Short Adsorption Time Research Articles

Isolation and Characterization of Two Novel Lytic Bacteriophages against Salmonella typhimurium and Their Biocontrol Potential in Food Products.

Foodborne pathogens, such as Salmonella, are major factors that pose significant threats to global food safety and public health. Salmonella typhimurium is a prominent serotype contributing to non-typhoidal salmonellosis, which is a prevalent foodborne illness affecting humans and animals. Bacteriophages are considered one of the most environmentally friendly biocontrol agents, particularly in the food industry, owing to their high specificity and high safety. However, the emergency of phage-resistant mutants limits the biocontrol effect of phage treatment, leading to the requirement for a high diversity of lytic phages. Therefore, the study isolated and characterized two novel lytic Salmonella bacteriophages (SPYS_1 and SPYS_2) targeting S. typhimurium ATCC14028 and evaluated their effectiveness in reducing the contamination rates for milk and chicken tenders. Morphological and genomic analyses indicated that Salmonella phages SPYS_1 and SPYS_2 are novel species classified under the genus Skatevirus and the genus Berlinvirus, respectively. Both phages exhibited high stability across a broad range of thermal and pH conditions. The one-step growth curve result suggested that both phages had a short adsorption time and a large burst size in a single lytic cycle. The phage SPYS_1 demonstrated a noteworthy inhibition effect on the growth of S. typhimurium ATCC14028 in milk, resulting in a ~2-log reduction within the 2 to 4 h range. Overall, both phages have shown significant potential for application in food safety in the future.

Mechanism analysis of enhanced desulfurization of pulverized coal through high-gradient magnetic separation with microwave radiation

Dry high gradient magnetic separation technology is a low-carbon green technology. It can be embedded in a power plant to remove coal pyrite with a high-efficiency magnetic separator and remarkable magnetic properties difference between coal pyrite and coal matrix. This study selected the microwave radiation method to improve the magnetic properties difference and carried out a desulfurization experiment with a self-developed high-gradient permanent magnetic separator using the tapered iron auxiliary magnetic pole. The results demonstrate that the pyrite content and specific magnetic susceptibility increase with the decrease in particle size. The desulfurization rate did not change significantly at 25 °C. The coal sample began to appear in the thermal reaction at 450 °C, and the pyrite can become a strong magnetic property pyrrhotite. The desulfurization rate can achieve 58.70 % at 700 °C, and is equivalent to the wet washing index, due to the supply of high magnetic field force. The dynamic characteristic response of magnetic particles becomes more obvious with short time adsorption, and the probability of carrying non-magnetic particles is reduced. This study demonstrates that the high-gradient magnetic separation technology of pulverized coal enhanced by microwave irradiation is feasible.

Efficient adsorption of methyl red, methyl orange and bromothymol blue by polyamine resin: Role of linearity and size of carboxylate in enhanced encapsulation and molecular matching

Dyes constitute the major contribution to the environmental organic pollutants. Besides being hazardous to aquatic life, dyes are highly toxic and injurious to human health. Herein, we disclose the synthesis of a novel hyper cross-linked, dubbed as BPA-PEA, for the adsorptive removal of methyl red (MR), methyl orange (MO) and bromothymol blue (BTB). BPA-PEA displayed maximum adsorption capacities (qmax) for the adsorptive removal of these ionic dyes as 230.6 mg/g, 117.7 mg/g, and 80.42 mg/g for MR, MO and BTB, respectively. Density Functional Theory (DFT) simulations indicate a spontaneous binding process, with binding order closely aligns with the experimentally observed order (MR > MO > BTB). Moreover, the higher interaction in the resin-MR complex was believed due to the linearity and smaller size of the carboxylate group in the MR. Response Surface Methodology (RSM) optimization shows excellent suitability from their statistical parameter as well as low SSE value with the experimental values. The kinetic and isothermal data suggest that the adsorption process followed a chemisorption pathway and adsorption equilibrium was achieved within 2, 6, and 18 h for BTB, MR, and MO, respectively. A significant influence of pH was also observed in the adsorption of MO (5.5), MR (6.1), and BTB (5.3). The BPA-PEA was found to be thermally stable (Td = 348 °C) and mesoporous in nature, having a high surface area (78.3 m2 g−1). The adsorption mechanism is mainly governed by electrostatic interaction between the dyes and adsorbent, however, other adsorptive mechanism such as H-bonding interactions, hydrophobic interactions or π-π interactions were also involved. In addition, the adsorption efficiency of BPA-PEA was maintained for consecutive 5 cycles, with slightly decline (less than 5 mg/g for MR, MO, and BTB) in the adsorption capacity. Given the high adsorption capacity, short adsorption time, and reusability, BPA-PEA can serve as a promising adsorbent for the removal of anionic dyes from wastewater.

