Search results for "adsorption"

Photocatalytic oxidation of gaseous toluene on polycrystalline TiO2: FT-IR investigation of surface reactivity of different types of catalysts

2000

Commercial TiO 2 Merck and TiO 2 Degussa P25 powders were employed as the catalysts for the photo-oxidation of toluene. By using TiO 2 Merck benzaldehyde was found in gas phase as the main product of the toluene partial oxidation. After an initial transient period, this catalyst exhibited a high stability in the presence of water vapour in the gaseous mixture, whereas the photoproduction of benzaldehyde sharply decreases after removal of H 2 O from the feed IR spectra of the used catalyst revealed that in the absence of water vapour benzaldehyde is molecularly held on the catalyst surface. This feature was confirmed by co-adsorbing benzaldehyde and water on the fresh catalyst. By contrast, …

Synthesis of a New Disulfide Affinity Adsorbent for Purification of Human Uterine Progesterone Receptor

2005

For purification of the human uterine progesterone receptor, an affinity adsorbent was synthesized in which the specific ligand (16 alpha-ethyl-3-oxo-19nor-androst-4-ene 17 beta-carboxylic acid) was bound to derivatized celulose using a disulfide-group-containing spacer. The purified receptor protein, isolated by reductive cleavage of the disulfide bond, bound the synthetic gestagen R5020 with high affinity (Kd 12.2 nmol/l). The affinity gel was highly efficient. A 24000-fold purification of progesterone receptor with a recovery of 40% could be achieved in a single step within 6 h. By means of dodecyl sulphate/polyacrylamide gel electrophoresis two main polypeptides with molecular weights o…

Aqueous phase/nanoparticles interface: hydroxypropyl cellulose adsorption and desorption triggered by temperature and inorganic salts

2012

The study highlighted the main forces driving the adsorption of hydroxypropyl cellulose (HPC) onto clay nanoparticles with a disk-like shape (Laponite RD). Modeling the isothermal titration calorimetry data provided the key thermodynamic properties, which enabled us to discuss the microscopic aspects contributing to the energetic and the entropic changes of the polymer adsorption at the nanoparticle/liquid interface. We evidenced that the process is strongly enthalpy-driven and that the interactions lead to constraints of the HPC configuration at interface. The functionalized nanoparticles enhanced the polymer solubility in water expanding the one-phase area of the binodal curve. Temperatur…

Hydrocarbons removal from synthetic bilge water by adsorption onto biochars of dead Posidonia oceanica.

2022

AbstractBilge waters are wastewaters produced on boats during navigation and usually contain hydrocarbons and oils. They cannot be directly released into the sea if not below a hydrocarbons concentration limit set by current legislation. Appropriate oil in water separator (OWS) systems can be installed on board boats to remove hydrocarbons from bilge water allowing their spillage into the sea. These systems may contain an adsorption step on a suitable adsorbent. Here, biochars produced from pyrolysis of dead Posidonia oceanica, pristine or chemically activated, have been tested as hydrocarbons adsorbents. Adsorption experiments with aqueous dispersions simulating bilge waters containing a m…

Hydrocarbons removal from wastewater by adsorption onto biochar from Posidonia oceanica

Environmental pollution by petroleum derivatives is a very current topic. In particular, low concentration of this kind of pollutants can seriously compromise the life of animals and plants of aquatic ecosystems [1]. For this reason, recent environmental legislation imposes severe restriction to oil-in-water content for overboard discharge with concentration limits from 15 to 5 ppm [2]. The shipping industry is trying to adapt to these directives by equipping ships with cleaning treatment devices in which there are several oil removal steps. Usually, the last step of bilge water treatment is based on adsorption onto suitable adsorbent materials that must be able to remove the last and most …

Biogenic Selenium Nanoparticles: A Fine Characterization to Unveil Their Thermodynamic Stability

2021

Among the plethora of available metal(loid) nanomaterials (NMs), those containing selenium are interesting from an applicative perspective, due to their high biocompatibility. Microorganisms capable of coping with toxic Se-oxyanions generate mostly Se nanoparticles (SeNPs), representing an ideal and green alternative over the chemogenic synthesis to obtain thermodynamically stable NMs. However, their structural characterization, in terms of biomolecules and interactions stabilizing the biogenic colloidal solution, is still a black hole that impairs the exploitation of biogenic SeNP full potential. Here, spherical and thermodynamically stable SeNPs were produced by a metal(loid) tolerant Mic…

Molecular Dynamics Simulations of the Initial Adsorption Stages of Fibrinogen on Mica and Graphite Surfaces.

2015

Fibrinogen, a blood glycoprotein of vertebrates, plays an essential role in blood clotting by polymerizing into fibrin when activated. Upon adsorption on material surfaces, it also contributes to determine their biocompatibility and has been implicated in the onset of thrombosis and inflammation at medical implants. Here we present the first fully atomistic simulations of the initial stages of the adsorption process of fibrinogen on mica and graphite surfaces. The simulations reveal a weak adsorption on mica that allows frequent desorption and reorientation events. This adsorption is driven by electrostatic interactions between the protein and the silicate surface as well as the counterion …

The Internal Dynamics and Early Adsorption Stages of Fibrinogen Investigated by Molecular Dynamics Simulations

2016

Fibrinogen, a plasma glycoprotein of vertebrates, plays an essential role in blood clotting by polymerizing into fibrin upon activation. It also contributes, upon adsorption on material surfaces, to determine their biocompatibility and has been implicated as a cause of thrombosis and inflammation at medical implants. Here we present the first fully atomistic simulations of the initial stages of the adsorption process of fibrinogen on mica and graphite surfaces. The simulations reveal a weak adsorption on mica that allows frequent desorption and reorientation events. This adsorption is driven by electrostatic interactions between the protein and the silicate surface as well as the counter io…

Catalytic transesterification of Pistacia chinensis seed oil using HPW immobilized on magnetic composite graphene oxide/cellulose microspheres

2018

Abstract In the present study, magnetic composite graphene oxide/cellulose (GO/CM@Fe3O4) microspheres were prepared as support material, which are cost-efficient, non-toxic and environmental friendly. The microspheres with higher adsorption capacity were further modified using triethylene tetramine (TETA), and H3PW12O40 (HPW) was immobilized to form GO/CM-NH2@Fe3O4-HPW microspheres as heterogeneous catalyst for biodiesel production. The novel heterogeneous catalyst was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) and X-ray diffractometry (XRD). For the first time, GO/CM-NH2@Fe3O4--HPW was applied in the tr…

Saving time when measuring BET isotherms.

2007

The measurement of adsorption isotherms and the detn. of surface properties of a solid by means of the BET equation usually takes a lot of time as it involves measurement of several dynamic adsorption curves each at a given gas pressure. Two different timesaving approaches are suggested: (a) the beginning of a single dynamic curve is considered and (b) the beginnings of a no. of different dynamic curves is considered. Approach (a) is less time consuming than approach (b), where approach (b) yields more accurate ests. of the BET-parameters. A discussion is given of the possibilities of using the time saving procedure of Jaentti for the two approaches. [on SciFinder (R)]