Simple Filtration Research Articles

Reagentless Chemistry "On-Water": An Atom-Efficient and "Green" Route to Cyclic and Acyclic β-Amino Sulfones via aza-Michael Addition Using Microwave Irradiation.

A reagentless, catalyst-free, and sustainable methodology was developed for facile access to cyclic and acyclic β-amino sulfones "on-water" using a microwave. A variety of aromatic and aliphatic amines undergo double aza-Michael addition on the surface of the water with water-insoluble divinyl sulfones upon microwave irradiation at 150 °C for 10 min to mostly afford solid cyclic β-amino sulfones as easily separable products in excellent yields by simple filtration avoiding any workup steps. Thus, all atoms of the substrates are reflected in the product making it a 100% atom-efficient method. Both electron-rich and electron-deficient amines participated well in the reaction as well as good functional group tolerance was observed. The competitive experiments expectedly revealed faster reaction kinetics for electron-rich amines. The methodology was extended to acyclic β-amino sulfones by interacting phenyl/ethyl vinyl sulfones with various amines in a similar manner. Expectedly, the method afforded very low environmental factors (in a range of 0.05-0.5) and a high Ecoscale score (up to 94). In an attempt toward sustainable development, this reagent-free, metal-free, organic solvent-free, cost-effective protocol is certainly a viable alternative to the available methods for β-amino sulfones.

Evaluation of Fe3O4 incorporated functionalized carbon nanotube self-standing buckypaper as electrodes for solid-state symmetric supercapacitor

Iron (II, III) oxide and carbonaceous materials drawn considerable attention in energy storage owing to their special features. In this study, simple reverse co-precipitation, acid functionalization and vacuum filtration methods adopted to synthesis Fe3O4 nanoparticles of size 11 nm and –COOH acid functionalized multi-wall carbon nanotubes (FMWCNT). And further used them to prepare and optimize Fe3O4 in FMWCNT as 15 wt% and 25 wt% self-standing buckypapers of around 30-μm thickness as electrodes for solid-state symmetric capacitor in the form of coin cell. The results show that 15 wt% and 25 wt% of Fe3O4-FMWCNT buckypapers hybrid nanostructures have Fe3O4 nanoparticles successfully incorporated in FMWCNT. The 25 wt% Fe3O4-FMWCNT electrodes with charge transfer resistance of 140 Ohm showed high areal specific capacitance (Cs) 78.5 mF/cm2 and retained 80 % of its Cs until 800 cycles even at high current density of 1 mA/cm2, scan rate of 100 mV/s whereas 15 wt% Fe3O4-FMWCNT showed low Cs of 47 mF/cm2 and retained 80 % of its Cs over 5000 cycles whereas only FMWCNT show Cs is 36 mF/cm2 with 54 Ohm. Finally, a solid-state symmetric supercapacitor coin cell with self-standing 25 wt% Fe3O4-FMWCNT buckypaper showed an excellent power density of 129.5 mW cm−3 and energy density of 3.6 mWh cm−3 is the innovation of the current work. This is mainly attributed to the combined effect of pseudocapacitive behavior from Fe3O4 by faradaic reaction with additional charge transfer resistance and electric double layer (EDLC) behavior from FMWCNTs by non-faradaic of electronic, ionic transport during charging-discharging. As-made solid-state symmetric supercapacitor appears as a high-performance storage device without extra support of current collectors for practical applications and for fabrication of planar capacitors.

Synthesis of 5-arylidenerhodanines in L-proline-based deep eutectic solvent.

Rhodanines and their derivatives are known to have many pharmacological activities that can be modulated through different functionalization sites. One of the most studied modification in those scaffolds is the introduction of a benzylidene moiety on C5 via a Knoevenagel reaction. Here, a facile synthesis of 5-arylidenerhodanines via a Knoevenagel reaction in an ʟ-proline-based deep eutectic solvent (DES) is reported. This method is fast (1 h at 60 °C), easy, catalyst-free and sustainable as no classical organic solvents were used. The expected compounds are recovered by a simple filtration after hydrolysis and no purification is required. Those derivatives were studied for their antioxidant activities and the results are consistent with those reported in the literature indicating that phenolic compounds are the more active ones.

