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Herein, a link has been established between cold acclimation and Cd uptake in Spirogyra aequinoctialis. The water samples supplemented with cadmium (0.1, 0.5, and 1.0 mg/L) were used for plant growth at two different temperatures. Cold-acclimated plants accumulated high concentrations (0.40 ± 0.02 µg/dry biomass) of Cd as compared to non-acclimated plants (0.30 ± 0.08 µg/dry biomass). The negative effects of Cd on the biomass, carotenoids, and chlorophyll contents in non-acclimated plants were more pronounced in non-acclimated plants as compared to the cold-acclimated plants. High concentrations of free proline and total phenolics in cold-acclimated plants were observed as compared to the non-acclimated plants. About 13 different phenolic compounds were identified using high-pressure liquid chromatography. Cold acclimation as well as the presence of Cd in water highly increased the concentrations of polyphenolics, while synergistic increase was recorded with the combination of cold acclimation and Cd treatments. The highest increase in the concentration of polyphenolics was recorded for syringic acid. Significant positive correlations of total phenolics were noted with dry biomass (R 2 = 0.51) and Cd accumulation (R 2 = 0.59) in plant tissues. Free proline concentration also showed positive correlations with dry biomass, Cd accumulation, and chlorophyll contents (R 2 = 0.80).

Abstract In this research, the adsorption capacity of the Ziziphora plant ash collected from the village of Kib, Jurm township of Badakhshan province of Afghanistan country were studied on the removal of methylene blue from aqueous solutions. At first, the adsorbent was prepared in its natural form and then turned into powder. The powder obtained by the furnace is turned into ash at 500 °C. Natural adsorbent Ziziphora plant ash were characterized by Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). In this study, investigated the effects of various factors such as pH, contact time, initial dye of concentration, dose of adsorbent, ionic strength and temperature. Then, the thermodynamic parameters of the adsorption process such as ∆H^°, ∆S^° and ∆G^° were calculated. Thermodynamic investigations showed that the adsorption of methylene blue dye increased by increasing the temperature on the natural adsorbent of the Ziziphora plant ash and that indicating the adsorption process was endothermic. The kinetic adsorption conditions were investigated with first and second order kinetic models and the results showed that the methylene blue absorption process were followed to the second-order kinetics model. The isotherm of the adsorption process were studied using Langmuir, Freundlich, Tamkin and Dobbin-Radskvich models. The results of the experiments showed that the adsorption process followed by Langmuir model with a maximum adsorption capacity (59.1 mg.g-1). Keywords: Removal, Methylene blue, Isotherm, Ziziphora plant ash

A simple, efficient and quick salting-out based centrifugeless dispersive liquid-liquid microextraction combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) has been successfully developed for the determination of selected parabens in environmental water samples. Herein, following the dispersion of the extracting solvent (1-undecanol) whose melting point is near the room temperature into the sample solution, the cloudy mixture is passed through a test tube filled with sodium chloride, acting as separating agent based on salting-out phenomenon. By immersing the tube inside an ice bath, the fine droplets of the extraction solvent are solidified, easily collected and after returning to the liquid state, injected into HPLC-UV. The values of the detection limit were in the range of 2.5-5.0 µg L-1 while the intra-day (n = 7) and inter-day (n = 9, within three days) precision were below 3.7 and 4.7%, respectively. A satisfactory linearity (0.997 ≥ r2 ≥ 0.996) and quite a broad linear range (5.0-250 µg L-1) were achieved. The relative errors as the accuracy were less than 6.4% in all experiments. The method was eventually employed for the preconcentration and determination of the analytes in various natural water samples and acceptable results were achieved.

