Degree Of Saponification Research Articles

Enhanced physical properties and water resistance of films using modified starch blend with poly(vinyl alcohol)

Research into sustainable biopolymer films is increasingly focused on finding viable alternatives to petroleum-based plastics. This study aims to address these challenges by examining the performance of a series of films prepared using polyvinyl alcohol (PVA) with varying degrees of saponification (DS) and polymerization (DP), combined with two modified starch: hydroxypropyl starch (HPS) and sodium octenylsuccinate starch (OctS). The findings demonstrate that increased PVA saponification and polymerization levels greatly improved the physical properties of the PVA/Starch blends because of the interactions and intermolecular entanglement between the PVA and starch chains. By altering the PVA and starch formulations, the blend films' tensile qualities and water resistance were greatly improved; at a 7:3 ratio, the highest tensile strength (TS) is ∼17.4 MPa, and elongation at break (EAB) is ∼476.8 %. The tensile properties and water resistance of the blend films were significantly enhanced by varying the PVA and starch formulations, achieving the highest tensile strength (17.4 MPa) and elongation at break (476.8 %) at a 7:3 ratio. Moreover, the PVA/OctS-7 blend exhibited superior water durability, and high transparency, with the lowest swelling (∼108.6 %) and certain wet strength, as well as varied solubility behaviors in different pH solutions, rendering it appropriate for use in packaging applications. As a result, PVA/Starch blend films' functional qualities can be significantly improved, making them appear as viable substitutes for petrochemical plastic packaging.

Lithium recovery from an alumina electrolysis slag leaching solution with strong acidity: Separation of lithium-ion and production of battery grade lithium carbonate

Lithium (Li) with excellent physicochemical properties is widely used in modern industries. However, the shortage and depletion of Li resources has hindered the sustainable economic development. Li recovery from waste resource was an effective approach, in particular, alumina electrolysis slag is exemplified as Li riched solid waste. In this work, separation of Li from alumina electrolysis slag leaching solution (AESLS) via solvent extraction using bis(2-ethylhexyl) hydrogen phosphate (P204) system was explored. Effects of saponification degree, phase ratio, and reaction time on metal ions impurities and Li extraction were investigated. Operational parameters including extraction, scrubbing, saponification and precipitation were optimized. Results showed that the extraction efficiencies of Mg2+, Ca2+, Al3+, Fe3+ and Li+ were 100 %, 100 %, 99.99 %, 100 % and 20.71 %, respectively, under the optimal single extraction conditions. The loss of Li after scrubbing of loaded organic phase using hydrochloric acid was as low as 1.59 %. The P204 extraction process was proved to be a thermodynamic process with spontaneous entropy increase, and the extraction order of metal ions was Al3+ > Fe3+ > Ca2+ > Mg2+ > Li+ according to the extraction driving force (ΔC); The solvent-extracted ligand mechanism was elucidated by infrared spectroscopy and nuclear magnetic resonance. Additionally, battery-grade lithium carbonate was produced. Our study paves a new way for recovery of Li in AESLS.

Effect of Degree of Saponification and Molecular Weights of PVA on Properties of Low Density Foam-formed Sheets

Effect of Degree of Saponification and Molecular Weights of PVA on Properties of Low Density Foam-formed Sheets

Recovery of lithium from the desorption solutions of salt lakes using β-diketone synergistic extraction system

Lithium has become increasingly important because of its irreplaceable role in lithium-ion batteries. Addressing the complex process and high energy consumption of the current adsorption-membrane integrated process for lithium extraction from high Mg/Li ratio salt lake brine, this study put forward an integrated process of adsorption-solvent extraction. Taking the desorption solution of adsorption method as raw material, the process parameters and extraction mechanism of lithium by the novel extraction system were investigated. A novel process of lithium recovery from the desorption solutions of salt lakes by solvent extraction was proposed for the first time. The composition of the extraction system was studied and determined to be HTTA-P113-kerosene. Compared with the previously reported neutral ligands (TOPO, Cyanex923), P113 not only exhibited excellent synergistic extraction ability but also had good miscibility and a green synthesis process. The effects of saponification degree, extraction time, temperature and phase ratio on lithium extraction and βLi/Na were systematically investigated. Through the four-stage countercurrent extraction, more than 99.2 % of lithium could be extracted by the organic phase consisting of 0.4 mol L−1 HTTA, 0.4 mol L−1 P113, saponification degree of 80 % at O/A ratio of 1:1 and equilibrium pH of 6.78. Furthermore, after the scrubbing and stripping process, the lithium-rich solution containing 21.64 g L−1 Li+ and 0.037 g L−1 Na+ was obtained. The Li2CO3 products with a purity of 99.5 % were successfully prepared from the lithium-rich solution by precipitation method. Finally, the extraction mechanism was studied via the slope analysis method and FT-IR spectra. It was indicated that the extracted lithium species were Li(TTA)(P113).

