Glycerol Hydrogenolysis to 1,2-Propanediol over Novel Cu/ZrO2 Catalysts

Glycerol is the main by-product of biodiesel production; its upgrading to more valuable products is a demanding issue. Hydrogenolysis to 1,2-propanediol is one of the most interesting processes among the possible upgrading routes. In this study, we propose novel copper/zirconia catalysts prepared by advanced preparation methods, including copper deposition via metal–organic framework (MOF) and support preparation via the sol–gel route. The catalysts were characterized by N2 physisorption, X-ray diffraction, Scanning Electron Microscopy, H2-TPR and NH3-TPD analyses and tested in a commercial batch reactor. The catalyst prepared by copper deposition via MOF decomposition onto commercial zirconia showed the best catalytic performance, reaching 75% yield. The improved catalytic performance was assigned to a proper combination of redox and acid properties. In particular, a non-negligible fraction of cuprous oxide and of weak acid sites seems fundamental to preferentially activate the selective pathway. In particular, these features avoid the overhydrogenolysis of 1,2-propanediol to 1-propanol and enhance glycerol dehydration to hydroxyacetone and the successive hydrogenation of hydroxyacetone to 1,2-propanediol.

A simple theoretical, quantitative approach to help understand the titration of weak acids and bases

What happens at the very beginning of the titration of a weak acid or base is a question sometimes asked by undergraduate students when introduced to the concept of buffer solution. To attempt to answer this question, a simple quantitative approach is developed, which also allows explaining more general properties of the weak acid or weak base titration process, while serving as well as an introduction to the theoretical, quantitative treatment of this subject. Using this approach, it can be shown that, at the beginning of the titration, the reaction between a weak acid (base) and a strong base (acid) does not occur on a one to one ratio when very small amounts of the strong base (acid) are added.

Sowing Systems as a Factor of Grain Yield in Sunflower Production

The paper presents the results of a triennial study of the sowing system influence on the yied, grain weight per head, plant set per ha and of the grain moisture of a medium-early sunflower hybrid . Standard sowing was performed with the PSK OLT sowing machine at a row spacing amounting to 70 cm, while a twin row sowing was performed with the MaterMacc Twin Row-2 sowing machine at a row spacing of 22*48 cm. Both sowing machines were adjusted according to the ISO standard 7256/1 and 7256/2, with a high QFI index (PSK OLT: 96.32 %; MaterMacc Twin Row-2: 93.93 %). The research was conducted at the Gorjani Experimental Field on psudogley bearing the textured markings of a silty loam, with a weak acid reaction and a small amount of humus. An analysis of variance determined a statistical significance of the sowing system on the grain yield and the grain mass per sunflower head. Sowing in twin rows achieved the higher yields for all three research years : 19.59% in 2017, 19.11% in 2018, and 18.45% in 2019. Plant density was not statistically significantly affected by the sowing systems and vegetation year, but the grain moisture was statistically significantly different between the analyzed research years .

Scale Mitigation for Field Implementation of Alkaline-Surfactant-Polymer ASP Flooding in a Heterogeneous High Temperature Carbonate Reservoir with High Divalent Cation Concentration in Formation Water

An alkaline-surfactant-polymer (ASP) pilot in a regular five spot well pattern is underway in the Sabriyah Mauddud (SAMA) reservoir in Kuwait. High divalent cation concentrations in formation water and high carbonate concentration of the ASP formulation makes the formation of calcite scale a concern. The main objective of this study is to investigate the severity of the calcium carbonate (CaCO3) scaling issues in the central producer in pursuit of a risk mitigation strategy to treat the potential scale deposition and reduce the flow assurance challenges. Calcite scaling risk in terms of Saturation Ratio (SR) and scale mass (in mg/L of produced water) in the pilot producer is potentially very severe and the probability of forming calcium carbonate scale at the production well is high. Produced Ca2+ concentration is high (> 800 mg/l), which makes the equilibrated calcite SR severe (> 500) and results in significant amount of scale mass precipitation. Different flooding strategies were modelled to evaluate a variety of flood design options to mitigate scale risks (varying slug size, Na2CO3 concentration, and volume of softened pre-flush brine), with marginal impact on scale formation. When the high permeability contrast of the different layers is reduced (to mimic gel injection), calcite SR and precipitated scale mass is significantly reduced to manageable levels. The option of injecting a weak acid in the production well downhole can suppress most of the expected calcite scale through reduction of the brine pH in the produced fluid stream for the ASP flood. Weak acid concentrations in the range of 4,000 to 5,000 mg/l are forecast to mitigate scale formation.

Online Module for Acid and Base Topic Based on 5E Model

Alternative conception or misconception is one of the problems that often be experienced by the students in science subjects including chemistry due to its abstractness and wide scope to be learned. Previous studies found that students often have misconceptions on strength of acid and base topic such as misconception in determining factor that affect the strength of acid and base, differences between strong and weak acid and base as well as the effect of strength of acid and base on conductivity. To overcome these misconceptions, an online teaching and learning module using 5E instructional model was developed. Analysis, Design, Development, Implementation and Evaluation (ADDIE) model is used for research and development. The module used interactive tools and medias to make students being active and understand chemistry well. This module was validated by five experts in term of module objectives, module content, usability, flexibility, learning activities and language aspects with average is ninety percent. The results prove that the module is very good and has high validity. Therefore, the application of online module for acid and base topic based on 5E (Engage, Explore, Explain, Elaborate, Evaluate) model is suitable to be implemented in online teaching and learning process.

