Volume 20 (2018): Edizione 4 (December 2018)

A simple and coumarin-based fluorescence probe has been designed and synthesized with silyl group as recognition group of fluoride ions (F−) in this study. The results showed that the fluorescence intensity of the probe displayed prominent enhancement with addition of F− at 445 nm with incubation of 1 min. There was an excellent linear relationship between fluorescence intensity and fluoride concentration from 0 to 30 μM (0~0.57 ppm), which offered the important condition for the quantitative analysis. In addition, the highly selective response to fluorion, the low detection limit with 28 nM (0.532 ppb), low toxicity and bioimaging afforded an advantage for practical application and detecting fluoride in biological systerms.

This work presents the studies on the epoxidation of limonene to 1,2-epoxylimonene with hydrogen peroxide and over the titanium-silicate Ti-SBA-15 catalyst. The main object of the research was a solvent effect on the epoxidation process. The influence of solvents, such as: methanol, toluene, propan-2-ol (isopropyl alcohol), acetonitrile and ethanol has been studied. Furthermore, the influence of temperature in the range of 0-120°C and the reaction time in the range of 0.25-48 h have been investigated. Gas chromatography and iodometric titration methods were used to establish the products of this process and amount of the unreacted hydrogen peroxide. 1,2-Epoxylimonene, 1,2-epoxylimonene diol, perillyl alcohol, carvone and carveol have been determined as the main products of this process. All these compounds are very valuable raw materials for organic syntheses, medicine or cosmetic and food industry.

In this work, an environmentally friendly type plasticizer was introduced. The synthesis consisted of two steps. In the first step, castor oil (CO) was acrylated and then the acrylated castor oil (ACO) was epoxidized with the presence of formic acid and hydrogen peroxide in the second step. The epoxidized acrylated castor oil (EACO) was characterized by FTIR and ¹H-NMR techniques. The EACO was used as a main plasticizer to obtain plasticized PVC materials and compared with DOP. The results showed that EACO improved polyvinyl-chloride (PVC) plasticization performance and reduced Tg from 81.06°C to 1.40°C. Plasticized PVC materials with EACO showed similar mechanical properties and better thermal stability than DOP. EACO had better volatility stabilities, migration and solvent extraction in PVC than DOP. EACO can be used to replace DOP to prepare soft films.

Ultrasonic irradiation is one of the advanced oxidation methods used in wastewater treatment. In this study, ultrasonic treatment of petroleum refinery effluent was examined. An ultrasonic homogenizator with a 20 kHz frequency and an ultrasonic bath with a 42 kHz frequency were used as a source for ultrasound. The effects of parameters such as ZnO amount, ozone saturation time, and type of ultrasound source on the degradation of petroleum refinery effluent were investigated. The degradation of petroleum refinery effluent was measured as a change in initial chemical oxygen demand (COD) and with time. According to the results, degradation increased with the addition of ZnO in an ultrasonic probe. There was also a positive effect of ozone saturation before sonication then applying ultrasound on the degradation for an ultrasonic probe. It was observed that there was no positive effect of ZnO addition and ozone saturation on degradation for an ultrasonic bath.

The aim of the present study was to investigate the effect of epoxy resin curing agents and aluminium surface modification on the properties of adhesive joints which were subjected to aging under thermal shock conditions. Composites containing reinforced aramid and carbon fibres with aluminium flat profiles (alloy Al 5754) were tested under shear conditions. Epoxy resin (Araldite LY 1564) with amine curing agents (Aradur 3486, Aradur 3487 and Aradur 3405) was used as a matrix. Composites were made using vacuum-assisted contact lamination. The degree of degradation was assessed on the basis of lap shear strength of adhesive joints in accordance with EN ISO 1465:2009. The research showed that epoxy composite samples based on Aradur 3405 (accelerated aliphatic polyamine) and sanded surface of aluminium presented the best lap shear adhesive strength, because this composite has the largest roughness. The hardness of the used adhesive is slightly increased with the cycle number.

