Convenient Recovery Research Articles

Fragmentation studies by non-explosive cylinder expansion technique

Expansion and fragmentation of metallic cylinders is an important area of study both for designing munitions and mitigation techniques against fragments as well as in the failure of pressurised pipes in industry. Most of the reported studies on fragmentation have been carried out by detonating explosively filled metallic cylinders. However, this approach has inherent limitations in terms of both safety and repeatability – not least due to packing issues with explosive fills. Fragmentation studies on hollow metallic cylinders of both mild and stainless steel of various thicknesses (2–4 mm) were carried out by firing a polycarbonate projectile from a single-stage light gas gun. Strain rates of the order of 2 × 104 s−1 were observed at cylinder expansion velocities of 400–450 m s−1, calculated from flash X-ray radiographs. The differences in fragmentation behaviour of both materials was observed, attributed to their different response to high strain-rate loadings.Microscopic analysis of mild steel fragments showed interesting alignment of ferrite and pearlite grains, similar to reported effects of explosive loading. This suggests the potential to employ this technique to simulate explosive cylinder expansion in a non-explosive laboratory environment enabling a convenient recovery of fragments. Numerical modelling with using ANSYS AUTODYN® allowed for a better understanding of the various parameters controlling expansion and fragmentation. Analysis of recovered fragments by a Fragment Weight Distribution Map (FWDM), a method generally used for characterising pipe bombs, could clearly demonstrate the effect of casing material and thickness.

Alcohols selective oxidation with H2O2 catalyzed by robust heteropolyanions intercalated in ionic liquid-functionalized graphene oxide

A set of heteropolyacid-based ionic heterogeneous catalysts (PW@IL-GO(m)) have been synthesized by intercalated heteropolyanions in ionic liquid (IL)-functionalized graphene oxide (GO) via amino-protonation and/or anion-exchange reaction. This immobilization method offered improved dispersity, accessibility and stability of active sites. The amphipathic nature of IL-GO sheets and porosity of PW@IL-GO(m) are beneficial to reducing mass transfer limitation in a water/organic substrate two-phase system. Then, these obtained hybrids were employed as efficient and robust catalysts for the selective oxidation of alcohols into carbonyl compounds using hydrogen peroxide as an oxidant under organic solvent-free condition. As expected, PW@IL-GO(m) catalysts showed even much better activity than the corresponding homogeneous HPW (phosphotungstic acid) catalyst. Particularly, PW@IL-GO(1.5) gave a benzyl alcohol conversion of 94% and benzaldehyde chemoselectivity of 91%. Moreover, owing to the heterogeneous nature and strong cation–anion interactions between cationic supporter and PW anions, the as-prepared catalyst presented advantages of convenient recovery, simple preparation and steady reuse, further providing the industrial application potential in sustainable oxidation reactions.

Synthesis of zeolite NaY supported Mn-doped ZnS quantum dots and investigation of their photodegradation ability towards organic dyes.

In this work, Mn-doped ZnS quantum dots capped by L-cysteine (Mn@ZnS/L-cyst) and polyethylene glycol (Mn@ZnS/PEG) and also Mn-doped ZnS on zeolite NaY (Mn@ZnS/Y) were synthesized. These compounds were characterized by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible and fluorescence spectroscopy. Then, the photodegradation ability of these three photocatalysts was investigated for degradation of 4',5'-dibromofluorescein dye under ultraviolet irradiation. In the next stage, the different effective parameters on degradation performance, such as pH, catalyst dosage, and initial dye concentration, were studied. Results demonstrated that the optimum initial concentration was 40mgL-1 for all three catalysts. The optimum catalyst dosage for both Mn-doped ZnS quantum dots capped by L-cysteine and Mn-doped ZnS on zeolite NaY was 0.017gL-1 and for Mn-doped ZnS quantum dots capped by polyethylene glycol was 0.033gL-1. The degradation efficiency of 97% for all three photocatalysts was achieved; therefore, by considering the higher production yield of quantum dots onto zeolite and also the more convenient recovery of the Mn-doped ZnS on zeolite NaY from the solution, it seems synthesis of quantum dots onto the zeolites is a reasonable strategy.

