WTC 2005-63049 SYNTHETIC LUBRICANTS BASED ON SEBACIC COMPLEX ESTERS

ABSTRACT The paper present the results carried out in order to produce synthetic ester oils with a complex structure on the basis of sebacic acid with beneficial tribological properties. Three series of unsymmetrical diesters have been synthesized by taking into account superior aliphatic alcohols such as 2-ethyl-hexanol, isodecanol and isotridecanol along with special alcohols of a complex alkyl-aryl structure, namely 2-phenoxy-ethanol, 2-[(o sec butyl)-phenoxy] ethanol and 2-[(p-nonyl)-phenoxy] ethanol, respectively. There were also synthesized the symmetrical (homogeneous) esters based on these special aliphaticaromatic alcohols. INTRODUCTION Synthetic lubricants were originally developed and used for applications where petroleum products were inadequate (e.g., at extremely high and low temperatures, under extreme wear conditions)or where special characteristics, such as long life, improved equipment efficiency, or non-flammability, were needed. It is estimated that approximately 80% of the worldwide synthetic lubricants market is represented by three generic groups: polyalphaolefins (~45%), organic esters (~25%), and polyglycols (~10%) Within this general trend we have chosen a specific way to built complex esters with a mixed (unsymmetrical) structure taking into account special alkyl-aryl alcohols along with medium and long aliphatic (normal or branched) alcohols. In our previous papers we have reported the synthesis of such products on the basis of trimellitic, pyromellitic, citric, phosphoric and o-phtalic acids The present paper is in consequence a part of a large program started many years ago and this research is grounded in fact on two main principles that is of: (1) Asymmetry and of (2) Polyfunctionality. This paper presents results concerning the synthesis and characterization of some diesters of sebacic acid built in such a manner to produce mixed structures or unsymmetrical derivatives, taking into account superior aliphatic alcohols and special alcohols of a complex alkylaryl structure, respectively. By varying the length of the aliphatic alcohols and also by modifying the length and position of an alkyl pendant group on the aromatic ring of the complex alkyl-aryl alcohols, three series of products have been realized. There have also been synthesized the symmetric (homogeneous) diesters by taking in consideration only the complex alkyl-aryl alcohols. Thes

Glass packing materials used for intensification of heat transfer at boiling on tubular surfaces

The paper presents the results obtained in determining the partial heat transfer coefficient at boiling on vertical and horizontal tubular surfaces surrounded by different types of glass packing material. In both cases, an intensification of heat transfer can be noticed as compared to the boiling on the same installation performed without glass packing materials. During the experiments pseudo-critical values of thermal flux appear on the vertical and horizontal heating tube with glass packing materials, and the boiling heat transfer coefficient, α, has lower critical values than that on nucleate ordinary boiling. This denotes a differential heating mechanism, determined by the presence of the glass package around the heating tube. The heat transfer intensification is greater with the horizontal tube than with the vertical one

Optimization, Equilibrium and Kinetic Modeling of Methylene Blue Removal from Aqueous Solutions Using Dry Bean Pods Husks Powder

In this research, dry bean pods husks (DBPH) were used as an adsorbent material after minimum processing (without chemical substances consumption and without thermal treatment) to remove methylene blue from aqueous solutions. The adsorbent surface characteristics were investigated using SEM and FTIR analysis. For maximum removal efficiency, several parameters that influence the dye adsorption were optimized using the Taguchi method. Equilibrium and kinetic modeling, along with thermodynamic studies, were conducted to elucidate the adsorption mechanism. Taguchi experimental design showed that the factor with the highest influence was the adsorbent dose, with a percent contribution established by the ANOVA analysis of 40.89%. Langmuir isotherm and pseudo-second order kinetic model characterizes the adsorption process. The maximum adsorption capacity, 121.16 (mg g−1), is higher than other similar adsorbents presented in scientific literature. Thermodynamic parameters indicate a spontaneous, favorable and endothermic adsorption process, and their values show that physical adsorption is involved in the process. The obtained results, and the fact that adsorbent material is inexpensive and easily available, indicate that DBPH powder represents an effective absorbent for treating waters containing methylene blue. Additionally, the Taguchi method is very suitable to optimize the process

A Novel High-Efficiency Natural Biosorbent Material Obtained from Sour Cherry (<i>Prunus cerasus</i>) Leaf Biomass for Cationic Dyes Adsorption

The present study aimed to investigate the potential of a new lignocellulosic biosorbent material derived from mature leaves of sour cherry (Prunus cerasus L.) for removing methylene blue and crystal violet dyes from aqueous solutions. The material was first characterized using several specific techniques (SEM, FTIR, color analysis). Then, the adsorption process mechanism was investigated through studies related to adsorption equilibrium, kinetics, and thermodynamics. A desorption study was also performed. Results showed that the Sips isotherm provided the best fit for the adsorption process of both dyes, with a maximum adsorption capacity of 168.6 (mg g−1) for methylene blue and 524.1 (mg g−1) for crystal violet, outperforming the capacity of other similar adsorbents. The contact time needed to reach equilibrium was 40 min for both studied dyes. The Elovich equation is the most suitable model for describing the adsorption of methylene blue, while the general order model is better suited for the adsorption of crystal violet dye. Thermodynamic analyses revealed the adsorption process to be spontaneous, favorable, and exothermic, with physical adsorption involved as the primary mechanism. The obtained results suggest that sour cherry leaves powder can be a highly efficient, eco-friendly, and cost-effective adsorbent for removing methylene blue and crystal violet dyes from aqueous solutions

