Reprocessability of PHB in extrusion: ATR-FTIR, tensile tests and thermal studies

Mechanical recycling of biodegradable plastics has to be encouraged, since the consumption of energy and raw materials can be reduced towards a sustainable development in plastics materials. In this study, the evolution of thermal and mechanical properties, as well as structural changes of poly(hydroxybutyrate) (PHB) up to three extrusion cycles were investigated. Results indicated a significant reduction in mechanical properties already at the second extrusion cycle, with a reduction above 50% in the third cycle. An increase in the crystallinity index was observed due to chemicrystallization process during degradation by chain scission. On the other hand, significant changes in the chemical structure or in thermal stability of PHB cannot be detected by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), respectively.National Foundation for Science and Technology Development (CNPq)Univ Fed Rio Grande Norte UFRN, Dept Mat Engn DEMat, Natal, RN, BrazilUniv Fed Sao Carlos UFSCar, Dept Mat Engn DEMa, Sao Carlos, SP, BrazilUniv Fed Paraiba UFPB, Dept Mat Engn DEMAT, Joao Pessoa, Paraiba, BrazilUniv Fed Rio Grande Norte UFRN, Dept Chem DQ, Natal, RN, BrazilUniv Fed Sao Paulo UNIFESP, Inst Sci & Technol ICT, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Paulo UNIFESP, Inst Sci & Technol ICT, Sao Jose Dos Campos, SP, BrazilWeb of Scienc

Applications of micelle and microemulsion systems containing aminated surfactants synthesized from ricinoleic acid as carbon-steel corrosion inhibitors

The high affinity of surfactant molecules to adsorb onto interfaces is responsible for their applications in several interfacial systems. For this reason, surfactants can be used as good corrosion inhibitors in metallic surfaces. The main objective of this work was to examine the anticorrosion ability of three novel surfactant molecules synthesized from ricinoleic acid, a castor oil derivative. The surfactants are: sodium 12-N,N-diethylamino-9-octadecenoate (AR1S), sodium 12-N,N-diethylamino-9,10-dihydroxy-octadecanoate (AE2S) and sodium 12-N,N-diethylamino-9-octadecanoate (AE1S). Their ability to inhibit corrosion in AISI 1010 carbon-steel has been investigated by preparing specific micellar solutions and microemulsion systems. Adsorption phenomena have been electrochemically studied with the Frumkin model, indicating that the surfactant solutions tested can inhibit corrosion with levels as high as 95%. On the other hand, the microemulsion systems, although featuring relatively lower performance, are advantageous in that they are able to dissolve more active matter. These results are useful as a basis to propose and study particular applications such as the transport of oil in petrochemical industries

Preparation and application of self-assembled systems containing dodecylammonium bromide and chloride as corrosion inhibitors of carbon-steel

The application of surfactant systems as inhibitors of corrosion on metallic surfaces is discussed in this work. The focus is now driven to the influence of cationic surfactants’ counterions on the adsorption mechanism at carbon-steel surfaces. The surfactants dodecylammonium bromide (DDAB) and dodecylammonium chloride (DDAC) have been synthesized and used to prepare micellar and microemulsion formulations. The surfactants were dissolved in aqueous hydrochloric acid as micellar solutions, and in microemulsions containing n-hexane as oil phase and butan-1-ol as cosurfactant. After characterization by phase behavior studies, a number of these formulations with varying surfactant concentration have been tested against acidic corrosion on carbon-steel surfaces. Potentiometry assays were carried out to determine the extent of coverage on the metallic surface, and the adsorption mechanism was modeled with the Frumkin isotherm. Efficiencies of corrosion inhibition as high as 98% were obtained for the DDAC systems, and 96% for the DDAB systems. The results suggest that the protective surfactant film could resist changes in pH, salinity and temperature that might occur during typical applications involving metallic equipment or ducts under a broad range of experimental conditions. This is particularly interesting for industrial applications of microemulsions and other self-assembled systems, which could be used as templates for novel formulations of corrosion inhibitors

Obtaining a stable olefin-based drilling fluid using non-treated produced water

Produced water is the main waste stream in the oil and gas sector, with significantly greater concentrations of hydrocarbons, heavy metals, and other contaminants. Several works and technologies were developed to reuse the produced water in many applications including drilling and completion fluids. However, in general, a pretreatment is required. According to our knowledge, the reuse of produced water in non-aqueous drilling is still not reported. Therefore, this work proposed the formulation of olefin-based drilling fluids containing between 20-40% of untreated produced water. Through factorial experimental design, the influence of produced water, emulsifier, and viscosifier on the properties of the formulated emulsions was investigated. Our results show that produced water without treatment can be used as an aqueous phase for olefin-based drilling fluids, with the best formulation being the test that has RO/A = 60/40, emulsifier concentration of 14.26 kg/m³ and viscosifier concentration of 2.85 kg/m³. The well-cleaning properties of the proposed formulation were evaluated through numerical simulation in a well with high inclination. The results showed that the hole cleaning was not affected by using untreated produced water in the fluid formulation. The results presented here open a new possibility to reuse produced water in drilling operations without performance loss.</p

