Ryszard J. Kalenczuk

Synthesis, dispersion, and cytocompatibility of graphene oxide and reduced graphene oxide.

The synthesis, characterization, and toxicity of graphene oxide and reduced graphene oxide are reported. Prior to the cytocompatibility tests the stability of the suspensions in a wide range of concentrations (3.125-100 μg/mL) of three different dispersants is studied. Polyethylene glycol (PEG), polyethylene glycol-polypropylene glycol-polyethylene glycol (Pluronic P123), and sodium deoxycholate (DOC) are investigated as the dispersants. The toxicity depends on the type of dispersant and concentration of the nanomaterials in the suspensions. Detailed analysis suggests that graphene oxide functionalized with PEG in the concentration range between 3125 μg/mL and 25 μg/mL exhibits the best biocompatibility with mice fibroblast cells (line L929).

Efficient production of B-substituted single-wall carbon nanotubes

We present an efficient method to achieve high-purity boron doped single-walled carbon nanotubes (SWCNT) using an adapted substitution reaction. We observe that around 15 at.% of the carbon atoms are substituted by boron, with local concentrations of up to 20 at.% (higher than previous report). The as-prepared material was characterised by local scale method: transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS) as well as by bulk sensitive methods like optical spectroscopy in the infrared energy range (IR), X-ray photoemission spectroscopy (XPS) and bulk sensitive high-resolution EELS.

Reduced diameter distribution of single-wall carbon nanotubes by selective oxidation

We report an easy way to narrow the diameter distribution of single-walled carbon nanotubes (SWNT) by oxidization treatments. Both a chemical treatment in 2 M HNO3 as well as oxidation in a reduced O2 atmosphere lead to a selective burning of the narrower SWNT in bulk samples and to a diameter distribution which is smaller by a factor of two. This is a first important step towards a selective production of SWNT with a defined diameter on a bulk scale.

The pH influence on photocatalytic decomposition of organic dyes over A11 and P25 titanium dioxide

Abstract The photocatalytic removal (decomposition+adsorption) of four azodyes (Reactive Red 198, Acid Black 1, Acid Blue 7 and Direct Green 99) in water was investigated using Tytanpol A11 (“Police” Chemical Factory, Poland) and Degussa P25 (“Degussa”, Germany) as photocatalysts. The effect of pH of the reaction solution has been examined. The degree of the dye removal in the solution was measured by UV-Vis spectroscopy. Photodecomposition of dye on photocatalyst surface was monitored by FTIR spectroscopy. A11 photocatalyst has lower activity in the reaction of photocatalytic decomposition of organic dyes than Degussa P25. The photocatalytic decomposition of the dyes takes place on the photocatalyst surface at pH=2 while at pH=12 photocatalytic reaction proceeds via photogenerated hydroxyl radicals for both A11 and P25.

Bulk synthesis of carbon-filled silicon carbide nanotubes with a narrow diameter distribution

We report on a simple and low-cost route to produce SiC nanotubes without the need for the more usual oxide based reactions using a high temperature substitution reaction between multiwall carbon nanotubes as a frame and Si powder. Local scale studies using transmission and scanning electron microscopy are also presented. The SiC nanotubes are carbon filled and open ended. Both their mean diameter and diameter distribution are smaller than previously reported for SiC nanotubes. Bulk scale studies using Raman and infrared as a probe showed the sample to be comprised of multiple polytypes and that finite size effects are present.

Exfoliated Graphite as a New Sorbent for Removal of Engine Oils from Wastewater

Abstract A commercial exfoliated graphite was used for checking its sorption capabilities for removing engine oil and dyes from wastewater. Slight oxidation of exfoliated graphite in the air at 400 °C was found to be effective to improve adsorption capacity for dyes, methylene blue and methyl orange. However, its treatment in HNO3 reduced all capacities for engine oil and dyes. A possibility for simultaneous removal of oil and dyes dispersed in wasted water was revealed.

Magnetic Silica Nanotubes: Synthesis, Drug Release, and Feasibility for Magnetic Hyperthermia

A new kind of silica nanotube with incorporated γ-Fe(2)O(3) nanoparticles has been successfully prepared through sol-gel processes. Hematite particles supported on carbon nanotubes served as templates for the fabrication of the magnetic silica nanotubes. The obtained nanostructures consisting of magnetic Fe(2)O(3) nanoparticles protected by a silica shell were fully characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), N(2) sorption and desorption, and magnetization studies. The hollow inner space and the magnetic functionalization render the material promising for applications in biology and medicine. This is underlined by studies in alternating magnetic fields which show a significant heating effect, i.e., the feasibility for applications in hyperthermia therapies. In addition, the material exhibits enhanced drug-loading capacity which is demonstrated by loading with rhodamine B molecules as drugs and corresponding release experiments. The results show that magnetic silica nanotubes can be straightforwardly synthesized and have a great potential as a multifunctional drug carrier system.

Studies of Exfoliated Graphite (EG) for Heavy Oil Sorption

Abstract Electrochemically intercalated graphite with H2SO4 was thermally expanded at 1000°C. Exfoliated samples of GIC-H2SO4 with different times of expansion revealed different expansion volumes. Both the surface area and the chemical character of samples also depend on the exfoliation time. A low density of the exfoliated graphite is demanded for the oil sorption. The oil sorption is restricted by the surface area and the bulk density.

ADSORPTION OF TRIHALOMETHANES (THMS) ONTO CARBON SPHERES

A high adsorption capacity of trihalomethanes, 18μmol of CHCl3 per 1 g of carbon spheres, from their aqueous solutions was obtained on carbon spheres derived from phenol resin by carbonization at 1000°C in CO2 atmosphere and by following oxidation in nitric acid and in air at 400°C for 4h. This high capacity was discussed from the pore size distribution and pore shape on the surface of carbon spheres which were determined from STM observations.

Template method synthesis of mesoporous carbon spheres and its applications as supercapacitors

Mesoporous carbon spheres (MCS) have been fabricated from structured mesoporous silica sphere using chemical vapor deposition (CVD) with ethylene as a carbon feedstock. The mesoporous carbon spheres have a high specific surface area of 666.8 m2/g and good electrochemical properties. The mechanism of formation mesoporous carbon spheres (carbon spheres) is investigated. The important thing is a surfactant hexadecyl trimethyl ammonium bromide (CTAB), which accelerates the process of carbon deposition. An additional advantage of this surfactant is an increase the yield of product. These mesoporous carbon spheres, which have good electrochemical properties is suitable for supercapacitors.