•We reviewed the recent findings in the effect of pulp refining on the fiber properties.•Pulp refining/beating is a mechanical treatment of fibers for improvement of the fiber quality.•A variety of ...changes occurs on structural and electrokinetic specifications of fiber during pulp refining.
The requirement for high quality pulps which are widely used in paper industries has increased the demand for pulp refining (beating) process. Pulp refining is a promising approach to improve the pulp quality by changing the fiber characteristics. The diversity of research on the effect of refining on fiber properties which is due to the different pulp sources, pulp consistency and refining equipment has interested us to provide a review on the studies over the last decade. In this article, the influence of pulp refining on structural properties i.e., fibrillations, fine formation, fiber length, fiber curl, crystallinity and distribution of surface chemical compositions is reviewed. The effect of pulp refining on electrokinetic properties of fiber e.g., surface and total charges of pulps is discussed. In addition, an overview of different refining theories, refiners as well as some tests for assessing the pulp refining is presented.
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•Novel chlorpromazine conjugates with gold nanoparticles were prepared in an electrostatically-driven self-organization process.•pH-dependent electrokinetic properties of ...chlorpromazine conjugates with gold nanoparticles were determined.•The chemical structure of chlorpromazine deposited on gold nanoparticles was determined using SERS and SEIRA.•The stability of novel conjugates under controlled conditions of pH was confirmed based on spectroscopic and electrokinetic investigations.
Scientific studies have demonstrated that conjugates of anticancer drugs with metal nanoparticles (MeNPs) lead to a more effective deactivation of tumor cells compared to free drugs. Similarly, it has been established that conjugates of antibiotics with MeNPs exhibit higher biocidal activity against bacteria than their unbound counterparts. However, limited information is available regarding conjugates formed from drugs other than anticancer and antibiotics. Therefore, our research aims to develop synthesis methods for conjugates of chlorpromazine (CPZ), a neuroleptic, with gold nanoparticles (AuNPs). CPZ-AuNP conjugates were prepared through a ligand exchange reaction conducted on the surface of quasi-spherical, negatively charged citrate-stabilized TC-AuNPs with an average size of 55 ± 5 nm. UV–vis spectroscopy was employed to determine the stability range of the conjugates under controlled conditions of pH and ionic strength. Based on electrokinetic measurements, it was observed that the zeta potential of CPZ-AuNP conjugates strongly depends on the amount of CPZ adsorbed on the TC-AuNP surface. Additionally, the conjugates exhibited an isoelectric point at pH 8.8. Surface-enhanced Raman spectroscopy (SERS) and surface-enhanced infrared absorption spectroscopy (SEIRA) were employed to elucidate the adsorption structure of CPZ on TC-AuNPs. The interpretation of the spectra was conducted based on the Raman and FTIR spectra of CPZ, along with calculations performed using Density Functional Theory (DFT). The results indicated that CPZ primarily interacts with the TC-AuNP surface through the angularly oriented phenothiazine ring and the propylene bridge. Furthermore, it was demonstrated that the C-N-C fragment is perpendicular to the surface of the TC-AuNP with which it interacts. The findings from this analysis suggest the potential for further research on the use of these conjugates in biomedical applications.
•This manuscript compares the surface properties of NiFe2O4 nanoparticles synthesized by two different routes.•NiFe2O4 nanoparticles were synthesized by chemical co-precipitation (NFOCP) and dc ...thermal plasma route (NFOTP).•dc thermal plasma route has several advantages over other conventional methods.•NFOTP are found to have higher colloidal stability as compared to NFOCP particles.•NFOTP particles clearly show the facetted surface morphology with sharp boundaries.•NFOCP is seen to be very ill-defined, probably indicating an amorphous layer.•NFOCP has larger effective hydrodynamic particle size as compared to NFOTP.•Surface properties of NiFe2O4 particles have revealing effect on antimicrobial activity.