Highly Defective Zirconium-Based Metal-Organic Frameworks for the Efficient Adsorption and Detection of Sugar Phosphates in the Biological Sample.

Enrichment and quantification of sugar phosphates (SPx) in biological samples were of great significance in biological medicine. In this work, a series of zirconium-based metal-organic frameworks (MOFs) with different degrees of defects, namely, HP-UiO-66-NH2-X, were synthesized using acetic acid as a modulator and were utilized as high-capacity adsorbents for the adsorption of SPx in biological samples. The results indicated that the addition of acetic acid altered the morphology of HP-UiO-66-NH2-X, with corresponding changes in pore size (3.99-9.28 nm) and specific surface area (894.44-1142.50 m2·g-1). HP-UiO-66-NH2-10 showed the outstanding performance by achieving complete adsorption of all four SPx using only 80 μg of the adsorbent. The excellent adsorption efficiency of HP-UiO-66-NH2-10 was also obtained with a wide pH range and short adsorption time (10 min). Adsorption experiments demonstrated that the adsorption process involved chemical adsorption and multilayer adsorption. By utilizing X-ray photoelectron spectroscopy and density functional theory to explain the adsorption mechanism, it was found that various interactions (including coordination, hydrogen bonding, and electrostatic interactions) collectively contributed to the exceptional adsorption capability of HP-UiO-66-NH2-10. Those results indicated that the defect strategy not only increased the specific surface area and pore size, providing additional adsorption sites, but also reduced the adsorption energy between HP-UiO-66-NH2-10 and SPx. Moreover, HP-UiO-66-NH2-10 showed a low limit of detection (0.001-0.01 ng·mL-1), high precision (<13.77%), and accuracy (80.10-111.83%) in serum, liver, and cells, good stability, high selectivity (SPx/glucose, 1:100 molar ratio), and high adsorption capacity (292 mg·g-1 for SPx). The practical detection of SPx from human serum was also verified, prefiguring the great potentials of defective zirconium-based MOFs for the enrichment and detection of SPx in the biological medicine.

Efficient adsorption performance and mechanism of fluoroquinolone antibiotic onto the acid wash-assisted Co NPs/N-C adsorbent

In this study, ZIF-67 was employed as a template, and applied a novel combined treatment method of thermal and acid treatment to provide rapid mass transfer channels and additional adsorption sites for pollutant molecules, thus achieving high adsorption capacity and shorter adsorption time. The adsorption of Co NPs/N-C on ciprofloxacin reached equilibrium within 70 min with a maximum adsorption capacity of 486.20 mg·g−1. Furthermore, the adsorption capacity was enhanced by 1.9 times after acid-wash. The fitted data indicated that the pseudo-second-order kinetics model could more accurately describe the adsorption process, with intraparticle diffusion and liquid film diffusion jointly determining the adsorption rate, primarily involving chemical adsorption. The Langmuir model best described the antibiotic adsorption isotherm, indicating monolayer adsorption on Co NPs/N-C. Based on various characterizations before and after adsorption, it was confirmed that antibiotics were adsorbed onto Co NPs/N-C through hydrogen bonding and π-π interactions. Additionally, this adsorbent exhibited strong continuous treatment capability, a simple and efficient desorption method, as well as efficient treatment efficiency for actual water bodies. This study suggests that Co NPs/N-C can be considered an efficient and promising adsorbent, and the proposed strategy can potentially serve as an antibiotic adsorbent for continuous wastewater treatment.

