Role of Surfactant in Other Organs
Jacques R. Bourbon in Pulmonary Surfactant: Biochemical, Functional, Regulatory, and Clinical Concepts, 2019
Adsorption is a particularly common process, especially of the weak physical type where van der Waals’ forces may hold layers several hundred molecules in thickness in loose association with the surface. Much stronger adsorption can be effected when one of the chemical groups (moieties) in the molecule forms a chemical bond with the surface known as chemisorption.1,2 This is still not obvious to an observer unless the two ends of the adsorbed molecule are of widely differing character, especially in their affinity for water, as one finds between the polar and nonpolar moieties of surfactant molecules. The attachment of a surfactant molecule by, for instance, electrostatic attraction between the polar moiety and a fixed charge on the surface orientates the molecule with its nonpolar group facing outward. This effects a total “change of personality” in which a highly wettable surface such as glass or cotton can be rendered hydrophobic and water repellent. Thus, droplets of water which would have spread spontaneously on clean glass now “bead up” to display a contact angle which provides a convenient index of the change in surface energy upon adsorption.3
Surfactants in Cosmetic Products
Heather A.E. Benson, Michael S. Roberts, Vânia Rodrigues Leite-Silva, Kenneth A. Walters in Cosmetic Formulation, 2019
Surfactants, being a class of substances that preferentially adsorbs at several types of interfaces due to their amphiphilic structure, are very useful in the detergency process. In most detergent-related adsorption processes it is the interaction of the hydrophobic moiety of the surfactant molecule with dirt particles that produces the detergent action. Such adsorption changes the chemical, electrical and mechanical properties at the various interfaces and depends strongly on the nature of each component. In cleaning the hair with anionic surfactants, for example, the adsorption of the surfactant onto the hair fibre and onto the dirt particles introduces repulsive electrostatic interactions that tend to reduce adhesion between the dirt and the hair, suspending the dirt and preventing its redeposition. The process is illustrated schematically in Figure 9.10 . With non-ionic surfactants the mechanism is less clear. However, the steric repulsion between layers of adsorbed surfactants and solubilization are extremely important.
Tuning the Properties of Silver Monolayers for Biological Applications
Huiliang Cao in Silver Nanoparticles for Antibacterial Devices, 2017
Self-assembly of nanoparticles is identified as an important process where the building blocks spontaneously organise into ordered structures. Therefore, the adsorption and deposition of molecules and colloidal particles at various interfaces without the additional external forces (e.g. centrifugal force) are referred to as self-assembly processes. In turn, the layers obtained in these processes are called self-assembled layers. The adsorption of molecules and particles usually occurs as a result of van der Waals and electrostatic interactions, although in some cases, chemisorptions can take place as well (Kumar 2010). In self-assembly processes, as in the case of the dip-coating technique, the substrate is dipped in the proper solutions containing molecules or particles, which are used for surface modification. However, in contrast to dip-coating, the monolayers are not formed during the withdrawal of the substrate from the solutions but directly during the storage of the substrates in these solutions.
Preparation of AC/KOH and AC/Fe3O4/ZnO nanocomposite from waste rice straw for the removal of cyclophosphamide from aqueous solutions
Published in Toxin Reviews, 2023
Ali Asghar Haghgoo, Mehrdad Cheraghi, Soheil Sobhanardakani, Bahareh Lorestani, Vida Izadkhah
Effluent and drinking water treatment operations have not been designed specifically for the removal of pharmaceuticals. Hence, plans for the elimination of pharmaceuticals from water samples have been predominantly investigated. Advanced wastewater treatment operations (e.g. flocculation, membrane nanofiltration, advanced oxidation, adsorption, and reverse osmosis) propose great removal rates for drug compounds (Al-Musawi et al.2021, Balarak et al.2021). However, there are concerns in regard with the unpleasant by-products and cost-effectiveness of these treatment processes. Among the above-mentioned methods, adsorption has been reported as a more preferable technique than the others owing to its high versatility, efficiency, relatively high cost-effectiveness with no secondary pollution (Sobhanardakani and Zandipak 2015, 2017, Zandipak and Sobhanardakani 2016, Ghoochian et al.2019).
Synthesis and characterization of water stable polymeric metallo organic composite (PMOC) for the removal of arsenic and lead from brackish water
Published in Toxin Reviews, 2022
Khalil Ahmad, Habib-Ur-Rehman Shah, Hafiza Ammara Nasim, Asif Ayub, Muhammad Ashfaq, Abdul Rauf, Syed Shoaib Ahmad Shah, Muhammad Mahboob Ahmad, Haq Nawaz, Ejaz Hussain
Adsorption process is proceeded by various procedures as reported in literature. Some of these are (i) surface area and volume, (ii) electrostatic interactions, (iii) hydrogen bonding, (iv) adsorbents having active sites, (v) chemical and porous nature of the adsorbent, (vi) π–π interaction, and (vii) acid–base interaction. Adsorption process takes place by physically or chemically; chemically based upon functional group and physically be influenced by the surface of adsorbents. Before and after the adsorption process, FTIR spectrum was accomplished to elucidate the adsorption mechanism of Co-MOF/PANI composite. From the FTIR spectrum, it was calculated that the spectra after adsorption indicated peaks at 542, 921.71, and 832.71 cm−1 which are due to the interaction of composite with arsenic and lead, and these peaks are not present in the spectrum before adsorption as shown in Figure S1. From this FTIR spectrum, it was revealed that the hydroxyl group is responsible for adsorption of Pb(II), As(III), As(V), and DMA upon the surface of adsorbent. Moreover, the peaks in FTIR spectrum at 542, 921.71, and 832.71 cm−1 were presented owing to As–O and Pb–O bond, respectively (Li et al.2020). Adsorption mechanism is also represented schematically in Figure 7.
Dyes adsorption properties of KOH-activated resorcinol-formaldehyde carbon gels -kinetic, isotherm and dynamic studies
Published in Toxin Reviews, 2022
Azrul Nurfaiz Mohd Faizal, Muhammad Abbas Ahmad Zaini
The release of pollutants into the water bodies is a subject of considerable concern. The damaging effect of water contaminants brings bad implications to aquatic ecosystem and human who relies on water resources for routine life. Adsorption is a preferable method that has been widely applied in wastewater treatment. Adsorption is a process where target solute is adhered to solid surface via several mechanisms such as π-π interaction, ion exchange, pore filling, and complex formation (Ming-Twang et al.2015). In addition, adsorption in continuous mode is suitable to handle large volume of wastewater because of simple and easy operation, less space needed for equipment and minimum costs for manufacturing, operating and maintenance. However, commercial adsorbents available today are normally in powder or granular form, so unfit for continuous process. Despite the large specific surface and rich surface chemistry of adsorbent, the column operation may suffer in escalating pressure drop due to hydraulic resistance, hence compromising the column performance and so increasing the operating cost (Masuda et al.2013).
Related Knowledge Centers
- Absorption
- Activated Carbon
- Atom
- Chemisorption
- Heterogeneous Catalysis
- Molecule
- Solvation
- Sorption
- Ion
- Surface Science