Heterogeneous activation of persulfate by Ag doped BiFeO3 composites for tetracycline degradation

Persulfate (PS) activation have been extensively considered as a promising technology for removing recalcitrant pollutants, due to their production of radicals with superior oxidation reactivity. However, a catalyst with high reactive and convenient recovery for PS activation still remains to be developed. In this work, the silver-doped bismuth ferrite (Agx-BiFeO3, x = 0.1, 0.2, 0.3 and 0.4) catalysts with variable Ag content were synthesized via a facile sol-gel method and applied as heterogeneous catalyst in PS activation for tetracycline (TC) degradation. Ag0.4-BiFeO3 presented the best catalytic activity compared with other Ag doped BiFeO3 composites, 91% TC could be efficiently removed within 60 min under optimized conditions and the reaction rate constant was 0.0338 min−1. On the basis of the characterization analysis and catalytic test results, Ag could be the effective active site in PS activation and had a significant effect on PS activation. Moreover, the initial pH has negligible effect on the catalytic performance, indicating that Ag0.4-BiFeO3/PS system could work in a wide pH range. The results of electron spin-resonance spectroscopy and radical quenching tests suggested that both SO4− and OH radicals were involved in the Ag0.4-BiFeO3/PS system. The possible mechanism of Ag0.4-BiFeO3 activating PS and the major degradation pathway of TC degradation were proposed. At last, the reusability experiment results proved that Ag0.4-BiFeO3 catalyst still has a high catalytic performance after 4 times used.

Spinel nanoparticles on stick-like Freudenbergite nanocomposites as effective smart-removal photocatalysts for the degradation of organic pollutants under visible light

A series of mixed nanocomposite materials was synthetized, containing a Ferrite phase type Zn1-xNixFe2O4 and a Freudenbergite phase type Na2Fe2Ti6O16, where x = 0; 0.2; 0.4; 0.6; 0.8; 1. The choice for this combination is based on the good adsorption properties of Freudenbergite for dye molecules, and the small bandgap energy of Ferrite spinel, allowing activation of the catalysts under visible light irradiation. A two steps synthesis protocol was used to obtain the smart-removal nanocomposites. Firstly, the spinel structure was obtained via the co-precipitation route followed by the addition of the Ti-source and formation of the Freudenbergite system. The role of cations on the formation mechanism and an interesting interchange of cations between spinel and Freudenbergite structures was clarified by a TEM-study. Part of the Ti4+ penetrated the spinel structure and, at the same time, part of the Fe3+ formed the Freudenbergite system. The photocatalytic activity was studied under visible light, reaching for the best catalysts a 67% and 40% mineralization degree for methylene blue and rhodamine 6G respectively, after 6 h of irradiation. In the same conditions, the well-known commercial P25 (Degussa) managed to mineralize only 12% and 3% of methylene blue and rhodamine 6G, respectively. Due to the remarkable magnetic properties of Ferrites, a convenient recovery and reuse of the catalysts is possible after the photocatalytic tests. Based on the excellent catalytic performance of the nanocomposites under visible light and their ease of separation out of the solution after the catalytic reaction, the newly developed composite catalysts are considered very effective for wastewater treatment.

Preparation of high molecular weight pH-responsive lignin-polyethylene glycol (L-PEG) and its application in enzymatic saccharification of lignocelluloses

Highly recyclable pH-responsive lignin-polyethylene glycol (L-PEG) was synthesized to achieve enhanced lignocellulosic hydrolysis and recycling cellulase. The performance of L-PEG could be easily regulated by adjusting the molecular weight and the amount of PEG. The large molecular weight facilitated L-PEG to reduce the invalid adsorption of cellulase on lignin during hydrolysis and enhance its flocculation effect at around pH 3.0. L-PEG1000-40 obtained by adding 40 wt% (based on lignin) PEG1000 could effectively enhance the enzymatic hydrolysis of lignocelluloses and recover most of cellulase after hydrolysis through simply adjusting the pH of hydrolysate. During eucalyptus hydrolysis, using L-PEG1000-40 to recycle cellulase could not only save 40% cellulase, but also increase the glucose yield by 121%. Due to the low synthesis cost of L-PEG and the simple and convenient recovery operation, this new method is beneficial to the improvement of lignocellulosic saccharification process and the high-value utilization of lignin.

