic properties, respectively, that contributed to the adsorption of Cd. The maximum Cd adsorption capacities observed for the Fe3O4 nanoparticles (MNPs) and porous magnetic chitosan (MCS) composite were 290 mg/g and 426 mg/g, respectively. Both the adsorption processes followed second-order kinetics. Batch adsorption studies were carried out to understand the optimum conditions for the fast adsorption process. Both the adsorbents could be regenerated for up to seven cycles without appreciable loss in adsorption capacity. The porous magnetic chitosan composite showed improved adsorption compared to MNPs. The mechanism for cadmium ion adsorption by MNPs and MCS has been postulated. Magnetic-modified chitosan-based composites that exhibit high adsorption efficiency, regeneration, and easy separation from a solution have broad development prospects in various industrial sewage and wastewater treatment fields.

Pb2+ ion removal from contaminated aqueous solution by adsorption onto Graphene Oxide Sand Composite (GOSC) for efficient water purification

Lead is a heavy metal which affects all the systems of human body. An easy method for removal of lead contamination was developed by using graphene oxide coated sand particle (GOSC). In this study, GOSC was prepared using sand particle and sucrose solution under controlled heating program which shows efficient adsorption behavior compared to other adsorbents. GOSC offered very fast removal of Pb+2 with small amount of GOSC (0.09g) in 100 ppm adsorbate solution. Characterization of GOSC was done by using several advanced techniques like FTIR, XRD, SEM, EDX, TEM, DSC, and Zeta Potential measurements before and after adsorption of lead ion (Pb2+). Adsorption shows superiority over other methods because it involves effective and high removal efficiency adsorption (above 90%). Various parameters like the effect of time, pH, adsorbent, dose effect, concentration and temperature were studied. Various adsorption and kinetic models were also investigated using adsorption data and results showed that removal of lead (Pb2+) ion follows Langmuir isotherm (R2 = 99%), second order kinetics (R2 = 98%) and higher intraparticle diffusion (R2= 98%). The high percentage removal of metal ions with little quantity of GOSC confirmed that GOSC is an excellent, effective and economic adsorbent.

Characterization of Green synthesised Iron nanoparticles and application of synthesised Iron nanoparticles as an effective catalyst for the removal of Carcinogenic metals in aqueous solution

The heavy metals such as chromium (Cr), lead (Pb) and cadmium (Cd) are considered as serious toxicants and act as carcinogenic agents that cause serious cancers to humans. The use of these heavy metals drastically increased in various industrial applications and subsequently increased the risk of contamination of these heavy metals in soil, water etc. To minimize the negative effects of these heavy metals, there is a need to reduce these heavy metals concentrations in environment samples. Hence this study focused to fabricate iron nanoparticles using Diospyros chloroxylon (Roxb.) for the removal of carcinogenic metals in water. The crystal structure, size and morphology of the nanoaprticles were evaluated and it was found that the particles were of rod shape with smooth surface and rhombohedral phase structure with an average particle size of 24 nm that contains 71.91 % of elemental iron. The heavy metal sorption experiments was conducted using selected concentration of heavy metal solution at various pH ranges, time and agitation rate. The maximum adsorption removal was 95.36 %, 98.42 % and 92.80 % within 120 min equilibrium time for Cr, Pb and Cd respectively suggesting that the nanoparticles possess high adsorption efficiency. The adsorption process follows pseudo-first order reaction kinetics with correlation coefficient of 0.978, 0.994 and 0.994 with rate constant (K) of 0.140, 0.280 and 0.108 respectively for Cr, Pb and Cd. The results suggest that the synthesized iron nanoparticles were biocompatible, stable and reusable that can be effectively utilized as promising agents for the removal of carcinogenic heavy metals in polluted water.

Biosynthesis of iron oxide nanoparticles at different temperatures and its application for the removal of Zinc by plant mediated nanoparticle, as an eco-friendly nanoadsorbent

