Browse

91 - 100 of 986 items :

  • Biotechnology x
Clear All
Water Demineralization by Membrane Distillation Utilizing Cooling Water From Municipal Waste Incinerator

Abstract

The membrane distillation performance was studied for production of demineralized water from surface water (river). Hot water from cooling water system of municipal waste incinerator was considered as an energy source for membrane distillation. The integration of membrane installation with such cooling water system allows to re-use up to 18 kW per 1 m2 of the membranes. The studies were performed with the application of polypropylene capillary membranes Accurel PP S6/2. The membrane modules were supplied with the feed heated to a temperature of 310 K and 330 K. The permeate fl ux obtained for these temperatures was 2.8 and 9.7 L/m2 h, and the distillate conductivity was 6 and 4 S/cm, respectively. The water demineralisation process was carried out for 1200 h without module cleaning. The behaviour of the permeate fl ux and distillate conductivity indicate that used membranes maintained their non-wettability over tested period. The performed SEM-EDS examinations confi rmed, that the deposits did not fi ll the pores and were mainly formed on the membrane surface. The scaling intensity was defi nitely smaller for lower temperature (310 K) of the feed. The amorphous deposits containing beside Ca also substantial amounts of the Si were mainly formed under these conditions, whereas at higher feed temperature dominated CaCO3 scaling.

Open access
Adsorptive removal of ciprofloxacin and isoniazid from aqueous solution

Abstract

This paper describes study of ciprofloxacin and isoniazid removal from aqueous solutions using coal fly ash (FA), kaolinite, perlite, talc and vermiculite. The adsorptive features of the adsorbents were evaluated for ciprofloxacin and isoniazid with regards to the effects of contact time, pH, the solid/liquid ratio and antibiotic concentration. All adsorbents were sterilised by dry heat before use to avoid the proliferation of antimicrobial resistance by the bacteria present on the adsorbents during experiments. The regression correlation coefficients indicate that the Langmuir model gives the best fit for the sorption of both antibiotics onto FA and talc, ciprofloxacin onto kaolinite, and isoniazid onto perlite and vermiculite with R2 values ranging from 0.908 – 0.999. The Freundlich isotherm best describes the sorption of ciprofloxacin onto vermiculite and isoniazid onto kaolinite with R2 values of 0.999 for both. The Tempkin model best describes the sorption of ciprofloxacin onto perlite with an R2 = 0.997. The values of the Freundlich exponent, 1/n, range from 0.221 – 0.998, indicating a favourable adsorption of ciprofloxacin and isoniazid onto the adsorbents. The heat of sorption, B, calculated from the Temkin plots has values ranging from 0.018 – 10.460 J/mol, indicating a physical adsorption process (physisorption). Adsorption equilibrium was achieved after 30 min for both antibiotics and the kinetic data obtained conforms best to the pseudo-second order equation with R2 values ranging from 0.998 – 0.999. The removal of ciprofloxacin and isoniazid by all adsorbents except FA was strongly influenced by the pH suggesting that electrostatic interactions play a major role in the adsorption processes.

Open access
Chemical composition and biological activity of seed oil of amaranth varieties

Abstract

The work is devoted to study of seed oil composition of amaranth varieties: Kharkov, Lera, Andijan and Helios, acclimatized in Uzbekistan. We demonstrated the possibility of using reversed-phase HPLC using a refractometric detector, which allows simultaneous determination of squalene and triacylglycerides in plant seeds and determining the authenticity of amaranth oils. Established seed oiliness ranged from 6.39 to 7.81 % of the initial mass. Amaranth oil samples contained quite large amount of unsaturated fatty acids 72.72 – 73.28 %, 1.17 % of which is omega-3-alpha-linolenic acid. The squalene content in the seeds ranged from 0.35 % to 0.55 %. It was established that the squalene content in oils obtained by extraction is greater than the one obtained by cold pressing. In the triacylglyceride composition of the investigated cold-pressed and extracted oils, no significant differences were found.

