High Adsorption Capability Research Articles

Sustainable nano-hybrids of magnetic biochar supported g-C3N4/FeVO4 for solar powered degradation of noxious pollutants- Synergism of adsorption, photocatalysis & photo-ozonation

In this research work we report synthesis of g-C3N4/FeVO4 (CI) and g-C3N4/FeVO4/Fe@NH2-Biochar (CIB) nano-hetero assemblies for removal of methyl paraben (MeP) and 2-cholrophenol (2-CP) via adsorption, photocatalysis and photo-ozonation. CI and CIB have been characterized by FT-IR, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–Vis spectroscopy, photoluminescence (PL), vibrating sample magnetometry (VSM), Brauner-Emmet Teller surface area analyzer (BET). CIB shows good photocatalytic activity owing to higher specific area, nanosheet porous structure, stability, broader solar spectrum response and reduced charge carriers recombination. Fe@NH2-biochar facilitates the degradation via high adsorption capability due to reduced recombination, better charge separation, adsorption and acting of biochar as sink of electrons. The CIB photocatalytic system was tested under three experimental conditions for photodegradation of MeP and 2-CP; adsorption followed by photo-degradation (AP); simultaneous adsorption and photocatalysis (SAP); SAP + O3. An apparent synergism between adsorption, photocatalysis and photo-ozonation brings out excellent and promising results. 98.4% of MeP and 90.7% of CP degradation was achieved under simultaneous adsorption and photocatalysis in presence of CIB. The results were analyzed in terms of reaction kinetics, adsorption isotherms, scavenger effect, liquid chromatography-mass spectrometry (LC-MS), Total Organic Carbon (TOC) analysis and cytotoxicity analysis of treated water. An efficient TOC removal 74.2 & 73.9% for MeP and 2-CP were respectively achieved under SAP + O3+CIB photocatalysis system. Degradation pathways have been proposed for degradation of MeP and CP thorough photo-degradation and photo-ozonation. The cyto-toxicity studies on Human peripheral blood lymphocytes provide a reference for removal of noxious pollutants in real systems. This experimental work paves a way to design tuneable simple junctions for photocatalytic applications by utilizing various experimental protocols.

A 3D Hybrid of Chemically Coupled Nickel Sulfide and Hollow Carbon Spheres for High Performance Lithium–Sulfur Batteries

Lithium–sulfur batteries are a promising next‐generation energy storage device owing to their high theoretical capacity and the low cost and abundance of sulfur. However, the low conductivity and loss of active sulfur material during operation greatly limit the rating capabilities and cycling stability of lithium–sulfur batteries. In this work, a unique sulfur host hybrid material comprising nanosized nickel sulfide (NiS) uniformly distributed on 3D carbon hollow spheres (C‐HS) is fabricated using an in situ thermal reduction and sulfidation method. In the hybrid material, the nanosized NiS provides a high adsorption capability for polysulfides and the C‐HS serves as a physical confinement for polysulfides and also a 3D electron transfer pathway. Moreover, NiS has strong chemical coupling with the C‐HS, favoring fast charge transfer and redox kinetics of the sulfur electrode. With a sulfur loading of up to 2.3 mg cm−2, the hybrid material‐based lithium–sulfur batteries offer a capacity decay as low as 0.013% per cycle and a capacity of 695 mA h g−1 at 0.5 C after 300 cycles. This unique 3D hybrid material with strong chemical coupling provides a promising sulfur host for high performance lithium–sulfur batteries.