The present work reports the role of surface properties of NiFe2O4 nanoparticles on the antimicrobial activity. The NiFe2O4 nanoparticles were synthesized by gas phase condensation and chemical co-precipitation route. These nanoparticles were extensively investigated using X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and electro-kinetic property measurements. The HRTEM was used to analyze surface morphology of nickel ferrite nanoparticles obtained by two different routes. Electro-kinetic properties of the nanoparticles under investigation were recorded, analyzed and correlated with the antimicrobial properties. It was observed that nickel ferrite nanoparticles synthesized by thermal plasma route (NFOTP) formed highly stable colloidal solution as compared to chemically synthesized (NFOCP), as the later tends to agglomerate due to low surface charge. The antimicrobial activity of NiFe2O4 nanoparticles were investigated on two Gram positive bacteria Staphylococcus aureus and Streptococcus pyogenes, two Gram negative bacteria Escherichia coli and Salmonella typhimurium and one fungal species Candida albicans. It was noted that the surface properties of NiFe2O4 particles have revealing effect on the antimicrobial activity. The NFOTP nanoparticles showed significant activity for gram negative E. coli bacteria however no activity was observed for other bacteria’s and fungi under study. Moreover NFOCP particles did not show any significant activity for both bacteria’s and fungi. Further, antimicrobial activity of nickel ferrite nanoparticles were studied even for different concentration to obtain the minimum inhibition concentration (MIC).
In the past decade, nanofluids have attracted much interest because of their reported superior thermal performance and many potential applications. However, there are many inconsistencies in reported ...experimental results of the thermophysical properties such as the effective thermal conductivity of nanofluids and controversies in the underlying enhanced mechanisms. In this paper, various aspects of nanofluids including synthesis, potential applications, experimental and analytical studies on the effective thermal conductivity, effective thermal diffusivity, convective heat transfer, and electrokinetic properties are critically reviewed.
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The activated carbons obtained from peat were applied for simultaneous removal of low-molecular weight poly(acrylic acid) – PAA (2 000 Da) and sodium dodecyl sulfate (SDS) from their ...mixed solution. There were applied three samples of activated carbons: N – obtained by peat pyrolysis followed by the steam activation, N9C – obtained from N by means of physical activation with CO2 and N9K – obtained from N by chemical activation with K2CO3. The final products are characterized by mesoporous structure, well-developed surface area and specific acidic-basic properties of the surface. The effect of solution pH, influencing PAA chains conformation (changes in polymer carboxyl groups dissociation) and solid surface charge density were examined. The applied adsorbents were characterized using the low-temperature nitrogen adsorption-desorption method, Fourier-transform infrared spectroscopy (FTIR), elemental analysis and back-titration method. Moreover, the adsorption affinity of PAA and SDS for the activated carbon surface was characterized based on the adsorption and electrokinetic data obtained from the spectrophotometric experiments, potentiometric titrations and zeta potential measurements. Additionally, the sizes of poly(acrylic acid) chains (hydrodynamic radius) in the solution as a function of pH were determined based on viscosity measurements. It was demonstrated that under specific pH conditions the prepared activated carbons exhibit high adsorptive affinity for PAA chains (reaching about 265 mg/g). Furthermore, it was also proved that these adsorbents can be successfully regenerated (using an appropriate desorbing agent) and reused. Therefore the low-cost activated carbons can be used for simultaneous removal of undesirable low-molecular polymers and surfactants from wastewaters.
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•Microporous activated carbon (CSDA) obtained by direct activation of cherry stones was prepared.•Adsorption of anionic poly(acrylic acid) − PAA on CSDA surface was examined.•Solution ...pH and PAA molecular weight influence on surface properties of activated carbon were determined.•The most favourable conditions for polymer removal from water solution were specified.•PAA amounts adsorbed on the CSDA surface were compared with those obtained for different metal oxide systems.
The adsorption properties of microporous activated carbon (CSDA) obtained by direct activation of cherry stones in relation to low-molecular weight poly(acrylic acid) − PAA were examined. The solution pH influence and molecular weight of the polymer were examined. The PAA adsorbed amounts were correlated with the solid surface charge density and zeta potential of the solid particle in the polymer presence. The obtained results indicated that the highest adsorption on the activated carbon surface is exhibited by PAA with lower molecular weight at pH 3 (it reaches the level of 25mg/g). Thus, under such conditions the CSDA is the most efficient adsorbent for poly(acrylic acid) removal from aqueous solution. The polymeric adsorption layer at pH 3 is composed of more coiled macromolecules (low degree of PAA carboxyl groups dissociation) which are electrostatically attracted to the positively charged solid surface. It was also proved that applied low-cost activated carbon can be used for removal of undesirable low-molecular polymers from wastewaters.