Through years beer became one of the best known alcoholic beverages in the world. For some reason e.g. healthy lifestyle, medical reasons, driver’s duties, etc. there is a need for soft drink with similar organoleptic properties as standard beer. There are two major approaches to obtain such product. First is to interfere with biological aspects of beer production technology like changes in mashing regime or to perform fermentation in conditions that promote lower alcohol production or using special (often genetic modified) microorganism. Second approach is to remove alcohol from standard beer. It is mainly possible due to evaporation techniques and membrane ones. All these approaches are presented in the paper.

The recombinant catalase isolated from a psychrotolerant microorganism belonging to Serratia genus exhibits a high activity in a wide range of pH. Due to a great catalytic potential in operational conditions, it can be used in various industrial applications whereby it acts as a hydrogen peroxide scavenger. To reduce the cost of biocatalyst the enzyme encapsulation into a hydrogel structure was proposed. The obtained results showed a high activity of encapsulated catalase in acidic conditions (pH in range 4.4 - 6.6) and at low temperatures (6-15°C). Moreover, immobilized catalase exhibited a high stability in natural media, especially in milk. Its activity during peroxide decomposition in milk, the possibility of re-using, as well as the fixed bed reactor performance confirmed wide application possibilities. High values of enzyme and substrate concentrations led to the beads burst due to rapid oxygen diffusion from the capsules, thus they are limited.

The efficiency of enzymatic depolymerization in a membrane reactor was investigated. The model analysis was performed on bovine serum albumin hydrolysis reaction led by three different enzymes, for which kinetic equations have different forms. Comparing to a classic reactor, the reaction yield turns out to be distinctly higher for all types of kinetics. The effect arises from increasing (thanks to the proper selectivity of the applied membrane) the concentration of reagents in the reaction volume. The investigations indicated the importance of membrane selectivity election, residence time and at non-competitive inhibition the substrate (biopolymer) concentration in feed stream. Presented analysis is helpful in these parameters choice for enzymatic hydrolysis of different biopolymers.

The performance of Vigna unguiculata coagulant (VUC) for colour removal from acid dye was investigated in this study. The proximate, structure and morphology of the coagulant were investigated using standard official methods, Fourier-Transform Infrared (FTIR) spectrometer and scanning electron microscopy (SEM), respectively. Response surface methodology (RSM) using face-centred central composite design (FCCD) optimized four process variables including pH, coagulant dosage, dye concentration and time. The colour removal efficiency obtained from the optimization analysis was 99.26% at process conditions of pH 2, coagulant dosage 256.09 mg/l, dye concentration 16.7 mg/l and time 540 min. The verification experiments agreed with the predicted values having a standard error value of 1.96%. Overlay contour plot established optimum areas where the predicted response variable is in an acceptable range (≥ 70%) with respect to optimum conditions. The FCCD approach was appropriate for optimizing the process giving higher removal efficiency when compared to the main effect plots.

We propose an indirect method of ASTM D-1200 for measurement of viscosity from 0.1 to 30 stokes (St) using Ford cup 5 (range 2~ 12 St) by developing a statistical relation. General purpose low styrene content polyester resin (without adding initiator, hardener and accelerator) was used for viscosity measurement. In existing ASTM D 1200 standard, ford cups (1-4) are used to measure the viscosity up to 2 St, while fifth cup is used for measurement from 2 to 12 St. Viscosity above 12 St is not estimated using existing ASTM D- 1200 method. In contrast, our method and statistical relation proposed in this paper estimates viscosity in the flexible range of 0.1 to 30 St by using Ford cup 5 only. The estimated values were confirmed by existing ASTM D-1200 (0.1 to 12 St) and by using Ubbelohde viscometer (12 to 30 St). Values estimated above 12 St are from the proposed model are also in good conformance (percentage error ~ 5% or less) with experimental results. The satisfaction level of the estimated values with the experiments suggests that the model has also the potential for application to paints, polymer and oil industry.

