Sintetička biomaziva bazna ulja od epoksidirane ricinolne kiseline poboljšanih niskotemperaturnih svojstava

This paper presents a series of structural modifications of epoxidized ricinoleic acid for biolubricant to improve the cold flow behavior and oxidation stability of vegetable oils through measurement of pour point (PP) and oxidation onset temperature (OT) and signal maximum temperature (SMT) of each synthetic compound. The results showed that butyl 10,12-dihydroxy-9-behenoxystearate with bulky ester behenyl mid-chain exhibited the most favorable low-temperature performance ϑPP=– 47 °C). On the other hand, butyl 10,12-dihydroxy-9-octyloxystearate exhibited higher oxidation stability (ϑOT = 221 °C) than the other synthetic esters. It was discovered that increasing chain length of the mid-chain ester had a positive influence on the low temperature properties of synthesized compounds. Improved oxidation stability is achieved when the chain length of the mid-chain ester decreases. The synthesized ester structures were confirmed by NMR and FTIR analysis.Opisan je veći broj strukturnih preinaka epoksidirane ricinolne kiseline kojima se poboljšavaju neka uporabna svojstva kada služe kao biomaziva ulja. Posebice su poboljšana svojstva niskotemperaturne tečljivosti i oksidacijske postojanosti. Također su utvrđeni indeksi viskoznosti, plamišta i iskoristivosti pri sintezi opisanih estera. Dobiveni rezultati ukazuju da je poboljšanje niskotemperaturnih svojstava izravno razmjerno povećanju veličine esterskih skupina središnjeg dijela molekula, dočim je suprotni utjecaj na njihovu oksidacijsku postojanost. Tako, najbolja niskotemperaturna svojstva (stinište -47°C) posjeduje butil-10,12-dihidroksi-9-behenoktilstearat, zahvaljujući velikim sterički ometanim esterskim skupinama središnjeg dijela molekula. S druge strane, najveću oksidacijsku postojanost posjeduje butil-10,12-dihidroksi-9-oktilstearat (ϑOT = 221 °C), zahvaljujući maloj veličini središnje esterske skupine. Struktura priređenih estera potvrđena je spektroskopskim metodama prvenstveno spektrima NMR i FTIR

Optimización de la cristalización con metanol para una separación altamente eficiente del ácido palmítico en mezclas de ácidos grasos de palma usando metodología de superficie de respuesta

The objective of the current study was to develop parameters for the separation of palmitic acid (PA) from a crude palm oil saturated fatty acid (SFAs) mixture by using the methanol crystallization method. The conditions of methanol crystallization were optimized by the response surface methodology (RSM) with the D-optimal design. The procedure of developing the solvent crystallization method was based on various different parameters. The fatty acid composition was carried out using a gas chromatography flame ionization detector (GC-FID) as fatty acid methyl esters. The highest percentage of SFAs was more than 96% with the percentage yield of 87.5% under the optimal conditions of fatty acids-to-methanol ratio of 1: 20 (w/v), the crystallization temperature of -15 °C, and the crystallization time of 24 hours, respectively. The composition of separated SFAs in the solid fraction contains 96.7% of palmitic acid (C16:0) as a dominant component and 3.3% of stearic acid (C18:0). The results showed that utilizing methanol as a crystallization solvent is recommended because of its high efficiency, low cost, stability, availability, comparative ease of recovery and its ability to form needle-like crystals which have good filtering and washing characteristics.El objetivo del presente estudio fue desarrollar parámetros para la separación de ácido palmítico (PA) en mezclas de ácidos grasos saturados (SFAs) de aceites de palma crudo mediante el método de cristalización con metanol. Las condiciones de cristalización con metanol se optimizaron utilizando la metodología de superficie de respuesta (RSM) con el diseño D-Optimal. El procedimiento de desarrollo del método de cristalización con disolvente se basó en diversos parámetros diferentes. La composición de ácidos grasos se llevó a cabo por cromatografía de gases (GC-FID) como ésteres metílicos de ácidos grasos usando un detector de ionización de llama. El porcentaje más alto de SFAs fue mayor del 96% con un rendimiento porcentual de 87,5% bajo las condiciones óptimas de relación de ácidos grasos:metanol de 1:20 (p/v), una temperatura de cristalización de -15ºC y un tiempo de cristalización de 24 horas. La composición de la fracción de SFAs separada en fracción sólida contiene 96,7% de ácido palmítico (C16:0) como principal componente y 3,3% de ácido esteárico (C18:0). Los resultados mostraron recomendar metanol como disolvente de cristalización debido a su alta eficiencia, bajo coste, estabilidad, disponibilidad, facilidad comparativa de recuperación y su capacidad para formar cristales de aguja que tienen buenas características de filtración y lavado

