Use of Aspergillus wentii for biosorption of methylene blue from aqueous solution

In this study, Aspergillus wentii was used as a biosorbent for the adsorption of methylene blue from aqueous solution. The effects of contact time, initial dye concentration, solution pH and temperature on biosorption were investigated. The contact time required (that is, the equilibrium time) for maximum dye biosorption was found to be 120 min. The amount of the dye biosorbed increased with increasing initial dye concentrations and solution pH, while it was decreasing with an increase in temperature. Percent biosorption was changed between 14.86 and 85.04 under all conditions studied. Desorption studies were performed by changing of the value pH among 3 - 10. Desorption was considerably affected by lower pH. The maximum percentage of desorption was found to be 29.51 at pH 3. Biosorption isotherm from equilibrium values followed Freundlich model

Mechanical, thermal, morphological properties and decay resistance of filled hazelnut husk polymer composites

Four different formulations of natural fiber-polymer composites were fabricated from mixtures of hazelnut (Corylus avellana) husk flour (HHF), polypropylene (PP) and high density polyethylene (HDPE).Variables examined included polymer and coupling agent types. All formulations were compression molded in a hot press for 3 minutes at 175 0C. The resulted specimens were tested for mechanical properties according to ASTM D-790 and ASTM D-638. In addition, scanning electron microscopy (SEM), thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) analysis were performed to characterize rheological properties of the fabricated composite. Furthermore, decay tests were performed to determine degradation of hazelnut husk polymer matrices. Hazelnut husk polymer composites had high mechanical properties for the tested formulations. The thermal studies showed that incorporation ofhazelnut husk into the polymer matrices used did not adversely affect the composite. The HDPE+50% wood + 3% MAPE (HHF2) formulation showed the highest natural durability with only 3,47% and 4,60% mass losses against Trametes versicolor and Postia plecenta, respectively, while Scots pine solid controls experienced around 32% mass loss under the same exposure condition

Study of the static characteristic I-V and the electrical parameters corresponding to the shunt resistance Rsh and series resistance Rs per unit area of a solar cell with grain size

This paper presents a new technique based on the junction recombination velocity (Sf: junction recombination velocity) at the grain size for the evaluation of the series and shunt resistances. The study of the response of the solar cell and the parameters of recombination in grain size, which are the object of the investigation, is related to the study of the static characteristic I-V and electrical parameters Rs and Rsh under a magnetic field. This study has allowed us to address some of the theoretical aspects of the field solar cell in order to draw a conclusion and some perspectives. Based on the results obtained for the photocurrent density and the photovoltage, we will study the I-V characteristic of the solar cell to then be able to propose a model for the determination of the shunt resistance Rsh and the series resistance Rs. Series resistance investigations, including numerical simulations and field data tests, are conducted to examine the energetic behavior of the PV modules for efficiency. Experimental results show that the proposed direct resistance-estimation method allows the PV modules to achieve their maximum power and efficiency under various operation conditions. © 2019 The Physical Society of the Republic of China (Taiwan

Effect of different acid catalysts on the properties of activated carbon fiber precursors obtained from phenolated wheat straw

In this study, wheat straw (WS) was successfully liquefied into phenol (Ph) in the presence of sulfuric and phosphoric acid at different Ph:WS ratios. The liquefied wheat straw (LWS) was mixed with the crosslinking agent hexamethylenetetramine and applied for manufacturing of activated carbon fiber precursors (ACFPs) via melt-spinning. The ACFPs were cured into a solution consisted of hydrochloric acid and formaldehyde. The morphological, thermal, and chemical properties of the ACFPs were investigated using microscopic, thermogravimetric, and spectroscopic analyses while the amount of the combined phenol (CPh) was determined via liquid chromatography. The results indicated that the type of the acid catalyst and Ph:WS ratio had a great impact on CPh and unliquefied residue. The sulfuric acid showed better performance due to its strong acidic characteristics. The results of the analyses depicted that the ACFPs obtained from sulfuric acid-based LWS resin had a more decent morphological texture, thermal resistance, and chemical structure

Enrichment of the Glycyrrhizic Acid from Licorice Roots (Glycyrrhiza glabra L.) by Isoelectric Focused Adsorptive Bubble Chromatography

