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Adsorption is one of the most crucial processes in water treatment today. It offers a low-cost solution that does not require specialized equipment or state-of-the-art technology while efficiently removing dissolved contaminants, including heavy metals. This process allows for the utilization of natural or artificial adsorbents or a combination of both. In this context, polymeric materials play a fundamental role, as they enable the development of adsorbent materials using biopolymers and synthetic polymers. The latter can be used multiple times and can absorb large amounts of water per gram of polymer. This paper focuses on utilizing adsorption through hydrogels composed of poly(acrylamide-co-itaconic acid) for removing Cu2+ ions dissolved in aqueous media in a semi-continuous process. The synthesized hydrogels were first immersed in 0.1 M NaOH aqueous solutions, enabling OH- ions to enter the gel matrix and incorporate into the polymer surface. Consequently, the copper ions were recovered as Cu(OH)2 on the surface of the hydrogel rather than within it, allowing the solid precipitates to be easily separated by decantation. Remarkably, the hydrogels demonstrated an impressive 98% removal efficiency of the ions from the solution in unstirred conditions at 30 °C within 48 h. A subsequent study involved a serial process, demonstrating the hydrogels' reusability for up to eight cycles while maintaining their Cu2+ ion recovery capacity above 80%. Additionally, these hydrogels showcased their capability to remove Cu2+ ions even from media with ion concentrations below 100 ppm.

RESUMO

Renewable polymers possess the potential to replace monomers from petrochemical sources. The design and development of polymeric materials from sustainable materials are a technological challenge. The main objectives of this study were to study the microstructure of copolymers based on itaconic acid (IA), di-n-butyl itaconate (DBI), and lauryl methacrylate (LMA); and to explore and to evaluate these copolymers as pressure-sensitive adhesives (PSA). The copolymer synthesis was carried out through batch emulsion radical polymerization, an environmentally friendly process. IA was used in a small fixed amount as a functional comonomer, and LMA was selected due to low glass transition temperature (Tg). The structure of synthesized copolymers was studied by FTIR, 1H-NMR, Soxhlet extraction, and molecular weight analyses by GPC. Furthermore, the viscoelastic and thermal properties of copolymer films were characterized by DMA, DSC, and TGA. The single Tg displayed by the poly(DBI-LMA-IA) terpolymers indicates that statistical random composition copolymers were obtained. Moreover, FTIR and NMR spectra confirm the chemical structure and composition. It was found that a cross-linked microstructure and higher molecular weight are observed with an increase of LMA in the feed led. The Tg and modulus (G') of the copolymers film can be tuned with the ratio of DBI:LMA providing a platform for a wide range of applications as a biobased alternative to produce waterborne PSA.

RESUMO

Poly(itaconic acid) (PIA) was synthesized via conventional radical polymerization. Then, functionalization of PIA was carried out by an esterification reaction with the heterocyclic groups of 1,3-thiazole and posterior quaternization by N-alkylation reaction with iodomethane. The modifications were confirmed by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (1H-NMR), as well as ζ-potential measurements. Their antimicrobial activity was tested against different Gram-negative and Gram-positive bacteria. After characterization, the resulting polymers were incorporated into gelatin with oxidized starch and glycerol as film adjuvants, and dopamine as crosslinking agent, to develop antimicrobial-active films. The addition of quaternized polymers not only improved the mechanical properties of gelatin formulations, but also decreased the solution absorption capacity during the swelling process. However, the incorporation of synthesized polymers increased the deformation at break values and the water vapor permeability of films. The antioxidant capacity of films was confirmed by radical scavenging ability and, additionally, those films exhibited antimicrobial activity. Therefore, these films can be considered as good candidates for active packaging, ensuring a constant concentration of the active compound on the surface of the food, increasing products' shelf-life and reducing the environmental impact generated by plastics of petrochemical origin.

RESUMO

Herein, the effectiveness of an itaconic acid (IA) graft copolymer on native corn starch (NCS) as a filter control agent in fresh water-based drilling fluids (WBDFs) was evaluated. The copolymer (S-g-IA_APS) was synthesized by conventional radical dispersion polymerization using the redox initiation system (NH4)2S2O8/NaHSO3. The modification of the starches was verified by volumetry, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). Then, three WBDFs were formulated in which only the added polymer (NCS, S-g-IA_APS, and a commercial starch (CPS)) was varied to control the fluid losses. The physico-chemical, rheological, and filtering properties of the formulated systems were evaluated in terms of density (ρ), pH, plastic viscosity (µp), apparent viscosity (µa), yield point (Yp), gel strength (Rg), and filtrated volume (VAPI). In order to evaluate the resistance to temperature and contaminants of the WBDFs, they were subjected to high pressure and high temperature filtering (VHPHT). The filter control agents were also subjected to aging and contamination with cement and salt. The S-g-IA_APS addition improved the filtering behavior at a high pressure and temperature by 38%.

