Izabela Polowczyk

Protein-Mediated Precipitation of Calcium Carbonate

Calcium carbonate is an important component in exoskeletons of many organisms. The synthesis of calcium carbonate was performed by mixing dimethyl carbonate and an aqueous solution of calcium chloride dihydrate. The precipitation product was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) measurements. In addition, the turbidity of the reaction solution was acquired to monitor the kinetics of the calcium carbonate structure’s growth in the investigated system. In this study, samples of CaCO3 particles obtained with individual proteins, such as ovalbumin, lysozyme, and a mixture of the proteins, were characterized and compared with a control sample, i.e., synthesized without proteins. The obtained data indicated that the addition of ovalbumin to the reaction changed the morphology of crystals from rhombohedral to ‘stack-like’ structures. Lysozyme, however, did not affect the morphology of calcium carbonate, yet the presence of the protein mixture led to the creation of more complex composites in which the calcium carbonate crystals were constructed in protein matrices formed by the ovalbumin-lysozyme interaction. It was also observed that in the protein mixture, ovalbumin has a major influence on the CaCO3 formation through a strong interaction with calcium ions, which leads to the coalescence and creation of a steric barrier reducing particle growth. The authors proposed a mechanism of calcium carbonate grain growth in the presence of both proteins, taking into account the interaction of calcium ions with the protein.

Characterization of Glass Beads Surface Modified with Ionic Surfactants

Knowledge of the wetting characteristic of mineral surfaces is very important in enhancing the efficiency of separation of valuable minerals from gangue using froth flotation or oil agglomeration. In this paper a capillary rise technique was used to characterize the glass beads surface modified with cationic surfactant. The glass microspheres were used as model particles with a spherical shape and smooth surface to eliminate the roughness effect. The value of the contact angle for water was found to be 21.5 for unmodified beads, and 61.8, 89.7, 68.4 for 0.1, 1.0, 10 mg/gsolid of CTAB, and 39.8, 68.6, 87.9 for 0.1, 1.0, 10 mg/gsolid of DDAHCl, respectively. Data revealed that the adsorption of surfactant onto glass beads decreased the value of the electron donor component, γ-, which defines the hydrophobicity of the surface. Also, the property of the surface was investigated by flotation and oil agglomeration experiments. It was observed that particles with low value of contact angle for water and high for 1-bromonaphthalene and low value of γ- were floated with a recovery equal to 91.1 and 83.1% for CTAB and DDAHCl, respectively, and effectively agglomerated. This indicates that the capillary rise method can be successfully used to predict the wetting properties of solid particles in mineral processing.

Influence of Hydrophobicity on Agglomeration of Dolomite in Cationic-Anionic Surfactant System

In this study the modified procedure of the oil agglomeration process was carried out, where the emulsion of dodecylammonium hydrochloride (DDAHCl) solution and kerosene was added to the mineral suspension. The aim of this work was to research the oil agglomeration of dolomite mineral by the contact angle, zeta potential and surface free energy measurements. The relationship between the investigated parameters and the oil agglomeration as well as shear flocculation was revealed. The mechanism of oil agglomeration of hydrophilic particles in cationic-anionic surfactant system has been proposed. It was concluded that oil droplets interact rather with aggregates of particles modified by anionic surfactant than the single mineral particles as was explained for naturally hydrophobic particles.

Extraction of organic impurities using 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6]

Extraction of organic impurities using 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6] Extraction of several chloro compounds from water has been examined. As the extracting liquid the 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], which is common hydrophobic ionic liquid, was used. Additionally, extraction of selected chlorinated compounds from tert-butylmethylether (MTBE) was investigated. The obtained results show the usefulness of [BMIM][PF6] to remove the organic impurities from water, particularly at the concentration range inappropriate for biological purification plants.

Use of fly ash and fly ash agglomerates for As(III) adsorption from aqueous solution

Abstract The objective of the present study is to assess the efficiency of fly ash and fly ash agglomerates to remove arsenic(III) from aqueous solution. The maximum static uptakes were achieved to be 13.5 and 5.7 mgAs(III)/adsorbent for nonagglomerated material and agglomerated one, respectively. Isotherm studies showed good fit with the Langmuir (fly ash) and the Freundlich (fly ash agglomerates) isotherm models. Kinetic studies indicated that the sorption of arsenic on fly ash and its agglomerates follows the pseudo-second-order (PSO) chemisorption model (R2 = 0.999). Thermodynamic parameters revealed an endothermic nature of As(III) adsorption on such adsorbents. The adsorption results confirmed that fly ash and its agglomerates can be used for As(III) removal from aqueous solutions. Fly ash can adsorb more arsenic(III) than agglomerates, which are easier to use, because this material is less dusty and easier to separate from solution.