Preventing emulsification during rare earths solvent extraction by the addition of Span 80 to enhance the interfacial stability of the P507 oil droplets

The demand for rare earth elements is increasing daily with rapid economic development, thereby increasing the requirements for its separation and purification technologies. The major method for purification and separation of rare earth elements in the industry is currently solvent extraction. In the actual production process, emulsification often occurs because of improper control of the organic phase, aqueous phase properties or operating conditions, and resulting in resource wastage and environmental pollution. This has become an issue that restricts the development of the rare earths industry. To prevent emulsification during rare earths solvent extraction, the organic structure of the P507-kerosene solution was regulated by the addition of Span 80 as a regulator. This study investigated the effects of Span 80 content, P507 concentration, saponification degree and the amount of pre-loading rare earth elements in the organic phase after adding Span 80 on the extraction efficiency of Er3+ and oil content in the raffinates. The results demonstrated that when the content of Span 80 was 6 %, the saponification degree of P507 in the organic phase was 10 %, the concentration of Er3+ in the aqueous phase was 0.5 g /L, the pH value in the aqueous phase was 3, the phase ratio (VO: VA) was 1:2, the extraction efficiency could still reach more than 99 %, and the oil content in the raffinates was 13.9 mg/L. The results demonstrated that the final extraction efficiency did not decrease; however, the extraction rate of rare earth elements did. Further, the oil content in the raffinates decreased greatly after the addition of Span 80. The mechanism was investigated using Fourier-transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM). The interfacial stability of P507 oil droplets was enhanced by the addition of Span 80. Emulsification was, thus, effectively prevented and the dissolution loss of the organic phase was greatly reduced. The results provide a novel method for preventing emulsification during rare earths extraction at the source, and a novel idea for preventing resource loss and protecting the ecological environment.

Selective recovery of transition metals from spent lithium-ion batteries leachate with Ni synergistic extraction system

Recycling spent lithium-ion batteries (LIBs) can not only generate ecological benefits but also realize low-carbon energy transition. Here, comprehensive recovery of transition metals from spent LIBs leachate using nickel (Ni) synergistic extraction system has been proposed. It was discovered that the combination of HEH(EH)P and Cyanex301 showed a strong synergistic extraction effect on Ni2+ and could also achieve the co-extraction of Ni2+, Co2+, Mn2+ after examining the extraction effects of single and mixed extractants of HEH(EH)P and Cyanex301. The mechanism of synergistic extraction of Ni2+ with mixed extractants was elucidate according to the slope analysis, FT-IR spectrometry and NMR spectrometry results. Then through a three stages of counter-current extraction process with 1.5 mol/L mixed extractant (XHEH(EH)P = 0.7, HEH(EH)P saponification degree of 60 %) and two stages of scrubbing process with 0.05 mol/L H2SO4, 99.18 % of Ni2+, 99.02 % of Co2+ and 99.93 % of Mn2+ were comprehensively recovered, while only 0.27 % of Li+ were lost. The Ni2+, Co2+, and Mn2+ loaded in the organic phase were entirely removed by a three stages of counter-current stripping process with HCl under O/A = 2.5/1. The synergistic extraction system still demonstrated outstanding reusability even after five cycles.