Carboxylate Catalysis: A Catalytic O-Silylative Aldol Reaction of Aldehydes and Ethyl Diazoacetate.

A mild catalytic variant of the aldol reaction between ethyl diazoacetate and aldehydes is described using a combination of N,O-bis(trimethylsilyl)acetamide and catalytic tetramethylammonium pivalate as catalyst. The reaction proceeds rapidly at ambient temperature to afford the O-silylated aldol products in good to excellent yield, and the acetamide byproducts can be removed by simple filtration.

Exploring the amide coupling of carboxylic acids with amines using green solvent limonene

Limonene was identified as green media for amide formation through quantum chemistry calculation. An environmentally benign and sustainable protocol for amide formation was developed with simple filtration without the need for extensive isolation and purification. Additionally, the scope and general compatibility of the proposed method were explored with aromatic and aliphatic substrates, giving moderate to excellent yields, and a gram-scale synthesis of SHP1 activator 3a-18 were easily performed for further biological evaluation.

Highly Efficient and Selective Oxidation of Benzyl Alcohol by WO42− Catalyst Immobilized by a Phosphonium-Containing Porous Aromatic Framework

Benzoic acid has found a wide range of applications in the chemical industry. The selective oxidation of benzyl alcohol is one of the main routes to produce benzoic acid. In this work, tris(4-bromobiphenyl)phosphine was chosen as a building block to synthesize PAF-181 with a high specific surface area and high yield via a Yamamoto–Ullmann reductive coupling reaction. Subsequently, the WO4@PAF-181 catalyst was successfully prepared via methylation and ion exchange, in which PAF-181 acts as a carrier while WO42− serves as the active catalytic site. The synergistic effect between functional carriers and active sites endows WO4@PAF-181 with distinctive catalytic property for efficient selective oxidation of benzyl alcohol to benzoic acid. Importantly, the catalyst can be conveniently recovered and reused by simple filtration, still maintaining its high catalytic activity.

Synergetic dielectric and magnetic losses of melamine sponge-loaded puffed-rice biomass carbon and Ni3ZnC0.7 for optimal effective microwave absorption

Multi-dimensional design and the combination of multiple phases can effectively enhance the dielectric loss properties and multiple reflection effects of absorbers. Herein, a novel multi-dimensional microporous nanostructured composite, melamine sponge (MS) loaded puffed-rice biomass carbon (C) together with bimetallic carbide material Ni3ZnC0.7 (Ni3ZnC0.7-MS/C) was synthesized by simple vacuum filtration and hydrothermal calcination. The result indicates that small Ni3ZnC0.7 particles with little Ni doping uniformly decorated on the surfaces of the three-dimensional (3D) melamine sponge and puffed rice carbons. The Ni3ZnC0.7-MS/C composite mixed with paraffin (weight ratio of 1:2) exhibited the best electromagnetic wave (EMW) absorption performance, and the minimum reflection loss (RLmin) value of the Ni3ZnC0.7-MS/C composite reaches −107.7 dB with a matching thickness of 2.78 mm and the maximum effective absorption bandwidth for RL below −10 dB (EABmax) is adjusted to 9.2 GHz at a matching thickness of 4.0 mm. The dipole polarization effect of the N doping and the different interfaces provided by the 3D structure of the MS carbon enhance the conduction loss and interface polarization, while the positive effects of eddy current and resonance caused by Ni3ZnC0.7 effectively improve the microwave absorption performances. This melamine sponge–loaded bimetallic carbon composite exhibited a magnetic/dielectric loss combination, resulting in a high-performance absorber with lightweight, cost-effective and efficient properties.