Graphene oxide cross-linked with phytic acid: an efficient adsorbent for the extraction of carbamates

A nanocomposite (designated as PAG) possessing amphiphilic properties was prepared by a single-step method from graphene oxide and phytic acid, in which phytic acid acts as both an inducer and cross-linking agent. The morphology and microstructure of PAG were characterized by nitrogen adsorption, scanning electron microscopy and transmission electron microscopy. The PAG possess a 3 dimensional network structure with interpenetrated nano- and micropores and represent a viable adsorbent for solid-phase extraction of carbamate pesticides prior to their quantitation by high performance liquid chromatography. Under optimum conditions, the calibration plot is linear in the 0.5 to 80 ng g−1 concentration range in case of apple samples, and in the 1.0 to 80 ng mL−1 range for juice samples. The respective limits of detection (for S/N = 3) are between 0.05 and 0.1 ng g−1, and between 0.2 and 0.3 ng mL−1. The PAG has a high adsorption capability, and in our preception it may become a useful adsorbent for the preconcentration of other organic pollutants.

Fullerol-facilitated transport of copper ions in water-saturated porous media: Influencing factors and mechanism

The environmental safety of carbon nanomaterials (CNMs) has become a hot spot of worldwide research work. The high stability, mobility and adsorption capability of CNMs may give rise to the enhancement of heavy metal transport. However, the understanding of facilitated transport of heavy metal ions by CNMs is still limited. In this research, fullerol nanoparticles (C60(OH)n) were used as a typical CNM to investigate its effect on Cu2+ transport in the water-saturated porous media. Column experiments showed that C60(OH)n could facilitate the transport of Cu2+. Meanwhile, flow velocity showed little impact on the facilitated transport while pH and fullerol concentration played an important role. The mechanism of fullerol-facilitated transport of Cu2+ was mainly due to the much higher adsorption capacity of C60(OH)n than that of the porous media. Besides, the existence of C60(OH)n decreased the adsorption kinetics of Cu2+ on the porous media, which led to a decreasing chance for Cu2+ to be retained and thus enhanced the transport of Cu2+.

Reducing agent-free formation of Cu(I) nanoclusters on gC3N4 for enhanced photocatalysis

Copper species with +1 oxidization state, Cu(I), in amorphous form can potentially be employed for photocatalytic activity improvement due to its ability to capture photoproduced hole. However, this proposition has never been confirmed experimentally, likely due to difficulty in forming such amorphous Cu(I) on the host photocatalyst surface. In the present work, Cu(I) amorphous nanoclusters are successfully deposited on the gC3N4 surface via ultrasonication without any external reducing agent for enhancement of visible light photocatalytic activity. Since Cu species are introduced in low concentrations and cannot be satisfactorily inspected using conventional characterization techniques, synchrotron-based techniques including XANES, EXAFS and soft-XAS are therefore used for interrogating the oxidation state and local structure of Cu(I) nanoclusters as well as the structural features of gC3N4. Appreciable enhancement of photocatalytic activity of Cu(I)/gC3N4 is shown for degradation and mineralization of atrazine under visible light. The Cu(I)/gC3N4 also exhibits relatively high adsorption capability for atrazine, which is up to 37% of total atrazine removal. These obtained results are very encouraging and may find applications in abatement of other recalcitrant organic contaminants combining adsorption and photocatalysis.

Facile synthesis of gelatin modified attapulgite for the uptake of uranium from aqueous solution

Gelatin modified attapulgite (ATT@Gel) with high adsorption capability for U(VI) was synthesized by plasma technique. The ATT and ATT@Gel composites were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA). The characterization results indicated that ATT@Gel was synthesized successfully. The adsorption capability of ATT@Gel for U(VI) was studied by batch adsorption technique. Experiment results indicate that the modified gelatin on ATT surface can markedly improves the adsorption efficiency of ATT@Gel for U(VI).