Efficient Recovery of Lithium from Spent Lithium Ion Batteries Effluent by Solvent Extraction Using 2-Ethylhexyl Hydrogen {[Bis(2-Ethylhexyl) Amino]methyl} Phosphonate Acid

In order to overcome the interface emulsification problem of TBP-FeCl3 systems and the instability of β-diketone systems in high-concentration alkaline medium, it is necessary to design and synthesize some new extractants. By introducing amino groups into a phosphorus extractant, a new 2-ethylhexyl hydrogen {[bis(2-ethylhexyl)amino]methyl} phosphonate acid (HA) extractant was synthesized. In this study, an efficient method of recovering lithium from the effluent of spent lithium-ion batteries (LIBs) is proposed. Experiments were conducted to assess the influential factors in lithium recovery, including the solution pH, saponification degree, extractant concentration, and phase ratio. Over 95% of lithium in the effluent was extracted into the organic phase, and nearly all lithium in the organic phase could be stripped into the aqueous phase using a 3 mol/L HCl solution. There was no significant decrease in extraction capacity after 10 cycles. The experimental results indicated that the extraction mechanism was a cation exchange process, and the extractive complex was proposed as LiA. Importantly, after three months of stable operation, the process demonstrated excellent stability and extraction efficiency, with rapid phase separation and a clear interface. This study offers an efficient, cost-effective, and environmentally friendly method for lithium extraction from the effluent of spent LIBs.

Efficient separation and recovery of Co and Ni from ammonium sulfate roasting‐water leaching solutions of oceanic cobalt‐rich crusts by sulfide precipitation and P507–Cyanex 272 synergistic extraction

AbstractOceanic cobalt‐rich crusts contain many valuable metals including Co, Ni, Cu, and Mn, of which Co and Ni are scarce metal resources on terrestrial land. Co, Ni, Cu, and Mn in cobalt‐rich crusts can be efficiently extracted by the ammonium sulfate roasting‐water leaching (ARWL) process, but separating and recovering Co and Ni from the leaching solution containing high concentrations of Mn is a challenging problem. In this study, a combination of sulfide precipitation and P507–Cyanex 272 synergistic extraction is proposed for the separation and recovery of Co and Ni from the ARWL solutions of oceanic cobalt‐rich crusts. Under the optimum sulfide precipitation conditions, Co and Ni were precipitated with 99.85% and 99.63% efficiency, respectively, while Mn was coprecipitated with only .79% efficiency. The Co–Ni mixed sulfides were dissolved by dilute sulfuric acid under oxidative conditions to obtain a solution containing 12.584 g/L Co, 11.012 g/L Ni, and a small amount of Mn. Subsequently, Co and Mn were extracted from this solution using P507–Cyanex 272 synergistic extraction, the single‐stage extraction efficiencies of Co and Mn were 95.76% and 99.73%, respectively, and the coextraction efficiency of Ni was 3.02%, under the conditions of a feed solution pH of 3.0, an extractant saponification degree of 70%, a total extractant concentration of 20% (P507 to Cyanex 272 ratio of 3:7), and an O/A ratio of 1.1:1. The results of the thermodynamic study showed that the reaction of Co extraction by this mixed extraction system was exothermic. Ni in the organic phase was washed with an H2SO4 concentration of .12 mol/L, followed by stripping of Co and Mn with an H2SO4 concentration of .6 mol/L. Mn in the stripping solution was removed by oxidative precipitation with (NH4)2S2O8, after which the Co3O4 product was obtained by precipitation with (NH4)2C2O4 and calcination. Similarly, NiC2O4·2H2O can be obtained from the raffinate by (NH4)2C2O4 precipitation. Finally, a flowsheet was developed for the separation and recovery of Co, Ni, Cu, and Mn from the ARWL solutions of oceanic cobalt‐rich crusts. The study provides a promising scheme for the recovery of various valuable metals from deep‐sea cobalt‐rich crusts or manganese nodules.

A Novel Fabrication of Heterogeneous Saponified Poly(Vinyl Alcohol)/Pullulan Blend Film for Improved Wound Healing Application.