RESUMO

Currently, advanced dosimeters like polymer gels are capable of obtaining reliable and accurate 3D dose distributions from correlations with the different polymerization degrees induced by incident radiation. Samples of polymer gel dosimeters are commonly read out using magnetic resonance imaging or optical methods like visible light transmission or laser computed tomography. Alternatively, this work proposes and evaluates the implementation of Raman spectroscopy to provide direct information on the effect of oxygen permeating through the walls of phantoms on the polymerization initiated by irradiation in three types of polymer gel dosimeters, namely NIPAM, ITABIS and PAGAT. The aim of the present study is to provide better and complete interpretations using three different containers, adequate for integral, 2D and 3D dose mapping. Moreover, Raman spectroscopy has been used to analyze the well-known effect of oxygen inhibition on the different polymer gel dosimeters remarking the importance of avoiding air exposition during sample storage and readout. Dose-response curves for different polymer gels were obtained in terms of measurements with a calibrated ionization chamber. Additionally, dedicated Monte Carlo simulations were performed aimed at characterizing dose for different X-ray irradiation setups, providing also suitable information to evaluate oxygen diffusion through the sample wall. The obtained results were contrasted with optical transmission readout as well as Monte Carlo simulations attaining very good agreements for all dosimeter types.

RESUMO

In this paper, chitosan was used as protective agent for dual temperature-/pH-sensitive poly(N-vinylcaprolactam-co-itaconic acid-co-ethylene- glycol dimethacrylate)- based hydrogel nanoparticles (poly(NVCL-co-IA-co-EGDMA)) aiming avoid their undesirable colloidal destabilization at different conditions of body human tissues. Thus, poly(NVCL-co-IA-co-EGDMA) was embedded into chitosan and a new solid dispersion was prepared via spray-drying and ketoprofen was used as carrier. Two different sizes of hydrogel nanoparticles (120.6 nm and 185.9 nm) were evaluated and they exhibited a drug encapsulation efficiency of the 39.6% and 57.8%, respectively. The smaller nanoparticles showed to be faster for releasing of ketoprofen at pH 7.4 and 37 °C due to their larger surface area and higher swelling ability. Chitosan played a role of a secondary barrier for the ketoprofen diffusion, extending its release compared to hydrogel nanoparticles alone. Among two concentrations (40 wt% and 70 wt%) of hydrogel nanoparticles related to chitosan, the first one induced higher percentages of ketoprofen release: 74.2% against 64.6%. In addition, the interactions between chitosan matrix and poly(NVCL-co-IA-co-EGDMA) did not change the multi-responsive behavior of hydrogels, suggesting the chitosan was efficient for keeping integrity of nanoparticles hydrogels. Chitosan/poly(NVCL-co-IA-co-EGDMA) hybrid microparticles seems to be a promising new carrier for release of hydrophobic drugs, such as ketoprofen.

Assuntos

RESUMO

The use of yeasts in bioprocesses can be considered one of the most relevant strategies in industrial biotechnology, and their potential is recognized due to the ability of these microorganisms for production of diverse value-added compounds. Yeasts from Ustilaginaceae family have been highlighted in the last years as a promising source of industrial interesting compounds, including enzymes, sugars, lipids, organic acids, and biosurfactants. These compounds may exhibit various applications in pharmaceutical, cosmetic, food, medical, and environmental fields, increasing the scientific attention in the study of ustilaginomycetous for biotechnological purposes. In this mini-review, we provide a comprehensive overview about the biotechnological use of yeasts from Ustilaginaceae family to produce value-added compounds, focusing in recent trends, characteristics of processes currently developed, new opportunities, and potential applications.

Assuntos

RESUMO

An elegant, efficient, and highly regioselective approach for the synthesis of novel methyl 5-amino-3-(methylthio)-1-differently substituted-1H-pyrazole-4-carboxylates is reported. The procedure involves the cyclocondensation of α-oxeketene S, S-dimethyl acetal building blocks with different alkyl, aryl, and heterocyclic acid hydrazides. The novel molecules were obtained in good yields and their identities confirmed by NMR and HRMS spectrometry.

Assuntos

RESUMO

Itaconic acid is a promising chemical that has a wide range of applications and can be obtained in large scale using fermentation processes. One of the most important uses of this biomonomer is the environmentally sustainable production of biopolymers. Separation of itaconic acid from the fermented broth has a considerable impact in the total production cost. Therefore, optimization and high efficiency downstream processes are technological challenges to make biorefineries sustainable and economically viable. This review describes the current state of the art in recovery and purification for itaconic acid production via bioprocesses. Previous studies on the separation of itaconic acid relying on operations such as crystallization, precipitation, extraction, electrodialysis, diafiltration, pertraction, and adsorption. Although crystallization is a typical method of itaconic acid separation from fermented broth, other methods such as membrane separation and reactive extraction are promising as a recovery steps coupled to the fermentation, potentially enhancing the overall process yield. Another approach is adsorption in fixed bed columns, which efficiently separates itaconic acid. Despite recent advances in separation and recovery methods, there is still space for improvement in IA recovery and purification.

Assuntos

RESUMO

New hyaluronic acid (HA)-itaconic acid (IT) films have been previously synthesized and used as potential topical drug delivery systems (DDS) for ocular administration. In this study we explored homogeneous and heterogeneous crosslinking reactions of HA using glutaraldehyde (GTA) and polyethylene glycol diglycidyl ether (PEGDE) in the presence of IT, a naturally occurring compound that is non-toxic and readily biodegradable. We have studied the morphology, mechanical properties and in vitro biocompatibility between these new materials and ocular surface cells (human corneal epithelial cell line) and evaluated the biopharmaceutical performance of the designed formulations. Although all the synthesized materials exhibited good mechanical properties, the PEGDE modified films exhibited the best biocompatibility, with in vivo assays showing good adhesive performance and minimal irritation. PEGDE films were also tested for their effects in the treatment of intraocular pressure (IOP) in rabbits using timolol maleate (TM) as the model drug. These results may be useful for further design of novel bioadhesive matrix containing drugs by topical application in ophthalmology.

Assuntos