Solvothermal polycondensation of novolacs phenolic-resin to nanopowders and their derived activated nanocarbons as efficient adsorbents for water cleaning

Novolacs phenolic-resin (PF) was easily polycondensed into polymeric powders with sizes and morphologies ranging from microspheres to nanoparticles by a simple solvothermal process without adding any crosslinking agent. Activating the highly divided PF powders by CO2 resulted in nanosize activated carbons with high specific surface area (2092 m2 g−1) and large pore volume (1.33 cm3 g−1) while preserving a high carbon yield of about 38 wt%. As for adsorption tests, the micropore-dominated activated nanocarbons exhibited fast and high adsorption capabilities towards both Cr(VI) ions and bulky rhodamine B molecules due to their much improved external surface area and the greatly shortened intra-particle diffusion distance. The equilibrium adsorption amounts of Cr(VI) and RB on the activated nanocarbons as estimated by the Langmuir model were 200 and 990 mg g−1, achieved within an adsorption time of 30 and 360 min, respectively.

Microwave-assisted catalytic degradation of methyl orange in aqueous solution by ferrihydrite/maghemite nanoparticles

Six-line ferrihydrite was successfully prepared by precipitation method and characterized with XRD, SEM, TEM, BET and FTIR spectroscopy. The as-prepared ferrihydrite was used as catalyst for the degradation of methyl orange (MO) in an artificial dye wastewater without adding any oxidant. It was found that the ferrihydrite nanoparticles with average size of about 90–220nm exhibited a high adsorption capability to MO and the dye molecules obey Langmuir type of adsorption. Batch degradation experiments show that the catalytic degradation of MO could be remarkably improved by coupling with microwave irradiation. The initial pH value of MO solution exerted notable influence on the degradation reaction and the optimal degradation efficiency was obtained under neutral conditions. Radical scavenger measurements indicated that OH radicals could generate during the catalytic process even without adding oxidant. We proposed that the microwave irradiation facilitates the generation of active oxygen species derived from water and/or oxygen dissolved in water, which are responsible to the excellent performance of the MW-assisted catalytic process.

Porous Al-doped ZnO rods with selective adsorption properties

Al-doped ZnO (ZnO:Al) rods with Al doping varying from 0 to 20% were successfully prepared via a solvothermal method. ZnO:Al rods exhibit the hexagonal wurtzite crystalline structure and their length were found to decrease from 127 to 12nm when increasing the dopant percentage from 0 to 20%. Simultaneously, their specific surface area increased from ca. 21 to 82m2/g. ZnO:Al (20%) rods exhibit high adsorption capability towards some negatively charged dyes like Orange II, Acid red 88 or Alizarin, which was attributed to the high specific surface of ZnO:Al rods and to the defects induced by the Al doping as demonstrated by XRD and Raman spectroscopy.

From waste Coca Cola® to activated carbons with impressive capabilities for CO2 adsorption and supercapacitors

We herein report the synthesis of heteroatoms doped, high surface area microporous activated carbons (AC) by utilisation of Coca Cola® as a potential source of waste biomass, for applications as CO2 adsorbent and electrodes of supercapacitors. N, S dual doped carbon spheres are firstly obtained by hydrothermal treatment of Coca Cola® and then thermally activated by either KOH or ZnCl2. The resulting KOH activated carbon material (CMC-3) exhibits extremely high adsorption capability for CO2 with 5.22 mmol g−1 at 25 °C and 1 atm, one of the highest values ever recorded for a carbonaceous material. On the other hand, ZnCl2 activated carbon material (CMC-2) performs excellently as an electrode for supercapacitor, exhibiting very high specific capacitance of 352.7 F g−1 at a current density of 1 A g−1 in 6 M KOH electrolyte, which again is one of the highest values recorded for a biomass derived AC. Coca Cola® has high content in carbon as sugars, provides in-situ doping of O, N and S and has constant composition, as opposed to other conventional biomass materials, making it an attractive and cheap alternative for synthesis of high performance AC for environmental and energy storage purposes.

Self-assembled magnetic nanoparticle supported zeolitic imidazolate framework-8: An efficient adsorbent for the enrichment of triazine herbicides from fruit, vegetables, and water.