RGO/β–Bi2O3/SrFe12O19 magnetic photocatalyst: facile synthesis and its photocatalytic activity

Magnetic photocatalysts utilized in dye wastewater photodegradation field has been attracting lots of attentions due to their convenient recovery and without secondary pollution. Here, rGO is introduced to boost the photocatalytic activity of magnetic photocatalyst β–Bi2O3/SrFe12O19. On the one hand, rGO can promote the migrate of photogenerated carriers and further suppress the recombination of photogenerated charge. On the other hand, the formation of heterojunction structure between β–Bi2O3 and SrFe12O19 can also spur the separation of photoinduced carriers because of the built-in electric field in the heterojunction system. This work will provide reference about the synthesis of high efficiency magnetic photocatalyst and stable magnetic composites.

Gd (III) and Tb (III) immobilized tryptophan functionalized magnetic nanoparticles for eco-friendly oxidation rections

In this study, Gd (III) and Td (III) immobilized magnetic nanocatalysts were prepared following a simple procedure using available materials. These nanoparticles were characterized by FT-IR, XRD, TGA, EDX, and ICP-OES studies and utilized in the S-oxidation reactions. It was observed that the rate of oxidation with Tb magnetic nanocatalyst was higher than that of Gd. Significant advantages of this environmental friendly process include short reaction times, high efficiency, and convenient recovery and reusability of the catalyst for several times without any significant loss of activity.

The growth model and its application for microalgae cultured in a suspended-solid phase photobioreactor (ssPBR) for economical biomass and bioenergy production

Attached cultivation could achieve the convenient recovery of microalgae cells during the microalgae-based biomass and bioenergy production. However, this cultivation pattern has a light/nutrient transfer problem in biofilms, which decreases the microalgae growth rate. A combination of attached and suspended microalgae cultivation patterns, i.e., a suspended-solid photobioreactor (ssPBR), has been proposed for the potential of economical biomass production. It was demonstrated that the increase in attached microalgae biomass was mainly attributed to the attachment of suspended microalgae cells rather than to the regrowth of attached microalgae. A specific growth model for the microalgae in an ssPBR was constructed based on the Logistic model, which provided a good fit to the experimental data (R2>0.93, p < 0.05). Therefore, the cultivation strategy was proposed as periodically recovering attached microalgae by capturing carriers and keeping the suspended microalgae at the fastest growth rate (half of the maximum suspended microalgal density). The results indicated that the addition of carriers with an attaching capability of 1.31 × 107 cells/mL into the 105 m3 ssPBR when the suspended Scenedesmus density was at 5.87 × 106 cells/mL and removing them after 5.15 d could achieve the large profit of 146 K dollars/d with an annual production of 3600 t microalgae biomass. In this way, high productivity and energy-saving recovery of microalgae could be achieved.

Hydrodechlorination of p-Chlorophenol on Pd-Coated Fe3O4@polypyrrole Catalyst with Ammonia Borane as Hydrogen Donor

Ammonia borane (AB) (hydrogen donor), was used for the hydrodechlorination of p-chlorophenol on Fe3O4@PPY@Pd at room temperature and pressure. Fe3O4@PPY@Pd was characterized by scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The high-performance liquid chromatography and carbon balance results showed that p-chlorophenol was efficiently and quantitatively transformed into phenol. At the AB and catalyst contents of 2.5 mmol and 60 mg, respectively, the dechlorination of p-chlorophenol (100 mg/L) followed pseudo-first-order kinetics (rate constant = 0.023 min−1), and removal efficiency up to 92.5% was obtained in 120 min. The apparent activation energy was 31.6 kJ/mol. The Fe3O4@PPY@Pd composite catalyst could be reused without a significant loss in activity. This confirms the good stability of the catalyst. Here, a reductive approach for the dechlorination of organic compounds in water is provided. It is also useful for the fabrication of Pd-based nanocatalysts with easy accessibility, superior activity, and convenient recovery.

Insights into the effect of chemical treatment on the physicochemical characteristics and adsorption behavior of pig manure-derived biochars.

