Linear Expansion Ratio Research Articles

Adsorption of Eosin B from Wastewater onto the Prepared Porous Anion Exchange Membrane.

This research describes the fabrication of the porous trimethylamine (TMA)-grafted anion exchange membrane (AEM) over a phase inversion process. The synthesis of the generated AEM was verified using Fourier transform infrared (FTIR) spectroscopy. The fabricated porous AEM showed 240% water uptake (WR), 1.45 mg/g ion exchange capacity (IEC), and a 9.0% linear expansion ratio (LER) at 25 °C. It exhibited a porous structure and higher thermal stability. It was utilized to remove eosin B (EB) from wastewater via the process of adsorption. The adsorption capacity of EB increased with time and the starting concentration of EB while decreasing with temperature and the AEM dosage. Adsorption isotherm investigation results showed that EB adsorption onto the porous AEM followed the Langmuir isotherm because the value of correlation coefficient (R2 = 0.992) was close to unity. Because the correlation coefficient was close to one, it was determined through adsorption kinetic experiments that the adsorption of EB on the produced porous AEM was suitable for a pseudo-second-order model. Thermodynamic study about process of EB adsorption on the porous AEM revealed that there was an exothermic (ΔH° = -16.60 kJ/mol) and spontaneous process.

Preparation of a Cation Exchange Membrane by a Sol-Gel Method-Based Polyvinyl Alcohol to Improve Alkali Recovery via Diffusion Dialysis in the Textile Industry

In this work, a novel silane coupled cationic precursor (SAGS) was synthesized by 3-glycidyloxypropyltrimethoxysilane and sodium 2-((2-aminorthyl)amino) ethanesulfonate. A series of cation exchange membranes were prepared with poly(vinyl alcohol) (PVA) and SAGS by a sol-gel-based process. The structure of the prepared membranes were characterized by Fourier transform infrared spectrum (FTIR) and scanning electron microscopy (SEM), and its properties were studied by water uptake (WR), cation exchange capacity (CEC), linear expansion ratio (LER), alkali stability, thermogravimetric analysis (TGA), mechanical properties, and diffusion dialysis performance. FTIR and X-ray photoelectron spectroscopy (XPS) confirmed the successful preparation of SAGS membranes, and SEM images showed that the prepared membranes were dense and uniform. The WR values of the SAGS membranes were in the range of 91.49–122.39%, and the LER values were 17.65–28.21%. In addition, the SAGS membranes had suitable CEC value, good alkali resistance, and thermal stability which ensured the application of membranes in the field of diffusion dialysis (DD) for alkali recovery. In the DD test, the dialysis coefficients of NaOH (UOH) ranged from 0.012 mm/h to 0.023 mm/h, and the separation factors (S) was in the range of 30.77–16.43. In conclusion, the prepared CEM containing silicon oxygen bonds by PVA and SAGS reaction has the advantages of low price, friendly environment, good alkali resistance, simple preparation process, and great application potential in the textile manufacturing wastewater recovery.

Fabrication of trimethylphosphine-functionalized anion exchange membranes for desalination application via electrodialysis process

The design of conductive, improved durable and selective anion exchange membranes (AEMs) for desalination application via electrodialysis (ED) process is critical for a more sustainable future. This work reports the design of a series of homogeneous trimethylphosphine (TMP)-functionalized anion exchange membranes (AEMs) for desalination application via electrodialysis (ED) process. Physico-chemical characterization and electrochemical performance of the trimethylphosphine-functionalized anion exchange membranes was conducted and the activity found to be tuned by varying the quantity of trimethylphosphine into the membrane architecture. For anion exchange membranes M1 to M4, the ion exchange capacity (IEC) was increased from 1.35 to 2.16 mmol/g, water uptake (WR) from 4.30 to 17.72%, linear expansion ratio (LER) from 3.70 to 12.50% with enhancing the quantity of trimethylphosphine into the polymer architecture. The ionic resistance decreased from 15.14 to 2.61 Ω cm2 with increasing quantities of trimethylphosphine whereas transport number increased from 0.98 to 0.99. The performance of synthesized trimethylphosphine-functionalized anion exchange membranes in desalination of NaCl was evaluated via electrodialysis process (flux of 3.42 mol/m2. h and current efficiency of 64.30%). Results showed that the prepared trimethylphosphine-functionalized membrane (optimum M4) possess improved desalination performance as compared to commercial membrane Neosepta AMX under identical experimental conditions.

