Investigation of Physicochemical Characteristics of Aspergillus niger Biomass and Examination of Its Ability to Separate Butyl Acetate Isomers.

Aspergillus niger is a species of fungus that is widely found in natural ecosystems and has an important role in various industrial fields and is readily available. To study the adhesion of microbial cells to solid substrates and to improve their properties, physicochemical characterization of microorganisms is extremely important. For this purpose, in this study, the surface properties of A. niger biomass were determined at low cost and with high accuracy by inverse gas chromatography (IGC), a physicochemical characterization technique. IGC experiments were conducted between 303.2 and 328.2 K at infinite dilution. Among these temperatures, various organic solvent vapors were passed over the A. niger biomass considered as stationary phase and their retention behavior was studied. Using the raw data, net retention volumes were calculated and retention diagrams were drawn. From the linear retention diagrams, the dispersive surface energy was calculated according to Dorris-Gray (48.73-46.09 mJ/m2), Donnet-Park (47.12-44.50 mJ/m2), Schultz (46.88-42.45 mJ/m2), and Hamieh (76.42-64.06 mJ/m2) methods. With the IGC method, the acidity-basicity parameters of A. niger biomass were determined and it was found that the surface was basic ( K D / K A = 4.871 ). In the second part of this study, the butyl acetate isomer series, which are difficult to be separated by conventional methods, were effectively separated by the IGC method using A. niger stationary phase.

Adsorptive removal of Safranine T dye from aqueous solutions using sodium alginate-Festuca arundinacea seeds bio-composite microbeads.

In this study, composite microbeads were prepared using Festuca arundinacea seeds and sodium alginate biopolymer at different ratios and utilized as sorbents for the sorption of Safranine T from wastewater. The sorbents were characterized by FTIR, SEM, XRD, and BET analysis. According to BET analysis, the specific surface area of the adsorbents was calculated to be 10.99 m2/g and the surface was found to be mesoporous. The optimum conditions for adsorption studies including initial pH (2-12), concentration (10-50 mg/L), contact time (0-150 min), and adsorbent mass (0.05 g/50 mL-0.25 g/50 mL) were determined at 25 °C. The raw data obtained from sorption tests were applied to Freundlich, Langmuir-1, Langmuir-2, Langmuir-3, Langmuir-4, Temkin, Toth, and Koble-Corrigan isotherm models. The best results were obtained from the Langmuir-2 and accordingly the qm values were calculated as 454.54, 833.33, and 625.00 mg/g for FA, FA-SA-20, and FA-SA-30 at 25 °C, respectively. Adsorption kinetic data illustrated that the process followed the PSO model. Reusability and desorption studies were performed for composite microbeads. Additionally, the thermodynamic studies were performed at 25, 35 and 45 °C. Considering all these results, it was seen that the FA-SA-20 composite had the highest adsorption capacity and the best desorption efficiency.

Thermodynamic Characterization of Polyetherimide/Single-Walled Carbon Nanotube Composites.

The aim of this study is to examine the interactions of composite materials obtained by adding single-walled carbon nanotubes (SWCNT) to polyetherimide (ULTEM) in different weight ratios with various organic solvents, and to evaluate the solubility of composites in these organic solvents. The characterization of prepared composites was performed with SEM analysis. Thermodynamic properties of ULTEM/SWCNT composites were determined by the inverse gas chromatography (IGC) method at 260-285°C in infinite dilution. According to the IGC method, the retention behaviors were examined by passing different organic solvent vapors over the composites used as stationary phase, and retention diagrams were drawn using the obtained retention data. Thermodynamic parameters including Flory-Huggins interaction parameters (${\chi}_{12}^{\infty }$), equation of state interaction parameters (${\chi}_{12}^{\ast }$), weight fraction activity coefficients in infinite dilution (${\Omega}_1^{\infty }$), effective exchange energy parameters (${\chi}_{\mathrm{eff}}$), partial molar sorption enthalpies ($\Delta{\overline{H}}_1^S$), partial molar dissolution enthalpies in infinite dilution ($\Delta{\overline{H}}_1^{\infty }$) and molar evaporation enthalpies ($\Delta{\overline{H}}_v$) were calculated using the linear retention diagrams. According to ${\chi}_{12}^{\infty }$, ${\chi}_{12}^{\ast }$, ${\Omega}_1^{\infty }$ and ${\chi}_{\mathrm{eff}}$ values, organic solvents were found to be poor solvents for composites at all temperatures. Besides, the solubility parameters of composites were determined by IGC method at infinite dilution.

Adsorptive removal of hazardous dye (crystal violet) using bay leaves (Laurus nobilis L.): surface characterization, batch adsorption studies, and statistical analysis.