Surface and underground water sources are threatened by various pollutants every day. Due to the fact that heavy metals do not disappear, their presence in the environment is very dangerous. Therefore, in this study, iron oxide nanoparticles were synthesized using Aloe vera extract and their application for Zinc removal from aqueous solution was studied. Nanoparticles were synthesized in different temperature conditions of 25 °C and 90 °C. The synthesized nanoparticle characteristics were identified using SEM, EDX, XRD, BET surface area, FTIR and UV–visible Spectroscopy. The SEM images indicated that the iron oxide nanoparticles synthesized at 25 °C and 90 °C had spherical morphology with average particle diameter 62.96 nm and 65.34 nm and based on BET results with a specific surface area of 37.450 and 42.520 m2 g−1, respectively. Adsorption of Zn(ΙΙ) in aqueous solution on the surface of synthesized nanoparticles was investigated and the highest adsorption efficiency was obtained at pH = 7, T = 25 °C, adsorbent concentration = 0.3 g/L, contact time = 90 min, adsorbed concentration = 10 mg/L. The adsorption fitted the pseudo second-order kinetic rate equation well, which confirmed that adsorption was via chemisorption. Freundlich model compared to Langmuir model can better describe the adsorption behavior of Zinc with iron oxide nanoparticles. Nanoparticles synthesized at 90 °C had a more uniform structure and higher absorption capacity. The absorption efficiency of 99 % was observed for nanoparticles synthesized.

Deep eutectic solvents for effective removal of indoor formaldehyde: Theoretical design, experiment, and adsorption mechanism study

Formaldehyde (HCHO) represents a prevalent indoor air pollutant, and its efficient removal continues to be an area of significant concern. Adsorption is a typical technique to capture this pollutant gas. In this work, the COSMO-RS theoretical framework guided the selection of three deep eutectic solvents (DES): L-arginine/glycerol, L-lysine/glycerol, and L-proline/glycerol, from a pool of 416 combinations involving 16 amino acids and 26 alcohols. These DES were used for the first time to adsorb HCHO. The adsorption experiments of HCHO illustrated that the DES system had a higher HCHO adsorption capacity than the pure fraction. Among them, L-arginine-glycerol-1:5 (A-G-DES) had the highest adsorption efficiency, requiring only 0.1 g to remove 92.7% HCHO in 6 h, which is consistent with the predicted results. The nucleophilic addition reaction between amino acids and HCHO during the adsorption was revealed by FT-IR and 13C NMR. DFT calculations analyzed the interaction strength of HCHO at different adsorption sites, and the formation of DES system was demonstrated to produce more favorable HCHO adsorption behavior through the interaction energy calculation. The molecular dynamics simulations (MD) verified that the main mode of HCHO adsorption was the non-covalent interaction between polar functional groups (such as −COOH, −NH and −OH) in DES system and O and/or C atoms in the HCHO molecules.

Design of a Novel Sericite-Phosphoric Acid Framework for Enhancement of Pb(II) Adsorption.

In this study, phosphoric acid was used to attach anions to the weak interlayer structure of sericite, one of the clay minerals composed of a tetrahedral structure of silicate, to increase the adsorption capacity of cations. Natural sericite beads (NSB) and activated sericite beads with phosphoric acid (PSB) were prepared as beads in order to increase reusability and facilitate the separation of adsorbates and adsorbents. Using this, lead (Pb(II)) removal efficiency from an aqueous solution was comparatively analyzed. The pHpzc was 6.43 in NSB but lowered to 3.96 in PSB, confirming that more acidic functional groups were attached to the PSB surface. According to FT-IR analysis, P=O, P-O-C, P=OOH and P-O-P bonds appeared on the surface of the PSB adsorbent, and the peaks of carboxyl groups and OH-groups were large and broad. The maximum adsorption capacity of Langmuir was 52.08 mg/g for NSB and 163.93 mg/g for PSB. The adsorption process was close to physical adsorption for NSB and chemical adsorption for PSB, and both adsorbents were endothermic reactions in nature in that the higher the temperature, the higher the adsorption efficiency. The adsorption mechanism of Pb(II) to PSB was achieved by ion exchange, electrostatic interaction, hydrogen bonding, and complexation. The adsorption of Pb(II) using PSB was not significantly affected by the adsorption of competing ions and showed a high adsorption efficiency of 94% in reuse up to 6 times. This confirms the favorable feasibility of removing Pb(II) from industrial wastewater using PSB.

Artemisia gum reinforced amidoxime gel membrane promotes rapid extraction of uranium from seawater

The development of high-efficiency adsorbents for rapid recovery of uranium from wastewater and seawater is considered an important condition for the sustainable development of nuclear energy. Herein, polyamidoxime (PAO) was introduced into a novel Artemisia sphaerocephala Krasch. gum -polyvinyl alcohol gel system, and ASKG-PVA/PAO gel membrane was prepared by crosslinking and membrane laying. Due to the high swelling capacity of ASKG, PAO chain is fully exposed, and ASKG-PVA/PAO membrane shows excellent uranium adsorption capacity of 681.20 mg·g−1 (pH = 6). The introduction of ASKG greatly improve the adsorption rate of the membrane, and the adsorption process reach equilibrium within 60 min (1/6 of original material). The static adsorption process conforms to the second-order kinetics and Langmuir model. X-ray photoelectron spectroscopy analysis shows that the strong coordination of N and O in amidoxime group is the main reason for uranium adsorption. ASKG-PVA/PAO membrane has great potential as uranium adsorbent due to its fast and efficient adsorption, easy separation and good recycling performance.