A sodium alginate gel bead adsorbent doping with amidoxime-modified hydroxyapatite for the efficient adsorption of uranium

In this work, the modified‑sodium alginate gel beads were prepared by sol-gel method. Due to the presence of water channels in the sodium alginate gel bead, amidoxime groups and PO43− were exposed to the surface of the adsorbent to the maximum extent, resulting in the excellent adsorption capacity of modified‑sodium alginate gel beads. The introduction of amidoxime-modified hydroxyapatite significantly improved the adsorption capacity and the adsorption rate of the gel beads. The adsorption capacity increased from 308.7 to 466.0 mg/g and the adsorption equilibrium time was shortened from 300 min to 120 min. The modified‑sodium alginate gel bead possessed the advantages of short adsorption time, high adsorption efficiency and large adsorption capacity, which could be regarded as a potential adsorbent for uranium. Moreover, the uranium removal ability on the modified gel beads was mainly attributed to the Coulomb force between PO43− and uranium and the complexation between uranium and amidoxime groups. In summary, this work would provide a new idea for the modification and application of sodium alginate-based materials.

Preparation of magnetic amphiphilic resin microspheres via the one-step polymerization method and extraction of four glucocorticoids for HPLC–MS analysis

Amphiphilic materials can be used for sample preparation of chromatography or mass spectrometry. Amphiphilic materials with magnetic properties in combination with magnetic suction devices allow for automated sample preparation. However, conventional synthesis methods are cumbersome and not suitable for the mass production of the material. In this study, a micro-suspension polymerization method was developed to synthesize magnetic amphiphilic resin microspheres (MARMs), providing new ideas for the preparation of amphiphilic microspheres. MARMs with particle sizes ranging from 3 to 6 μm were successfully prepared, with BET surface area up to 653.2 m2/g. A magnetic solid-phase extraction method based on MARM-5 was developed for the extraction of four glucocorticoids including Cortisone, Hydrocortisone, Cortodoxone, and Corticosterone. This method had a very short adsorption time of 0.5 min and a total extraction time of only 13 min. The limit of detection for the four glucocorticoids ranged from 0.22 to 0.82 ng/L. There was a good linear relationship between sample concentration and peak area in the range of 25∼500 ng/L. Relative recovery of 98 %∼108 % and internal standard normalized matrix effect factors of 95∼114 % were obtained, and the relative standard deviation was between 2.3 % and 6.3 %. The MARMs would be used as excellent solid extraction material for glucocorticoids.

Film electrode by incorporating polypyrrole/carbon black into cross-linked binders of chitosan/cationic polyacrylamide for selective chloride extraction in wastewater

Water-based binders are usually free of volatile organic compounds and hazardous reagents, which reduces the impact on the environment, and research and development of water-based binders has been progressing in recent years. In order to increase the adhesion and mechanical properties of the composite film electrode, lower the resistance to ion transfer, and improve the adsorption capacity of Cl−, a unique cross-linked aqueous binder composite film electrode was created. The film electrode for the electrochemically switched ion exchange (ESIX) system's Cl− adsorption and desorption was successfully prepared by incorporating polypyrrole (PPy-Cl)/carbon black (C) into chemically cross-linked chitosan (CS) and cationic polyacrylamide (CPAM) by glutaraldehyde (GA). The film electrode of formulated PPy-Cl/C/CS-c-CPAM had advantages over the film electrode of PPy-Cl/C/PVDF (polyvinylidene fluoride). The PPy-Cl/C/CS-c-CPAM film electrode had 33.56 mg g−1 adsorption capacity when operated at 0.8 V for the oxidation potential, high selectivity, short adsorption time, and excellent adhesions. CS-c-CPAM composite binders provide a new direction for realizing the superior performance of the film electrodes.

Ionic liquid-modified UiO-66-NH2 as sorbent of dispersive solid-phase extraction for rapid adsorption and enrichment of benzoylurea insecticides.

Ionic liquid (IL)-modified UiO-66-NH2 composite was prepared and used as sorbent of dispersed solid-phase extraction (dSPE) for extracting trace benzoylurea insecticides (BUs) from complex environmental matrices. The IL in framework endowed the prepared material had electropositive characteristics, which can produce interaction with electron rich guest molecules, such as BUs. The high thermal and chemical stability of UiO-66-NH2/IL enabled it to be reused for 16 times without significant reduction in adsorption performance. Due to the multiple forces including π-π, hydrogen bonding, and fluorine-fluorine interaction, UiO-66-NH2/IL showed good adsorption performance, short adsorption time (20 s) and rapid desorption ability (60 s) for BUs. Under the optimal conditions, the method exhibited wide linear range (0.02-500 ng mL-1) with correlation coefficient (R2) not worsethan 0.9928, high enrichment factor (252-300), and low detection limit (0.005-0.4 ng mL-1). The dispersed solid phase extraction coupling with high-performance liquid chromatography-diode array detector (dSPE-HPLC-DAD) was successfully used to detection of BUs in real environmental samples and satisfactory recoveries were obtained (80.5%±2.4-118%±3.2). The results indicated that UiO-66-NH2/IL composite can be a potential sorbent for the preconcentration of trace insecticidesin environmental samples.

