Polish Journal of Chemical Technology

The aim of this study was to determine the adsorption capacity of the smectite clays (from the overburden of the lignite deposit in Belchatow) for two anionic dyes, i.e. Reactive Blue 81 (RB-81) and Direct Blue 74 (DB-74). Additionally, the influence of the thermal and chemical (acid and alkali) clay modifications on the amount of bonded dyes was investigated. The adsorption capacity of the clay (natural and modified) was different for studied dyes and depended on the initial concentration and modification type. All the modified clays adsorbed the dyes at pH>pH_PZC as the negatively charged surfaces of their particles (in accordance with the formula: AOH ↔ AO^- + H⁺) prevented the formation of electrostatic bonds between the anionic dyes and the clay surface. The dyes were mainly bound with the hydrogen bonds forming between the donor groups in the dyes and the acceptor groups (-SiO and -Al₂OH) in the clays. The coefficients in the adsorption isotherms were estimated with the linear and non-linear regression. The linear regression method was found that the Freundlich and Dubinin-Radushkevich isotherms described the dye sorption much better than the Langmuir model. On the other hand, all three models described well the experimental data in the non-linear regression method. Furthermore, the 1/n value (<1) obtained from the Freundlich equation for all the dye-sorbent systems indicated the favorable sorption.

Application of 1-butyl-3-metyhlimidazaolium hexafluorophosphate ([C4mim][PF₆]), in the extraction of rubidium and cesium from brine solutions using 1,4,7,10,13,16-hexaoxacyclooctadecane (18C6) as extractant was investigated. Parameters that affect the extraction including pH of aqueous phase, equilibration time, dosage of the ionic liquid, phase ratio, concentration of 18C6 were studied. Under the optimal conditions, the single extraction efficiency of rubidium ions and cesium ions were up 84.11% and 94.99%, respectively. The stripping of alkali metal ions from the loaded organic phase with different stripping agents and concentrations were also investigated. The initial value of the K/Cs and K/Rb ratios were 93.0 and 104.3, respectively, which have dropped 91.21% and 88.01%, respectively, after the extraction and stripping experiments. It was taken a big step in the separation and enrichment of cesium (rubidium) ion and potassium ion. The extraction mechanism was revealed most likely to be a cation exchange mode in this system.

The study investigated the suitability of waste rubber powder (WRP) use as filler in adhesive formulation for plywood application. Melamine Urea Formaldehyde (MUF) was employed as resin for formulating the wood adhesive. To improve chemical properties and bonding quality of adhesive, WRP was treated by different chemicals like 20% nitric acid, 30% hydrogen peroxide and acetone solution. The treated WRP were analysed by XRD and it showed that inorganic compounds were removed and carbon was remained as major component under the treatment of 20% HNO₃. The treatment improved the mechanical properties like shear strength and formaldehyde emission of plywood (high shear strength and low formaldehyde emission). The physico-chemical interaction between the wood, resin and filler was investigated using fourier transform infrared spectroscopic (FTIR) technique and the interactions among N-H of MUF and C=O of wood and WRP were identified. The morphology of wood-adhesive interface was studied by field emission scanning electron microscope (FESEM) and light microscope (LM). It showed that the penetration of adhesives and fillers through the wood pores was responsible for mechanical interlocking. Therefore, chemically treated WRP proved its potential use as filler in MUF based adhesive for making plywood.

Acrylic pressure-sensitive adhesives (PSA) are non electrical conductive materials. The electrical conductivity is incorporated into acrylic self-adhesive polymer after adding electrically conductive additives like carbon black, especially nano carbon black. After an addition of electrical conductive carbon black, the main and typical properties of pressure-sensitive adhesives such as tack, peel adhesion and shear strength, are deteriorated. The investigations reveals that the acrylic pressure-sensitive adhesives basis must be synthesised with ameliorated initial performances, like high tack, excellent adhesion and very good cohesion. Currently, the electrical conductive solvent-borne acrylic PSA containing carbon black are not commercially available on the market. They are promising materials which can be applied for the manufacturing of diverse technical high performance self-adhesive products, such as broadest line of special electrically conductive sensitive tapes.

The effect of six SiO₂ nanosized concentrations (0, 5, 20, 40, 60 and 80 mg L^-1) and three seed prechilling treatments (control, seed prechilling before nano SiO₂ treatments, treatments of seed with nano SiO₂ before prechilling) on germination and seedling growth of tall wheatgrass (Agropyron elongatum L.) were studied. Results indicated that application of SiO₂ nanoparticles significantly increased seed germination of tall wheatgrass from 58 percent in control group to 86.3 and 85.7 percent in 40 and 60 mg L^-1, respectively. Applying SiO₂ nanoparticles increased dry weight of shoot, root and seedling of tall wheatgrass. Increasing concentration of nanoparticle from 0 up to 40 mg L^-1 increased seedling weight around 49 percent compared to the control, nevertheless decreased under 60 and 80 mg L^-1 treatments. In conclusion, seed prechilling in combination with SiO₂ nanoparticles largely broke the seed dormancy for A. elongatum.

A new method for the preparation of 7H-indolo[1,2-a]quinolinium solvatochromic dye precursors has been investigated. 5-(6-Hydroxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium perchlorate, 5-(5-bromo-6-hydroxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium perchlorate and 5-(5-nitro-6-hydroxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium perchlorate were obtained via demethylation of the corresponding 5-(5-X-6-methoxynaphthyl-2)-7,7-dimethyl-7H-indolo[1,2-a]quinolinium salts. The application of pyridinium hydrochloride in the demethylation of the methoxy perchlorates allowed to obtain the products with the almost quantitative yield in a very short time, especially when the reaction was carried out using microwave irradiation.

Gallium (Ga) is considered an important element in the semiconducting industry and as the lifespan of electronic products decrease annually Ga-containing effluent has been increasing. The present study investigated the use of biodegradable polymer powders, crab shell and chitosan, in the removal of Ga(III) ions from aqueous solution. Ga(III) biosorption was modeled to Lagergren-first, pseudo-second order and the Weber-Morris models. Equilibrium data was modeled to the Langmuir, Freundlich and Langmuir-Freundlich adsorption isotherms to determine the probable biosorption behavior of Ga(III) with the biosorbents. The biosorbents were investigated by Fourier Transform Infrared Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy/Energy Dispersive Spectra analysis.

Starmerella bombicola a teleomorph of Candida bombicola is capable of producing extracellular secondary metabolites known as sophorolipids. In the present work the performance of Starmerella in producing sophorolipids, with standard medium ingredients glucose, sunflower oil, yeast extract and urea was studied. The quantities of different medium ingredients were optimized to maximize the production of sophorolipids. Variation in tensiometric properties like surface tension and interfacial tension during the incubation period were also reported. The optimized mixed substrate composition was found to be 200 g/l, containing equal amounts of glucose and sunflower oil, 4 g/l of yeast extract and 0.6 g/l of urea. With the optimized substrate composition 38.6 g/l of sophorolipids was obtained. The minimum surface tension produced by the culture free cell broth was 36.2 mN/m. Increasing the temperature from 25°C to 35°C has shown adverse effects on sophorolipids production.