Amino-induced cadmium metal–organic framework based on thiazole ligand as a heterogeneous catalyst for the epoxidation of alkenes

Selective epoxidation of olefins is of high interest in the chemical industry due to the many applications of epoxides. This study reports on the synthesis of Cd-MOF, [Cd(DPTTZ)(5-AIP)] (IUST-1) (where DPTTZ = 2, 5-di (pyridine-4-yl) thiazolo [5, 4-d] thiazole, 5-AIP = 5-Aminoisophthalic acid), by a reflux method, which can be considered as a fast and simple process. The morphology and structure of the synthesized IUST-1 were determined by using FE-SEM (Field Emission Scanning Electron Microscopy), EDX (Energy Dispersive Analysis of X-ray), Mapping (Elemental Mapping), CHNS (Elemental analysis), XRD (X-Ray Diffraction), FT-IR (Fourier Transform Infrared), and TGA (Thermo Gravimetric Analysis). The epoxidation of cyclooctene was investigated using the activity of catalytic IUST-1. The results showed that in the presence of tert-butyl hydroperoxide and CCl4 in a 1:2 alkene/oxidant ratio, a high epoxide yield (99.8%) was obtained. In addition, IUST-1 can be easily separated by simple filtration and recycled five times successfully with a slight decrease in activity. This compound has some advantages such as high yield, short reaction time, and ease of reuse, which make it a suitable heterogeneous catalyst for the epoxidation of cyclooctene.

Salt-induced nanoporous gold electrodes: One-step scalable fabrication of high-performance flexible electrochemical sensors from gold nanoparticles

Here, a simple filtration method for the fabrication of salt-induced nanoporous gold electrodes (SINPGEs) from gold nanoparticles (AuNPs) is reported. This method employs sodium chloride (NaCl) to trigger the aggregation, room-temperature sintering and region-selective deposition of AuNPs on patterned polyvinylidene fluoride (PVDF) membranes during filtration, which enables the one-step scalable fabrication of flexible SINPGEs three-electrode arrays with high conductivity, good mechanical property, large surface area and extremely low cost. Moreover, compared with traditional gold disc electrodes, the nanoporous structure of SINPGEs was demonstrated to apparently improve the electrochemical responses of various electroactive species, e.g., dopamine (DA), uric acid (UA), ascorbic acid (AA) and hydrogen peroxide (H2O2), reflected by the apparent enlargement of redox currents. In addition, the passivation effect of chloride ions (Cl−) on the oxidation of H2O2 at SINPGEs can be greatly repressed by a simple electrochemical activation approach, producing a sensitive H2O2 sensor with a calibration range of 1.0–1000 μM in the presence of 0.1 M Cl−. The present work thus establishes a new approach to the scalable construction of gold electrode-based electrochemical sensors with high performance and low cost.

Aqueous Extract of Musa Acuminata: An Ecofriendly Catalyst for Knoevenagel Condensation

AbstractAn efficient and greener approach for Knoevenagel condensation between substituted aldehydes and ketones with active methylene compound as starting substrate has been achieved using aqueous extract of Muca Acuminata as a neutral heterogeneous biocatalyst (Characterized by XRD, TEM, EDS, and ICP‐MS) at room temperature is reported. We found that this method is advantageous over the traditional methods that include refluxing, heating, use of toxic and highly expensive catalyst or solvents and also reduced the reaction time. It is ascertained that the reactions via this protocol are very clean and the isolated crude solid product is more than 95 % pure. The synthesized arylidene compounds exhibited great antioxidant potential and also acts as specific protein‐tyrosine kinase inhibitors and thus serves as an anticancer agent. The final product is separated by simple filtration and is characterized by various spectroscopic techniques like FT‐IR, 1H‐NMR, 13C‐NMR, 19F‐NMR and MS. The cheaper, simple and green approach suggests the possible use of this protocol for large scale preparations.

Robust oil/water separation through super-wettable in-situ grown Si@NiFe-LDH nanosheets on nickel foam

Oil/water separation is a globally challenging problem due to the occurrence of increased oil spills during large scale oil transportation, the outflow of huge wastage of organic pollutants from industries, and increased automation in the manufacturing sector. On the other hand, developing a material that can effectively clean-up oil pollution in an aqueous system is gaining significant importance. In this direction, the present study attempts to prepare superhydrophobic Si@NiFe-LDH grown on nickel foam (NF) with a microstructure having a selective affinity to oil in water via a simple hydrothermal method. Here, NiFe-LDH@NF was silanized through a covalent bond, this process in the development of the very superhydrophobic surface, as evidenced by the significantly higher water contact angle (WCA) of 149˚, and the cauterization of the superhydrophobic Si@NiFe-LDH@NF composite was performed using XRD, SEM, and WCA measurements. The composite assured for separation of oil from contaminated water and oil/water mixture having various organic solvents form having with a high separation efficiency of 98.0% and > 99.9% purity. The separation efficiency was maintained even after 50 cycles of reuse by simple filtration under gravity. This study then offers a new perspective on the use of in-situ grown LDH on the NF for various oil-contaminated pollutants, and the materials can be of great potential for extended industrial cleaning processes towards oil/water separation.

