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Textile Odour Control by Adsorption
Published in G. Thilagavathi, R. Rathinamoorthy, Odour in Textiles, 2022
Ayşegül Çetmeli Bakadur, Ahmet Çay
In general, the adsorption process can be classified into two categories, physical and chemical adsorption. Physical adsorption, or physisorption, is a physical attraction between the adsorbate and adsorbent by van der Waals forces. Due to the interaction through a weak bond, it is a reversible process. On the other hand, chemical adsorption, or chemisorption, is the development of chemical bonds between adsorbate and adsorbent. Adsorbed molecules can form multiple layers in physical adsorption, whereas a single layer always occurs in chemical adsorption (Bansal and Goyal 2005; LeMinh et al. 2018; Saha and Grappe 2017; Webb 2003). Under favourable conditions, both physical and chemical adsorption processes can occur simultaneously or alternately (Dabrowski 2001).
Adsorbents
Published in Deepak Gusain, Faizal Bux, Batch Adsorption Process of Metals and Anions for Remediation of Contaminated Water, 2021
Shikha Dubey, Deepak Gusain, Yogesh Chandra Sharma, Faizal Bux
Physical adsorption or physisorption is an adsorption process in which the forces operating amid adsorbate and adsorbent are weak intermolecular forces (van der Waals forces) of attraction. This is characterized by the formation of multiple layers of adsorbed molecules over the adsorbent surface via van der Waals forces, electrostatic interaction, hydrogen bonds, weak covalent bonding, or dipole–dipole interaction (Lima et al. 2015).
Corrosion Inhibitors for Metals and Alloys in an Alkaline Medium
Published in Susai Rajendran, Gurmeet Singh, Titanic Corrosion, 2019
Susai Rajendran, Gurmeet Singh
The inhibition effect is due to the adsorption of the inhibitor molecule on the metal surface. Adsorption may be physical adsorption (physisorption) or chemical adsorption (chemisorption), depending on the adsorption strength. In chemisorption, one of the reacting species acts as an electron donor and the other one acts as an electron acceptor. The energy of the HOMO (Ehomo) measures the tendency toward the donation of an electron by a molecule. High values of Ehomo have a tendency of the molecule to donate electrons to appropriate acceptor molecules.
Biosorption of heavy metals from water: mechanism, critical evaluation and translatability of methodology
Published in Environmental Technology Reviews, 2022
Risha Jasmine Nathan, Arvind Kumar Jain, Rhonda J. Rosengren
The interaction between the biosorbent and biosorbate may occur via physisorption or chemisorption mechanisms. Physisorption reactions involve weak forces such as van der Waals forces, hydrogen bonds or ∏−∏ interactions, and are reversible in nature, whereas, in chemisorption, strong chemical bonds are formed by exchange of electrons between the ions and surface functional groups [236]. Physisorption and chemisorption may occur either simultaneously or alternatively [199]. For understanding this biosorbent–biosorbate interaction, experiments are performed with different initial metal concentrations. Biosorption capacity at equilibrium (qe) is plotted against the corresponding equilibrium solution concentration (ce) at constant temperature and such plots are known as biosorption isotherms [239,240]. Various isotherm models are used to describe the mechanism of biosorption.
Adsorption kinetics of lac dye on eri silk yarn
Published in The Journal of The Textile Institute, 2022
Vatita Leamkaew, Phattaraporn Thongsamai, John B. Bremner, Montra Chairat
The obtained adsorption rate constants (k) at different temperatures were then applied to determine the activation energy (Ea) of the adsorption of lac dye on eri silk yarn by the Arrhenius equation (5): where Ea, R and A refer to the Arrhenius activation energy, the gas constant (8.314 J K−1 mol−1) and the Arrhenius factor respectively. In the Arrhenius equation (5), but not in a later modified Arrhenius equation (Laidler, 1996), A is considered to be temperature independent. The former equation was applied in this work. The activation energy (Ea) was thus calculated from the slope of a plot of ln k versus 1/T. The activation energy (Ea) for the adsorption of lac dye on eri silk yarn was found to be 35.9 kJ mol−1 (R2 = 0.9847) as shown in Table 1. Generally, physical adsorption or physisorption is the process, when the forces of attraction existing between adsorbate and adsorbent are weak Van der Waals forces of attraction. It has low activation energy in the range 20-40 kJ mol−1. For chemical adsorption, the adsorption of adsorbates on adsorbents is due to the formation of chemical bonds between them. Chemical adsorption can take place at all temperatures. The value of the activation energy for chemical adsorption is about 80-240 kJ mol−1. The adsorption of lac dye on eri silk yarn was found to be predominantly a physisorption process.
The adsorptive removal of lead ions in aquatic media: Performance comparison between advanced functional materials and conventional materials
Published in Critical Reviews in Environmental Science and Technology, 2020
Botao Liu, Azmatullah Khan, Ki-Hyun Kim, Deepak Kukkar, Ming Zhang
As aforementioned, adsorption-based removal of Pb2+ has been one of the preferable options due to various advantages (e.g., facile operation, recovery of adsorbent/adsorbate, and cost-efficiency). The adsorption mechanism involves physisorption and chemisorption (Ho, Ng, & McKay, 2001; Unuabonah, Adebowale, & Olu-Owolabi, 2007). Physisorption, also known as van der Waals adsorption, is the adsorption between adsorbate and adsorbent based on intermolecular forces, including electrostatic and dispersive forces, between the solid surface and adsorbate molecules. Chemisorption is the adsorption in which adsorbate and adsorbent interact to generate chemical bonds (e.g., metal organic complexes or cation exchange reactions). For more detailed contents about the adsorption mechanism, readers may refer to SM 2.2.2.