Open access
The effect of 2-hydroxypropyl β-cyclodextrin on the stability of polyphenolic compounds from Moringa oleifera Lam leaf extracts in a natural low-transition temperature mixture

Abstract

Polyphenol extracts from Moringa oleifera leaves (MoL) were obtained with a glycerol-based low-transition temperature mixture (LTTM) and a combination of LTTM with 2-hydroxypropyl β-cyclodextrin (HP-β-CD). The extracts were maintained at 4, 22 and 50 °C for 18 days and the antiradical activity (AAR) was recorded to detect modifications in the antioxidant activity of the extracts. AAR displayed a constant decline at every temperature tested, following pseudo first-order kinetics and the decay constants suggested that the presence of HP-β-CD had a protective action, slowing down AAR decline. The analysis of the polyphenolic profiles using liquid chromatography-diode array-mass spectrometry revealed that after storage for 18 days at 50 °C, the major quercetin glycosides occurring in MoL were extensively degraded. Based on the detection of protocatechuic acid in the stored extracts, putative pathways of flavonol glycoside degradation were proposed. It was concluded that the decomposition of these components was mainly responsible for the AAR decline observed.

Open access
HPLC separation and determination of dicoumarol and other simple coumarins in sweet clover

Abstract

Dicoumarol is a mycotoxin, that acts as a blood anticoagulant, is formed during the microbial action of molds and fungi in spoiled hay or silage containing high-coumarin plant. A HPLC-DAD method for determination of coumarins, including dicoumarol, coumarin, and 4-hydroxycoumarin was developed. Methanol and acetic acid were used as mobile phase with gradient elution. The simultaneous separation was performed using C18 type of stationary phase. The recoveries were 88.6 – 92.6 %, 91.8 – 95.0 %, and 89.7 – 94.1 % (evaluated for three concentration levels) for dicoumarol, coumarin, and 4-hydroxycoumarin respectively. The parameters of system suitability (repeatability of retention times and peak areas) were determined for evaluation of the method. The method showed a good linearity in the concentration range 0.7 – 100 μg.mL−1 for dicoumarol, 0.05 – 100 μg.mL−1 for coumarin and 4-hydroxycoumarin with correlation coefficients higher than 0.9885. Extracts of sweet clover herb, hay, and spoiled hay were subjected to HPLC-DAD analysis. The most abundant compound in sweet clover herb and hay extracts was coumarin. In spoiled sweet clover hay extract the 4-hydroxycoumarin was detected in addition. The formation of 4-hydroxycoumarin was also observed in the synchronous fluorescence spectra recorded at the wavelength difference of 90 nm (difference between emission and excitation wavelength).

Open access
A machine learning approach in predicting mosquito repellency of plant – derived compounds

Abstract

The increasing prevalence of mosquito – borne diseases has prompted intensified efforts in the prevention of being bitten by the vector. Among the various strategies of vector control, the application of repellents provides instant and effective protection from mosquitoes. However, emerging concerns regarding the safety of the widely used repellent, DEET, has led to initiatives to explore natural alternatives. In order to fully realize the potential of natural repellents, focusing on the discovery of natural compounds eliciting repellency is of paramount importance. In this paper, machine learning was utilized to establish association between the mosquito repellent activity of 33 natural compounds using 20 chemical descriptors. Individually, the descriptors had insignificant monotonic relationship with the response variable. But when optimized, the formulated model through boosted trees regression exhibited reliable predictive ability (r2train = 0.93, r2test = 0.66, r2overall = 0.87). The findings presented have also introduced new descriptors that exhibited association with repellency through ensemble learning such as heat capacity, Log P, entropy, enthalpy, Gibb’s free energy, energy, and zero-point energy.

Open access
Modeling of the soybean oil bleaching and optimization of its conditions in the refining process for environmental interest

Abstract

In this work, we propose mathematical models describing the soybean oil bleaching process as a function of its parameters (temperature: 80 – 120 °C, clay dosage: 0.25 – 2 %, contact time: 10 – 30 min). The crude soybean oil visible spectrum shows three values of maximum wavelength (λmax). A value at 426 nm corresponding to the chlorophyll-a, the values at 451 and at 479 nm were assigned to β-carotene pigment. The models were developed using multiple linear regression analysis (MLRA) and were performed with Matlab programming language. The input variables are the temperature (X1), the clay dosage (X2) and the contact time (X3). The output parameter is the bleaching capacity (Y in % uptake). Statistical analysis methods were used to analyze and to confirm the reliability of the selected models. The optimal bleaching conditions for the soybean oil were: temperature 100 °C; clay dosage 2 % w/w and contact time 30 min. The highest bleaching capacity was found to be 81.04 % at 426 nm, 90.60 % at 451 nm and 93.66 % at 479 nm. The developed models allowed predicting the bleaching capacity representing the removal of the β-carotene and chlorophyll-a pigments present in the crude soybean oil at each λmax. Also they allowed a better control of the most influencing parameters on the bleaching step and contribute to the optimization of the spent bleaching clay rejects by optimizing the amount of bleaching clay used in the refining process; consequently, to reduce risks of pollution.