Effects of the combination of compression and impregnation with phenolic resin on the dimensional stability in the multiscale wood structure of Chinese fir

Chinese fir wood was pretreated by phenol–formaldehyde (PF) resin and followed by the compression along the radial direction at the compression ratio of 10%, 20% and 30%, respectively. The microscopic images of the control and modified wood at different humidity were then collected to evaluate the dimensional stability of wood cellular structures. The interactions between the cell wall and resin were also observed by SEM and Raman spectroscopy to reveal the fixation effects of resin on the compressed wood at cell-level. Results indicated that the number of wood cells filled with PF resin increased significantly with the increase of impregnation pressure and processing time, which contributed to an obvious decrease in the linear and volumetric expansion ratio of wood at high humidity, in particular at the RH of 90%. The filling of PF resin in the wood cell lumen and the open pits on the tracheid walls not only inhibited the entry of water molecules but also had a chemical interaction with cell-wall, which could significantly reduce the set-recovery of the compressed wood. The radial expansion ratio of wood at a compression ratio of 30% has been reduced by about 65% at the RH of 90% after PF resin impregnation.

Effect of sintering activation energy on Si3N4 composite ceramics

This study investigated the activation energy and kinetic characteristics of silicon nitride (Si3N4) composite ceramics produced using different preparation methods. The effects of the linear shrinkage, expansion ratio, and heating rate on the sintering process were analysed in detail. The obtained results reveal that the finer particle size produced using the urea homogeneous precipitation method obviously enhanced the densification rate and reduced the atomic diffusion distance. Moreover, the densification sintering process was carried out efficiently, and the largest densification rate was achieved in advance. According to the Arrhenius curve, the activation energy of the Si3N4 composite ceramics calculated using the urea homogeneous precipitation method (310.94 kJ/mol) was lower than that achieved using the mechanical ball-milling method (365.11 kJ/mol). Additionally, the flexural strength and hardness of the Si3N4 composite ceramic prepared using the urea homogeneous precipitation method were 740 ± 42 MPa and 16.20 ± 30 GPa, respectively, which is attributed to this composite ceramic's higher diffusion rate and small grain size.

Synthesis of Porous BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis.

Diffusion dialysis (DD) is an anion exchange membrane-based functional separation process used for acid recovery. TMA (trimethylamine) and BPPO (brominated poly(2,6-dimethyl-1,4-phenylene oxide) were utilized in this manuscript to formulate AEMs (anion exchange membranes) for DD (diffusion dialysis) using the phase-inversion technique. FTIR (Fourier transfer infrared) analysis, proton NMR spectroscopy, morphology, IEC (ion exchange capacity), LER (linear expansion ratio), CR (fixed group concentration), WR (water uptake/adsorption), water contact angle, chemical, and thermal stability, were all used to evaluate the prepared membranes. The effect of TMA content within the membrane matrix on acid recovery was also briefly discussed. It was reported that porous AEMs have a WR of 149.6% to 233.8%, IEC (ion exchange capacity) of 0.71 to 1.43 mmol/g, CR (fixed group concentration) that ranged from 0.0046 mol/L to 0.0056 mol/L, LER of 3.88% to 9.23%, and a water contact angle of 33.10° to 78.58°. The UH (acid dialysis coefficients) for designed porous membranes were found to be 0.0043 to 0.012 m/h, with separation factors (S) ranging from 13.14 to 32.87 at the temperature of 25 °C. These observations are comparable to those found in the DF-120B commercial membrane with UH of 0.004 m/h and S of 24.3 m/h at the same temperature (25 °C). This porous membranes proposed in this paper are excellent choices for acid recovery through the diffusion dialysis process.

Quaternized Diaminobutane/Poly(vinyl alcohol) Cross-Linked Membranes for Acid Recovery via Diffusion Dialysis.

