Effects of membrane content, feed phase, and stripping phase for palladium solution extraction by using a polymer inclusion membrane.

Palladium is now frequently utilized in fuel cells, electroplating, electronics, and catalysis. Due to their rarity and high cost, precious metal recovery has taken on a significant role. The extraction method frequently utilized in polymer inclusion membranes (PIMs) is both efficient and simple since it has been demonstrated that precious metal adsorption on the membrane significantly controls the mechanism of chemical adsorption. In this study, polyvinyl chloride (PVC) as a polymer, A336 as a plasticizer, and trioctylamine (TOA) as a carrier were used to produce a PIM by evaporation. After the production of PIMs, palladium extract was studied. The stripping phase, palladium concentration in the feed phase, and components of the membrane were changed to determine the optimum condition with better extraction ability. When 0.5 M of HCl was used, higher kinetic parameter results and higher than 85% extraction efficiency were achieved compared to other concen- trations. When the EDX results were examined, 3.3% palladium was retained on the membrane surface. When the palladium concentration was selected at 2.5 ppm, higher kinetic parameters were observed, and the extraction efficiency was over 90%. The best membrane was the PIM containing 40% PVC-40% A336-20% TOA.

Competition among Refined Hollow Structures in Schiff Base Polymer Derived Carbon Microspheres.

Synthetic polymer-derived hollow carbon spheres have great utilitarian value in many fields for which the synthesis of proper polymer precursors is a key process. The exploration of new suitable polymer precursors and the construction of refined hollow structures in emerging polymers are both of great significance for synthetic methodology and novel carbon materials. Here, for the first time Schiff base polymer (SBP) colloid spheres with refined hollow structures were synthesized by tandem gradient growth and confined polymerization processes. The Hill equation was employed as a mathematical model to explain the gradient growth of SBP spheres. The size-dependent inner structure of SBP spheres can be adjusted from hollow to multichamber-surrounded hollow, and then to a multichamber structure. SBP-derived carbon spheres having similar surface area and chemical composition but different inner structures provide an effective way to investigate the relationship between inner structure and performance.

Schiff-base Polymer Immobilized Ruthenium for Efficient Catalytic Cross-coupling of Secondary Alcohols with 2-amino- and γ-aminobenzyl Alcohols to Give Quinolines and Pyridines.

A Schiff-base porous polymer has been impregnated with ruthenium trichloride for acceptor-free dehydrogenation coupling (ADC) of secondary alcohols with γ-amino- and 2-aminobenzyl alcohols to give pyridines and quinolines. This heterogenous catalyst exhibited high catalytic efficiency over repeated cycles with wide functional group tolerance.

Fracture strength of Er,Yag laser treated PMMA denture-based polymer (DBP) colonized with C. albicans, S. aureus, S.mutans, and E.coli.

AIM: To assess and equate the efficacy of different disinfection protocols autoclave, chlorhexidine (CHX), PDT utilizing Rose Bengal (RB), chitosan, and Er, Yag laser and their effect on fracture strength of PMMA denture-based polymer (DBP) colonized with C. Albicans, S. aureus, S.mutans, and E.coli. MATERIAL AND METHODS: A total of 50 (n = 10) PMMA DBP were manufactured and adulterated with the American Type Culture Collection (ATCC) of diverse microbial colonies inhabited by C. Albicans, S. aureus, S.mutans, and E.coli. The specimens were subjected to different denture disinfection approaches by randomly distributing in into five groups i.e., Er, Yag laser, RB, autoclave, CHX, and Chitosan, respectively for appraising antimicrobial effectiveness. PMMA fracture load was also assessed and statistical analysis was performed for CFU/mL (log10) of exposed C. Albicans, S. aureus, S.mutans, and E.coli by one-way ANOVA and Tukey's multiple comparison test at a significance level of p < 0.05. RESULTS: Intergroup comparison disclosed that denture disinfection with Er, Yag laser, autoclave, Chitosan, and CHX (control) validated comparable antimicrobial efficacy to denture against all inspected CFU/mL (log10) (p>0.05). The intragroup comparison revealed that DBP sanitization with Er, Yag laser, autoclave, Chitosan, RB, and CHX substantiated equivalent effective antimicrobial efficacy in plummeting CFU/mL (log10) of S. mutans and E. coli (p>0.05) but in consideration to S.aureus and C.albicans, all groups resulted in declining their count except 5µm RB activated by PDT(p < 0.05). No significant difference was perceived in fracture load of PMMA denture base among Er, Yag laser, RB, chitosan, and CHX (control) (p > 0.05) except autoclave decontamination procedure that indicated the least fracture strength of DBP when disinfected (p < 0.05). CONCLUSION: Er, Yag laser, and Chitosan activated by PDT have the potential to be used as an alternative to chlorhexidine for disinfecting Polymethyl methacrylate denture base as they demonstrated the highest antimicrobial efficacy against E. coli, C. Albicans, S aureus, and S. mutans with optimal fracture load.