Chemical treatment could improve the adsorption performance of biochars (BC). In order to deal with Pb(II) pollution, four types of biochars including unmodified, acid-treated, alkali-treated, and magnetic-treated pig manure-derived biochars (PBCs) were prepared. The effect of chemical treatment on the physical property, chemical composition, and the adsorption behavior of biochars was compared. Magnetic and alkali treatment improved pore volume and specific surface areas, and the adsorption capacity and rates were enhanced. In contrast, the adsorption capacity of acid-treated BC decreased due to the significant decrease of ash content. The magnetic samples displayed the satisfactory absorption performance, which could achieve 99.8% removal efficiency within 15min at a Pb(II) concentration of 50mg/L. Considering its properties of excellent adsorption performance, fast reaction rate, and convenient recovery by an external magnetic field, magnetic biochar based on pig manure may provide an effective way to remove heavy metals and decrease the pig manure solid waste.

New perspective to catalytic epoxidation of olefins by Keplerate containing Keggin polyoxometalates

Different Keggin encapsulated in Keplerate polyoxometalates (Mo72Fe30, PMo12 ⊂ Mo72Fe30, SiMo12 ⊂ Mo72Fe30 and BW12 ⊂ Mo72Fe30) have been synthesized and their catalytic efficiency in the epoxidation of olefins with hydrogen peroxide investigated. Results were confirmed that Keggin encapsulated in Keplerates could show higher catalytic activity than parent ones. These POM catalysts lead to heterogeneous epoxidation of alkenes by hydrogen peroxide with green features of convenient recovery, steady reuse, high conversion and selectivity, and simple preparation.

Cocoa bean shell waste valorisation; extraction from lab to pilot-scale cavitational reactors

The use of zero-waste processes to integrate food-waste valorisation into the circular economy equation is currently one of the hottest topics in sustainability research. This goal is still far from being fully achieved despite the release of a number of patents and papers that deal with the topic.The present work aims to valorise cocoa shells, one of the main by-product of the roasting process, in order to enhance the effective extraction of high added value compounds by means of green protocols. The high potential added value of the residual waste has been demonstrated via a direct analytical comparison of extracts and bean composition.A range of raw matrix extraction procedures have been investigated in order to define the best solvent and technology; ultrasound (US) and hydrodynamic cavitation (HC) were compared with conventional methods. The high-energy microenvironments generated by cavitation substantially promote fast biomass deconstruction with low energy consumption. The optimized protocol couples a HC reactor with a ternary water/ethanol/hexane mixture, simultaneously providing a hydrophilic product, which is rich in methylxanthines and polyphenols, and a lipid layer.Sequential milling and sieving pretreatment provided an enriched shell fraction via the partial removal of husk fibres (54.45 vs. 81.36 w/w % total fibres). The disposal of the latter reduces mass balance, but is rerouted into animal feedstock components and crop mulching.The protocols herein reported produce valuable extracts, which are rich in antioxidant flavanols (catechins and epicatechins), theobromine (32.7 ± 0.12 mg/g shells), caffeine (1.76 ± 0.08 mg/g shells) and cocoa butter, in a simple and easy manner. This new valorisation process afforded 20.5 w/w % and 15.8 w/w % hydrophilic and lipophilic fractions, respectively, when scaled up to function in a pilot flow reactor. The fatty acids, obtained in remarkable yield (forming the 96.4 w/w % of the total light part) well match the commercial cocoa butter profile. The antioxidant extract shows an impressive total phenolic content of 197.4 mg/g extract (gallic acid eq.), with a radical scavenging activity of 62.0 ± 3.1 μg/mL (expressed in DPPH EC50). This work should facilitate industrial design for the convenient recovery of cocoa by-products as part of a zero-waste strategy.

Versatile Poly(Diallyl Dimethyl Ammonium Chloride)-Layered Nanocomposites for Removal of Cesium in Water Purification.