In this study, the surface properties of Laurus nobilis L. were determined by inverse gas chromatography. From this, the surface of Laurus nobilis L. was found to be an acidic ([Formula: see text]). Then, the adsorption of hazardous crystal violet dye on Laurus nobilis L. was examined. For the adsorption process, the optimum conditions were determined as contact time (60 min), adsorbent dosage (1.0 g/L), agitation rate (200 rpm), and initial pH (≅ 7). The efficiencies of initial concentration, contact time, temperature, and their binary combinations on the improvement of adsorption percentage were statistically investigated via three different two-way ANOVA analyses. Adsorption data were applied to different isotherms, and it was determined that the Langmuir isotherm (r2 = 0.9998) was the most suitable isotherm for the adsorption process. The [Formula: see text] value was calculated as 400.0 mg/g at 25 °C from the Langmuir isotherm. According to kinetic models, it was observed that the adsorption occurred in three steps. According to enthalpy (+ 7.52 kJ/mol), activation energy (+ 8.91 kJ/mol), and Gibbs free energy (- 30.0 kJ/mol) values, it was determined that the adsorption occurred endothermically and spontaneously. As a result of reusability studies, it was determined that the adsorbent could be used repeatedly.

Adsorptive removal of crystal violet from wastewater using sodium alginate-gelatin-montmorillonite ternary composite microbeads.

In this study, the performance of the montmorillonite-filled sodium alginate/gelatin (SA-GEL-MMT) ternary biocomposite microbeads on the adsorptive removal of crystal violet (CV) dye was investigated. Firstly, the composites containing different weight ratios of MMT such as 10 %, 15 %, and 20 % were prepared. The composite beads were cross-linked using a calcium chloride (3%wt/v) solution. To determine the optimum sorption conditions the studies were performed at different parameters namely temperature, pH, contact time, sorbent dose, and dye concentration. From the sorption studies, the maximum capacity of the microbeads was found as 1000.0 mg/g whereas the maximum removal of the dye was 92.1 % at pH = 7 and a temperature of 25 °C. Additionally, the kinetic studies showed that the sorption of the dye followed the pseudo-second-order kinetics. Moreover, the adsorptive removal of the dye occurs spontaneously. This study suggests that the use of SA-GEL-MMT can be highly effective and reusable for the treatment of wastewater.

A comparative study of surface properties of Urtica dioica (nettle) leaves, roots, and seeds and examination of their ability to separate xylene isomers.

INTRODUCTION: Urtica dioica (nettle) is a plant species of the Urticaceae family that grows in various parts of the world and exerts antioxidant, antibacterial, antiulcer, antiviral, and anti-inflammatory effects. Their leaves, roots, and seeds are used in various fields such as food, medicine, and cosmetics. OBJECTIVES: Inverse gas chromatography (IGC) was used to evaluate the surface characteristics and separation ability of U. dioica leaves, roots, and seeds. Characterization of these biomasses was performed by Fourier transform infrared spectroscopy (FTIR) analyses. METHODOLOGY: The surface properties of the biomasses including dispersive surface energy, adsorption enthalpy, Gibbs free energy, and acidity-basicity constants were determined at infinite dilution using various organic solvents. These properties were compared with each other. Dispersive surface energies were calculated using the Dorris-Gray, Donnet-Park, and Schultz methods. The accuracy of these methods and their applicability were evaluated. In the last stage of this study, the separation of xylene isomers was investigated by using U. dioica biomasses as stationary phases. RESULTS: The surface functional groups were determined by FTIR analysis. As a result of the IGC studies, it was found that the adsorption of polar solvents on biomasses occurred exothermically and spontaneously. Besides, it was found that the surfaces of biomasses were basic. From the retention diagrams and selectivity coefficients, it was determined that xylene isomers were effectively separated. CONCLUSION: IGC is a promising, low-cost, easy-to-apply, and high-accuracy technique for the investigation of the surface properties of biomasses and their ability to separate isomers.

Investigation of the Surface Properties of Hexagonal Boron Nitride and Boron Phosphate by Inverse Gas Chromatography at Infinite Dilution.

The boron-based ceramics namely hexagonal boron nitride (h-BN) and boron phosphate (BPO4) were synthesized and characterized by Fourier transform infrared spectroscopy and X-ray diffraction analysis. The surface properties of h-BN and BPO4 were examined by inverse gas chromatography method. The dispersive surface energy and the acidic-basic character of h-BN, and BPO4 surfaces were estimated by the retention time with probes such as n-hexane, n-heptane, n-octane, n-nonane, n-decane, acetone, ethyl acetate, dichloromethane, chloroform and tetrahydrofuran at infinite dilution region. The dispersive surface free energies calculated using both Schultz and Dorris-Gray methods, decreased linearly with increasing temperature. The specific adsorption free energy and the specific adsorption enthalpy corresponding to acid-base surface interactions were determined. By correlating with the donor and acceptor numbers of the probes, the acidic and the basic parameters of the h-BN and BPO4 were calculated. The values obtained for and parameters indicated that h-BN has a basic character, whereas BPO4 has an acidic character.

Adsorption of methylene blue dye on sodium alginate/polypyrrole nanotube composites.