In this study, a novel film of poly(vinyl alcohol) (PVA)/pullulan (PULL) with improved surface characteristics was prepared from poly(vinyl acetate) (PVAc)/PULL blend films with various mass ratios after the saponification treatment in a heterogeneous medium. According to proton nuclear magnetic resonance (1H-NMR), Fourier transform infrared, and X-ray diffraction results, it was established that the successful fabrication of saponified PVA/PULL (100/0, 90/10, and 80/20) films could be obtained from PVAc/PULL (100/0, 90/10, and 80/20) films, respectively, after 72 h saponification at 50 °C. The degree of saponification calculated from 1H-NMR analysis results showed that fully saponified PVA was obtained from all studied films. Improved hydrophilic characteristics of the saponified films were revealed by a water contact angle test. Moreover, the saponified films showed improved mechanical behavior, and the micrographs of saponified films showed higher surface roughness than the unsaponified films. This kind of saponified film can be widely used for biomedical applications. Moreover, the reported saponified film dressing extended the lifespan of dressing as determined by its self-healing capacity and considerably advanced in vivo wound-healing development, which was attributed to its multifunctional characteristics, meaning that saponified film dressings are promising candidates for full-thickness skin wound healing.

Mechanisms underlying the stability and instability of concentrated oil-in-water emulsions: Effect of the chemical structure of amphiphilic polymers

Despite extensive experimentation to efficiently prepare concentrated oil-in-water (O/W) emulsions with sufficient stability, the effect of the chemical structure of the polymeric surfactants on the emulsion stability is not yet understood in detail at the molecular level. We investigated the effect of the degree of saponification and arrangement of the hydrophobic (acetyl) groups of poly(vinyl alcohol) (PVA) on the stability of the concentrated emulsion via a combination of experiments and coarse-grained molecular simulations. This was accomplished by varying the degree of saponification and the arrangement of the hydrophobic groups on PVA, and by systematically changing the volume fraction of PVA molecules. The stability of the emulsion was adversely affected by the presence of an excess or the complete absence of hydrophobic groups on PVA. The former situation promotes the aggregation of PVA molecules with each other; conversely, fully saponified PVA molecules penetrate the water phase, thereby decreasing the number of PVA molecules at the O/W interface. Thus, the depletion of the interface of PVA molecules increases the interfacial tension, and, consequently, destabilizes the interface. Adjustment of the degree of saponification to a suitable value (80%) led to the formation of stable, concentrated emulsions with a smaller amount of PVA. For PVA with an appropriate degree of saponification, the interfacial behavior of concentrated O/W emulsions was to a lesser extent affected by the arrangement of the hydrophobic groups of PVA compared to the degree of saponification. Furthermore, the individual PVA chains at the interface had planar conformations, regardless of the arrangement of the hydrophobic groups. Our results indicate that careful tuning of the degree of saponification, rather than the arrangement of the hydrophobic groups of PVA, is necessary to control the interfacial stability of concentrated O/W emulsions using PVA. The findings of this study provide support for departing from empirical trial-and-error approaches and may facilitate the development of emulsifiers with enhanced performance.

Comprehensive recovery process of impurities removal and valuable metals co-extraction from simulated leaching solution of spent LIBs with CA12-TBP system

Effective recycling of valuable metals from the spent lithium-ion batteries (LIBs) is of great importance from the perspective of resource recycling and environmental conservation. In this work, a comprehensive recovery process of impurities removal and valuable metals co-extraction from simulated leaching solution of spent LIBs with CA12-TBP system was investigated. Firstly, more than 99.7% of Al, Fe and Cu were removed by co-extraction with 30 vol% CA12 (25% saponification degree) and 20 vol% TBP after three-stage extraction. The Ni, Co and Mn lost in the organic phase were decreased to 0.18%, 0.09% and 0.06% by single-stage scrubbing. Then, Fe, Cu and Al loaded in organic phase were completely stripped by 0.5 mol/L H2SO4 and 0.01 mol/L Na2SO3 through a four-stage stripping. After impurities removal, more than 99.9% of Ni, Co and Mn in the raffinate solution were selectively co-extracted with 30 vol% CA12 (60% saponification degree) and 15 vol% TBP after a three-stage extraction, and 7.88% of Li was co-extracted. Then, after a four-stage scrubbing experiment, only 0.52% of Li was lost in the loaded organic phase, which demonstrated that our system possesses the potential of efficient recovery of Ni, Co and Mn from the spent LIBs. Further, Ni, Co and Mn loaded in the organic were completely stripped with 1 mol/L sulfuric acid, and could be directly used for the preparation of the recycled ternary material precursors. Finally, Li in the raffinate solution was recovered by precipitation using Na2CO3, with the yield and purity of 96.4% and 99.6%. Overall, this recycling process with high impurity removal efficiency and valuable metals recovery efficiency not only simplify the production process, but also greatly reduces production costs, which is helpful for the regeneration and utilization of spent LIBs.