Leaching of ilmenite to produce titanium based materials: a review

Naturally available ilmenite mineral is being used as a starting material to produce titanium based products that have wide applications. Transformation of ilmenite to different titanium based materials by strong and weak acid, and base digestion, is discussed. Effects of temperature, concentration of acid/base, reaction time on dissolution of ilmenite are extensively reviewed. Characterization of the starting materials, intermediates and the products by x-ray diffraction, thermogravimetry, brunauer–emmett–teller surface area analysis, and scanning electron microscopy are presented. Further, advantages and disadvantages associated with the digestion methods are discussed.

Three types of passivators on the stabilization of exogenous lead-contaminated soil with different particle sizes

Study on the form partitioning and content of heavy metals in soil particles with different sizes is crucial for preventing and controlling heavy metals pollution, but few studies regard soil contaminated by heavy metals as a homogeneous body. In this study (Fig. 1), goat manure, lime and phosphate were used to stabilize exogenous lead (Pb). These soil passivators’ differential effects on total Pb and Pb with different chemical forms in soil particles of different sizes as well as Pb immobilization in soil were investigated. By passivation experiment in laboratory for 45 days, the passivation effect of the single and combined application treatments on exogenous Pb and partitioning characteristics were analyzed and compared. The characterization method of fine sand microstructure and mineral composition analysis was used. The results showed that the single application of P5 and combined application of LP5 had optimum passivation efficiency. The content of DTPA-Pb was reduced with P5 by 65.27% and the percentage of available Pb decreased significantly in soil particles of the four sizes. The content of TCLP-Pb and available Pb (weak acid extraction and reducible Pb) significantly decreased by 71.60 and 25.12% respectively after the application of LP5 in the original soil. Furthermore, most of the total Pb was enriched in coarse sand and clay, while its content was lower in fine sand and silt. The combined application treatment of GL5 significantly increased the content of weak acid extractable and reducible Pb in fine sand, silty sand and clay. Through SEM and XRD analysis, it was found that the diffraction peak of P5 treatment groups might be related to the formation of insoluble Pb that contained compounds, which were mainly mineral components, including quartz, feldspar and mica, and LP showed a big potential in the study on passivation of heavy metal Pb-contaminated soil in the natural environment. In conclusion, further studies on the different dosage and metal-contamination levels as well as different combination forms of passivators should be considered under natural conditions, the selection of suitable passivators according to soil texture is of great significance for remediation of Pb-contaminated soil.

Acid Treated Montmorillonite—Eco-Friendly Clay as Catalyst in Carvone Isomerization to Carvacrol

Acid-treated montmorillonites (MMT) were used as catalysts of carvone isomerization to carvacrol. Mineral acids—sulfuric, hydrochloric, nitric acids and organic acids (acetic and chloroacetic)—were used for the acid treatment. Prepared materials were characterized by available characterization methods, namely XRD, EA, TPD, TPO, UV-Vis, laser light scattering and nitrogen physisorption. The structure of montmorillonite remained intact after treatment. However, TPD proved the increase of acidity of acid-treated materials comparing pure montmorillonite. All materials were tested in the isomerization of carvone, producing carvacrol as the desired product. The initial reaction rate increased using the materials in the row MMT-COOH < MMT-HNO3 < MMT-ClCOOH < MMT-H2SO4 < MMT-HCl, which is in accordance with the pKa of acids used for the treatment. The number of weak acid sites strongly influenced the selectivity to carvacrol. The optimal solvent for the reaction was toluene. Total conversion of carvone and the selectivity to carvacrol 95.5% was achieved within 24 h under 80 °C, with toluene as solvent and montmorillonite treated by chloroacetic acid as catalyst. The catalyst may be reused after calcination with only a low loss of activity.

An assessment of the evidence for antibacterial activity of stinging nettle (Urtica dioica) extracts

Stinging nettles (Urtica spp.) have been used in a diverse range of traditional and historical medicines from around the world for the treatment of skin diseases, wounds, urinary disorders, respiratory diseases, bone and joint pain, anaemia and other circulatory problems, as well as in cosmetic preparations for skin and haircare. As part of an interdisciplinary exploration of nettle-based remedies, we performed a systematic review of published evidence for the antimicrobial activity of Urtica spp. extracts against bacteria and fungi that commonly cause skin, soft tissue and respiratory infections. We focussed on studies in which minimum inhibitory concentration (MIC) assays of U. dioica were conducted on the common bacterial opportunistic pathogens Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Staphylococcus aureus. No studies used fresh leaves (all were dried prior to use), and no studies prepared nettles in weak acid (corresponding to vinegar) or in fats/oils, which are common combinations in historical and traditional preparations. We addressed this gap by conducting new antibacterial tests of extracts of fresh U. dioica leaves prepared in vinegar, butter or olive oil against P. aeruginosa and S. aureus. Our systematic review and additional experimental data leads us to conclude that there is no strong evidence for nettles containing molecules with clinically useful antimicrobial activity. It seems most likely that the utility of nettles in traditional topical preparations for wounds may simply be as a "safe" absorbent medium for keeping antibacterial (vinegar) or emollient (oils) ingredients at the treatment site.