Diffusion dialysis (DD) using anion exchange membranes (AEM) is an effective process for acid recovery and requires the preparation of suitable materials for AEMs, characterized by unique ions transport properties. In this work, novel AEMs composed of quaternized diaminobutane (QDAB) and poly(vinyl alcohol) (PVA) were cross-linked by tetraethoxysilane (TEOS) via the sol–gel process. The prepared AEMs were systematically characterized by Fourier-transform infrared (FTIR) spectroscopy, ion-exchange capacity (IEC) analysis, thermo gravimetric analysis (TGA), water uptake, linear expansion ratio (LER), and mechanical strength determination, scanning electron microscopy (SEM), and DD performance analysis for acid recovery using a hydrochloric acid/iron chloride (HCl/FeCl2) aqueous mixture and varying the QDAB content. The prepared AEMs exhibited IEC values between 0.86 and 1.46 mmol/g, water uptake values within 71.3 and 47.8%, moderate thermal stability, tensile strength values in the range of 26.1 to 41.7 MPa, and elongation from 68.2 to 204.6%. The dialysis coefficient values were between 0.0186 and 0.0295 m/h, whereas the separation factors range was 24.7–44.1 at 25 °C. The prepared membranes have great potential for acid recovery via diffusion dialysis.

Branched Polyvinyl Alcohol Hybrid Membrane for Acid Recovery via Diffusion Dialysis

AbstractA branched polymer was prepared by grafting allyltrimethylammonium chloride onto polyvinyl alcohol (PVA) via free‐radical polymerization. Afterwards, a series of hybrid membranes were prepared by sol‐gel cross‐linking between quaternary ammonium‐PVA and tetraethoxysilane. The obtained membranes were characterized in terms of infrared spectroscopy, ion exchange capacity, water uptake, linear expansion ratio, and acid resistance. The thermal properties of the membranes were investigated as well. The diffusion dialysis performances of the membranes were tested by using a simulated feed solution containing HCl and FeCl2. The diffusion dialysis coefficients and the separation factors were much better than those of the commercial DF‐120 membrane.

Quaternized chitosan-based anion exchange membrane for alkaline direct methanol fuel cells

We synthesized a novel quaternized anion exchange membrane (AEM) that exhibits high ionic conductivity and structural stability, even under high pH conditions, by copolymerizing a chitosan-based membrane with vinylimidazole derivatives. During the process, a quaternized poly[O-(2-imidazolyethylene)-N-picolylchitosan (QPIENPC) was synthesized by modifying chitosan with a 4-pyridinecarboxaldehyde derivative and then copolymerizing the modified chitosan with 1-vinylimidzaole. The results revealed that the degree of quaternization is correlated with ionic exchange capacity, water absorption ability, linear expansion ratio, and hydroxide conductivity of the resulting membrane. The QPIENPC membrane was characterized by a high ionic conductivity of 10.15mScm−1, 14 times greater that of the unfunctionalized chitosan membrane, as well as by low water absorption ability (36.17%) and linear expansion ratio (20.49%) at 80°C. An alkaline direct methanol fuel cell (ADMFC) was fabricated using the prepared QPIENPC membrane as an anion exchange electrolyte membrane, with PtRu/C and Pt/C as the anode and cathode, respectively. The performance of this ADMFC is promising even under high pH conditions, with the peak power density of 10.42mWcm−2 and corresponding current density of 28.76mAcm−2. Moreover, the thermochemical and mechanical strengths of the QPIENPC membrane were higher than those of the chitosan membrane.

Synthesis of SGO composite interpenetrating network (CIPN) cation exchange membranes: Stability and salt removal efficiency