Zeolitic imidazolate frameworks have positive surface charges and high adsorption capabilities. In this work, zeolitic imidazolate frameworks-8 and negatively charged magnetic nanoparticles were self-assembled by electrostatic attraction under sonication. The extraction performance of the synthesized hybrid material was evaluated by using it as a magnetic adsorbent for the enrichment of triazine herbicides in various sample matrices prior to analysis using ultrafast liquid chromatography. The main parameters, that is, extraction time, adsorbent dosage, salt concentration, and desorption conditions, were evaluated. Under the optimum conditions, good linear responses from 2.5 to 200 ng/mL for atrazine (simazine) and 1 to 200 ng/mL for prometryn (ametryn), with correlation coefficients (R2 ) higher than 0.9992 were obtained. The detection limits of the method (S/N = 3) were 0.18-0.72 ng/mL. The proposed method was successfully used to determine triazine herbicides in six samples, namely, apple, pear, strawberry, pakchoi, lettuce, and water. The amounts of simazine in all the fruit and vegetable samples were 10.8-25.2 ng/mL. The recoveries of all the analytes were 88.0-101.9%, with relative standard deviations of less than 8.8%.

Facile solvent-thermal synthesis of ultrathin MoSe2 nanosheets for hydrogen evolution and organic dyes adsorption

The flower-like MoSe2 nanospheres with average size of 200nm which composed of ultrathin nanosheets were synthesized by facile solvent-thermal method. AFM analysis indicated that the thickness of the MoSe2 nanosheets could be changed from 3.4 to 6.4nm by changing the chains of n-alcohol solvent. The as prepared MoSe2 nanosheets in ethanol solvent exhibited the best electrochemical performance and the highest adsorption capability as compared to samples synthesized in other n-alcohol solvent with longer chains. It was due to MoSe2 synthesized in ethanol exhibited higher crystallinity and better wettability than other samples. The maximum adsorption capability of Rhodamine B (RhB) on MoSe2 nanosheets reached 133mgg−1 in 5min, while the same adsorption capabilities on activated carbon need 20min. Electrochemical results exhibited a relatively small onset potential (120mV), small Tafel slope (71mV/dec), and long term stability for MoSe2 synthesized in ethanol which making it a promising candidate for hydrogen evolution reaction.

Removal of nitroimidazole antibiotics from water by adsorption over metal–organic frameworks modified with urea or melamine

Adsorption of nitroimidazole antibiotics (NIABs, such as dimetridazole, metronidazole, or menidazole) over metal–organic frameworks (MOFs, in this case, MIL-101(Cr)) was studied in order to examine the possible applications of MOFs in the purification of water contaminated with NIABs. The MOFs, especially after grafting with urea or melamine, effectively adsorbed the NIABs. For example, urea-MIL-101, compared with any reported result, showed the highest adsorption capacity for metronidazole. Based on the adsorption results over a wide range of conditions, a plausible adsorption mechanism could be suggested for the improved performance: H-bonding between NO2 of the NIABs and NH2 of the MOF (introduced via grafting with urea or melamine). The MOFs were shown as a promising adsorbent of NIABs because of their high adsorption capability and reusability (which was confirmed with recyclability testing and FTIR).

Highly efficient and selective removal of trace lead from aqueous solutions by hollow mesoporous silica loaded with molecularly imprinted polymers

A novel type of adsorbent for the selective recognition and adsorption of trace Pb2+ from aqueous solutions has been successfully constructed simply by grafting molecularly imprinted polymers (MIPs) onto hollow mesoporous silica (HMS). Attractively, the HMS loaded with MIPs (H-MIPs) exhibits a fast adsorption kinetics, marked adsorption capacity of 40.52mg/g and extremely high selectivity toward Pb2+ over Cu2+, Zn2+, Co2+, Mn2+ and Ni2+, and the selectivity coefficients have been determined to be as high as 50. Moreover, such high adsorptive capability and selectivity were retained for at least 6 runs, indicating the stability and reusability of H-MIPs. Lead ion contaminants in real water samples were successfully concentrated and approximately 100% recovered using H-MIPs. Theoretical analysis shows that the adsorption process of H-MIPs follows the pseudo-second-order kinetic and Langmuir isotherm models. These demonstrate that H-MIPs are greatly potential for the rapid and highly efficient removal of trace Pb2+ ions in complicated matrices.

