Studies on selected properties of natural mineral modified leathers with the addition of polyhexamethylenebiguanide-based preparation

Zbadano strukturę i wybrane parametry fizyko-mechaniczne, higieniczne i mikrobiologiczne podszewkowych skór obuwiowych z wypełnieniem opartym na naturalnych kompozytach mineralnych: zeolicie (MMZ), montmorylonicie (MMT) z dodatkiem preparatu na bazie poliheksametylenobiguanidy (PHMB). Badania wykazały poprawę badanych właściwości modyfikowanych próbek w odniesieniu do skór bez dodatku PHMB.The structure and the selected physical and mechanical, hygienic and microbiological parameters of footwear lining leather with filling based on natural mineral composite materials: zeolite (MMZ), montmorillonite (MMT) with an addition of a preparation based on polyhexamethylene biguanide (PHMB) were tested. The research has shown an improvement in the tested properties of the modified samples in relation to leather without PHMB

Porous structure of natural and modified clinoptilolites

The evaluation of the pore-size distribution (PSD) of natural and modified mesoporous zeolites, i.e., clinoptilolites is presented.We demonstrate the SEM results showing that the pores of fracture-type from 25–50 nm to 100 nm in size between clinoptilolite grains, as well as pores between crystal aggregates up to 500 nm in size are present in the studied material. The detailed distribution of pore sizes and tortuosity factor of the above-mentioned materials are determined from the adsorption–desorption isotherms of nitrogen measured volumetrically at 77 K. To obtain the reliable pore size distribution (PSD) of the above-mentioned materials both adsorption and desorption branches of the experimental hysteresis loop are described simultaneously by recently developed corrugated pore structure model (CPSM) of Androutsopoulos and Salmas. Evaluated pore size distributions are characterized by well-defined smooth peaks placed in the region of the mesoporosity.Moreover, the mean pore diameter calculated from the classical static measurement of nitrogen adsorption at 77 K correspond very well to the pore diameters from SEM, showing the applicability of the CPSM for characterization of the porosity of natural zeolites. We conclude that classical static adsorption measurements combined with the proper modeling of the capillary condensation/evaporation phenomena are a powerful method which can be applied for pore structure characterization of natural and modified clinoptilolites

Ammonium sorption from aqueous solutions by the natural zeolite Transcarpathian clinoptilolite studied under dynamic conditions

The scope of this study is ammonium-ion uptake from synthetic aqueous solutions onto raw and pretreated forms of the natural zeolite Transcarpathian clinoptilolite under dynamic conditions. Hydrogen ions displaced exchangeable cations on the clinoptilolite in distilled water (sodium ions) and hydrochloric acid (sodium, potassium, and calcium ions) and destroyed the zeolite framework structure in the last case. Ammonium uptake onto the zeolite occurs by exchange with Na+, Ca2+, and K+ ions. Although Na+ ions were observed to be more easily exchanged for both hydrogen and ammonium ions, the role of Ca2+ ions increased with zeolite saturation by NH+4 ions. The maximum sorption capacity of the clinoptilolite toward NH+4 ions, estimated under dynamic conditions, is significantly higher than that measured under static conditions; proximity of the values of a distribution coefficient and a retardation factor for different conditions (215-265 dm3/kg and 979¿1107, respectively) allows us to use these parameters to model ammonium uptake onto the clinoptilolite. Slowing down or interruption in filtration resulted in the improvement of ammonium sorption properties of the zeolite. The ammonium removal improves with use of the finer fractions of the clinoptilolite up to 0.35 mm. A recycling study results confirmed the importance of external diffusion for ammonium sorption by the clinoptilolite. Preliminary treatment of the sorbent confirmed the predominant importance of the ion-exchange mechanism. The advantage of prior NaCl treatment of the clinoptilolite in improvement of ammonium removal over the other techniques was shown

Structural Evolution of Polyimide-Derived Carbon during Phosphoric Acid Activation

Carbon adsorbents were obtained by carbonization of polyimide polymer with and without the presence of phosphoric acid at temperatures in the range of 400–1000 °C. Carbons produced in the presence of phosphoric acid have been demonstrated to contain up to 13.2% phosphorus. The structure of phosphorus-containing compounds was investigated by XPS and 31P MAS NMR methods. Deconvolution of the P 2p peak with variable binding energy showed the presence of only phosphates/polyphosphates. However, a low value of the O/P ratio is an indirect indication of the possible presence of phosphonates. A 31P MAS NMR study revealed the existence of several kinds of phosphates as well as a minor quantity (1–9%) of phosphonates. All discovered phosphorus-containing compounds are acidic and therefore give carbon the ability to absorb metal cations. The study of copper ion adsorption demonstrated that phosphorus-containing carbon shows a significant adsorption capability even in extremely acidic conditions. At pH 3–6, phosphorus-containing carbon may completely remove copper from the aqueous solution. Phosphorus-containing carbon has a higher adsorption capacity for copper ions than ion exchange resins with carboxyl or sulfo groups