Flexible and electrically robust graphene-based nanocomposite paper with hierarchical microstructures for multifunctional wearable devices

Multifunctional and flexible wearable devices play a crucial role in a wide range of applications, such as heath monitoring, intelligent skins, and human-machine interactions. Developing flexible and conductive materials for multifunctional wearable devices with low-cost and high efficiency methods are highly desirable. Here, a conductive graphene/microsphere/bamboo fiber (GMB) nanocomposite paper with hierarchical surface microstructures is successfully fabricated through a simple vacuum-assisted filtration followed by thermo-foaming process. The as-prepared microstructured GMB nanocomposite paper exhibits not only a high volume electrical conductivity of ∼45 ​S/m but also an excellent electrical stability (i.e., relative changes in resistance are less than 3% under stretching, folding, and compressing loadings) due to its unique structure features. With this microstructured nanocomposite paper as active sensing layer, microstructured pressure sensors with a high sensitivity (−4 ​kPa−1), a wide sensing range (0–5 ​kPa), and a rapid response time (about 140 ​ms) are realized. In addition, benefitting from the outstanding electrical stability and mechanical flexibility, the microstructured nanocomposite paper is further demonstrated as a low-voltage Joule heating device. The surface temperature of the microstructured nanocomposite paper rapidly reaches over 80 ​°C when applying a relatively low voltage of 7 ​V, indicating its potential in human thermotherapy and thermal management.

EXPERIMENTAL CHEMISTRY WORKSHOP IN PANDEMIC TIMES: A SUPPORT ACTIVITY FOR STUDENTS OF THE GRADUATE CHEMISTRY COURSE

The Covid-19 pandemic caused several impacts on education, causing teachers and students to adapt to a new reality, as a result, educational institutions had to adhere to Emergency Remote Teaching (ERE). This measure adopted, especially, by Higher Education Institutions (HEIs) totally affected the training of students, above all, of Licentiate in Chemistry (LQ) courses. In this sense, among the aforementioned problems involved in the experiences of LQ students, the departure from experimental subjects is presented as one of the main challenges in the teaching and learning process. From this assumption, with the objective of mitigating the damages caused by the ERE, through a qualitative and participative research, the Tutorial Education Program - PET Química, of the Federal Institute of Paraíba - IFPB, João Pessoa campus, carried out an activity of teaching called “Oficina de Química Experimental (OQE)” in which experimental practices alluding to the menu of the subject of Experimental Chemistry I (DQEI) of the LQ course of that institution, were offered to all students who completed it remotely. This workshop had as target audience the students belonging to the classes of the periods 2020.1, 2020.2 and 2021.1. The application of this teaching intervention was divided into five moments: i) Bibliographic research; ii) Development of the workshop; iii) Practical activity of measuring the volume of liquids and Practical activity of weighing substances; iv) Practical activity of simple filtration and vacuum filtration and Practical activity of materials and substances; v) Practical activity of electrolyte conductivity and Practical activity of alkali metals and alkaline earth metals. With the execution of the above mentioned phases, an effective participation and interest was verified during the whole process of the activity, on the part of the licensees. However, the action developed by PET Química was uplifting, as it served as a professional aggrandizement for the scholarship holders of the program, as well as for the workshop participants, since the science of Chemistry is essentially experimental and must necessarily be present in the training of future graduates in Chemistry.