Накопичення флуоридів рослинами виду Bidens tripartita L. на ендемічних територіях

The influence of edaphic and geographic factors on accumulation of fluorides by the plants of the species growing on the territory with deficit of fluorine was studied. To assess the influence of geographic factors on the content of fluorine in the soil–plant system the influence of the macrorelief was studied by comparing the fluorides’ content depending on plants’ habitat in different physical-geographical areas of the Chernivtsi region; the influence of mesorelief was also studied by comparison of fluorides’ content in plants growing on the slopes, plains, dry and inundable ecotopes. The ability of the plants from Bidens tripartit а L. species to accumulate fluorides in favorable growing conditions was observed. It was determined that high soil adsorption capability adversely affects the accumulation of fluorides. The impact of plants’ habi­tat on the fluorides’ content in the plants from Bidens tripartit а L. species is related to the content of water-soluble fluorine forms in the soil and to the increase of migrational capability (availability) of its active forms in the conditions of increased moiste­ning. It was proven that the content of fluorides in plants growing on plain meadows is determined by water-soluble and active forms of fluorine, and the content of fluorides in the over- and underground parts of plants from inundable meadows is higher than in plants from dry lands. Variability of fluorides’ content in the plants from Bidens tripartit а L. species depends on physical-chemical characteristics of the soil, natural environment and climatic conditions of plants’ growth.

SERS-active metal-organic frameworks with embedded gold nanoparticles.

Surface-enhanced Raman scattering (SERS) has been widely used in the detection of targets and strongly depends on the interaction and the distance between the targets and nanoparticles. Herein, metal-organic frameworks (MOFs) were first easily synthesized on a large scale via a water bath method, especially Uio-66 and Uio-67. MOFs embedded with gold nanoparticles (AuNPs) for SERS enhancement were successfully fabricated via an impregnation strategy. The synthesized AuNPs/MOF-199, AuNPs/Uio-66, and AuNPs/Uio-67 composites, with LSPR properties and high adsorption capability of MOFs to preconcentrate the analytes close to the surface of the AuNPs, exhibited excellent SERS activity. The effects of the reducing concentrations of sodium citrate on the SERS activity, and the stability and reproducibility of the AuNP/MOFs have been discussed via the detection of acetamiprid. The SERS intensity enhanced by the composites was retained for more than 40 days under ambient conditions with the reducing concentrations of sodium citrate at 0.16%, 0.20%, and 0.16%. The limits of detection with the signal/noise ratio higher than 3 at the characteristic peak 632 cm-1 were 0.02 μM, 0.009 μM, and 0.02 μM for acetamiprid. Most interestingly, the AuNP/MOF-199 composites, whose morphology was long tube sheet, exhibited excellent SERS activity. These novel composites with high sensitivity, stability, and reproducibility provide a new route for the detection of pesticides via the SERS technology.

Adsorption of As(V) and As(III) from aqueous solution by lepidocrocite (γ-FeOOH) nanoparticle

γ-FeOOH nanorods an adsorbent for As(V) and As(III) removal was prepared by a chemical co-precipitation method. The maximum adsorption capacities at pH6 for As(V) and As(III) were 63.75 and 88.99 mg/g, respectively, higher than those of Fe2O3, Fe3O4... The adsorption data accorded with Freundlich isotherms. At the study pH, for arsen, the adsorption equilibrium was gained after 90 min. Kinetic data fitted well to the pseudo-second-order reaction model. The adsorption of γ-FeOOH for As (V) and As(III) could be competed by some other ion such as sulfate, ammonium and chloride. The high adsorption capability and good performance on other aspects make the γ-FeOOH nanorod a promissing adsorbent for the removal of As (V) and As(III) from the groundwater.

