Amounts Of Reagents Research Articles

Novel stationary phases based on epoxidized polystyrene-divinylbenzene for three modes of liquid chromatography

Mixed-mode stationary phases based on epoxidized copolymer of styrene and divinylbenzene have been obtained by amination with methylamine, further alkylation with 1,4-butanediol diglycidyl ether and opening the terminal oxirane rings with dimethylethanolamine. To evaluate the effect of the number of anchor amino and diol groups on the degree of hydrophilization of resins, the quantity of reagents was varied. Polymerization of glycidol in the functional layer at an increased pH of the reaction medium was carried out for additional shielding of the substrate. It was found that increasing the number of anchor amino groups is promising for increasing hydrophilicity in suppressed ion chromatography and hydrophilic interaction liquid chromatography modes, while polymerization of glycidol increases the degree of substrate shielding. The applicability of the most hydrophilic adsorbent in three HPLC modes was demonstrated. Novel mixed-mode stationary phase allows the separation of six nucleosides and nitrogenous bases by hydrophilic interaction liquid chromatography, 7 alkylbenzenes by reversed phase liquid chromatography, and 20 organic and inorganic anions by suppressed ion chromatography.

Wood Esterification by Fatty Acids Using Trifluoroacetic Anhydride as an Impelling Agent and Its Application for the Synthesis of a New Bioplastic.

Fatty acids (FA) and their derivatives with long alkyl chain structures are good candidates for wood esterification to confer thermoplastic properties to wood. Nevertheless, they do not react easily with hydroxyl groups of wood. In this study, we investigated the reactivity of wood with various fatty acids of different chain lengths using trifluoroacetic anhydride (TFAA) as the impelling agent in various reaction conditions. Generally, the esterification of fatty acids without solvents resulted in higher Weight Percentage Gain (WPG) and ester content than the reaction in the presence of CH2Cl2. The esterification reaction could be performed effectively at room temperature, though an increased reaction temperature provoked degradation of the esterified wood. WPG of 67% was obtained for the C3 and 253% for the C16 alkyl chain analogs, respectively. Nevertheless, the ester content was fairly uniform, with values between 10.60 and 11.81 mmol ester/gram of wood for all chain lengths. A higher quantity of reagent led to higher ester content, which tended to stabilize after a ratio of 1:4 wood and TFAA/FA. The esterification reaction was performed rapidly, with an ester content between 7.65 and 9.94 mmol ester/gram of wood being achieved only after 15 min of reaction. Fourier transform infrared spectroscopy (FTIR) analysis was performed to confirm the drastic chemical changes of wood before and after esterification. Morphological observation by scanning electron microscope (SEM), softening measurement by thermomechanical analysis (TMA), and contact angle measurements demonstrated the possibility of esterified spruce wood being applied as a new bioplastic.

Recent Advances in In Vivo Somatic Cell Gene Modification in Newborn Pups.

Germline manipulation at the zygote stage using the CRISPR/Cas9 system has been extensively employed for creating genetically modified animals and maintaining established lines. However, this approach requires a long and laborious task. Recently, many researchers have attempted to overcome these limitations by generating somatic mutations in the adult stage through tail vein injection or local administration of CRISPR reagents, as a new strategy called "in vivo somatic cell genome editing". This approach does not require manipulation of early embryos or strain maintenance, and it can test the results of genome editing in a short period. The newborn is an ideal stage to perform in vivo somatic cell genome editing because it is immune-privileged, easily accessible, and only a small amount of CRISPR reagents is required to achieve somatic cell genome editing throughout the entire body, owing to its small size. In this review, we summarize in vivo genome engineering strategies that have been successfully demonstrated in newborns. We also report successful in vivo genome editing through the neonatal introduction of genome editing reagents into various sites in newborns (as exemplified by intravenous injection via the facial vein), which will be helpful for creating models for genetic diseases or treating many genetic diseases.