Facile and economic one-pot synthesis of rigid functional-polyurethane for the effective treatment of heavy metal-contaminated urban storm water run-off

In this study, highly permeable rigid polyurethanes (PU) incorporating calcium oxide (CaO) (PU/CaO) composite materials were prepared via a facile and economic one-pot synthesis method and characterized for remediation of heavy metal-contaminated urban storm water run-off (USR) in a fixed-bed column. Column tests were conducted to investigate various parameters, and data were interpreted using the Bed Depth Service Time model to predict service time. Among the media tested, 25% CaO-incorporated PU (PU/CaO-25) had the highest adsorption capacity of Cu(II). PU/CaO-25 had about 2.5-fold higher rigidity (0.38 MPa) than a “typical” rigid polymer (0.15 MPa). Hydraulic conductivity tests showed PU/CaO-25 (avg. 0.4 mm) had a permeability (0.108 cm s−1) equivalent or higher than reference sands. Specific structural features of PU/CaO-25 and the remediation mechanism were also determined using FESEM/EDS, XRD, N2 gas isotherm and chemical equilibrium modeling. Moreover, column tests using simulated USR showed that all heavy metals were removed by PU/CaO-25 to below their regulation levels at ~1,100 bed volumes. Based on the physicochemical properties and functionality, PU/CaO-25 may be useful as an effective filter material in USR treatment and reuse applications

Study on zinc ions binding to the individual casein fractions: αS1-, β- and κ-casein.

The presented work is focused on the isotherm study on the Zn2+ ions binding to the individual casein fractions: αS1-, β- and κ-casein (αS1CN, βCN and κCN). The experimental isotherms were evaluated using Freundlich and Langmuir models. Subsequently, the stability of the obtained complexes in the respective Zn2+ ion concentrations (120, 350, 600 mg/L) was determined by carrying out zeta potential measurements. Capillary electrophoresis combined with inductively coupled plasma mass spectrometry (CE-ICP-MS) confirmed the occurring binding process. Additionally, physicochemical characteristics of the obtained metal-protein complexes was performed including scanning electron microscopy (SEM) in two modes (SE and Z-contrast) and the binding sites of caseins to Zn2+ ions were indicated using attenuated total reflectance infrared spectroscopy (FTIR-ATR) and Raman analysis as well as mass spectrometry technique (MALDI-TOF MS). Isothermal studies indicated a heterogeneously complex zinc ion adsorption process, and a stability study showed that the zeta potential is strongly related to the hydrophobicity, size and structure of the casein isoforms studied. Electron microscopy confirmed the modification of casein surfaces due to the addition of Zn2+ ions. Spectroscopic techniques indicated the interaction of zinc ions with polar amino acids of casein, such as glutamic acid (Glu) and aspartic acid (Asp), but also His, Cys. The influence of phosphate groups was also observed. Finally, the study culminated in a molecular docking study of the Zn2+ ion binding process, which confirmed the presence of the listed amino acids responsible for the binding process

Formation of Leather Biostability with the Use of Cationic Polyelectrolytes

The creation of new preparations with a wide range of biocidal action on the pathogenic microorganisms, long-term protective action and, at the same time, with low toxicity for humans and safe for the environment, is a relevant direction in the development of modern technologies in the production of leather materials.In the present article we report the results of examining the antibacterial properties of leather, modified with a composition of natural minerals (zeolite, montmorillonite) and polyhexamethyleneguanidine hydrochloride (PHMG-HC) – cationic polyelectrolyte. PHMG-HC is related to the biocides with a wide range of antimicrobial action, it provides surfaces that are treated with a long-lasting bactericidal effect (up to 8 months), which is why it is called a unique biocide with prolonged action. However, up to now, the use of PHMG-HC to provide leather materials with anti-bacterial properties has not been explored.The research was conducted using the lining leather, impregnated with the dispersed solutions of zeolite and montmorillonite. The modification of leather with PHMG-HC, the substance included in the register of preparations permitted by the EU, was carried out at the stage of after-tanning processes in the production of leather. We propose to use the preparation as a polyfunctional material that fixes the filling and greasing materials in the dermis structure and simultaneously provides it with antibacterial properties.As a result of research, we established special features of the anti-bacterial properties of leather depending on the treatment of a semi-finished product with the solutions of PHMG-HC at different concentration and the type of mineral filler. It is shown that the examined samples acquire a certain level of biostability when treated with the solution of PHMG-HC at concentration not lower than 2.5 %.It is determined that the structure of natural minerals and their location in the leather dermis affect the degree of absorption of the biocide by a semi-finished product. It was found that the leather materials, modified with PHMG-HC, exert a pronounced bactericidal effect on the bacteria of the genus Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis.Research results demonstrated the possibility of obtaining leather materials with special antibacterial properties when using environmentally safe biocidal preparation (polyhexamethyleneguanidine hydrochloride) and accessible and cheap natural minerals (zeolite, montmorillonite)