Nanomaterials have recently come to the fore as potential adsorbents due to their high surface, high efficiency, and adsorption capacity. This study the performance of polypyrrole nanotube incorporated sodium alginate (SA/PPyNT) on the adsorptive removal of methylene blue dye from an aqueous solution was investigated. Firstly, polypyrrole nanotubes were synthesized by oxidative chemical polymerization. Then, polypyrrole nanotubes were added to the sodium alginate gel and the composite beads were prepared by a crosslinking process in a 3% CaCl2 solution. The composite beads were characterized using Fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscope (SEM), and atomic force microscopy analyzes. In the adsorption studies, to determine the optimum conditions, experiments were carried out at different conditions namely temperature (25-45 °C), contact time, initial pH (2-12), adsorbent dosage (1-5 g/L), dye concentrations (10-50 mg/L). The studies indicated that the removal percentage of MB reached up to 90.5% at pH = 7 and 25 °C. Furthermore, different isotherm models such as Freundlich, Langmuir, D-R, and Harkins-Jura were applied. Considering the correlation coefficients, the Langmuir isotherm model was found to be the most suitable model (r2 = 0.9974). The adsorption capacity showed the maximum at 666.7 mg/g in pH = 7 at 25 °C. As a result of the kinetic studies, it was seen that adsorption followed the pseudo-second-order kinetic model (r2 = 0.9976). When thermodynamic parameters were examined, it was seen that the adsorption occurred exothermically (∆HA = - 68.1 kJ/mol) and spontaneously (∆GA298 = - 27.4 kJ/mol). From the data obtained, it was concluded that the SA/PPyNT composites are promising material as an adsorbent.

Evaluation of the surface properties of 4-(Decyloxy) benzoic acid liquid crystal and its use in structural isomer separation.

The selectivity of 4-(Decyloxy) benzoic acid (DBA) liquid crystal in surface adsorption region (303.2-328.2 K) and thermodynamic region (423.2 - 433.2 K) was investigated by inverse gas chromatography at infinite dilution (IGC-ID). The selectivity parameters of the structural isomer series named butyl acetate, butyl alcohol, and amyl alcohol series were calculated for the DBA using IGC-ID technique. Additionally, the surface properties including dispersive surface energy (gS D), free energy (DGA S), enthalpy (DHA S), and acidity-basicity constants were calculated with net retention volumes obtained from IGC-ID experiment results. When the DHA S and DGA S are constants, DBA surface was found to be an acidic character (KD/KA @ 0.89).

Radioactive cesium ion removal from wastewater using polymer metal oxide composites.

Radioactive cesium ion (Cs-137) removal from wastewater was investigated by novel composite adsorbents, chitosan-bone powder (CS-KT) and chitosan-bone powder-iron oxide (CS-KT-M) at 25 and 50 °C. The characterization of adsorbents was performed by Fourier-Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscope (SEM), X-Ray Diffraction (XRD), Brunauer-Emmett-Teller and Barrett-Joyner-Hallenda (BET-BJH), and Atomic Force Microscopy (AFM) analyses. While BET surface areas of CS-KT and CS-KT-M adsorbents were found to be 131.5 and 144.9 m2/g, respectively, average pore size and pore volume values were 4.69 nm/0.154 cm3/g and 7.49 nm/0.271 cm3/g, respectively. Amongst Freundlich, Langmuir, and Dubinin-Radushkevich (D-R) models, Langmuir model fits well for Cs+ ion sorption by these adsorbents. The maximum adsorption capacity obtained from Langmuir adsorption isotherm was 0.98 × 10-4 mol/g at 25 °C, and 1.16 × 10-4 mol/g at 50 °C for CS-KT; it was found to be 1.79 × 10-4 mol/g at 25 °C and 2.24 × 10-4 mol/g at 50 °C for CS-KT-M. FT-IR analyses showed that Cs+ sorption occurs by its interaction with CO32-, PO43- and -NH2 groups. The average adsorption energy "E" was calculated as ca.11 kJ/mol from D-R adsorption isotherm. The adsorption kinetics was interpreted well by pseudo-second order model.

Adsorption of methylene blue on sodium alginate-flax seed ash beads: Isotherm, kinetic and thermodynamic studies.

In the present study, the adsorptive removal of methylene blue (MB) from wastewater was studied using the novel composite prepared by sodium alginate (SA) and flax seed ash (FS). The adsorption of MB was carried out using the composite beads consisting of different weight amounts of FS at different pH values and temperatures using different dye concentrations. The characterization studies of the composite beads were performed using Fourier-Transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and Brunauer-Emmett-Teller and Barrett-Joyner-Hallenda (BET-BJH) analyses. BET and BJH surface area values of SA-FS adsorbent beads were found to be 45.01 m2/g and 14.35 m2/g, respectively. During the studies, it was determined that the adsorption percentage of MB reached the maximum with 90% at pH = 7 and 50 °C. Furthermore, Langmuir model fits well for the adsorption of MB using SA-FS with different FS ratios, SA, and FS adsorbents. The maximum adsorption capacity obtained from Langmuir model was found to be 333.3 mg/g for SA-FS-2 composite beads at pH = 7 and 50 °C. The adsorption kinetics were interpreted well by pseudo-second order model for SA, FS and SA-FS adsorbents. The calculated thermodynamic parameters indicated that MB adsorption by FS, SA, and SA-FS were spontaneous and an endothermic.