Polymer inclusion membrane applications for transport of metal ions: A critical review.

The co-existence of heavy metals in industrial effluents is a prevalent problem. Heavy metals are not biodegradable and can remain in the environment when left untreated. Therefore, metals must be removed from wastewater to protect people's health and the environment. Also, these pollutants usually have dissimilar compositions and properties. Generally, metal treatment is performed using traditional methods, but new processes have been developed due to the disadvantages of traditional methods. Especially in the last 20 years, studies on polymer inclusion membranes have been carried out and the transport performance of metal ions has been investigated. It is a more convenient process than both ion exchange and liquid-liquid extraction methods due to the potential and performance of polymer inclusion membranes. When the studies in the literature are examined, it is seen that the performance of polymer inclusion membranes is higher than expected and also when the production conditions are examined, polymer inclusion membrane is more advantageous than other processes. This review is a summary of the studies on the removal and transport of metal by using polymer inclusion membranes in the literature over the last 20 years.

Biomass Schiff base polymer-derived N-doped porous carbon embedded with CoO nanodots for adsorption and catalytic degradation of chlorophenol by peroxymonosulfate.

The development of highly active and multifunctional carbocatalysts modified with heteroatoms or metal species is crucial for practical environmental remediation applications. In this study, nitrogen-doped porous carbon embedded with highly dispersed CoO nanodots (CoO-N-C) was successfully prepared from a biomass-derived Schiff base polymer for the first time. The morphology analysis shows that CoO nanodots were embedded in the N doped carbon layer with size of ∼6.5 nm. CoO-N-C catalyst exhibited excellent 4-CP adsorption efficiency as well as excellent catalytic performance in the activation of peroxymonosulfate (PMS) for 4-CP degradation. Total organic carbon (TOC) removal was close to 99.7% and involved a combination of adsorption and degradation processes. Singlet oxygen (1O2) was found to be the dominant oxidative species for 4-CP degradation. The underlying mechanism of these processes were elucidated, and it was found that the introduction of CoO nanodots in CoO-N-C not only enhanced radical catalytic processes, but also significantly enhanced the non-radical catalytic processes of PMS activation. This derived from the synergistic effect between the embedded CoO nanodots and doped nitrogen for the increase of electron density on carbon surface of catalyst, thereby accelerating the electron transfer process for PMS activation and improving the catalytic performance.

Ratiometric fluorescence detection of O2•- based on dual-emission schiff base polymer/rhodamine-B nanocomposites.

A novel ratiometric fluorescent sensor for superoxide radical (O2•-) detection was developed based on Schiff base polymer (SBP)/rhodamine-B (SBP/RDB) nanocomposites. The SBP/RDB was investigated by atomic force microscopy, scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, N2 adsorption/desorption isotherms and fluorescence spectroscopy, etc. The results showed the SBP was two-dimensional (2D) crystalline nanosheet with the thickness of 0.5 nm. RDB could be self-assembled on each of 2D SBP surface to form SBP/RDB due to the hydrogen bond between N atoms of SBP and -COOH of RDB as well as π-π interaction. The SBP/RDB exhibited the characteristic fluorescence emission of both SBP at 485 nm and RDB at 585 nm under an excitation of 270 nm. The 2D SBP was not only acted as template to assemble RDB, but also used as reference fluorescence for O2•- detection. The SBP/RDB fluorescence probe for O2•- detection demonstrated high sensitivity and selectivity with good linear range (11.1 ±â€¯0.76 nM-8.0 ±â€¯0.36 µM) and low detection limit (3.7 ±â€¯0.42 nM). Because of the low cost and simple operation, the work sheds some new light to construct ratiometric fluorescent sensors based on SBP to detect O2•- in drinking water and human blood serum for commercial applications.