Current study demonstrate the alternative route for synthesis of interpenetrating network (IPN) type composite cation exchange membranes (CEM) based on PVC-St/DVB with different content sulfonated graphene oxide (SGO) via simple solution casting method. First, the synthesis of GO was confirmed by TEM and XRD analysis. Functional group characterization of GO and SGO was done by using FT-IR spectroscopy. Water content related assets like water uptake, linear expansion ratio, and ion transport properties like: ion exchange capacity, ionic conductivity of composite IPN membranes were evaluated. Ion exchange capacity and ionic conductivity for PM-5 IPN CEM was found to highest with values of 1.76 meq/g and 4.7 × 10−3 S/cm, respectively. Thermal and mechanical stabilities of prepared membrane were characterized by TGA, DSC, DMA and UTM analysis. Composite interpenetrating network cation exchange membranes (IPN CEM) show better thermal and mechanical stability in comparison with virgin membrane. The suitability of synthesized composite IPN membranes towards electro-membrane processes was evaluated against salt removal by electrodialysis for water desalination. Power consumption and current efficiency during salt removal for PM-5 IPN CEM composite membrane was found to be 1.07 kWh/kg and 82% respectively which was superior among the IPN membrane.

Acid resistant PVDF based copolymer alkaline anion exchange membrane for acid recovery and electrodialytic water desalination

A facile approach has been chosen for the synthesis of PVDF based copolymer anion exchange membrane using nonhazardous chemicals. The synthetic route was achieved through free radical polymerization between dehydrofluorinated PVDF-co-HFP (DYPVDF) and morpholine functionalized vinyl benzyl chloride (VBC). The variations in properties of formed membranes were evaluated by varying the concentration of VBC. FT-IR, as well as 1H NMR, confirms the formation of the desired molecular structure of copolymer in form of a membrane. Surface morphology of copolymer anion exchange membranes was checked through TEM and AFM analysis. Standardized techniques were used to evaluate the physicochemical and electrochemical properties of the membranes like ion exchange capacity (IEC), water uptake (WU), ionic conductivity (IC) and linear expansion ratio (LER). The highest value of water uptake and IEC was found to be 28% and 1.27 meq/g for PQM-40 copolymer anion exchange membrane. Membranes were subjected to Fenton's test to evaluate their oxidative stability. Maximum weight loss of 1.67%, 1.44% and 1.39% was found in PQM-40, PQM-30, and PQM-20 respectively. Further, synthesized copolymer membranes were subjected to salt removal by electrodialysis and acid recovery by diffusion dialysis (DD). Maximum current efficiency during desalination and highest separation factor for acid recovery by diffusion dialysis were confirmed by PQM-40, the values are 82.36% and 25% respectively.

Internal cross-linked anion exchange membranes with improved dimensional stability for electrodialysis

Anion exchange membranes (AEMs) with a high ion exchange capacity, striking water uptake and excellent dimensional stability were prepared via an internal crosslinking networks strategy. Internal crosslinking networks were formed by reacting 4,4′-bipyridine with brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). 4,4′-bipyridine not only provides a functional group but also comprises a cross-linking agent without requirements of post-functionalization. The variation of the 4,4′-bipyridine amount into the casting polymer solution was explored to regulate the performance of the anion exchange membranes, and the membrane properties were evaluated by AFM, ion exchange capacity (IEC), water uptake, the linear expansion ratio, tensile strength, thermal stability, membrane area resistance and electrodialysis experiments, etc. The results showed that the cross-linked membrane with the IEC of 1.98mmol/g has much more outstanding dimensional stability (water uptake: 11.68%; swelling ratio: 3.8%) than non-cross-linked BPPO-Tri membrane (water uptake: 53.26%; swelling ratio: 7.71%) and commercial Neosepta AMX membrane (water uptake: 60.29%; swelling ratio: 5.08%), at the high temperature (50°C). When being applied in ED application, the cross-linked BPPO-20 membrane (NaCl remove: 59.7%; energy consumption: 5.97kWh/kg NaCl) exhibits slightly higher desalination efficiency and lower energy consumption than commercial Neosepta AMX membrane (NaCl remove: 58.3%; energy consumption: 6.51kWh/kg NaCl), suggesting its promising application in ED.

