Filip Ciesielczyk

Adsorption of Ni(II) from model solutions using co-precipitated inorganic oxides

The aim of this work was to obtain an inorganic oxide system containing silica and magnesium oxide, and characterized by specific physicochemical properties, in particular well-defined adsorption parameters. The preparation process was carried out according to a co-precipitation method using solutions of sodium silicate and selected inorganic magnesium salt. The oxide system obtained (MgO·SiO2) was used as a support (adsorbent) of nickel(II) ions, whose precursors were model solutions of nitrates. The effectiveness of the adsorption process was evaluated using many different analytical techniques, including atomic absorption spectroscopy, energy dispersive X-ray spectroscopy and equivalent point titration. Moreover the stability of adsorbent/adsorbate bonding was estimated. The oxide systems—adsorbents—used in the process were also analyzed according to their physicochemical properties, especially changes in adsorption parameters. The last part of the study involved evaluation of the kinetics of the adsorption process depending on time and the pH of the reaction system.

The sol–gel approach as a method of synthesis of xMgO·ySiO2 powder with defined physicochemical properties including crystalline structure

The physicochemical properties of synthetic powders depend strongly on the method of their preparation. The present work concerns the use of the sol–gel method to prepare xMgO·ySiO2 powders with defined physicochemical and structural properties. An important objective was to determine how the basic process parameters (including the type and concentration of the reactants) influence the physicochemical properties of the resulting material. To obtain a synthetic powders, organic precursors of magnesium (magnesium ethoxide), and silicon (tetraethoxysilane) were used. Selected products were subjected to calcination to identify the crystalline structure of the powders and to determine the impact of the proposed method of preparation on this parameter. This aspect of the research will significantly improve the range of application of the manufactured products. The powders obtained by the proposed method were thoroughly analyzed in terms of chemical composition, crystalline structure, morphology and nature of dispersion, parameters of porous structure, and thermal as well as electrokinetic properties. The sol–gel process proved very effective in the synthesis of highly active powders, as evidenced by the very high values obtained for the products’ surface area. It was also confirmed that the physicochemical parameters are strongly dependent on the mass ratio of the reactants and on the method of final treatment of the precipitates.

Treatment of model and galvanic waste solutions of copper(II) ions using a lignin/inorganic oxide hybrid as an effective sorbent

A study was made concerning the removal of copper(II) ions from model and galvanic waste solutions using a new sorption material consisting of lignin in combination with an inorganic oxide system. Specific physicochemical properties of the material resulted from combining the activity of the functional groups present in the structure of lignin with the high surface area of the synthesized oxide system (585m2/g). Analysis of the porous structure parameters, particle size and morphology, elemental composition and characteristic functional groups confirmed the effective synthesis of the new type of sorbent. A key element of the study was a series of tests of adsorption of copper(II) ions from model solutions. It was determined how the efficiency of the adsorption process was affected by the process time, mass of sorbent, concentration of adsorbate, pH and temperature. Potential regeneration of adsorbent, which provides the possibility of its reusing and recovering the adsorbed copper, was also analyzed. The sorption capacity of the material was measured (83.98mg/g), and the entire process was described using appropriate kinetic models. The results were applied to the design of a further series of adsorption tests, carried out on solutions of real sewage from a galvanizing plant.

The Influence of Spray Drying on the Dispersive and Physicochemical Properties of Magnesium Oxide

Magnesium hydroxide was obtained in a precipitation reaction with the use of magnesium nitrate or magnesium sulphate and sodium hydroxide. The influence of the temperature of the process, the mode and rate of substrate supply, as well as the concentration and ratio of the substrates on the products properties, were tested. The intermediate product Mg(OH)2 was subjected to drying by static and spray techniques followed by calcination to obtain magnesium oxide. To establish the effect of the synthesis conditions and drying techniques on the dispersive and physicochemical properties of the magnesium oxide obtained, this product was characterized using a number of experimental methods to obtain the bulk density, polydispersity index, and particle size distribution in the nano- and micrometric ranges. Moreover, the wettability profiles in water system were examined. For selected magnesium oxide samples the crystalline structure was determined by the WAXS method, and adsorptive properties (surface area, volume, and size of pores) as well as electrical properties (dielectric permittivity and electrical conductivity) were measured. Application of all the above-mentioned methods enabled a comprehensive characterization of the products and revealed a significant effect of spray drying on their properties, in particular on their dispersion and morphology.

Fluoroalkylsilane versus alkylsilane as hydrophobic agents for silica and silicates

Hydrophobic powders were obtained via surface modification of silica or magnesium silicate with selected silanes. A modified precipitation method, carried out in an emulsion system, was used for monodisperse silica synthesis, while magnesium silicate was precipitated in a traditional water system. Functionalization of the obtained inorganic supports was performed with selected alkylsilanes: one newly synthesized, 3-(2,2,3,3,4,4,5,5-octafluoropentyloxy)propyltriethoxysilane (OPF), and two commercial, octadecylsilane (ODS) and octyltriethoxysilane C14H32O3Si (OCS), in amounts of 3, 5, or 10 weight parts by mass of SiO2. It was determined how the chemical modification of the silica or magnesium silicate surface affected its physicochemical properties. The dispersive characteristics of both unmodified and functionalized silica-based systems were evaluated. The morphology and microstructure of the samples obtained were analyzed using scanning electron microscopy. The parameters of porous structure of the prepared systems were evaluated on the basis of BET equation as well as nitrogen adsorption/desorption isotherms. Wettability tests as well as elemental analysis of the obtained inorganic oxide hybrids were also performed. In order to verify the effectiveness of silica and magnesium silicate surface functionalization with selected silanes, FTIR spectra were investigated. The resulting experimental data allowed calculation of the degree of coverage of the silica-based systems with modifying agents.