Influence of pH on arsenic(III) removal by fly ash

ABSTRACT The objective of this study was to compare arsenic(III) removal at natural pH (pH 10.5) with that at high alkaline (pH 12.2). Experiments were carried out using fly ash from burning brown coal and biomass from the power plant (Zgierz, Poland). Experimental data were well described by the Langmuir and the pseudo-second-order chemisorption models. The maximum adsorption capacity was 19.04 and 42.73 mg/g at pH 10.5 and 12.2, respectively. It can be explained by the fact that a phase CaAsO2OH is formed at highly alkaline pH. The value of thermodynamic parameters revealed that arsenic(III) adsorption is a spontaneous and endothermic process.

Improved Synthesis of Nanosized Silica in Water-in-Oil Microemulsions

Present contribution describes modified Stober synthesis of silica nanoparticles in oil-in-water microemulsion, formulated using heptane, 2-ethylhexanol, Tween® 85 nonionic surfactant, and tetraethyl orthosilicate (TEOS). After some specified incubation time, ammonium hydroxide was added and the reaction mixture was stirred for 24 hours at room temperature. Prior to synthesis, pseudoternary diagram was created for oil-rich area and Winsor IV region was identified. These microemulsions were used for synthesis of silica particles. Resulting particles were characterized by dynamic light scattering, electrokinetic measurements, specific surface area measurements, and powder diffraction. Particles’ diameter was ranging between ca. 130 and 500 nm; usually monodisperse distribution was obtained. The specific surface area of nanoparticles was ranging between 250 and 300 m2/g. Notably, productivity per unit volume of solution was 3 to 5 times higher than for previously reported procedures. Our method can be extended, because polymeric materials can be added to dispersed aqueous phase. In our studies, β-cyclodextrin and hydroxyethylcellulose have been used, giving particles between 170 and 422 nm, with the surface area larger than 300 m2/g.

A method of thermal and chemical activation of waste bleaching earth for preparation of a low-cost carbon-mineral adsorbent for chromium(VI) removal

ABSTRACT In this study, the use of a spent bleaching earth for removal of Cr(VI) ions from aqueous solutions was investigated. The waste material derived from the process of vegetable oil purification was subjected to thermal and chemical activation. The so-prepared carbon-mineral adsorbents were characterised by the uptake of chromium(VI) from synthetic solutions. The highest adsorption capacities were obtained for adsorbents carbonised at 400°C (15.9 mg∙g−1) and activated with H2SO4 (15.8 mg∙g−1). Based on the equilibrium and kinetic studies, it was concluded that the adsorption mechanism was based on chemisorption only since no correlation with the porous texture was found.

Chapter 6 – Adsorption of Boron by Minerals, Clays, and Soils

Boron is a vital microelement, necessary for the growth of plants, albeit there is only a narrow gap between desirable and toxic concentrations. The tolerance varies among different species. For example, avocado, lemons, and wheat are sensitive, while cotton, tomato, and oat are relatively tolerant. There are many sources of possible contamination, due to anthropogenic activity and natural processes, the main source being natural weathering.

Adsorption of Silver Nanoparticles on Glass Beads Surface

Colloidal silver is widely used owing to its specific properties, which enable it to be applied in various fields. In this work, adsorption of commercially available silver nanoparticles (AgNPs; NanoSilver PVP 1000) on glass beads was investigated. The glass microspheres (70–110 μm) were used as model particles. The adsorption of AgNPs on the glass beads surface was investigated in terms of adsorbent dosage. The adsorption isotherm was determined with the adsorbent dosage of 100 g/l and the AgNPs in range 100–1000 mg/l. It was found that adsorption isotherm data best fitted the Langmuir model. Kinetics of AgNPs adsorption onto glass beads followed a pseudo-second-order model. The interaction between glass microspheres surface and polyvinylpyrrolidone (PVP)-coated AgNPs is due to hydrogen bonding with oxygen of carbonyl groups of PVP and silanol groups on the glass surface.