Open access
Nutritional composition, total phenolic compounds and antioxidant activity of quinoa (Chenopodium quinoa Willd.) of different colours

Abstract

Quinoa (Chenopodium quinoa Willd.) has been nutritionally highlighted when compared to other grains. In recent years the research on this pseudocereal has increased. In this work, six quinoa samples were studied: three from Peru, one from Brazil and two commercial samples. The samples were physically and physicochemically characterized, including macro- and micronutrient analysis, phenolic compounds content and antioxidant activity. Black, red and white samples showed as main difference the size, weight, ashes and dietary fibre content. Black samples were the smallest and lightest and had the lowest starch content but presented the highest levels of ashes and dietary fibre. The protein content (16.9 %) in the white Brazilian variety was higher than the others. Red and black samples had the highest levels of most minerals analysed. The antioxidant capacity measured by the DPPH method was higher for black and red samples in comparison with the white ones. However, the white Brazilian variety showed a significantly higher antioxidant capacity measured by the ABTS assay. With regard to the phenolic content, a difference was found between the samples which ranged from 55.5 to 95.5 g GAE 100 g−1. The colour of the grain was found as not related to a higher content of phenolic compounds. Because their compositions are generally similar to light-coloured grains, and in some parameters such as dietary fibre and content of some micronutrients are superior, the grains of dark-coloured quinoa varieties (RPP, BCP) would have to be explored to develop foods that take advantage of this colour diversity.

Open access
Oil characteristics of safflower seeds under different nutrient and moisture management

Abstract

Safflower is one of the most important oilseed crops in semi-arid regions. The soil of semi-arid areas often encounters micronutrient deficiencies. However, nutrients imbalance seems to affect the quantitative and qualitative aspects of the oil as well as plant growth. Current experiment was carried out to evaluate the impact of different application practices (soil application and foliar spray) of micronutrients (Fe, Zn, Mn) on oil content, fatty acid profile and yield components of safflower under full and limited irrigations. Results showed that all of investigated traits were significantly affected by fertilizer treatment and irrigation system. The highest seed protein content was recorded for plants grown by soil application of Zn under limited irrigation condition. The highest oil content was achieved by soil application of Zn under full irrigation condition. The water deficit significantly reduced some qualitative characteristics such as oleic acid, palmitic aid, stearic acid, linoleic acid, iodine value and saponification value. The highest head number per plant, seed number per head and seed yield recorded in plants grown by soil application of Fe and Zn under full irrigation condition. Although the use of micronutrients improved qualitative characteristics in comparison with control, the best qualitative characteristics were achieved with the soil application of Zn and Fe. The elimination of micronutrient deficiencies and the balanced supply of nutrients through soil along with optimal and timely irrigation can significantly increase the efficiency of safflower production systems and improve the quality of the oil.

Open access
Preparation of metal nanoparticles by femtosecond laser ablation

Abstract

Nanoparticles (NPs) proved to have numerous applications in various fields, including biomedicine and environmental sciences. In this work, we designed and created an apparatus for fabrication of metal NPs directly in liquids initiated by femtosecond laser pulses. The laser parameters leading to ~10 μJ/pulse energy and 0.1 GW peak power resulted in predominantly spherical particles with the sizes varying from <10 nm to ~100 nm in diameter. NPs generated from Cobalt and Zinc targets were smaller in order of magnitude compared to that of Nickel. The fabricated NPs were characterized by scanning electron microscopy, while spectroscopic properties were investigated by absorption spectroscopy and spectrally resolved fluorescence imaging. We also tested the possible interaction of the created NPs with living algae for their potential use for environmental research. Employing such ultrashort laser opens route to provide on-demand production of NP's in-situ at even factory environment.

Open access