An N,S-codoped TiO₂/Montmorillonite nanocomposite, as a photocatalyst, was synthesized in the sol-gel method and used for the degradation of ciprofloxacin (Cip) in an aqueous solution. N,S-codoped TiO₂/Montmorillonte was characterized by powder X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy (DRS), field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and X-ray fluorescence (XRF) analyzes. A central composite design (CCD) was used to optimize the variables for the removal of Cip by the N,S-codoped TiO₂/Montmorillonite. A maximum decomposition of 92% of Cip was achieved in optimum conditions. The band gap value for the nanocomposite was 2.77 eV. Moreover, with the use of nanocomposite in the four consecutive runs, the final removal efficiency was 66%. The results show that the N,S-codoped TiO₂/ Montmorillonite under simulated sunlight irradiation can be applied as an effective photocatalyst for the removal of Cip from aqueous solutions.

Four infrared spectroscopic techniques - photoacoustic (PAS), diffuse reflectance (DRS), attenuated total reflectance (ATR) and transmission (TS) - were evaluated for the qualitative analysis of the biochar obtained from willow feedstock during pyrolysis. Increase in pyrolysis temperature resulted in more aromatic and carbonaceous structure of biochars. These changes could easily be detected from Fourier transform infrared (FT-IR) spectral differences. The comparison of the spectra obtained by the four FT-IR techniques allowed to conclude that there are differences in the spectra acquired using different IR technique caused by different signal acquisition. PAS and ATR were the best techniques used in order to obtain spectra with smooth and sharp peaks, in contrast to TS, where bands were less-separated. DRS turned out to be the weakest of all techniques, due to poor spectral quality and poor separation of the bands.

Selenium is one of the trace elements playing a crucial role in a proper function of living organisms. Selenium intake varies, largely based on the selenium content of food. The daily Se intake recommended for adults amounts to 55 μg per day. The mean level of selenium in the population varies considerably between countries. Recent studies on the selenium dietary intakes in Poland showed that it is not sufficient to meet the daily requirement for this microelement so it is strongly recommended to employ selenium supplementation. The commercial product SEL-BRCA1^® being a selenium diet supplement was subjected to chemical and microbial analysis to determine its stability in storage time and conditions. Basing on the obtained results it can be stated that the stability of studied supplement, stored in the closed bottles, can be confirmed for the period of time up to 45 months after the production date and it is not recommended to store opened bottles for the period of time longer than 12 months. The studied supplement showed a very high microbial stability what underscores its usefulness as human medicines.

In this work, three-phase partitioning (TPP) was used for the purification of laccase from liquid cultures of Trametes versicolor. For determining the optimal conditions of TPP process, parameters such as initial pH (6.5, 7.0, 7.5, 8.0), ammonium sulphate saturation (20%-80%) and the water phase to tert-butanol ratio (1:0.5, 1:1, 1:2), were analyzed. The best conditions with 73% recovery and 24-fold purification was obtained with the use of 50% saturation with ammonium sulphate, water phase to tert-butanol ratio of 1:1 and initial pH 7.0. The molecular mass of the purified laccase secreted by analyzed strain T. versicolor was found for ≈ 66 kDa. The results showed that TPP is an efficient method for the fractionation and purification of laccase obtained from liquid cultures of T. versicolor and it allows for obtaining the relatively pure enzyme without the use of time-consuming and costly chromatographic methods.

Acrylamide/acrylic acid copolymers (AAm/AA) have been synthesized by microemulsion polymerization in absence and presence of trivalent cations Al⁺³ and Fe⁺³. Starch materials were obtained by introducing cations Al⁺³ and Fe⁺³, in the form of aqueous solutions of sulphates(VI) (modif. starch/Me⁺³), into the oxidized starch (modif. starch). The flocculation performance of obtained polyacrylamide copolymers and the one based on the natural polymer was compared with the performance of the commercial AAm/AA flocculant (CF). All materials were characterized by capillary viscometry, FTIR and DSC methods. An aqueous suspension of talc was used for the flocculation studies. The flocculation effectiveness was evaluated on the basis of reduction of suspension extinction and the sludge volume. It was found that synthesized AAm/AA/Me⁺³ copolymers and modif. starch/Me⁺³ materials exhibit better flocculation properties for a model talc suspension than a commercially available floculant.