Modeling study on a two-stage hydrogen purification process of pressure swing adsorption and carbon monoxide selective methanation for proton exchange membrane fuel cells

A two-stage hydrogen purification process based on pressure swing adsorption (PSA) and CO selective methanation (CO-SMET) is proposed to meet the stringent requirements of H2-rich fuel for kW-scale skid-mounted or distributed proton exchange membrane fuel cell systems. The reforming gas is purified using dynamic adsorption model of PSA with activated carbon for initial purification and then kinetic model of CO-SMET with 50 wt% Ni/Al2O3 for CO deep removal. Sensitive analyses of the gas hourly space velocity, adsorption time and adsorption pressure etc. are studied. The results show that excellent H2 purity and CO concentration below 1000 ppm for the initial target using the three-bed and four-bed PSA system at shorter adsorption time and higher pressure, and then CO concentration below 10 ppm with H2 purity over 99.94% on CO-SMET. This work provides a small-scale and hydrogen-saving process for hydrogen purification can be achieved by the two-stage process.

Physical stability, microstructure and interfacial properties of solid-oil-in-water (S/O/W) emulsions stabilized by sodium caseinate/xanthan gum complexes

Calcium carbonate (CaCO3) has poor suspension stability, which severely limits its application in food processing and products. In this study, sodium caseinate (NaCas) and sodium caseinate (NaCas)-xanthan gum (XG) mixtures were compared for the stable preparation of solid/oil/water (S/O/W) emulsions for the delivery of calcium carbonate (CaCO3) to solve the problem of poor suspension stability. The physical stability, particle size distribution, and microstructure of S/O/W emulsions were investigated to prove the successful construction of the system. The dynamic surface pressure and surface swelling properties of 2.0 wt% NaCas with different concentrations of XG were investigated to clarify the effect of interfacial properties of NaCas-XG mixtures on the emulsion stability of S/O/W emulsions. The results showed that the addition of XG resulted in enhanced physical stability, reduced particle size distribution, and enhanced encapsulation effect of the emulsion, forming a more three-dimensional core–shell structure via dendritic links. XG had a significant effect on the dynamic properties of the NaCas adsorption membrane: NaCas interacted with XG and the diffusion (kdiff) of NaCas to the interface decreased in short adsorption time, thus limiting the protein adsorption effectiveness; the presence of XG reduced the penetration (kP) and rearrangement (kR) rates at the interface during long adsorption times. Meanwhile, the NaCas-XG mixture has a high swelling elasticity. The results of this study can be used to improve the quality of related emulsion products or to prepare delivery systems for bioactive compounds.

Rapid adsorption of selenium removal using iron manganese-based micro adsorbent

Selenium in wastewater is of particular concern due to its increasing concentration, high mobility in water, and toxicity to organisms; therefore, this study was carried out to determine the removal efficiency of selenium using iron and manganese-based bimetallic micro-composite adsorbents. The bimetallic micro-composite adsorbent was synthesized by using the chemical reduction method. Micro-particles were characterized by using energy-dispersive X-ray spectroscopy for elemental analysis after adsorption, which confirms the adsorption of selenium on the surface of the micro-composite adsorbent, scanning electron microscopy, which shows particles are circular in shape and irregular in size, Brunauer–Emmett–Teller which results from the total surface area of particles were 59.345m2/g, Zeta particle size, which results from average particles size were 39.8 nm. Then it was applied to remove selenium ions in an aqueous system. The data revealed that the optimum conditions for the highest removal (95.6%) of selenium were observed at pH 8.5, adsorbent dosage of 25 mg, and contact time of 60 min, respectively, with the initial concentration of 1 ppm. The Langmuir and Freundlich isotherm models match the experimental data very well. The results proved that bimetallic micro-composite could be used as an effective selenium adsorbent due to the high adsorption capacity and the short adsorption time needed to achieve equilibrium. Regarding the reusability of bimetallic absorbent, the adsorption and desorption percentages decreased from 50 to 45% and from 56 to 53%, respectively, from the 1st to the 3rd cycle.