The Blue Molybdenum Reaction for the Determination of Phosphate in Natural Water and Detergent Samples

Background:
 The ideal reaction conditions for the quantitative detection of phosphate in various natural water and detergent samples were carefully researched in order to produce and preserve the colored complex product. The blue complex was identified using a simple and accurate UV-VIS spectrophotometer with a maximum wavelength of 870 nm.
 Even though phosphate is an essential ingredient for the development of aquatic species, it is important to know exactly how much is present because an excess amount of phosphate can eutrophic water. Since detergents are one of the sources of phosphate in natural water, determining the concentration of phosphate in detergent samples is also essential.
 Materials and Methods:
 The method is based on the addition of sodium molybdate, which causes the interaction of orthophosphate with molybdate to produce an intense, stable, and water-soluble phosphomolybdate blue complex. Then, this combination is reduced using hydrazine hydrate in a sulfuric acid solution.
 Results:
 With a correlation coefficient of 0.9944, the system complies with Lambert-Beer's law at 870 nm in a concentration range of (0.05-9) ppm. Molar absorptivity was determined to be 12.16x103 L mol-1 cm-1 and Sandell's sensitivity was found to be 0.0156 g cm-2. Water samples were collected from Warte, Choman, Jundeyan, and Bexal in Kurdistan's vicinity of Soran. Further, detergent samples that were obtained from the market and their phosphate level were examined. The Bexal waterfall had the lowest concentration of phosphate, 0.18 ppm, while the Warte and Jundeyan water samples had the highest concentrations, 3.31 ppm, and 3.04 ppm, respectively. Moreover, similar phosphate concentrations in the two detergent samples were discovered to be at 20.43 and 24.76 ppm.
 Conclusion:
 The molybdenum blue reaction has been successfully employed to provide a sensitive and quick measuring method to quantify the phosphate content in various water and detergent samples using UV-VIS spectrophotometry by applying the right reaction conditions and reagent quantities.

Practical Manipulation for the Preparation of Mesoporous Silica Nanoparticles for Drug Delivery Vehicles.

Optimization of MSNs is the most important process for efficient and safe drug delivery systems. In this study, the physicochemical properties of MSNs were evaluated using various compositions of individual reagents. MSNs were synthesized according to a modified Stöber method. The physicochemical properties of MSNs were evaluated. Spherical uniform particles were observed in the scanning electron microscope (SEM) and transmission electron microscopy (TEM) image and the meso-structure of MSNs was confirmed. The amorphous and specific hexagonal structure of MSNs was confirmed through Xray diffraction (XRD) and SAXRD. The particle size and surface area according to changes in amounts of reagents ranged from 34.5 ± 2.3 to 216.0 ± 17.1 nm and from 549.79 to 1154.26 m2/g, respectively. A linear relationship was found between the surface area of MSNs and the adsorption rate of methylene blue (MB). MSNs exhibited no apparent cytotoxic effect on Caco-2 cell up to 200 μg/mL. The amounts of tetramethyl ammonium silicate and tetraethyl ortho silicate (TEOS), NaOH, and hexadecyl trimethyl ammonium bromide (CTAB) were adjusted to control the particle size and surface area of MSNs, and it was found that the amounts of synthetic reagents affected the physicochemical properties such as particle size and surface area of MSNs. MSNs with a large surface area adsorbed a large amount of MB. These results indicated that drug adsorption is related to the surface area of MSNs. MSNs did not show cytotoxicity to Caco-2 cells. MSNs may be a promising nanomaterial that could be applied as a carrier for various drugs.

Applications of Lab on a Chip in Antimicrobial Susceptibility of Staphylococcus aureus: A Systematic Review.