In recent years, the service life of building materials has become the focus of attention. Among them, the service life of concrete and steel bars is particularly affected by the corrosion of ...external ions (such as Cl
) in the environment. To solve this problem, a new type of composite nanocolloid was prepared through a controllable preparation method. The composite nanocolloid is prepared from aluminum chloride sol and silica sol as raw materials. The prepared colloidal particles have a particle size distribution between 10.5 and 17.5 nm, exhibiting excellent stability and dispersibility. In order to verify the improvement effect of the composite nanocolloid on the properties of building materials, the influence of it on the porosity of concrete and the anti-corrosion performance of steel bars was experimentally studied. The results indicate that the moisture absorption and dehumidification speed of concrete treated with composite nano colloids is slower, and the pore size distribution is mainly concentrated in 100–1,000 nm, indicating that the colloids can effectively optimize the pore structure of concrete. In addition, the processed steel plate samples showed high AC impedance values and low corrosion current logarithmic values in electrochemical testing, indicating that composite nanocolloids have a significant protective effect on the corrosion of steel bars, which can effectively improve the performance of building materials and extend their service life.
The activated biocarbons obtained from corncobs and peanut shells were applied for simultaneous removal of poly(acrylic acid) – PAA macromolecules and lead(II) ions from their mixed solution. The ...biocarbons were prepared via the two-step chemical activation, including pyrolysis of the precursors at 500 °C in nitrogen atmosphere, followed by impregnation with K2CO3 and heat treatment at 800 °C. The obtained materials were characterized using the low-temperature nitrogen adsorption-desorption method, elemental analysis and back-titration method. The activation products were micro/mesoporous biocarbons of medium developed surface area (862 and 654 m2/g, respectively), showing slightly acidic character of the surface. The average molecular weight of PAA ensured penetration of polymer coils into the adsorbent pores under specific pH conditions. The nanostructure of PAA adsorption layer without and with Pb(II) cations on the activated carbons surface was characterized based on the adsorption, electrokinetic, stability and microscopic data obtained from the spectrophotometric experiments, both potentiometric titration and zeta potential measurements, turbidimetric experiments and SEM imaging, respectively. It was shown that the micro/mesoporous biocarbons are effective and cheap adsorbents for simultaneous removal of polymeric macromolecules and heavy metal ions from the liquid medium (the presence of both adsorbates has an extremely favorable effect on their adsorbed amounts).
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•Corncobs- (CPA) or peanut shells- (NPA) based activated biocarbons were prepared.•Adsorption mechanism of anionic PAA polymer and Pb(II) cations was examined.•Mesoporous biocarbons removes polymer-metal complexes effectively at pH 3.•The solid-polymer-metal aggregates can be effectively separated from liquid phase.•Maximal PAA and Pb(II) adsorption reaches about 200 and 400 mg/g, respectively.
This paper presents a study on the influence of hydroxyl groups and oxygen atoms together with chain length and branching of carrier fluid on the rheological and electrokinetic properties of shear ...thickening fluid (STF). An STF is non-Newtonian fluid behaviour in which the increase of viscosity increases with the applied shear rate. Ethylene glycol, triethylene glycol, 1,3-propanediol, glycerin, poly(propylene glycol) of different molecular weight and poly(propylene glycol) triol were used as the carrier fluids (dispersants). Silica powder with an average particle size of 100nm was used as the solid phase. Zeta potential, particle size distribution (by DLS technique), steady-state and dynamic rheological measurements were conducted. Experimental results indicate that a different amount of hydroxyl groups and oxygen atoms together with chain length and branching of carrier fluids have a significant influence on the intermolecular interactions thereby and on the rheological properties of suspensions. Depending on the composition, it is possible to control rheological properties. The use of a suitable carrier fluid allows the required pattern flow to be obtained, from Newtonian through shear thinning to shear thickening, given specific shear conditions.
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