In this work, we elucidate polymer-layered hollow Prussian blue-coated magnetic nanocomposites as an adsorbent to remove radioactive cesium from environmentally contaminated water. To do this, Fe3O4 nanoparticles prepared using a coprecipitation method were thickly covered with a layer of cationic polymer to attach hollow Prussian blue through a self-assembly process. The as-synthesized adsorbent was confirmed through various analytical techniques. The adsorbent showed a high surface area (166.16 m2/g) with an excellent cesium adsorbent capacity and removal efficiency of 32.8 mg/g and 99.69%, respectively. Moreover, the superparamagnetism allows effective recovery of the adsorbent using an external magnetic field after the adsorption process. Therefore, the magnetic adsorbent with a high adsorption efficiency and convenient recovery is expected to be effectively used for rapid remediation of radioactive contamination.

Systematic Evaluation of 2-Arylazocarboxylates and 2-Arylazocarboxamides as Mitsunobu Reagents.

2-Arylazocarboxylate and 2-arylazocarboxamide derivatives can serve as replacements of typical Mitsunobu reagents such as diethyl azodicarboxylate. A systematic investigation of the reactivity and physical properties of those azo compounds has revealed that they have an excellent ability as Mitsunobu reagents. These reagents show similar or superior reactivity as compared to the known azo reagents and are applicable to the broad scope of substrates. p Ka and steric effects of substrates have been investigated, and the limitation of the Mitsunobu reaction can be overcome by choosing suitable reagents from the library of 2-arylazocarboxylate and 2-aryl azocarboxamide derivatives. Convenient recovery of azo reagents is available by one-pot iron-catalyzed aerobic oxidation, for example. SC-DSC analysis of representative 2-arylazocarboxylate and 2-arylazocarboxamide derivatives has shown high thermal stability, indicating that these azo reagents possess lower chemical hazard compared with typical azo reagents.

Synthesis and characterizations of FeNi3@SiO2@TiO2 nanocomposite and its application in photo- catalytic degradation of tetracycline in simulated wastewater

Tetracycline (TC) is an antibiotic widely used in veterinary medicine and in treatment of human infection, and enters aquatic environments. Conventional treatment have not had much impact on removal of TC, as a result, in this study photocatalysis degradation of TC have been considered.FeNi3@SiO2@TiO2 was synthesized, and its characterization were determined using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dissipation spectroscopy, and Fourier transform infrared spectroscopy. Then, its efficiency as a photo-catalyst for TC degradation was examined in a batch reactor and the effects of pH, contact time, initial concentration and nanocomposite dose were investigated. The results showed that the efficiency of the photocatalytic process was 100% using FeNi3@SiO2@TiO2 for degradation of TC at a concentration of 10mg/L, for 200min, at pH9, with nanocomposite dose (0.005g/L). The kinetics of TC degradation followed the pseudo-first-order model.The results of this study showed that FeNi3@SiO2@Tio2 nanocomposite has a reasonable efficiency in degradation of TC, as its relatively simple synthesis and convenient recovery, it could be a suitable catalyst for removal and degradation of pharmaceutical organic pollutants.

A simpler and more cost-effective peptide biosynthetic method using the truncated GST as carrier for epitope mapping.

There is a need to develop better methods for epitope mapping and/or identification of antibody-recognizing motifs. Here, we describe improved biosynthetic peptide (BSP) method using a newly developed plasmid pXXGST-3 as vector, which has a viral E7 gene in the cloning sites of pXXGST-1. It is crucial to employ pXXGST-3 instead of pXXGST-1, since it makes use of the BSP method simpler and easier to perform, and more cost-effective for epitope mapping. These merits are embodied in two aspects: i) convenient recovery of double enzyme-digested product due to the existence of 315 bp inserted between BamH I and Sal I sites, and thus greatly reducing the production of self-ligation clones, and ii) no longer requiring control protein when screening recombinant (r-) clones expressing 8/18mer peptides by running polyacrylamide gel electrophoresis. The protocol involves the following core steps: (i) design of plus and minus strands of DNA fragments encoding overlapping 8/18mer peptides; (ii) chemical synthesis of the designed DNA fragments; (iii) development of r-clones using pXXGST-3 vector expressing each 8/18mer peptide fused with truncated GST188 protein; (iv) screening r-clones by running the cell pellets from each induced clone on SDS-PAGE gel followed by sequencing of inserted DNA fragments for each verified r-clone; and (v) Western blotting with either monoclonal antibodies or polyclonal antibodies. This improved GST188-BSP method provides a powerful alternative tool for epitope mapping.