Background and Objectives: Staphylococcus aureus is a prevalent bacterium capable of inducing various infections, including skin and soft tissue infections, bloodstream infections, pneumonia, and surgical site infections. The emergence of antimicrobial resistance in S. aureus, particularly methicillin-resistant S. aureus, has raised substantial concerns within global healthcare settings. Prior to antibiotic prescription, the ideal approach is antimicrobial susceptibility testing (AST); however, this is frequently perceived as excessively complex and time-intensive. Lab-on-a-chip (LOC) technology holds promise in addressing these challenges and advancing fundamental microbiological research while also aiding in the development of therapeutic strategies. This systematic review aims to evaluate the potential utility of LOC for AST of S. aureus. Materials and Methods: This study adhered to the PRISMA guidelines. Various databases, including SCOPUS, PubMed/MEDLINE, SCIELO, and LILACS, in addition to gray literature sources, were employed in the review process. Results: Sixteen studies were included in this systematic review. All these studies detailed the effectiveness, rapidity, and predictability of LOC systems for assessing S. aureus susceptibility to various antibiotics. When comparing the LOC approach to traditional manual methods, it was evident that LOC requires a minimal quantity of reagents. Furthermore, most studies reported that the entire LOC procedure took 10 min to 7 h, with results being equally accurate as those obtained through traditional AST protocols. Conclusions: The potential application of LOC for AST of S. aureus is emphasized by its ability to provide rapid access to minimum inhibitory concentration data, which can substantially aid in selecting the most suitable antibiotics and dosages for treating challenging infections caused by this microorganism. Moreover, the rapid AST facilitated by LOC holds promise for enhancing the appropriateness and efficacy of therapy in clinical settings.

Startup performance and microbial composition of a pilot-scale rapid sand filter for the treatment of manganese-containing mine water

The inexpensive removal of soluble manganese [Mn(II)] from mine water that contains large quantities of Mn(II) should be prioritized given that large quantities of alkaline reagents are typically used in the chemical treatment of Mn-rich water from abandoned mines. Rapid sand filter (RSF) systems are widely used as a cost-effective technology in drinking water treatment processes to remove iron and Mn from groundwater. Here, we applied a pilot-scale RSF to treat mine water with a neutral pH and containing approximately 22 mg/L of Mn(II). Following a lag phase from its startup (day 1–day 26), Mn removal rates increased to approximately 40% for around 1 month (day 27–day 55) without the use of alkaline reagents but did not increase during further operation. Quantitative elemental analysis revealed Mn oxides on the sand filters during the Mn removal period. The bacterial communities on the RSFs, recorded on day 42 and day 85, were characterized and compared using 16S rRNA gene amplicon sequencing. Although the well-known Mn-oxidizing bacteria (MOB) were not listed among the ten most dominant operational taxonomic units (OTUs) on the sand filters (relative abundances: >0.68%), a significant increase in the OTUs related to well-known alphaproteobacterial MOB, such as Pedomicrobium spp., were observed during the period.

Electron beam irradiation-induced co-grafting and degradation of cotton cellulose with ionic liquid

We developed a cellulose upgrading method based on electron beam processing technology by using a carbon-carbon double bond-containing ionic liquid as an auxiliary reagent. The irradiation of cellulose was implemented by a 10 MeV high-energy electron accelerator or a 200 keV low-energy electron accelerator. The established method enabled grafting of the ionic liquid onto cellulose while triggering an irradiation degradation of cotton cellulose. By employing irradiation co-grafting degradation with a high-energy electron accelerator in the dose range of 30–40 kGy, highly uniform cotton cellulose with a high degree of polymerization (DP) of 500 and low degree of polymerization deviation (DPD) was obtained. By using a low-energy accelerator in the dose range of 4–6 kGy, cotton cellulose with a high DP of 1000 and low DPD was prepared. This method to upgrade cellulose has advantages of simple operation, short reaction time, and minimal amount of chemical reagents. It opened an avenue to access high quality of cellulose that cannot be attained with other method.

Palladium-Catalyzed Combinatorial Synthesis of Biphenyls on Droplet Microarrays at Nanoliter Scale.