Reinforcing and toughening bacterial cellulose/MXene films assisted by interfacial multiple cross-linking for electromagnetic interference shielding and photothermal response

Ultrathin MXene composite films, with their flexibility, metal-level conductivity, and multifunction compatibility, are an ideal choice for electromagnetic interference (EMI) shielding materials in future developments. Nonetheless, the dilemma between electrical conductivity and robustness in these composite films remains a challenge. Herein, an ammonium polyphosphate (APP) assisted interfacial multiple cross-linking strategy, achieved via simple solution blending and filtration, was employed to reinforce and toughen the “brick–mortar” layered MXene/bacterial cellulose (MBCA) films without compromising their conductivity and EMI shielding ability. The introduction of a small amount of APP leads to multiple interfacial interactions between MXene and bacterial cellulose, resulting in significant enhancements in mechanical strength (360.8 MPa), Young's modulus (2.8 GPa), fracture strain (17.3%), and toughness (34.1 MJ/m3). Concurrently, the MBCA film displayed satisfactory conductivity values of 306.7 S/cm and an EMI SE value of 41 dB upon optimizing the MXene content. Additionally, the MBCA film demonstrated a consistent, rapid-response photothermal conversion capability, achieving a photothermal conversion temperature of 97 °C under a light intensity of 200 mW/m2. Consequently, this tough and multifunctional EMI shielding film holds substantial promise for protecting electronic equipment.

Incorporation of Zr-based metal-organic polyhedron into the PDA/PVDF adsorptive membrane for rapid removal of Cr(VI)

Zirconium-based metal-organic polyhedra (ZrMOPs) have gained significant attention owing to their well-defined cavities, stability and potential applications. Herein, a novel composite membrane (PDA/ZrT-1-NH2/PVDF) was developed by incorporating amino-functionalized ZrMOP (ZrT-1-NH2) into polydopamine (PDA) and trimesoyl chloride (TMC) cross-linking system. Notably, the cationic ZrT-1-NH2 cages were immobilized onto the membrane surface by a simple vacuum filtration method, which thus endowed the surface positive charge for the membrane. A pre-prepared composite membrane was used to remove Cr(VI) from the wastewater. The effects of pH, contact time, initial Cr(VI) concentration, temperature, coexisting ions competition and reusability were investigated in batch experiments. The results revealed the as-prepared composite membrane exhibited high removal efficiency of 96.6 % for Cr(VI) ions within 5 min. In addition, the adsorption rate was very fast, reaching adsorption equilibrium in less than 30 min. Finally, a possible adsorption mechanism was proposed. The adsorption process was dominated by physical adsorption accompanied by a partial reduction of Cr(VI) to Cr(III).

Surface modification of chitosan with Ni(II) Schiff base complex: A new heterogeneous catalyst for the synthesis of xanthones

A new biocomposite of chitosan, chitosan-supported di(pyridine-2-yl)methanone-Ni(II) complex, CS-DPM-Ni, is synthesized for the first time. The biocomposite is thoroughly characterized by FTIR, PXRD, XPS, FESEM, EDX, TGA, ICP-OES, and elemental analysis. The synthesized composite is successfully used as a heterogeneous catalyst in the synthesis of a library of xanthone derivatives by the intermolecular catalytical coupling of 2-substituted benzaldehydes and phenols. The catalyst could be retrieved from the reaction mixture by simple filtration and reused for up to four catalytic cycles. All products were isolated in good to high yields (65–90 %) with good turnover numbers (TONs), and fully characterized by 1H and 13C{1H} NMR spectroscopy. The green chemistry metrics values for the reaction were discerned and found to be close to the ideal values.

Clay-based durable catalyst membranes of porous layered double hydroxide and gold nanoparticle nanocomposites for fast and continuous-flow reactions

We synthesized the hybrid catalyst of a porous layered double hydroxide (LDH) decorated with ultrasmall Au nanoparticles. The porous LDH was prepared by coprecipitation and ethanol washing, producing thin LDH nanoplatelets. Thereafter, spray drying was carried out, affording a few hundred nm of the hydrangea-like structure of the LDH with an extensive open network and a Brunauer–Emmett–Teller surface area of 386 m2/g. Its sizable open frame and active hydroxide surface enabled the uniform decoration of average 4-nm-diameter Au nanoparticles (Au/P-LDH) through one-pot chemical reduction using NaBH4 at room temperature. We applied the Au/P-LDH for the fabrication of catalyst membranes, which are potentially valuable for the continuous flow of catalytic reactions, e.g., the hydrogenation of p-nitrophenol. This study suggested that their porous structure and active Au nanoparticle catalyst allowed fast and mass catalytic functions by simple filtration without washing or catalyst recovery steps. We found no significant damage to the hybrid membrane during the reactions with a few liters; thus, we expect strong bindings of the Au nanoparticles on the surface of the porous LDH.