Combining ability analysis and gene action of grain quality traits in rice (Oryza sativa L.) using line × tester analysis

In rice, twelve lines were crossed with five testers in a line × tester mating design and the resultant 60 hybrids along with their parents were evaluated for their combining ability effects for 15 grain quality traits. The results revealed that the ratio of GCA: SCA variances computed for all the fifteen grain quality traits showed the predominance of non-additive gene action. Among the lines, ADT (R) 47 showed significant desirable gca effects at 1% probability level (p = 0.01) for 11 grain quality traits viz., hulling percentage, milling percentage, head rice recovery percentage, kernel breadth, kernel breadth after cooking, breadth wise expansion ratio, gelatinization temperature, amylose content, gel consistency, water uptake and volume expansion ratio. Among the testers, Pusa 1460 showed significant desirable gca effects at 1% probability level (p = 0.01) for 10 grain quality traits viz., kernel length, kernel breadth, kernel length/breadth ratio, kernel length after cooking, kernel breadth after cooking, linear elongation ratio, gelatinization temperature, amylose content, water uptake and volume expansion ratio and hence they were adjudged as the best combiners for the improvement of the respective traits. Among the hybrids, the hybrids CO 47/Imp., Samba Mahsuri, ADT (R) 47/IRBB 21 and ADT (R) 46/IRBB 21 were identified as best hybrids for exploitation of grain quality traits since they revealed significant sca effects at 1% probability level (p = 0.01) for eight, eight and five grain quality traits, respectively.

Preparation and performance evaluation of novel alkaline stable anion exchange membranes

Abstract Novel alkaline stable anion exchange membranes are prepared from various amounts of N-methyl dipicolylamine (MDPA) and brominated poly (2,6-dimethyl-1,4-phenylene oxide) (BPPO). The dipicolylamine and MDPA are synthesized through condensation reaction and confirmed by 1 H NMR spectroscopy. The morphologies of prepared membranes are investigated by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FTIR), 1 H NMR spectroscopy and scanning electron microscopy (SEM). The electrochemical and physical properties of AEMs are tested comprising water uptake (WU), ion exchange capacity (IEC), alkaline stability, linear expansion ratio (LER), thermal stability and mechanical stability. The obtained hydroxide conductivity of MDPA-4 is 66.5 mS/cm at 80 °C. The MDPA-4 membrane shows good alkaline stability, high hydroxide conductivity, low methanol permeability (3.43 × 10 −7 cm 2 /s), higher selectivity (8.26 × 10 7 mS s/cm 3 ), less water uptake (41.1%) and lower linear expansion (11.1%) despite of high IEC value (1.62 mmol/g). The results prove that MDPA membranes have great potential application in anion exchange membrane fuel cell.

Evaluation of alkali reactivity of concrete aggregates via AC impedance spectroscopy

The alkali reactivity of concrete aggregates was evaluated by AC impedance spectroscopy as the main method along with linear expansion ratio, relative dynamic elastic modulus, and mercury intrusion porosimetry tests. The electrochemical parameters of AC impedance spectra showed a close relationship with the hydration reaction and microstructure of cement-based materials. The results obtained by the linear expansion ratio, the relative dynamic elastic modulus, and the pore structure characteristics were basically consistent with those obtained by the impedance spectra. Therefore, the ASR trend shown by the resistance in AC impedance spectra, Rs, and the phase angle θ, can be considered as basically reliable. The intensity of the ASR of concrete changed with different contents of alkali aggregates. The test showed that in the ASR at an early age, the ratio between the active and inactive aggregates had the worst point. As the content of active alkali aggregates was at the worst point, the ASR led to the maximum expansion ratio and caused the most severe harm to the concrete specimens.

BPPO-Based Anion Exchange Membranes for Acid Recovery via Diffusion Dialysis.

To reduce the environmental impact of acids present in various industrial wastes, improved and robust anion exchange membranes (AEMs) are highly desired. Moreover, they should exhibit high retention of salts, fast acid permeation and they should be able to operate with low energy input. In this work, AEMs are prepared using a facile solution-casting from brominated poly-(2,6-dimethyl-1,4-phenylene oxide) (BPPO) and increasing amounts of 2-phenylimidazole (PI). Neither quaternary ammonium salts, nor ionic liquids and silica-containing compounds are involved in the synthesis. The prepared membranes showed an ion exchange capacity of 1.1–1.8 mmol/g, a water uptake of 22%–47%, a linear expansion ratio of 1%–6% and a tensile strength of 0.83–10.20 MPa. These membranes have potential for recovering waste acid via diffusion dialysis, as the acid dialysis coefficient (UH) at room temperature for HCl is in the range of 0.006–0.018 m/h while the separation factor (S) is in the range of 16–28, which are higher than commercial DF-120B membranes (UH = 0.004 m/h, S = 24).