Amorphous magnesium silicate — synthesis, physicochemical properties and surface morphology

Abstract Studies were undertaken on the precipitation of highly dispersed magnesium silicate. Solutions of sodium metasilicate and of magnesium salts [chloride, sulfate(VI) or nitrate(V)] were employed. The chemical reaction of silicate precipitation was corrected by supplementation of the system with diluted (5-15 wt%) solutions of sodium hydroxide. Optimum parameters of the precipitation process were established. The precipitated magnesium silicates were comprehensively examined. Their chemical composition and principal physicochemical properties were established, including bulk density, capacities to absorb water, dibutyl phthalate and paraffin oil as well as the sedimentation rate in linseed oil. Moreover, their morphology, microstructure and particle size distribution were studied, using scanning electron microscopy and dynamic light scattering technique. The obtained products manifested variable physicochemical properties. The presence of sodium hydroxide solution in the course of precipitation proved to significantly affect the quality of the obtained magnesium silicates.

Influence of selected alkoxysilanes on dispersive properties and surface chemistry of titanium dioxide and TiO 2 -SiO 2 composite material

The paper reports on characterisation of titanium dioxide and coprecipitated TiO2-SiO2 composite material functionalised with selected alkoxysilanes. Synthetic composite material was obtained by an emulsion method with cyclohexane as the organic phase, titanium sulfate as titanium precursor, and sodium silicate solution as precipitating agent were applied. Structures of titania and composite material samples were studied by the wide angle X-ray scattering method. The chemical composition of TiO2-SiO2 composite material precipitated was evaluated based on the energy dispersive X-ray spectroscopy technique. The functionalised TiO2 and TiO2-SiO2 composite material were thoroughly characterised to determine the yield of functionalisation with silanes. The characterisation included determination of dispersion and morphology of the systems (particle size distribution, scanning electron microscope images), adsorption properties (nitrogen adsorption isotherms), and electrokinetic properties (zeta potential).

Removal of nickel(II) and cadmium(II) ions from aqueous solutions using an oxide adsorbent of MgO·SiO2 type

AbstractThe principal aim of the present work was to obtain an inorganic oxide system, MgO·SiO2, with unique physicochemical and electrokinetic properties which would enable its use as an effective adsorbent of nickel(II) and cadmium(II) ions. An important component of the work was involved in determining, how the pH and the quantity of adsorbent affect the efficiency of the process for the removal of nickel(II) and cadmium(II) ions from model aqueous solutions. The effectiveness of the adsorption process was evaluated using various analytical techniques, including atomic absorption spectroscopy and energy dispersive X-ray spectroscopy. Nickel or cadmium elution was also tested, in order to determine the durability of the bonds between adsorbent and adsorbate. At the next stage, Langmuir’s and Freundlich’s models were used to describe the equilibrium adsorption isotherms, applying the method of nonlinear regression. The experimental data were found to fit well with Langmuir’s isotherm model. The maximum a...

Electrokinetic properties of hybrid pigments obtained via adsorption of organic dyes on the silica support

Purpose – The purpose of this paper is to characterise the electrokinetic properties of pigments supported on both unmodified and modified silica. The paper describes the preparation of hybrid pigments via adsorption of organic dyes on silica supports and determination of the zeta potential and electrophoretic mobility of the materials obtained.Design/methodology/approach – The materials studied were hybrid pigments obtained as a result of adsorption of two basic dyes: C.I. Basic Red 1 and C.I. Basic Orange 14 and one acidic dye C.I. Mordant Red 3 from solutions of concentrations of 500, 2,000 and 3,000 mg/dm3 on the surface of both unmodified and modified silica supports. The agent used for modification of the silica surface was N‐2‐(aminoethyl)‐3‐aminopropyltrimethoxysilane.Findings – The modification of the silica surface with aminosilane was found to change, significantly, the electrokinetic character of the inorganic support. This change was interpreted as being due to the ionisation of −NH2 groups f...

TiO2‐SiO2 inorganic barrier composites: from synthesis to application

Purpose – The purpose of this paper is to report on a method of synthesis of TiO2‐SiO2 oxide composites characterised by spherically shaped particles with sizes in the micrometric ranges, which can be applied as a new generation of textile/TiO2‐SiO2 composites with barrier properties against UV radiation. Synthesis and characterisation of TiO2‐SiO2 oxide composites with a high degree of dispersion were performed, and their influence on the barrier properties of textile fabrics was investigated.Design/methodology/approach – The precipitation was performed with the use of solutions of titanium sulphate and sodium silicate as the precipitating agent, which are cheap alternatives to organic precursors of Ti and Si. The reaction was conducted in an emulsion system, where cyclohexane was used as the organic phase and non‐ionic surfactants NP3 and NP6 as emulsifiers were applied.Findings – The direction of substrate supply, concentration of the reagents and their ratio and other conditions of precipitation proce...