Miscibility and ternary diagram of aqueous polyvinyl alcohols with different degrees of saponification

Liquid–liquid phase separation (LLPS), an important phenomenon in the field of polymer science and material design, plays an essential role in cells and living bodies. Poly(vinyl alcohol) (PVA) is a popular semicrystalline polymer utilized in the synthesis of artificial biomaterials. The aqueous solutions of its derivatives with tuned degrees of saponification (DS) exhibit LLPS. However, the miscibility and LLPS behavior of PVA aqueous solution are still unclear. This study describes the miscibility diagram of the ternary mixture, where water and two types of poly(vinyl alcohol) (PVA) with different DSs [98 (PVA98), 88 (PVA88), 82 (PVA82), and 74 mol% (PVA74)] were blended. UV–Vis measurement was conducted to evaluate the miscibility. Immiscibility was more pronounced at elevated temperatures, exhibiting LLPS. The ternary immiscibility diagram, displaying miscible–immiscible behaviors in the aqueous mixtures of PVA74:PVA98, PVA82:PVA98, and PVA88:PVA98 (blended at a constant volume ratio), indicated that increasing the concentration, temperature, and blend ratio of PVAs at a lower DS increased immiscibility, suggesting that the free energy of mixing increases with increasing these parameters. The miscible–immiscible behaviors of PVAs/water systems provide fundamental knowledge about LLPS and the design of PVA-based materials.

Extracting Li+ from high Na/Li solution and comparing the affinity of nonylphenol oxygen anion to Na+ and Li+

Lithium extraction has become a hot topic because of global efforts to control carbon emissions. However, the efficient separation of Li/Na is a great challenge. In this study, the lithium carbonate precipitation mother liquor with Li+ content of 1.7910 g/L and Na+ content of 111.2438 g/L was used as the raw material solution. Due to its high Na/Li ratio, we found that the affinity of nonylphenol oxygen anion with Li+ is stronger than that with Na+ through quantum chemical analysis. And through the optimization of the effects of saponification degree, pH, temperature, and phase ratio, after twelve rounds of a five-stage countercurrent extraction, the ELi (%) reached 99% and the maximum βLi/Na reached 114799.73. After scrubbing with 0.5 mol/L HCl + 0.5 g/L LiCl solution and stripping with 2 mol/L HCl solution, Li+ and Na+ could be effectively separated. This study proved that nonylphenol oxygen anion had a significant effect on the extraction of Li+, and could effectively separate Li+ from Na+, which brings a new idea for the treatment of high Na/Li solution.

Separation of Lithium and Transition Metals in Leaching Solution of Used Lithium Ion Battery with Sec‐octylphenoxyacetic Acid

AbstractThe recovery of critical metals from spent lithium‐ion batteries (LIBs) is important to sustainable development and environment protection. In this paper, sec‐octylphenoxyacetic acid (CA‐12) was first used to recover valuable metals in LIBs. The effects of phase modifier, initial feed pH, extraction kinetics and thermodynamics, CA‐12 concentration and saponification degree were studied and optimized. Under the optimal conditions, 99 % of nickel, cobalt and manganese were co‐extracted to the organic phase, and the loss of lithium was 7 %. The extracted metal ions could be stripped with 0.04 mol/L HCl equivalently. In the spent LIBs powder leaching experiment, leaching efficiencies of all components were greater than 95 %. In the impurity removal stage, extractant N902 was used to remove copper, while iron and aluminum were eliminated by hydrolysis. After two‐stage extraction, the total extraction efficiencies of nickel, cobalt and manganese reached 99.7 %, 99.4 %, 98.45 %, respectively. Finally, lithium in the raffinate was precipitated by saturated Na2CO3, the purity of recovered Li2CO3 was up to 97.7 %. After 5 times cycles, CA‐12 still maintained excellent extraction capacity, showing its potential application prospects for recovering critical metals form spent LIBs.