Effect of Zircon Content on the Microstructure and Physical Properties of Chamotte Refractories

In this work, chamotte with dispersions of up to 30wt% zircon is sintered at 1500 °C to investigate the effect of zircon content on the microstructure and physical properties of chamotte refractories. The microstructure and physical properties of samples are investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS), three-point bending and dilatometer. The result shows that the main phases of chamotte with and without sintering at 1500 °C are mullite and cristobalite, the addition of zircon has no impact on the main phase compositions of chamotte matrix. For the sintered samples, zircon grains are wrapped with glass and no obvious bonding are detected between the interface of zircon and mullite grains. Increasing zircon content leads to the increase in bulk density and has a negative effect on the flexural strength, besides, linear thermal expansion ratio decreases as the zircon content increases.

Design of Anion Exchange Membranes and Electrodialysis Studies for Water Desalination.

Anion exchange membranes are highly versatile and nowadays have many applications, ranging from water treatment to sensing materials. The preparation of anion exchange membranes (AEMs) from brominated poly(2,6-dimethyl-1,6-phenylene oxide) (BPPO) and methyl(diphenyl)phosphine (MDPP) for electrodialysis was performed. The physiochemical properties and electrochemical performance of fabricated membranes can be measured by changing MDPP contents in the membrane matrix. The influence of a quaternary phosphonium group associated with the removal of NaCl from water is discussed. The prepared membranes have ion exchange capacities (IEC) 1.09–1.52 mmol/g, water uptake (WR) 17.14%–21.77%, linear expansion ratio (LER) 7.96%–11.86%, tensile strength (TS) 16.66–23.97 MPa and elongation at break (Eb) 485.57%–647.98%. The prepared anion exchange membranes were employed for the electrodialytic removal of 0.1 M NaCl aqueous solution at a constant applied voltage. It is found that the reported membranes could be the promising candidate for NaCl removal via electrodialysis.

Facile synthesis of pyridinium functionalized anion exchange membranes for diffusion dialysis application

Abstract Pyridinium functionalized anion exchange membranes are prepared for diffusion dialysis using polyvinyl alcohol (PVA) as base material. Four membranes have been prepared by varying the content of pyridinium salt. The ion exchange (IEC), water uptake (WU), thickness and linear expansion ratio have been measured or calculated. These membranes have shown excellent thermal and chemical stabilities. When applied in diffusion dialysis with a simulated solution mixture of HCl and FeCl2, the membranes show successfully good acid recovery and separation factor. The acid dialysis coefficients are in the range of 1.74–2.48 (10−2 m/h) and separation factors in the range of 30.49–57.51. The obtained acid dialysis coefficients and separation factors are greater than that of the widely used commercial membrane DF-120 with (UH = 0.9 × 10−2 m/h) and (S = 18.5). Hence, the results of this study suggest that the pyridinium functionalized AEMs can be potentially applied in diffusion dialysis process for acid recovery.

Mechanical and thermal properties of ABS/montmorillonite nanocomposites for fused deposition modeling 3D printing

Acrylonitrile butadiene styrene (ABS) nanocomposites with organic modified montmorillonite (OMMT) were prepared by melt intercalation. ABS nanocomposite filaments for fused deposition modeling (FDM) 3D printing were produced by a single screw extruder and printed by a commercial FDM 3D printer. The 3D printed samples were evaluated by tensile, flexural, thermal expansion and dynamic mechanical tests. The structure of nanocomposites were analyzed by TEM and low angle XRD. Results showed that the addition of 5wt% OMMT improved the tensile strength of 3D printed ABS samples by 43% while the tensile strength of injection moulding ABS samples were improved by 28.9%. It was found that the addition of OMMT significantly increased the tensile modulus, flexural strength, flexural modulus and dynamic mechanical storage modulus, and decreased the linear thermal expansion ratio and the weight loss of TGA. These novel ABS nanocomposites with better mechanical and thermal properties can be promising materials used in FDM 3D printing.