Hydrogel‐biochar composites for removal of methylene blue: Adsorption performance, characterization, and adsorption isotherm, kinetics, thermodynamics analysis

AbstractLow‐concentration organic dye wastewater severely threatens the growth and reproduction of animals and plants, as well as the survival and development of human beings and the environment. Although versatile hydrogel composites have been prepared owing to their excellent adsorption performance, the high‐removal efficiency and fast adsorption rate are still two crucial problems related to practical applications. Herein, xanthan gum‐g‐poly (acrylic acid‐co‐acrylamide)/biochar composite hydrogels with high‐removal efficiency and fast adsorption rate of methylene blue (MB) are synthesized using sodium dodecyl sulfate as a pore‐foaming agent. The composite hydrogels exhibit rough and porous three‐dimensional structures, which can make the internal active adsorption sites to be fully exposed and facilitate the MB diffusion process. MB's removal efficiency can reach 96.64% within 30 minutes, which is almost the first time that a biochar‐contained hydrogel could show superior removal efficiency of more than 95% in such a short adsorption time. The factors affecting the adsorption performance are studied comprehensively. Langmuir and pseudo‐second‐order models fit the adsorption process well. Moreover, the MB removal rate still exceeds 80% after eight cycles, which is also a vital indicator for practical treatment. Adsorption mechanism analysis shows that the synergistic effect among biochar, xanthan gum, and polymer chains and the porous structure improve the adsorption performance of the composite hydrogels. The proposed hydrogel‐biochar composites with high‐removal efficiency and adsorption rate are highly promising as an alternative adsorbent for advanced printing and dyeing wastewater treatment.

Facile preparation of methionine-functionalized graphene oxide/chitosan polymer nanocomposite aerogel for the efficient removal of dyes and metal ions from aqueous solutions

Heavy metal ions and organic compounds are often discharged together with the industrial and textile wastewaters. These effluents often cause severe toxicological impacts on the human health and environment. In this study, we propose a simple and an efficient approach to obtain methionine-functionalized graphene oxide/ chitosan polymer nanocomposite aerogel (Meth-GO/CH) to be used for the removal of dyes and metal ions from aqueous solutions through batch adsorption. Characterization of Meth-GO/CH nanocomposites was performed to determine the morphology of the prepared material. The elimination of dyes and metal ions from aqueous solutions by the adsorbent material was studied under different influencing factors. The adsorption process followed the Langmuir model for monolayer adsorption. Maximum adsorption capacities were: 46.511 mg/g for Rhodamine B, 243.902 mg/g for Crystal Violet, 66.225 mg/g for Ni(II) and 149.253 mg/g for Cu(II), respectively, at room temperature. The kinetic results revealed good fitting for the pseudo-second-order kinetic model, which showed the highest linear regression coefficient and lowest values for error functions. These results suggest that the chemical adsorption is the rate determining step, which involves sharing of electrons between the adsorbent and the adsorbate. Moreover, the thermodynamic parameters revealed the feasibility, spontaneity, and the endothermic nature of the adsorption process. The as-prepared Meth-GO/CH could be successfully reused up to five cycles of consecutive adsorption–desorption experiments, where 80 % of the original adsorption value was still achieved in the 5th cycle. Overall, the short-time adsorption process, high adsorption capacity and good regenerability of the safe, biodegradable and cost-effective Meth-GO/CH aerogel material makes it as an advantageous reusable promising tool for wastewater treatment.

Partial substitution of conventional synthetic surfactant by biosurfactant enhances the stability of micro-droplets of crude oil in surfactant solution in flow state and within sub-second period

Microbial lipopeptides have been proposed to adsorb at interface rapidly and have synergistic effect with synthetic surfactant, and we assumed that stable droplets of oil would generate and oil-in-water emulsion with good stability would be obtained using the mixture of microbial lipopeptides and synthetic surfactant in short time scale. Here, the interfacial properties of the mixture of microbial lipopeptide and petroleum sulphonates has been evaluated using the coalescence frequency of the micro-droplets of crude oil in surfactant solutions in flow state and within sub-second period based on a microfluidic method. Results showed that partial substitution of petroleum sulphonates by lipopeptide enhanced the stability of micro-droplets of crude oil in surfactant solutions. To form stable micro-droplets of crude oil, less lipopeptide/petroleum sulphonates mixture (m:m=1:1) was needed than petroleum sulphonates. Moreover, higher salt tolerance, less demand of alkali, and shorter adsorption time were obtained for lipopeptide/petroleum sulphonates mixture to form stable emulsion comparing with that of individual petroleum sulphonates mixture. The present study provide novel information of lipopeptide/petroleum sulphonates mixture in generating stable crude oil-in-water emulsion at flow state.