Synthesis, Organo-Functionalization, and Catalytic Properties of Tungsten Oxide Nanoparticles As Heterogeneous Catalyst for Oxidative Cleavage of Oleic Acid As a Model Fatty Acid into Diacids

A series of tungsten oxide nanoparticles (NPs) has been synthesized via a green and straightforward approach exploiting bare tungsten powder as a precursor. The synthesized NPs were further organo-functionalized by cetyltrimethylammonium bromide (CTAB) in order to adjust their surface state and enhance their compatibility with biphasic oxidation of vegetable oils with H2O2. Simply, different structures of tungsten oxide were observed, which were characterized by XRD, FTIR, TGA, TEM, N2 adsorption/desorption isotherms, and zeta potential analysis. All the synthesized nanocatalysts could fully convert oleic acid, and the highest yield of production of the desired diacid (azelaic acid), ∼80%, was achieved by optimization of the CTA+ amount on the nanocatalyst’s surface, which show excellent activity compared to the reported heterogeneous works. Thanks to the organo-functionalization, this water-tolerant catalyst exhibited no significant leaching, as well as convenient recovery and steady reuse without a noti...

Highly Active Ruthenium Supported on Magnetically Recyclable Chitosan‐Based Nanocatalyst for Nitroarenes Reduction

AbstractA Ru supported on a magnetically separable chitosan‐based nanomaterial (Mn@CS@Ru) was prepared by wet impregnation based on ionic gelation using sodium tripolyphosphate as a cross‐linking agent. The ionic gelation of chitosan leads to a supporting matrix to promote the embedding of manganese(II) ferrite and Ru nanoparticles (NPs) by electrostatic interactions. The effects of the formulation and method parameters on the fabrication process were investigated, and the resulting as‐prepared Mn@CS@Ru nanocatalyst was characterized. The catalytic activity of the Mn@CS@Ru nanomaterial was evaluated in the reduction of 4‐nitrophenol (4‐NP) and 4‐nitroaniline (4‐NA) in the presence of sodium borohydride as a reducing agent at room temperature. The turnover frequency values in the reduction of 4‐NP and 4‐NA were 273.9 and 336.5 min−1, respectively, which were attributed to the very small size of the hybrid nanomaterial (32.0±2.8 nm with 3.9±0.1 nm Ru NPs) that provided a large surface‐area‐to‐volume ratio for the chemical reaction. Furthermore, the hybrid nanocatalyst was recovered easily by magnetic separation after the catalytic reaction and could be reused in at least 10 cycles without a loss of catalytic activity, which confirms its high stability. The present route is a new approach to synthesize highly active magnetic heterogeneous catalysts for the reduction of nitroarenes based on metallic NPs with easy accessibility, excellent activity, and convenient recovery.

Magnetic separable chitosan microcapsules decorated with silver nanoparticles for catalytic reduction of 4-nitrophenol

In the work, we have synthesized silver (Ag) nanoparticles deposited chitosan (CS) microcapsules with magnetic multiple Fe3O4 cores (denoted as Fe3O4/CS-Ag) as efficient catalysts for the reduction of 4-nitrophenol. The Fe3O4/CS-Ag catalysts are prepared by coating hydrophobic Fe3O4 nanoparticles with chitosan via a multiple emulsion-chemical crosslinking method and following in situ deposition of Ag nanoparticles onto the surfaces. The morphology and composition of the Fe3O4/CS-Ag microcapsules are characterized by Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy. Moreover, the catalytic activity of the Fe3O4/CS-Ag catalyst was investigated, which shows a conversion efficiency as high as 98% within 15min for the reduction of p-nitrophenol to p-aminophenol. At the same time, the recovered Fe3O4/CS-Ag catalyst with an external magnet can retain good activity after 10 cycles. These results indicate that the multiple emulsion-chemical crosslinking method is an efficient and simple way for the preparation of magnetic separable chitosan microcapsules, and the fabricated Fe3O4/CS-Ag is a promising catalytic material with excellent catalytic activity and convenient recovery ability.