Concentrating synthetic estrogen 17α-ethinylestradiol using microporous polyethersulfone hollow fiber membranes: Experimental exploration and molecular simulation

A synthetic hormone, 17α-ethynylestradiol (EE2), has received much attention due to its widespread occurrence and adverse effects on aquatic animals. The removal of EE2 from water has been very challenging mostly because of its low concentration in environmental waters. Here we report a simple and novel approach for concentrating EE2 through adsorption and elution using microporous polyethersulfone (PES) hollow fiber membrane in a cross-flow filtration system, which can be easily scalable for practical applications. Our results showed that microporous PES hollow fiber membrane has a high EE2 adsorption capability (∼100% from water containing 20μg/L of EE2) and the adsorbed EE2 could be eluted using a small volume of 10% ethanol solution to achieve a recovery efficiency of 75.9±8.5%. We further demonstrated that the PES hollow fiber membrane maintained ∼100% removal of EE2 throughout five cycles of adsorption and elution. Our results from molecular simulation suggest that the strong affinity between PES and EE2 is mainly attributed to the π- π interaction and the hydrogen bonding. This proof-of-concept demonstrates for the first time that PES hollow fiber membrane system can remove EE2 at low concentrations, and elute EE2 solutions at a much higher concentration over multiple cycles in a sustainable and environmentally-benign condition.

Cr(VI) Adsorption on Red Mud Modified by Lanthanum: Performance, Kinetics and Mechanisms.

Water pollution caused by the highly toxic metal hexavalent chromium (Cr(VI)) creates significant human health and ecological risks. In this study, a novel adsorbent was used to treat Cr(VI)-containing wastewater; the adsorbent was prepared using red mud (RM) generated from the alumina production industry and the rare earth element lanthanum. This study explored adsorption performance, kinetics, and mechanisms. Results showed that the adsorption kinetics of the RM modified by lanthanum (La-RM), followed the pseudo-second-order model, with a rapid adsorption rate. Cr(VI) adsorption was positively associated with the absorbent dose, pH, temperature, and initial Cr(VI) concentration; coexisting anions had little impact. The maximum Cr(VI) adsorption capacity was 17.35 mg/g. Cr(VI) adsorption on La-RM was a mono-layer adsorption pattern, following the Langmuir isotherm model. Thermodynamic parameters showed the adsorption was spontaneous and endothermic. The adsorption of Cr(VI) on La-RM occurred as a result of LaOCl formation on the RM surface, which in turn further reacted with Cr(VI) in the wastewater. This study highlighted a method for converting industrial waste into a valuable material for wastewater treatment. The novel absorbent could be used as a potential adsorbent for treating Cr(VI)-contaminating wastewater, due to its cost-effectiveness and high adsorption capability.

RETRACTED: Preparation of granulated N-doped TiO2/diatomite composite and its applications of visible light degradation and disinfection

Abstract The industrial application of TiO 2 as photocatalyst is still limited due to its low reusability and requirement for UV light. For this reason, we combined nitrogen-doping with particle immobilization to prepare granulated N-doped TiO 2 /diatomite (GNTD) composite for both water treatment and bacteria inactivation. Pretreated diatomite was found to be a good TiO 2 supporter, due to its high adsorption capability to enrich target molecules around TiO 2 nanoparticles, which improves its photo-oxidation efficiency, and granulation increases its recoverability. Kinetic studies indicated that GNTD catalyst showed good degradation capability towards Rhodamine B ( RhB ) under visible light irradiation. It also demonstrated its superior ability to inactivate bacteria, including gram-positive Staphylococcus aureus ( S. aureus ) and gram-negative Escherichia coli ( E. coli ). Characterization results show that TiO 2 nanoparticles were immobilized onto the surface of diatomite via chemical bonding. Moreover, GNTD composite could be simply recycled for reuse, and still showed stable photo-activity. All these advantages of GNTD composite prove itself as a promising material for industrial applications.