Isolation of a lytic bacteriophage against extensively drug-resistant Acinetobacter baumannii infections and its dramatic effect in rat model of burn infection.

Objectives Acinetobacter Baumannii is an opportunistic nosocomial pathogen belonging to the Moraxellaceae family. The emergence of multidrug resistant strains of this pathogen caused many problems for hospitals and patients. The aim of the current study was to isolate, identify, and morphologically, physiologically, and in vivo analyze a new lytic bacteriophage targeting extensively drug‐resistant (XDR) A. baumannii.Materials and MethodsDifferent wastewater samples were tested for isolation of lytic bacteriophage against 19 A. baumannii isolates obtained from patients hospitalized in a hospital in Arak, Iran, from January 2019 to March 2019. The phenotypic and genotypic characteristics of A. baumannii strains (resistance genes including: adeA, adeB, adeC, adeR, adeS, ISAba1, blaOXA‐23, blaOXA‐24) were analyzed. The isolated phage characteristics including adsorption time, pH and thermal stability, host range, one‐step growth rate, electron microscopy examination, and therapeutic efficacy of the phage were also investigated. Therapeutic efficacy of the phage was evaluated in a rat model with burn infection of XDR A. baumannii. The lesion image was taken on different days after burning and infection induction and was compared with phage untreated lesions.ResultsThe results showed unique characteristics of the isolated phage (vB‐AbauM‐Arak1) including high specificity for Acinetobacter baumannii, stability at a relatively wide range of temperatures and pH values, short adsorption time, short latent period, and large burst size. In relation to the therapeutic efficacy of the phage, the lesion area decreased in phage‐treated groups over 14 days than in those untreated, significantly (p < 0.05).ConclusionOur findings demonstrated that isolated lytic phage was able to eliminate burn infections caused by XDR A. baumannii in a rat model. So, it may be recommended as alternative options toward to developing a treatment for extensively drug resistant Acinetobacter infections.

In Vitro and In Vivo Assessments of Two Newly Isolated Bacteriophages against an ST13 Urinary Tract Infection Klebsiella pneumoniae.

Antibiotic resistance represents a major public health concern requiring new alternatives including phage therapy. Klebsiella pneumoniae belongs to the ESKAPE bacteria and can cause urinary tract infections (UTIs). The aims of this study were to isolate and characterize new bacteriophages against a K. pneumoniae strain isolated from UTIs and to assess their efficacy in vitro and in vivo in a Galleria (G.) mellonella larvae model. For this purpose, two bacteriophages were newly isolated against an ST13 K. pneumoniae strain isolated from a UTI and identified as K3 capsular types by wzi gene PCR. Genomic analysis showed that these bacteriophages, named vB_KpnP_K3-ULINTkp1 and vB_KpnP_K3-ULINTkp2, belong to the Drulisvirus genus. Bacteriophage vB_KpnP_K3-ULINTkp1 had the narrowest host spectrum (targeting only K3), while vB_KpnP_K3-ULINTkp2 also infected other Klebsiella types. Short adsorption times and latent periods were observed for both bacteriophages. In vivo experiments showed their ability to replicate in G. mellonella larvae and to decrease host bacterial titers. Moreover, both bacteriophages improved the survival of the infected larvae. In conclusion, these two bacteriophages had different in vitro properties and showed in vivo efficacy in a G. mellonella model with a better efficiency for vB_KpnP_K3-ULINTkp2.

Lanthanum ion modification of aminated cyclomatrix polyphosphazene-coated porous carbon nanosheets for rapid, efficient and selective removal of phosphate