Wearable electrochemical sensor based on bimetallic MOF coated CNT/PDMS film electrode via a dual-stamping method for real-time sweat glucose analysis

Non-invasive wearable sweat glucose sensors are expected to be highly desirable for personalized diabetes management. Therefore, developing facile, convenient, and scalable manufacturing method of such wearable sensors is urgently needed. Herein, we report a simple and low-cost stamping-vacuum filtration dry transfer (SVFDT) method for construction of a wearable sweat glucose electrochemical sensor. In this patch, a three-electrode array template was made by using a polyvinyl chloride (PVC) stamp, followed by the preparation of multiwalled carbon nanotubes (MWCNTs)/polydimethylsiloxane (PDMS) (MP) film electrode using the vacuum-filtration dry transfer method. In addition, for further enhancing the conductivity of the electrode, another similar stamp with a raised surface dipping carbon nanotubes (CNTs) conductive coating was stamped on the surface of the MP electrode to obtain CNTs/MWCNTs/PDMS (CMP) electrode. CMP electrode was modified with the enzyme-like Ni-Co metal-organic framework (MOF) material which showed good electro-catalytic activity and achieved high sensitivity for glucose detection with a low detection limit of 6.78 μM and a wide linear range of 20 μM - 1.1 mM. More importantly, the Ni-Co MOF modified CMP (NCMP) electrode also displayed high stability under stretching and bending conditions. Finally, the sweat absorbent cloth was combined with the NCMP film electrode to form a wearable flexible electrochemical sensor patch, which could adhere to the skin to enrich sweat and realize real-time detection of sweat glucose with high accuracy. This SVFDT method can also be applied to the fabrication of other electronic devices.

Removal of chlorine and monochloramine from tap water using graphene oxide membranes

Residual levels of chlorine and monochloramine (chlor(am-)ine) in water not only cause unpleasant odour and taste but also pose a challenge for chlor(am-)ine sensitive applications such as polymeric membranes used in reverse osmosis for desalination. Current solutions to remove chlor(am-)ine have their limitations and it is thus desirable to develop an alternative technology that can remove chlor(am-)ine in a simple filtration process. In this study, we show that graphene oxide (GO) membranes can be used to remove chlor(am-)ine from tap water. The tested feed chlorine and monochloramine concentrations are up to 50 ppm and 9 ppm respectively. For all tested feed concentrations, the permeate chlor(am-)ine concentration is < 0.1 ppm after passing through GO membranes. We show that both flat sheet and hollow fibre GO membranes filter out chlor(am-)ine over days of continuous operation. Especially our hollow fibre GO membranes offer a great opportunity for easy scalability. Thus our study highlights not only the filtration properties of GO membranes but also its feasibility as an excellent contender for next-generation membrane technology.

Green Synthesis of Five-Membered Hetarene N-Oxides: A Designed Approach to the Synthesis of Substituted Chromeno[3,4-c]pyrrole-2-oxides

AbstractAn efficient and chemoselective synthesis of biologically valuable chromeno[3,4-c]pyrrole 2-oxides containing one chiral stereocenter is described. In this method, by using a sequential nucleophilic addition reaction involving coumarins (α,β-unsaturated coumarins or 3-acetylcoumarins), activated acetylenic compounds, triphenylphosphine as a catalyst, and hydroxylammonium chloride (HAC) as an NO source, substituted chromeno[3,4-c]pyrrole 2-oxides were prepared with excellent efficiency. Readily available starting materials, absence of a metal catalyst, green and mild conditions, chemoselectivity, easy purification (the products can be purified by simple filtration and washing with EtOH), and synthetically useful yields are some highlighted advantages of this unprecedented transformation.