Nanosized silica–titanium oxide as a potential adsorbent for C.I. Acid Yellow 219 dye removal from textile baths and wastewaters

Adsorption, viscosity and thermal behaviour of nanosized proteins with different internal stability immobilised on the surface of mesoporous activated biocarbon obtained from the horsetail herb precursor

The thermal analysis methods were used for the description of the adsorption behaviour of selected proteins differing in internal stability (ovalbumin (OVA) and lysozyme (LSZ)). These proteins were immobilised on the surface of activated biocarbon obtained from the horsetail herb precursor. The values of the hydrodynamic radius of both biopolymer macromolecules in the solution were determined by the use of the viscosimetry method. This parameter is important for the specification of the possibility of proteins nano-molecules to penetrate the nano-pores of the adsorbent which leads to the increase of biopolymers adsorption. Such behaviour is observed at the pH value which is very close to the pI value of specific biopolymer (the greatest adsorption of proteins on the activated carbon surface occurs- at pH 5 for OVA being 323 mg/g, as well as at pH 11 for LSZ which is 464 mg/g). Under such conditions, the proteins macromolecules assume conformations characterized by the lowest values of hydrodynamic radius, i.e. 2.76 nm for OVA and 1.07 nm for LSZ. The data obtained from the analysis of gaseous products of thermal decomposition of the samples indicated the types of biocarbon surface groups as well as the enabled specification of the protein macromolecules adsorption mechanism.

Hybrid Silica Materials Applied for Fuchsine B Color Removal from Wastewaters

Hybrid materials, with applications in fuchsine B color removal from wastewaters, were obtained by in situ incorporation of platinum nanoparticles and/or Pt-porphyrin derivatives into silica matrices. The inorganic silica matrices were synthesized by the sol-gel method, conducted in acid-base catalysis in two steps and further characterized by Nitrogen porosimetry, Small Angle Neutron Scattering (SANS), Scanning electron microscopy, Atomic force microscopy and UV-vis spectroscopy. All of the investigated silica hybrid materials were 100% efficient in removing fuchsine B if concentrations were lower than 1 × 10^-5 M. For higher concentrations, the silica matrices containing platinum, either modified with Pt-metalloporphyrin or with platinum nanoparticles (PtNPs), are the most efficient materials for fuchsine B adsorption from wastewaters. It can be concluded that the presence of the platinum facilitates chemical interactions with the dye molecule through its amine functional groups. An excellent performance of 197.28 mg fuchsine B/g adsorbent material, in good agreement with the best values mentioned in literature, was achieved by PtNPs-silica material, capable of removing the dye from solutions of 5 × 10^-4 M, even in still conditions.

Adsorption affinity of Zn (II) ions for nanostructured zirconium phosphate/silica or titania composites

The paper presents the kinetics of Zn (II) ions adsorption as well as its dependence as a function of pH on nanostructured zirconium phosphate and its composites with silica and titania. The nanostructured zirconium phosphate-containing composites were obtained by mechanical processing in the Pulverisette-7 (Fritsch Gmbh) mill. The obtained composites were characterized by a heterogeneous surface coverage of silica gel or titanium oxides. Zinc ions adsorption studies on these adsorbents showed practically complete removal of Zn (II) from aqueous solutions with an initial concentration of < 0.0001 mol/dm3 and a pH > 4 within 10 min.

Hybrid Materials Based on Silica Matrices Impregnated with Pt-Porphyrin or PtNPs Destined for CO2 Gas Detection or for Wastewaters Color Removal

Multifunctional hybrid materials with applications in gas sensing or dye removal from wastewaters were obtained by incorporation into silica matrices of either Pt(II)-5,10,15,20-tetra-(4-allyloxy-phenyl)-porphyrin (PtTAOPP) or platinum nanoparticles (PtNPs) alone or accompanied by 5,10,15,20-tetra-(4-allyloxy-phenyl)-porphyrin (TAOPP). The tetraethylorthosilicate (TEOS)-based silica matrices were obtained by using the sol-gel method performed in two step acid-base catalysis. Optical, structural and morphological properties of the hybrid materials were determined and compared by UV-vis, fluorescence and FT-IR spectroscopy techniques, by atomic force microscopy (AFM) and high resolution transmission electron microscopy (HRTEM) and by Brunauer–Emmett–Teller (BET) analysis. PtTAOPP-silica hybrid was the most efficient material both for CO₂ adsorption (0.025 mol/g) and for methylene blue adsorption (7.26 mg/g) from wastewaters. These results were expected due to both the ink-bottle mesopores having large necks that exist in this hybrid material and to the presence of the porphyrin moiety that facilitates chemical interactions with either CO₂ gas or the dye molecule. Kinetic studies concerning the mechanism of dye adsorption demonstrated a second order kinetic model, thus it might be attributed to both physical and chemical processes.