This paper reports the results of studies concerning an alternative method of obtaining dicarboxylic acids, which consist of the oxidation of cyclic ketones with oxygen or air. The raw materials used were cyclopentanone, cycloheptanone, cyclooctanone, cyclododecanone, 1-tetralon, 2-methylhexanone, 3-methylcyclohexanone and 4-methylcyclohexanone. Oxidation reactions were conducted at 70-100°C, under pressure of 0.1 or 0.4 MPa, for 6 h, utilizing the salts of transition metals as catalyst and acetic acid as solvent. For example, when cyclopentanone was oxidized in the presence of Mn(II) salt, a conversion above 98% and selectivity to glutaric acid up to 68% were obtained. Among synthesized dicarboxylic acids, 1,12-dodecanoic acid was obtained with the highest selectivity of 76%.

Fertilizer encapsulation through polymer membranes can reduce fertilizer losses and minimize environmental pollution. In this paper, an emulsion of ethyl cellulose (EC)/vinyl acetate (VAc)/butyl acrylate (BA) was successfully prepared by pre-emulsified semi-continuous seed emulsion polymerization. EC/BA/VAc films showed biodegradability. The influence of the EC content on the properties of EC/BA/VAc films was also investigated by DSC, a water absorbency analysis, etc. Controlled-release urea encapsulated by EC/BA/VAc latex was prepared in a film coating machine and conformed to the standards for slow-release fertilizers of the Committee of European Normalization. The release of urea from controlled-release urea encapsulated by EC/BA/VAc latex containing 0%, 5%, 10%, and 15% EC was 75.1%, 65.8%, 70.1% and 84.1%, respectively, after 42 days, and controlled-release urea encapsulated by EC/BA/VAc latex (5% EC) had the best controlled-release ability. Therefore, controlled-release urea encapsulated by EC/BA/VAc latex has many potential applications in agricultural industry.

With the polymer-coated fertilizer as background, the permeability of P- and K-nutrient through a representative polymer membrane-polystyrene membrane were investigated by measuring their permeability in the solutions of KH₂PO₄-water and urea-KH₂PO₄-water at nominal temperature of 298 K using the Ussing chamber method. To analyze and interpret the variation of permeability with solute concentration, the solubility of permeate in polymer membrane were determined experimentally and the permeate diffusion coefficient were assessed by the measurements of density and apparent molar volume of the aqueous fertilizer solutions. An interesting “increase-decrease” trend for the permeability of both phosphorous (P)-nutrient, and potassium (K)-nutrient fertilizer with permeate concentration was observed, in which the increases in permeability at low concentrations of permeate could be attributed to the increase in solubility of KH₂PO₄ in polymer while the decreases in permeability at high concentrations was due to the decrease in diffusion coefficient of permeate in polymer membrane. Finally, the release kinetics of these nutrients from a PS-coated urea-KH₂PO₄ compound fertilizer granule was predicted using the Shaviv’s model along with the permeability data of P- and K-nutrient generated.

It is shown that natural cellulose obtained from the walnut shell (Juglans regia) can be used for chemical modification of the selective boron sorbent. The modification was carried out by the coupling technique of chlorine derivatives of the polyhydric alcohols or polyols (mannitol, xylitol, sorbitol or glycerol). In this case new hybrid substances (sorbents) were obtained and they are represented by the formula: R-O-(CHOH)_n-CH₃, where R is a residue of the cellulose backbone, n is the number of functional (OH) groups of the polyhydric alcohols. The pulp mercerization was carried out by processing the ground walnut shell (WS) with hot solution of sodium hydroxide. Chlorination of polyhydric alcohols was carried out by gaseous hydrochloric acid sparging through the polyhydric alcohol aqueous solution. The coupling process proceeds according to the mechanism of substitution of the cellulose hydroxyl groups with chlorine atoms.

The aim of this study is to investigate the effect of the blade shape on the characteristic of the flow patterns in a stirred tank. A new impeller blade design has been proposed. It is characterized by a converging hollow. The investigations of the flow structure generated in the vessel are made by using the computer code ANSYS CFX (version 16.0). The analysis has shown that the converging hollow blade yields highly radial flows which gave an increase in the radial velocity by 35% with less power consumption than the flat blade. Also, the effectiveness of the energy dissipation and the quality of mixing has been obviously noted. A validation test of our predicted results with other literature data was done, and a satisfactory agreement has been found.