The rising costs of pharmaceutical research are currently limiting the productivity of drug discovery and development, but can potentially be diminished via miniaturization of the synthesis and screening of new compounds. As droplet microarrays already present themselves as a versatile tool for highly miniaturized biological screening of various targets, their use for chemical synthesis is still limited. In this study, the influential palladium-catalyzed Suzuki-Miyaura reaction is successfully implemented at the nanoliter scale on droplet microarrays for the synthesis of an 800-compound library of biphenyls. Each reaction is carried out in individual 150nL droplets. Remarkably, the synthesis of these 800 compounds requires a minimal amount of reagents, totaling 80µmol, and a solvent volume of 400µL. Furthermore, the cleavage kinetics and purity of the obtained biphenylic compounds are investigated. Via the solid-phase synthesis approach, the compounds could be purified from excess reactants and catalyst prior to the analysis and a UV-cleavable linker allows for fast and additive-free cleavage of each compound into the individual 100nL droplet. This novel approach expands the toolbox of the droplet microarray for miniaturized high-throughput chemical synthesis and paves the way for future synthesis and screening of chemical compounds in a single platform.

Superhydrophobicity transfer effect in superwetting coatings for strengthening anti-pollution flashover performance

Superhydrophobic (SH) and superamphiphobic (SAP) coatings have been viewed as an alternative to conventional hydrophobic room temperature vulcanizing (RTV) silicone rubber coatings in anti-pollution flashover application. However, being one of the most important properties in RTV-based anti-flashover materials and devices, the hydrophobicity transfer property was rarely documented for SH and SAP coatings, which restricts their practical applications in environments with heavy contamination. Herein, we propose for the first time a superhydrophobicity transfer effect in superwetting (SW) coatings (e.g., SAP and SH coatings) containing low-surface-energy molecules (e.g., polydimethylsiloxane (PDMS)) as a migratory reagent. When the surface is stained by artificial simulated pollutants, PDMS molecules can migrate from the coating to the contamination layer, followed by a surface modification. Through this process, the surface wettability of the contaminant layer gradually evolves from superhydrophilicity to hydrophobicity, and finally to SH state. This evolution is investigated in relation to the amount and species of migratory reagents, migration time, pollution grade, and pollutant species. The superhydrophobicity transfer effect offers the coated glass insulators an outstanding anti-pollution flashover strength. This work can provide a novel and universal protocol to realize a superhydrophobicity transfer property in SW coatings, which may stimulate further investigation and applications in not only anti-pollution flashover but also other fields such as anti-fouling and anti-icing.

Utilization of a novel PVC- optical sensor for high sensitive and selective determination of zinc ion in real samples

A novel and highly specific bulk membrane optode was developed for the ultra-sensitive detection of zinc(II) in biological, pharmaceutical, and water samples. The polymer inclusion membrane (PIM) utilized in this study consists of 50% polyvinyl chloride (PVC) as a base polymer, 9.00% DOP (dioctylphthalate) as the plasticizer, and 40.0% D2EHPA (di(2-ethlyhexyl)phosphoric acid) as the carrier. To facilitate the spectrophotometric determination of zinc(II), a colorimetric reagent, namely 4-(2-arsonophenylazo) salicylic acid (APASA) {1.00%, m/v}, was employed. When Zn(II) was extracted into the PIM, it led to the creation of the zinc-D2EHPA complex. This complex then underwent a reaction with APASA, resulting in the formation of a red Zn − APASA complex with a maximum absorption wavelength (λmax) of 558 nm. To optimize the response of the optode, a central composite design was employed, considering variables such as the amount of additive and reagent, response time, and pH. When operated under the specific optimal conditions, the sensor demonstrated a limit of quantification (LOQ) of 0.74 ng/mL (equivalent to 1.17 × 10−8 M) and a limit of detection (LOD) of 0.22 ng/mL (equivalent to 3.44 × 10−9 M). The optode membrane demonstrated excellent reproducibility, stability, and a relatively long lifespan, making it suitable for precise and accurate monitoring of Zn(II) ion content. Regeneration of the optode was achieved effectively using 0.25 nitric acid solution, and its response exhibited reversibility and reproducibility, showed a relative standard deviation of less than 1.33%. Moreover, the PIM-APASA optode exhibited a high level of effectiveness in accurately determining the presence of Zn(II) ions in real environmental samples.