Clean and cost-efficient preparation of vanadium electrolyte from the vanadium-rich solution of black shale by solvent extraction

This study proposes a clean and cost-efficient preparation process for vanadium electrolytes from the vanadium-rich solution of black shale. The introduction of saponified D2EHPA promoted vanadium recovery and further separation of impurities from vanadium-rich solutions. The preparation of a high-purity vanadium electrolyte was achieved by a four-stage countercurrent extraction at an initial pH as low as 1.0, 8 min, D2EHPA concentration of 30%, saponification degree of 60%, and phase ratio of 1:1, as well as a three-stage countercurrent stripping with 4 mol L−1 H2SO4 at phase ratio (O/A) of 6:1, 30 min. The developed electrolyte showed qualified electrochemical and charge-discharge performance, with coulombic efficiency, voltage efficiency, and energy efficiency reaching 91.07%, 93.44%, and 85.10%, respectively. This method saves 30.28% in preparation costs over the traditional method and produces no ammonia, nitrogen, or harmful gases. The technology is technologically advanced, economically sensible, and ecologically friendly, and is expected to be applied to large-scale production and promote the development of VRFB and new energy.

Experimental study on size effect and durability properties of PVA reinforced ice at Arctic low temperatures

To promote the application of PVA reinforced salt-water ice (PRSI) as a new construction material in the Arctic and cold regions, this paper experimentally studied the size effect, freezing point, melting time, and durability of plain salt-water ice (PSI) and PRSI. To study the size effect of ice, 20 PSI and 12 PRSI ice stub columns with varying diameters (D) were tested at −60 °C. Test results showed that PSI exhibited an obvious size effect whilst PRSI was not sensitive to the varying D. A formula was proposed to predict the compressive strength of PSI under different D. Eight specimens were tested to study the influence of PVA powder and NaCl on freezing point and melting resistance. It showed that adding PVA powder in ice increased its freezing rate and prolonged the melting time, which proved the availability of this reinforcing method in the workability. Finally, 18 PRSI columns and nine concrete specimens were tested on their freeze-thaw durability properties. Key parameters in this testing program included the number of freeze-thaw cycles, the saponification degree of PVA powder, and the contrast between PRSI and concrete. Considering the workability and durability of PRSI, using PRSI as a construction material to replace traditional construction steel and concrete materials provided an alternative for engineering infrastructures and temporary constructions in cold regions.

Environmentally Friendly Strategy for Treating In Situ Leaching Solutions of Ion-Adsorption Type Yttrium-Rich Heavy Rare-Earth Ore by a Bubble-Supported Organic Liquid Membrane

A novel environmentally friendly strategy based upon bubble-supported organic liquid membrane (BSOLM) extraction using saponified naphthenic acid as extractant is proposed in the present work for treating the in situ leaching solutions of ion-adsorption type yttrium-rich heavy rare-earth ores in South China. It was revealed that selectively preferential separation of non-yttrium rare earths from yttrium can be achieved, while the electrolyte aluminum salt can be retained in the raffinates for subsequent return as the leaching reagent for performing in situ leaching of ion-adsorption type heavy rare-earth ores. The BSOLM extraction exhibits an obvious advantage over conventional extraction in promoting the competitive mass transfer and separation of coexisting rare earths from yttrium and other non-rare-earth impurity ions. Using erbium as a representative of heavy rare earths, it was found that the differences in diffusive mass transfer rate of Er3+, Y3+, and Al3+ ions in the boundary layer of laminar flow near the surface of the extractant liquid membrane result in their enhanced separation. The BSOLM extraction prevents the convective disturbance along the normal vertical direction of the interface due to the irregular movement of dispersed oil droplets in the conventional extraction and therefore inhibit the co-extraction of Al3+ ions. The effects of Al3+ ion concentrations in aqueous feed solutions, initial aqueous pHs, concentrations of naphthenic acid, and its saponification degree on the separation efficiency were investigated. Experimental results confirmed that competitive hydration and adsorption of Al3+ ions at the interface play an important role in increasing the difference in concentration distribution of Er3+ and Y3+ ions near the interface during BSOLM extraction; therefore, the separation of rare earths from yttrium can be controllable.