Lamellar mesoporous Mg-containing silicate adsorbents derived from iron ore tailings for high-efficient adsorption of mycotoxins and antibiotics

Iron ore tailing (IOT), as a typical solid waste, is in urgent need of high value-added utilization. The resource endowment and silicate composite characteristics owe IOT inherent potentials to prepare environmental functional materials. However, the Si-O-Si(M) bonds in IOT, having both ionic and covalent bonding properties, are very strong, which makes IOT difficult to efficiently utilize. Herein, sodium silicate, magnesium sulfate and potassium sodium tartrate (PST) were simultaneously introduced to promote the reconstitution of IOT as lamellar mesoporous Mg-containing silicate adsorbent. The adsorbents possess high specific area of 280.18 m2/g and abundant active sites, whose adsorption capacities for aflatoxin B1 (AFB1) and tetracycline hydrochloride (TC) were 30.05 mg/g, 217.39 mg/g, respectively. It is expected that the present work could lay a theoretical and experimental foundation for the high value-added functional utilization of IOT.

Performance evaluation and efficiency of functionalized cellulose nanocomposites for the removal of pharmaceutical contaminants from the aqueous environment

Water pollution caused by pharmaceuticals has raised many concerns about the potential risks to human health and living organisms. Therefore, it is important to develop a high-efficiency adsorbent for the removal of organic pollutants from wastewater. Cellulose-based nanomaterials can be effectively used for wastewater treatment. In the present work, new nanocomposites are designed through the functionalization of cellulose with β-cyclodextrin (β-CD/Cell), cucurbit [6] (CUR/Cell), and calixarene (CAL/Cell) groups with Tetrafluoroterephthalonitrile (TFP) linker. Then, the adsorption of pharmaceutical agents such as propranolol (PRO), levofloxacin (LEV), and metformin (MET) is examined on nanocomposites as efficient adsorbents. The obtained results show that the systems containing the β-CD functional group have a higher adsorption for all three types of drugs compared to the other two nanocomposites. It should be noted that both types of interactions (Van der Waals and electrostatic) between β-CD/Cell and CAL/Cell nanocomposites with micropollutant molecules are significant, whereas, between CUR/Cell and drugs, the electrostatic interaction is dominant. Also, the most number of hydrogen bonds exist between the MET drug and nanocomposite membranes, which leads to stronger electrostatic interactions. In addition, our findings confirm that the system containing β-CD/Cell nanocomposite and LEV drug has the highest number of contacts (2300) at the beginning of the simulation and the most interaction energy (368.5 kJ/mol). It is worth mentioning that the negative values of the interaction energies show that all of the investigated drug molecules exothermically and spontaneously adsorbed on the surface of cellulose nanocomposites.

Uranium recovery from weakly acidic wastewater using recyclable γ-Fe2O3@meso-SiO2

U(VI)-containing acidic wastewater produced from uranium mining sites is an environmental hazard. Highly efficient capture of U(VI) from such wastewater is of great significance. In this study, a mesoporous core–shell material (i.e. γ-Fe2O3@meso-SiO2) with magnetically and vertically oriented channels was rationally designed through a surfactant-templating method. Batch experiment results showed that the material had an efficiency level of >99.7% in removing U(VI) and a saturated adsorption capacity of approximately 41.40 mg/g, with its adsorption reaching equilibrium in 15 min. The U(VI) adsorption efficiency of the material remained above 90% in a solution with competing ions and in acidic radioactive wastewater, indicating its ability to selectively adsorb U(VI). The material exhibited high adsorption efficiency and desorption efficiency in five cycles of desorption and regeneration experiments. According to the results, the mechanism through which γ-Fe2O3@meso-SiO2 adsorbs U(VI) was dominated by chemical complexation and electrostatic attraction between these two substances. Therefore, γ-Fe2O3@meso-SiO2 is not only beneficial to control the environmental migration of uranium, but also has good selective adsorption and repeated regeneration performance when used to recover U(VI) from weakly acidic wastewater in uranium mining.