Understanding Molecular Transfer between Aqueous Phase and Reverse Micelles and Its Application to Bioassays in Microfluidics

Abstract Micrometer-sized water-in-oil droplets (microdroplets) are attracting attention as carriers for the high-throughput parallel analysis of trace samples. By confining trace amounts of water-soluble samples or reagents within a microdroplet, reactions and detection can be performed while suppressing diffusion dilution. Although many manipulation methods for droplets, such as mixing, merging, and splitting using microfluidic channels have been reported, concentration enrichment and purification techniques for microdroplet inclusions have been limited. Our recently developed method for selective concentration enrichment of microdroplet contents focuses on molecular transport between microdroplets and reverse micelles.

STUDY OF THE VARIABILITY OF RHEOLOGICAL PROPERTIES OF WATER-BASED BIOPOLYMER DISPERSIONS IN DRILLING FLUIDS

Link for citation: Lambin A.I., Averkina E.V. Study of the variability of rheological properties of water-based biopolymer dispersions in drilling fluids. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 8, рр. 91-97. In Rus. The relevance. Water-based biopolymer drilling fluids have become quite widespread in the technology of oil and gas well construction. Much attention is paid to the methods of regulating the physical and mechanical properties of biopolymer systems. In particular, rheological properties of solutions based on xanthan gum are of great practical interest. The effectiveness of the use of polymers is determined by the amount of the main reagent and modifying additives necessary to impart the required properties to the washing liquid. Biopolymer water drilling fluids based on xanthan gum have shown their effectiveness in many regions of the Russian Federation. However, the evaluation of the effectiveness of the solutions is difficult due to the differences in the saleable products of the producing companies in solubility, swelling and composition, which affects the optimized performance of the drilling mud. The main aim: consideration of the differences in aqueous solutions of a number of samples of xanthan gum in terms of power dependence: K-coefficient of consistency and n-degree of deviation from the Newtonian flow regime of the study. Objects: rheology of aqueous solutions of several xanthan samples, both purely aqueous and based on aqueous brines of potassium chloride (KCl) and sodium (NaCl). Methods: instrumental methods for determining the parameters of drilling fluids according to SS 33213-2014; the difference in the parameters of the power rheological dependence was determined by comparing its indicators after measuring the viscosity of solutions on a viscometer with direct indications. Results. The influence of a fixed concentration of NaCl and KCl salts on the considered indicators of the power model is shown. A generalized optimization indicator is proposed for solutions obeying a power-law rheological law. The calculated dependence of the accuracy of approximation of experimental data by a power model, which showed acceptable accuracy, is presented.

Degradation of veterinary antibiotics by Fenton process: Products identification and toxicity assessment

The aim of the work was primarily to determine the relationship between the doses of Fenton's reagents and the effectiveness of the ecotoxicity removal of aqueous solutions containing selected antibiotics. The degradation process of ampicillin, doxycycline, and tylosin in an acidic environment in the presence of H2O2 and FeSO4 was studied. The effect of reagent doses on the degree of degradation and identification of antibiotic transformation products was measured by the UPLC qTOF method. The degree of mineralisation was determined based on changes in the concentration of total organic carbon. The ecotoxicity of products was determined with commercial MARA® and MICROTOX® bioassays, as well as against unselected microorganisms from polluted rivers and wastewater treatment plant effluent.It was found that the complete degradation of antibiotics and the simultaneous elimination of the toxicity of the Fenton process products required the use of a precisely defined amount of reagents. When an insufficient dose of reactants was used, the post-reaction solutions contained antibiotic derivatives showing antimicrobial activity. On the other hand, the toxicity of the post-reaction solution against to microbiocenoses was observed when too high doses of H2O2 were used in the process. This effect resulted from the presence of unreacted reagent or other unidentified peroxides.

Fabry-Perot Interferometric Fiber-Optic Sensor for Rapid and Accurate Thrombus Detection.