Evaluation of the flexural mechanical properties of various thermoplastic denture base polymers.

This study evaluated the flexural mechanical properties of various thermoplastic denture base polymers (six polyamides, four acrylic resins, polyester, polypropylene, and polycarbonate) by three different testing conditions; specimens were tested in water bath at 37°C (Wet/Water, by ISO 20795-1), or in ambient air (Wet/Air) after being immersed in distilled water for 50 h, or after desiccation for 7 days (Dry/Air). The mean ultimate flexural strength (UFS) and flexural modulus (FM) for most products ranged from 27 to 61 MPa and from 611 to 1,783 MPa respectively, which failed to meet the minimum requirements of the international standard, except for polycarbonate (89 and 2,245 MPa). The mean UFS and FM values were ranked Dry/Air>Wet/Air>Wet/Water (p<0.05). In conclusion, the flexural mechanical properties of denture base polymers varied with the products and were significantly affected by the testing medium (air or water) and specimen conditions (wet or dry).

Highly Permeable Matrimid®/PIM-EA(H2)-TB Blend Membrane for Gas Separation.

The effect on the gas transport properties of Matrimid®5218 of blending with the polymer of intrinsic microporosity PIM-EA(H2)-TB was studied by pure and mixed gas permeation measurements. Membranes of the two neat polymers and their 50/50 wt % blend were prepared by solution casting from a dilute solution in dichloromethane. The pure gas permeability and diffusion coefficients of H2, He, O2, N2, CO2 and CH4 were determined by the time lag method in a traditional fixed volume gas permeation setup. Mixed gas permeability measurements with a 35/65 vol % CO2/CH4 mixture and a 15/85 vol % CO2/N2 mixture were performed on a novel variable volume setup with on-line mass spectrometric analysis of the permeate composition, with the unique feature that it is also able to determine the mixed gas diffusion coefficients. It was found that the permeability of Matrimid increased approximately 20-fold with the addition of 50 wt % PIM-EA(H2)-TB. Mixed gas permeation measurements showed a slightly stronger pressure dependence for selectivity of separation of the CO2/CH4 mixture as compared to the CO2/N2 mixture, particularly for both the blended membrane and the pure PIM. The mixed gas selectivity was slightly higher than for pure gases, and although N2 and CH4 diffusion coefficients strongly increase in the presence of CO2, their solubility is dramatically reduced as a result of competitive sorption. A full analysis is provided of the difference between the pure and mixed gas transport parameters of PIM-EA(H2)-TB, Matrimid®5218 and their 50:50 wt % blend, including unique mixed gas diffusion coefficients.

Effect of heat treatment of polymethyl methacrylate powder on mechanical properties of denture base resin.

OBJECTIVES: The aim of this research was to investigate the effects of heat treatment of polymethyl methacrylate powder on mechanical properties of denture base resin. METHODS: PMMA powder was applied after heat treatment at 100°C for 2h (code: HT100) or 130°C for 2h (code: HT130). The test specimens were fabricated from autopolymerizing resin to investigate the flexural properties of denture base resin cross-linked with methacrylated dendrimer, the surface microhardness of PMMA beads, and the thickness of the swollen layer of PMMA beads. The specimens were autopolymerized, and all specimens were stored in 37°C water for 24h. Half of the specimens were immersed in 37°C water for an additional 6 months (water storage period: 24h and 6 months). The flexural strength and flexural modulus (n=10/group) were measured with a three point bending test. Statistical analysis was performed using ANOVA and the Newman-Keuls test at a significance level of 0.05. RESULTS: Heat treatment and the water storage period had a significant effect on flexural strength. The flexural strength of HT130 showed significantly higher values than in other groups. The surface microhardness of PMMA beads of HT130 showed a significantly greater microhardness than other groups. The thickness of a swollen layer of PMMA beads of HT100 and HT130 was significantly decreased. CONCLUSIONS: The flexural strength and the surface microhardness were increased after heat treatment at 130°C. The thickness of a swollen layer of PMMA beads was decreased after heat treatment.