Phosphate removal has been the top priority in eutrophic wastewater treatment. Herein we reported a fast, efficient and selective adsorbent, PCNs@PCP-La, for phosphate removal from an aqueous medium. The adsorbent was fabricated via two steps: (1) synthesis of PCNs@PCP composite through in situ polymerization of hexachlorocyclotriphosphazene and polyethyleneimine on the porous carbon nanosheets; and (2) lanthanum ion (La3+) modification of PCNs@PCP via an impregnation process to create PCNs@PCP-La hybrid. Multiple characterizations showed that the atomically dispersed La3+ ions could be facilely chelated with nitrogen-rich cyclomatrix polyphosphazene framework, significantly improving the application efficiency of La3+ ions as active adsorption sites. Comparative tests confirmed that PCNs@PCP-La had a high phosphate uptake capacity of up to 121.2 mg P g−1 (pH = 4.0) at 298 K and performed well even in a wide pH range (3.0–9.0). Also, PCNs@PCP-La showed a particularly short saturated adsorption time (5 min), indicating a fast adsorption kinetic process. Meanwhile, PCNs@PCP-La presented a superior adsorption selectivity for phosphate under interference with coexisting anions/cation and humic acid, and owned an attractive reusability (after 5th cycles, 85% capacity retention). The plausible adsorption mechanism can be ascribed to electrostatic attraction, inner-sphere complexation, and the formation of LaPO4·0.5H2O precipitates between adsorbent and adsorbate.

Sonochemical Preparation of a Magnet-Responsive Fe3O4@ZIF-8 Adsorbent for Efficient Cu2+ Removal.

This work presents a novel approach to synthesizing magnetic core-shell nanocomposites, consisting of magnetic nanoparticles and a metal-organic framework, for environmental applications. The synthesis is based on the encapsulation of magnetic Fe3O4 nanoparticles with microporous zeolitic imidazolate framework-8 (ZIF-8) nanocrystals via ultrasonic activation under a continuous supply of precursor solutions. This sonochemical approach is proven to be a fast, cost-effective, and controllable route for the preparation of magnet-responsive Fe3O4@ZIF-8 nanoparticles with a core-shell structure. The functional nanomaterial possesses a high content of ZIF-8 and combined micro/mesoporosity, and thus can be used as adsorbents that can be easily separated using a magnet. In particular, the sonochemically prepared Fe3O4@ZIF-8 exhibits significant adsorption performance for the removal of copper ions from water: a short adsorption time (10 min), high maximum uptake capacity (345 mg g−1), and excellent removal efficiency (95.3%). These performances are interpreted and discussed based on the materials characteristics of Fe3O4@ZIF-8 established by microscopy, gas sorption, X-ray diffraction, and thermal analysis.

Graphene oxide decorated with fullerenol nanoparticles for highly efficient removal of Pb(II) ions and ultrasensitive detection by total-reflection X-ray fluorescence spectrometry

• Superior nanoadsorbent for highly effective adsorption of Pb(II) ions. • Impressive adsorption capacity and selectivity of the adsorbent toward Pb(II). • Extremely small adsorbent dosage and very short adsorption time. • Very low detection limit of 2.3 pg mL −1 using a benchtop TXRF instrument. • Simple and accurate analysis of complex matrix samples. In this paper, the graphene oxide (GO) decorated with fullerenol nanoparticles C 60 (OH) 22 has been designed for the highly selective separation and ultrasensitive determination of lead ions. The grafting fullerenol nanoparticles to the surface of GO solves the problem of their high solubility in aqueous solutions and simultaneously uses their high hydrophilicity and deprotonation ability. The research has revealed unique adsorption properties of GO-C 60 (OH) 22 toward Pb(II) ions at pH 5.5, i.e., minimal adsorbent dose (5 mg L −1 ), impressive resistance to ionic strength (up to 1 mol L −1 ), and enormous adsorption capacity (1307 mg g −1 ), much higher than those of any of the currently reported sorbents. The adsorption isotherms, kinetics, and effect of ionic strength indicate that an inner-sphere model based on surface complexation is the main mechanism of Pb(II) adsorption on GO-C 60 (OH) 22 . The high-resolution O1s and Pb4f X-ray photoelectron spectra confirm the strong chelation of Pb(II) ions and suggest the various coordination of Pb(II) ions to the oxygen functional groups. The exceptional properties of GO-C 60 (OH) 22 , including the possibility of application in micro-quantities, were the basis for the development of the method for ultra-sensitive detection of Pb(II) ions using such micro-analytical technique as total-reflection X-ray fluorescence spectrometry (TXRF). The method allows obtaining an extremely low detection limit of 2.3 pg mL −1 using a low-power TXRF instrument. Due to the impressive selectivity of the method, the ultra-trace Pb(II) ions can be highly accurately determined in complex matrix samples, including high salinity waters challenging to analyze using other analytical techniques.