We present a fiber-optic sensor based on the principles of a Fabry-Perot interferometer (FPI), which promptly, sensitively, and precisely detects blood clot formation. This sensor has two types of sensor tips; the first was crafted by splicing a tapered fiber into a single-mode fiber (SMF), where fine-tuning was achieved by adjusting the tapered diameter and length. The second type is an ultra-compact blood FPI situated on the core of a single-mode fiber. The sensor performance was evaluated via clot-formation-indicating spectrum shifts induced by the varied quantities of a thrombin reagent introduced into the blood. The most remarkable spectral sensitivity of the micro-tip fiber type was approximately 7 nm/μL, with a power sensitivity of 4.1 dB/μL, obtained with a taper fiber diameter and length of 55 and 300 μm, respectively. For the SMF type, spectral sensitivity was observed to be 8.7 nm/μL, with an optical power sensitivity of 0.4 dB/μL. This pioneering fiber-optic thrombosis sensor has the potential for in situ applications, healthcare, medical monitoring, harsh environments, and chemical and biological sensing. The study underscores the scope of optical technology in thrombus detection, establishing a platform for future medical research and application.

Periodate-Mediated Aerobic Oxidation of Sulfides over a Bifunctional Porphyrin-polyoxometalate Catalyst: Photosensitized Singlet Oxygen Oxidation of Iodate to Periodate.

Regeneration of terminal oxidants by molecular oxygen in metal-catalyzed oxidations of organic substrates has the advantage of avoiding the use of stoichiometric amounts of hazardous and/or expensive reagents to meet (some of) the green chemistry requirements. In the present study, photosensitized singlet oxygen oxidation of iodate to periodate has been used to regenerate the oxidant in polyoxometalate (POM)-catalyzed oxidation of sulfides to sulfoxides with periodate in water. To the best of our knowledge, it is the first report on singlet oxygen oxidation of iodate to periodate. In order to determine the contribution of photooxidation and oxidation pathways in the formation of sulfoxide, the oxidation of diphenyl sulfide with a very low reactivity toward aerobic photooxidation was studied; a sevenfold increase in the conversion of the sulfide to the diphenyl sulfoxide was observed for the reaction conducted in the presence of H2TMPyP-PW12O40/IO3-/O2/hν compared to that in the presence of H2TMPyP-PW12O40/O2/hν. Also, under the same conditions, a ca. 1.5-fold increase was observed in the case of methyl phenyl sulfide, which shows high reactivity toward both the oxidation and photooxidation reactions. A porphyrin-POM nanocomposite formed by the electrostatic immobilization of meso-tetra(N-methylpyridinium-4-yl)porphyrin (H2TMPyP) on PW12O40 was employed for the one-pot oxidation and photooxidation reactions. Field-emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), diffuse-reflectance UV-vis spectroscopy, thermal gravimetric analysis, and Fourier transform infrared were used to characterize the formation of the hybrid compound. An average particle size of 42 nm was estimated for H2TMPyP-PW12O40 from XRD peak broadening using the Scherrer equation. Also, FESEM images showed the formation of nearly spherical nanoparticles with a size of ca. 200 nm. The redshift of the Soret band of H2TMPyP upon immobilization on POM was attributed to strong N-H···O hydrogen-bond interactions between POM and porphyrin.

Targeted electro-redox facilitating efficient delithiation of lithium manganese ion-sieve selective electrode

The electrically switched ion exchange (ESIX), as the most promising technique for the efficient extraction of lithium from brine, especially the lithium manganese ion-sieve membrane electrode, possesses the advantages of high selectivity, high adsorption capacity, and high stability. And to enable the simultaneous lithium intercalation and de-intercalation at the cathode and anode, respectively, the selective electrode ought to be delithiated before use. Traditional chemical and electrochemical delithiation and electrochemical techniques consume enormous amounts of reagents and energy, respectively. Thermodynamics and electrochemical analysis indicated that the cathodic reaction induced the high cell voltage, which in turn caused the emitting of toxic gases and high energy consumption. Thus, in this study, a targeted-redox system was adopted to alleviate the above problems. By adding excessive Cu2+ into the cathode compartment, the cell voltages in 5 h reduced from 3 V to about 1.5 V and further reduced to 1.2 V if diluted HCl was also added. With lower cell voltage and higher current density, a higher delithiation rate can be reached (95.83 %). Furthermore, Cu2+ can be regenerated by bubbling O2 under an acidic atmosphere, which enables the re-utilization of the cathodic solution. The targeted electro-redox system can reduce 2980.49 J of the energy consumption compared with the current electrochemical delithiation method, meanwhile, the utilization of cheaper counter electrode makes it economically viable.