Study on manufacturing hot water-resistant PVOH coated paper by gas grafting palmitoyl chloride (I) – Penetration of palmitoyl chloride during gas grafting of PVOH-coated paper

Abstract Gas grafting treatment with fatty acid chloride is a hydrophobization method based on the principle of forming ester bonds by reacting hydroxyl groups on the surface of hydrophilic substances with a gaseous fatty acid chloride. In order to increase the hydrophobization efficiency through gas grafting treatment, it is necessary to form an ester bond concentrated on the surface of the polyvinyl alcohol (PVOH) coating layer. When palmitoyl chloride, a fatty acid chloride, reacts with the hydroxyl groups of PVOH to form polyvinyl palmitate, the by-product hydrochloric acid promotes the dehydration of PVOH, causing discoloration while producing polyacetylene. Using this discoloration principle of polyene, it was estimated whether evaporated fatty acid chloride penetrated into the PVOH coating layer. The top layer was coated with PVOH having a saponification degree of 89 %, and the bottom layer was coated with PVOH having a saponification degree of 99 %. There was a difference in the discoloration according to the degree of saponification of PVOH, even the amount of palmitoyl chloride was small as much as 300 mg/m2. It was confirmed that the vaporized fatty acid chloride during gas grafting treatment permeates the PVOH layer of 7 g/m2 even in a very small amount.

Alkaline Treatment Variables to Characterize Poly(Vinyl Alcohol)/Poly(Vinyl Butyral/Vinyl Alcohol) Blend Films.

Novel poly(vinyl alcohol) (PVA)/poly(vinyl butyral–vinyl alcohol) (P(VB-VA)) films with improved hydrophobicity were prepared from poly(vinyl acetate) (PVAc)/poly(vinyl butyral) (PVB) blend films with various mass ratios by saponification in a heterogeneous medium. The successful conversion of PVAc to PVA and PVAc/PVB to PVA/P(VB-VA) films was confirmed by Fourier transform infrared spectrometry, X-ray diffraction, and proton nuclear magnetic resonance analysis. This study also shows that the degree of saponification (DS) depends on the saponification time. The maximum DS of 99.99% was obtained at 96 h of saponification for all films, and the presence of PVB did not affect the DS at saponification times of 48–96 h. The effects of the PVAc/PVB blend ratio before and after saponification were determined by contact angle measurement, and the hydrophobicity was found to increase in both cases with increasing PVB content. Additionally, all the films exhibited improved mechanical properties after saponification, and the treated films possessed an unusual porous and uneven surface, in contrast with the untreated films. The prepared films with improved hydrophobicity can be used for various applications, such as biomaterials, filters, and medical devices.

New Approach for Trace Thallium Removal in High Purity Ammonium Rhenate Solution by P204 Extraction

Thallium (Tl) is an extremely toxic rare metal to the eco-environment. Trace thallium impurity in ammonium perrhenate is harmful to the high-temperature mechanical properties of rhenium metal used for aeroengine single crystal blade. The di(2-ethylhexyl) phosphoric acid (P204) extraction to remove thallium in ammonium perrhenate solution without additive was innovatively proposed. The migration behavior of trace thallium with the concentration of P204, saponification degree and organic/aqueous phase (O/A) ratio, distribution law of thallium in the extraction system of P204, and mechanism of thallium removal were revealed. It was found Tl removal was rapidly increased to 98.5%, at conditions of P204 0.75 mol/L saponified 70% by ammonia, Tl 3.27 mg/L, O/A 1:1, T 298.15 ± 2 K, 250 rpm, and 3 min. McCabe-Thiele Tl extraction equilibrium isotherms indicates Tl concentration of raffinate less than 18.7 μg/L, a theoretical extraction of two stages and a theoretical stripping of two stages are required when both O/A work lines were at 1.0. Therefore, the method of the P204 solvent extraction system can effectively extract Tl in the forms of TlA(org), TlA3(org), TlOHA2(org), and Tl(OH)2A(org). Meanwhile, the new approach can be a promising process for ammonium rhenate refining.