New Glass Ceramic Materials Obtained from Cathode Ray Tubes Glass Wastes and Fly Ash

This paper presents an alternative way to recycle cathode ray tube glass waste, together with fly ash and kaolin, into new glass ceramic materials. The samples were obtained using three firing temperatures: 700, 800, and 900 °C. The effect of the fly ash/CRT waste ratio upon the materials’ firing shrinkage, apparent density, apparent and total porosity, chemical stability, and compression strength was investigated. The firing shrinkage used as a dimensional stability parameter, a firing shrinkage range between 2.19–8.18%, was positively influenced by the waste mix amount. The apparent density of the obtained materials is positively affected by the heat treatment temperature, rising from 2.09 to 2.93 (g·cm−3), while the apparent porosity decreases with the increase of the firing temperature from 6.08 to 2.24 %. All the studied glass ceramics show very good chemical stability and complete immobilization of the Pb2+ and Ba2+ ions in the glass ceramic matrix. The compression strength of the sintered materials ranges between 1.42–11.83 (N·mm−2), being positively influenced by the kaolin amount and negatively influenced by porosity. The obtained results confirm the viability of the proposed alternative to use CRT waste and fly ash together with kaolin to obtain glass ceramic materials that can be used for outdoor paving applications

Crystal Violet Adsorption on Eco-Friendly Lignocellulosic Material Obtained from Motherwort (Leonurus cardiaca L.) Biomass

The performance of a new eco-friendly adsorbent, obtained from motherwort (Leonurus cardiaca L.) biomass after minimum processing, in crystal violet dye removal from aqueous solutions was studied. Firstly, the adsorbent material was characterized using several technics, such as FTIR, pHPZC determination, SEM and color analysis. The next step was to determine the influence of initial dye concentration, contact time, temperature, pH, adsorbent dose and ionic strength on adsorbent adsorption capacity. Equilibrium, kinetic, thermodynamic, optimization and desorption studies were performed in a batch system for studying all aspects related to the adsorption process. The sips isotherm best fit the experimental data with a predicted maximum adsorption capacity of 125.6 (mg g&minus;1). The kinetic data indicate that equilibrium is reached at 50 min and that general order is the best kinetic model to describe the dye retention. The process is endothermic, spontaneous, favorable and supposed to be a physical adsorption. In addition to establishing the optimal adsorption conditions, Taguchi methods and ANOVA analysis showed that the pH is the most influencing parameter of the adsorption process, having a contribution of 61.64%. All the presented data show that the motherwort biomass powder is very suitable to be used as at low-cost, easy available and effective adsorbent for the crystal violet dye removal from aqueous solutions

Removal of Methylene Blue from Aqueous Solutions Using a New Natural Lignocellulosic Adsorbent&mdash;Raspberry (Rubus idaeus) Leaves Powder

In this work, raspberry (Rubus idaeus) leaves were converted to powder and used as a new natural lignocellulosic low-cost adsorbent for methylene blue removal from aqueous solutions. Different techniques (FTIR, SEM, color analysis, and pHPZC determination) were applied for adsorbent characterization. The effects of pH, ionic strength, contact time, adsorbent dose, initial deconcentration, and temperature on adsorption capacity were investigated. Equilibrium, kinetic, and thermodynamic studies have shown that the adsorption is best described by the Sips isotherm and pseudo-second-order kinetic model and that the process is spontaneous, favorable, and endothermic, involving physisorption as the main mechanism. The maximum adsorption capacity was 244.6 (mg g&minus;1) higher compared to other adsorbents based on plant leaves. The Taguchi method and the ANOVA analysis were used to optimize the adsorption conditions. The contact time was the factor with the highest influence on the process, while the temperature had the lowest influence. A desorption study was also performed to determine the possibility of adsorbent regeneration

A Novel Approach of Bioesters Synthesis through Different Technologies by Highlighting the Lowest Energetic Consumption One

Fatty acids esters have a wide application as bioplasticizers and biolubricants in different industries, obtained mainly in classic batch reactors, through an equilibrium complex reaction, that involves high temperatures, long reaction times, vigorously stirring, and much energy consumption. To overcome these shortcomings, we synthesized a series of fatty acid esters (soybean oil fatty acids being the acid components with various hydroxyl compounds) through novel low energy consumption technologies using a bubble column reactor, a microwave field reactor and for comparison meaning, a classic batch reactor. The obtained bioesters physicochemical properties were similar to one another, a good concordance among their rheological properties was obtained, but the energetic consumption is lower when using the bubble column or the microwave reactors instead of the classical batch reactor