Design and Discovery of Water-Soluble Benzooxaphosphole-Based Ligands for Hindered Suzuki-Miyaura Coupling Reactions with Low Catalyst Load.

We report a new class of highly effective, benzooxaphosphole-based, water-soluble ligands in the application of Suzuki-Miyaura cross-coupling reactions for sterically hindered substrates in aqueous media. The catalytic activities of the coupling reactions were greatly enhanced by the addition of catalytic amounts of organic phase transfer reagents, such as tetraglyme and tetrabutylammonium bromide. The optimized general protocol can be conducted with a low catalyst load, thereby providing a practical solution for these reactions. The viability of this new Suzuki-Miyaura protocol was demonstrated with various substrates to generate important building blocks, including heterocycles, for the synthesis of biologically active compounds.

N,S-codoped biochar outperformed N-doped biochar on co-activation of H2O2 with trace dissolved Fe(Ⅲ) for enhanced oxidation of organic pollutants

Co-activation of H2O2 with biochar and iron sources together provides an attractive strategy for efficient removal of refractory pollutants, because it can solve the problems of slow Fe(Ⅱ) regeneration in Fenton/Fenton-like processes and of low •OH yield in biochar-activated process. In this study, a wood-derived biochar (WB) was modified by heteroatom doping for the objective of enhancing its reactivity toward co-activation of H2O2. The performance of the co-activated system using doped biochars and trace dissolved Fe(Ⅲ) on oxidation of organic pollutants was evaluated for the first time. The characterizations using X-ray photoelectron spectroscopy (XPS), Raman spectra and electrochemical analyses indicate that heteroatom doping introduced more defects in biochar and improved its electron transfer capacity. The oxidation experiments show that heteroatom doping improved the performance of biochar in the co-activated process, in which the N,S-codoped biochar (NSB) outperformed the N-doped biochar (NB) on oxidation of pollutants. The reaction rate constant (kobs) for oxidation of sulfadiazine in NSB + Fe + H2O2 is 2.25 times that in NB + Fe + H2O2, and is 72.9 times that in the Fenton-like process without biochar, respectively. The mechanism investigations indicate that heteroatom doping enhanced biochar's reactivity on catalyzing the decomposition of H2O2 and on reduction of Fe(Ⅲ) due to the improved electron transfer/donation capacity. In comparison with N-doping, N,S-codoping provided additional electron donor (thiophenic C–S–C) for faster regeneration of Fe(Ⅱ) with less amount of doping reagent used. Furthermore, co-activation with NSB maintained to be efficient at a milder acidic pH than Fenton/Fenton-like processes, and can be used for oxidation of different pollutants and in real water. Therefore, this research provides a novel, sustainable and cost-efficient method for oxidation of refractory pollutants.

Chemical Recycling of Flexible Polyurethane Foams by Aminolysis to Recover High-Quality Polyols.

Polyurethane foams (PUFs) are widely used commodity materials, but most of them end up in landfills at the end of their life, which is not in line with the circular economy approach. Here, we introduce microwave-assisted aminolysis with amine reagents that contain primary and tertiary amino groups in the structure. These reagents enable complete degradation of the urethane groups in the structure of the flexible PUFs with a much lower amount of degradation reagent than is typically required for solvolysis reactions. The purified, recovered polyols are close equivalents to the corresponding virgin polyols in terms of their structural and molar mass characteristics. Therefore, they can be used for the production of high-quality PUFs without having to adapt the synthesis process. The flexible PUFs made from recovered polyols have comparable mechanical properties to those made from virgin polyols.