The main aim of this study was to enrich glycyrrhizic acid ammonium salt known as one of the main compounds of licorice roots (Glycyrrhiza glabra L.) by isoelectric focused adsorptive bubble separation technique with different foaming agents. In the experiments, four bubble separation parameters were used with β-lactoglobulin, albumin bovine, and starch (soluble) preferred as foaming agents and without additives. The enrichment of glycyrrhizic acid ammonium salt into the foam was influenced by different additive substances. The results showed that highest enrichment values were obtained from β-lactoglobulin as much as 368.3 times. The lowest enrichment values (5.9 times) were determined for the application without additive. After enrichment, each experiment of glycyrrhizic acid ammonium salt confirmed that these substances could be quantitatively enriched into the collection vessel with isoelectric focused adsorptive bubble separation technique. The transfer of glycyrrhizic acid ammonium salt into the foam from standard solution in the presence of additive was more efficient than aqueous licorice extract

Antimicrobial and Antifungal Properties of Madder Root (Rubia tinctorum) Colorant Used as an Environmentally-Friendly Wood Preservative

The aim of this study was to determine the antifungal and antimicrobial properties of madder root extract when used as an environmentally-friendly wood preservative and against blue stain. Plant dyestuff was extracted from the root of madder by using an ultrasonic assisted method and then applied to Turkish oriental beech, Scots pine, oak, and walnut wood blocks with the immersion (classic) and immersion + ultrasonic assisted methods. For mordants, ferrous sulfate, aluminum sulfate, copper sulfate, and vinegar were used. In order to compare the performances of the natural paints, a synthetic dye was used. The abilities of the extracts to suppress attack by brown rot (Postia placenta) and white rot (Trametes versicolor) were investigated. Treated blocks were exposed to P. placenta and T. versicolor attacks for 16 weeks according to the TS 5563-EN 113 method. Antimicrobial activity of the extracts was determined with the agar dilution method by using the disk diffusion method for bacteria. Results showed that the mordant mixes were considerably more resistant to fungal decay compared to their untreated and synthetic counterparts. In general, control (non-mordant) and vinegar mixtures showed good performance against brown and white rot fungi. Copper mixes showed better antimicrobial activity against all types of microorganisms. In conclusion, it was found that madder root extracts and mordant mixes could be used as wood preservatives

Mechanical, thermal, morphological properties and decay resistance of filled hazelnut husk polymer composites

Four different formulations of natural fiber-polymer composites were fabricated from mixtures of hazelnut (Corylus avellana) husk flour (HHF), polypropylene (PP) and high density polyethylene (HDPE).Variables examined included polymer and coupling agent types. All formulations were compression molded in a hot press for 3 minutes at 175 0C. The resulted specimens were tested for mechanical properties according to ASTM D-790 and ASTM D-638. In addition, scanning electron microscopy (SEM), thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) analysis were performed to characterize rheological properties of the fabricated composite. Furthermore, decay tests were performed to determine degradation of hazelnut husk polymer matrices. Hazelnut husk polymer composites had high mechanical properties for the tested formulations. The thermal studies showed that incorporation ofhazelnut husk into the polymer matrices used did not adversely affect the composite. The HDPE+50% wood + 3% MAPE (HHF2) formulation showed the highest natural durability with only 3,47% and 4,60% mass losses against Trametes versicolor and Postia plecenta, respectively, while Scots pine solid controls experienced around 32% mass loss under the same exposure condition

Investigating changes in the chemical constituents and dimensional stability of heat-treated hornbeam and Uludag fir wood

Changes in chemical constituents and some physical properties such as swelling and water absorption of hornbeam (Carpinus betulus L) and uludag fir (Abies bornmulleriana Mattf.) wood were investigated after heat treatment at three different temperatures (170 o C, 190 o C, and 210 o C) for three different durations (4, 8, and 12 hours) by using thermal gravimetric analysis (TGA) and Fourier transform infrared (FTIR) spectrometry. The results of TGA show that there was less weight loss in the main degradation region (300-500 o C) for the heat-treated samples as compared to untreated (control) samples. In addition, there was greater weight loss of hornbeam wood than of uludag fir wood in a similar degradation region. This difference could be due to the chemical constituents of softwoods and hardwoods. The results of FTIR spectrometry show that the chemical constituents of the hornbeam wood samples were more affected by heat treatment. All heat-treated samples exhibited lower water absorption and swelling compared to control samples. It was found that the relative decrease in swelling and water absorption for uludag fir was higher than for hornbeam. The maximum decrease in water absorption and swelling was found for both species that were heat-treated at 210 C for 12 hour