The Influence of Organizational External Factors on Construction Risk Management among Nigerian Construction Companies

Background: Substantial empirical research has shown conflicting results regarding the influence of organizational external factors on construction risk management, suggesting the necessity to introduce a moderator into the study. The present research confirmed whether rules and regulations matter on the relationships between organizational external factors and construction risk management. Methods: Based on discouragement and organizational control theory, this research examined the effects of organizational external factors and rules and regulations on construction risk management among 238 employees operating in construction companies in Abuja and Lagos, Nigeria. A personally administered questionnaire was used to acquire the data. The data were analyzed using partial least squares structural equation modeling. Results: A significant positive relationship between organizational external factors and construction risk management was asserted. This study also found a significant positive relationship between rules and regulations and construction risk management. As anticipated, rules and regulations were found to moderate the relationship between organizational external factors and construction risk management, with a significant positive result. Similarly, a significant interaction effect was also found between rules and regulations and organizational external factors. Implications of the research from a Nigerian point of view have also been discussed. Conclusion: Political, economy, and technology factors helped the construction companies to reduce the chance of risk occurrence during the construction activities. Rules and regulations also helped to lessen the rate of accidents involving construction workers as well as the duration of the projects. Similarly, the influence of the organizational external factors with rules and regulations on construction risk management has proven that most of the construction companies that implement the aforementioned factors have the chance to deliver their projects within the stipulated time, cost, and qualities, which can be used as a yardstick to measure a good project

Hydrolysis optimization and characterization study of preparing fatty acids from Jatropha curcas seed oil

<p>Abstract</p> <p>Background</p> <p>Fatty acids (FAs) are important as raw materials for the biotechnology industry. Existing methods of FAs production are based on chemical methods. In this study potassium hydroxide (KOH)-catalyzed reactions were utilized to hydrolysis <it>Jatropha curcas </it>seed oil.</p> <p>Results</p> <p>The parameters effect of ethanolic KOH concentration, reaction temperature, and reaction time to free fatty acid (FFA%) were investigated using D-Optimal Design. Characterization of the product has been studied using Fourier transforms infrared spectroscopy (FTIR), gas chromatography (GC) and high performance liquid chromatography (HPLC). The optimum conditions for maximum FFA% were achieved at 1.75M of ethanolic KOH concentration, 65°C of reaction temperature and 2.0 h of reaction time.</p> <p>Conclusions</p> <p>This study showed that ethanolic KOH concentration was significant variable for <it>J. curcas </it>seed oil hydrolysis. In a 18-point experimental design, FFA% of hydrolyzed <it>J. curcas </it>seed oil can be raised from 1.89% to 102.2%, which proved by FTIR and HPLC.</p

Organizational Factors, Construction Risk Management and Government Regulations in Nigerian Construction Companies: Data Screening and Preliminary Analysis

The aim of this paper is to investigate the accumulated data pertaining to the organizational factors, construction risk management and government regulations in Nigerian construction companies. A total sample of 238 were selected from the total population of 338 contractors operating in Abuja and Lagos State construction companies in Nigeria. Therefore, a proportionate stratified random sampling approach was employed for this study to further divide the companies into different strata, and they were all picked randomly from each stratum. Furthermore, data cleaning and screening were conducted with the intent to fulfil the multivariate analysis assumptions. Hence, this study carried out various tests like missing data analysis, outliers, normality, Multicollinearity, non-response bias and common method variance with the use of Statistical Package for Social Science (SPSS) v21. Lastly, it was discovered that the data fulfil all the requirements for multivariate analysis

Building sustainability in the construction industry through firm capabilities, technology and business innovativeness: empirical evidence from Malaysia

While the identification of the drivers of social sustainability in construction firms has remained one of the popular topics in the literature, many questions about these drivers remain unanswered, especially in the context of the developing countries. This study empirically determines some organizational internal drivers influencing the social sustainability performance in construction firms. To achieve this, we developed a conceptual model and tested on a sample of registered and active large construction firms from the Malaysian Construction Industry Development Board, using partial least-squares structural equation modelling for analysis. The study reveals that organizational internal drivers could trigger social sustainability performance. However, our analysis shows that organizational capabilities – complex tangible and intangible resources that are controlled by a firm through certain organizational practices and which enable it to implement value-creating strategies-partially mediates the relationship between these drivers and social sustainability. While few limitations of this study include the fact that the data used are the subjective opinions of the top officials who responded to the survey, our findings reveal that construction firms with efficient resource capabilities tend to adopt more sustainability in project delivery. This study contributes to the ongoing discussion on the important factors for social sustainability in construction