In this research, flame retardant polymer-nanocomposites with polyester fibers and inorganic nano materials were prepared to investigate the reduction of flammability. Nano calcium tetraborate (CaB4O7) and Nano barium tetraborate (BaB4O7) were synthesized by precipitation method onto polyester fibers to achieve flame retardant fiber nanocomposite. The prepared fiber nanocomposites were characterized by several techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR), vertical flammability test, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The CaB4O7 and BaB4O7 with less than 100 nm in size, was found to be well-dispersed throughout the matrix without the formation of large aggregates which is showed efficient flame-retardancy properties. The optimum values for donation of flame-retardancy were obtained 8.02 and 9.5% for calcium tetra borate and barium tetra borate, respectively. TGA/DTG and DSC analysis of pure, treated fibers was accomplished and their thermograms were compared and commented. The results show that the flame retardancy mechanism of obtained flame retardant coated fiber is a condensed-phase phenomenon due to the formation of a protective char layer that acts as a mass transport barrier and a thermal insulator.

Intrinsically conducting polymers (ICPs) such as polyaniline and polypyrrole which have advantages such as high conductivity, high flexibility, ease synthesis routes, high stability and good mechanical properties, have aroused intense of many researches for various application such as electrolytic capacitors, electronic and electrochromic devices, sensors, light-weight batteries, membrane separation and radar absorbing materials (RAMs). In this research, polypyrrole (PPy) with novel morphology was synthesized successfully, using a microstructured MnO2 microcube as a self-reactive template and oxidizing agent for the beginning of the polymerization reaction. MnCO3 microcubes were synthesized by hydrothermal method at 150 °C. They were utilized as precursors for MnO2 microcube synthesis. XRD patterns of MnO2 and PPy revealed that the MnO2 templates consumed almost completely as an initiator or an oxidizing agent in polymerization reaction. Also, FESEM images demonstrated that PPy structures are totally inherited their morphologies from MnO2 templates.

Quantitative structure–reactivity relationship (QSRR) can be considered as a variant of quantitative structure property relationship (QSPR) studies, where the chemical reactivity of reactants in a specified chemical reaction is related to chemical structure. As follows, the sulfonation reaction yield of 24 amines, alcohols and phenols with sulfonyl chloride was studied by QSRR. Quantum chemical calculations (b3lyp/6-31+g (d)) were carried out to obtain the optimized geometry. The suitable set of molecular descriptors was calculated to represent the molecular structures of compounds, such as constitutional, topological, geometrical, electrostatic and quantum-chemical descriptors. The genetic algorithm (GA) was applied to select the variables that resulted in the best-fitted models. After the variable selection, multiple linear regression (MLR) was utilized to construct linear QSRR models. The maximum relative error in prediction (5.26) showed that the predictive ability of the model was satisfactory and it can be used for designing similar reactants with efficient sulfonation reaction.

An efficient method for the preparation of 1-amidoalkyl-2-naphthols has been described using a multi-component, one-pot condensation reaction of 2-naphthol, aldehydes and amides in the presence of boric acid under solvent-free conditions.DOI: http://dx.doi.org/10.4314/bcse.v26i3.18

Mercury is a toxic metal, without biological effect in human body and causes CNS and renal disease. So, removal of mercury vapor through sorbents is an important environmental problem. Due to high capability of nano particle sorbents, nano particle palladium modified on multi wall carbon nano tube (NPd-MWCNT) and single wall carbon nano tube(SWCNT) were selected for this investigation. In this study, instrumental conditions, method procedure and different effect parameters such as, absorption and adsorption efficiency, absorption capacity, temperature, time and repeatability were studied and optimized. In addition the efficiency of sorbents was compared. Absorption capacity and efficiency of sorbents depend on the amount of sorbent, kind of nano particle and mercury mass concentration. For 80 mg of sorbents, working range of NPd-MWCNT and SWCNT were achieved 0.01-3 μg and 0.02- 0.7 μg respectively. Limit of detection (LOD) of NPd-MWCNT (0.003 μg) and SWCNT (0.006 μg) were obtained. In this research, mercury vapor was determined and produced by cold vapor atomic absorption spectrometry (CV-AAS) and mercury pilot respectively. The results show us, the maximum absorption capacity of NPd-MWCNT (8 μg g-1) was higher than SWCNT (0.5 μg g-1) and NPd-MWCNT that had high potential mercury removal.