Dual Role of a Ricinoleic Acid Derivative in the Aqueous Synthesis of Silver Nanoparticles

We show that sodium 9,10-epoxy-12-hydroxytetradecanoate (SEAR), an epoxidized derivative of ricinoleic acid, simultaneously functioned as reducing and stabilizing agents in the synthesis of silver nanoparticles in alkaline aqueous medium. The advantage of using SEAR is its biodegradability and nontoxicity, which are important characteristics for mitigation of environmental impact upon discharge of nanoparticles into terrestrial and aquatic ecosystems. The SEAR concentration was found to impact considerably the size distribution of silver nanoparticles (AgNPs). A concentration below the SEAR critical micelle concentration (CMC) generated 23 nm sized AgNPs with 10 nm standard deviation, while 50 nm sized AgNPs (σ=21 nm) were obtained at a concentration above the SEAR CMC. FTIR analysis revealed that the carboxylate that constitutes the SEAR hydrophilic head binds directly to the AgNPs surface promoting stabilization in solution. Finally, AgNPs turned into Ag2S upon contact with wastewater samples from Wastewater Treatment Plant at Federal University of Rio Grande do Norte (UFRN), Brazil, which is an interesting result, since Ag2S is more environmentally friendly than pure AgNPs

Reprocessability of PHB in extrusion: ATR-FTIR, tensile tests and thermal studies

Abstract Mechanical recycling of biodegradable plastics has to be encouraged, since the consumption of energy and raw materials can be reduced towards a sustainable development in plastics materials. In this study, the evolution of thermal and mechanical properties, as well as structural changes of poly(hydroxybutyrate) (PHB) up to three extrusion cycles were investigated. Results indicated a significant reduction in mechanical properties already at the second extrusion cycle, with a reduction above 50% in the third cycle. An increase in the crystallinity index was observed due to chemicrystallization process during degradation by chain scission. On the other hand, significant changes in the chemical structure or in thermal stability of PHB cannot be detected by Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), respectively

Chrysin-Loaded Microemulsion: Formulation Design, Evaluation and Antihyperalgesic Activity in Mice

Chrysin is a bioactive flavonoid found in pollens, passion flowers, honey, royal jelly, and propolis, which is commonly used as an ingredient in natural food supplements and is primarily responsible for their pharmacological properties. A transparent chrysin-loaded microemulsion (CS-ME) prepared through a ternary phase diagram was evaluated for use as an antihyperalgesic formulation. It was formulated with 40% Labrasol&reg; (surfactant), 5% isopropyl myristate (oil phase) and 55% water (aqueous phase) and classified as an oil-in-water (O/W) microsized system (74.4 &plusmn; 15.8 nm). Its negative Zeta potential (&minus;16.1 &plusmn; 1.9 mV) was confirmed by polarized light microscopy and dynamic light scattering analysis. In vitro studies in Franz-type static diffusion cells showed that chrysin release from CS-ME followed zero-order kinetics. Oral administration of CS-ME in mice resulted in a statistically significantly reduction (p &lt; 0.05) in carrageenan-induced mechanical hyperalgesia compared to the control group. Treatment with CS-ME also showed anti-inflammatory activity by significantly decreasing the TNF-&alpha; level (p &lt; 0.01) and increasing that of IL-10 (p &lt; 0.05) compared to the control group. These results suggest that the proposed microsystem is a promising vector for the release of chrysin, being able to improve its capacity to modulate inflammatory and nociceptive responses

Chrysin-Loaded Microemulsion: Formulation Design, Evaluation and Antihyperalgesic Activity in Mice

Chrysin is a bioactive flavonoid found in pollens, passion flowers, honey, royal jelly, and propolis, which is commonly used as an ingredient in natural food supplements and is primarily responsible for their pharmacological properties. A transparent chrysin-loaded microemulsion (CS-ME) prepared through a ternary phase diagram was evaluated for use as an antihyperalgesic formulation. It was formulated with 40% Labrasol® (surfactant), 5% isopropyl myristate (oil phase) and 55% water (aqueous phase) and classified as an oil-in-water (O/W) microsized system (74.4 ± 15.8 nm). Its negative Zeta potential (−16.1 ± 1.9 mV) was confirmed by polarized light microscopy and dynamic light scattering analysis. In vitro studies in Franz-type static diffusion cells showed that chrysin release from CS-ME followed zero-order kinetics. Oral administration of CS-ME in mice resulted in a statistically significantly reduction (p p p < 0.05) compared to the control group. These results suggest that the proposed microsystem is a promising vector for the release of chrysin, being able to improve its capacity to modulate inflammatory and nociceptive responses