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Recent Advances in Heavy Metal Removal: Using Nanocellulose Synthesized from Agricultural Waste
Published in Sunil K. Deshmukh, Mandira Kochar, Pawan Kaur, Pushplata Prasad Singh, Nanotechnology in Agriculture and Environmental Science, 2023
Mandeep Kaur, Parueen Sharmal, Santosh Kumari
Cellulose and chemical moieties like esters, phosphate, etc. present in agricultural wastes enhance sequestration of heavy metals by complexation (Volesky and Holan, 1995; Hossain et al., 2012). Adsorption is a surface phenomenon in which a molecular species gets deposited onto the surface as demonstrated in Fig. 16.4. The molecular species which get adsorbed on the surface is adsorbent and the surface on which adsorption takes place is adsorbate (Grassi et al., 2012). Adsorption occurs because of raised free surface energy of the solids because of their enhanced surface area. Adsorption is of two types: physical adsorption and chemical adsorption. Physical adsorption (also known as physisorption) occurs due to Van der Waals forces of attraction between the adsorbate and the adsorbent. Physical adsorption combines many layers of adsorbate on the adsorbent and takes place at low temperature. Chemical adsorption (also known as chemisorption) occurs due to chemical forces of attraction or a chemical bond between the adsorbate and the adsorbent. Schematic representation of adsorption process.
Physical and Chemical Properties of Pesticides and Other Contaminants: Volatilization, Adsorption, Environmental Distribution, and Reactivity
Published in James N. Seiber, Thomas M. Cahill, Pesticides, Organic Contaminants, and Pathogens in Air, 2022
James N. Seiber, Thomas M. Cahill
When a solid absorbs a liquid mixture or part of it (e.g., a chemical contaminant dissolved in the liquid), a mass of liquid moves into the solid. For example, a clay pot used to store water may absorb some of the water. This mass transfer takes place at the interface between the solid and the liquid, at a rate depending on both the solid and the liquid. For example, pots made from certain clays are more absorbent than others. Absorption involves the whole volume of the material, while adsorption is a surface-based process. The term sorption encompasses both processes, while desorption is the reverse of them.
Design of Pump and Meat Systems
Published in Jimmy H.C. Wong, Chin Hong Lim, Greg L. Nolen, Design of Remediation Systems, 2020
Jimmy H.C. Wong, Chin Hong Lim, Greg L. Nolen
Many factors affect the adsorption process, such as water quality, temperature, flowrate, concentration of the target adsorbate(s), type of adsorbate(s), number of adsorbates, and level of adsorbate(s) removal required.
Thermodynamic studies of Congo red dye adsorption: avoiding erroneous conclusions from the use of isotherm models
Published in Journal of Dispersion Science and Technology, 2022
Adsorption is a process in which gas molecules, solid molecules, or ions in solution are attracted and held to the surface of a porous solid adsorbent by physical or chemical interaction. In physical adsorption, the interaction is due to van der Waals attraction, with bond strength typically less than 20 kJ. Chemisorption on the other hand arises from covalent bond with bond strength between 250 and 500 kJ. The adsorption phenomenon has found useful applications in biology, chemistry, industrial, natural and physical processes. The equilibrium behavior of adsorbent and adsorbate which are in contact at a fixed temperature is described by the adsorption isotherm. Adsorption isotherm are also affected by the nature of adsorbate, adsorbent, ionic strength of the medium and pH of the solution.[1,2] Knowledge of the isotherm is therefore important in predicting the behavior of an adsorption system for useful applications. Adsorption studies is crucial for the understanding of adsorption properties of the adsorbent–adsorbate system and is useful in characterization of adsorbent system and in industrial designs.[3]
Reduction of COD and ammoniacal nitrogen from stabilized landfill leachate by using green mussel and zeolite as composite adsorbent
Published in Journal of the Air & Waste Management Association, 2022
Amir Detho, Zawawi Daud, Mohd Arif Rosli, Halizah Awang
Adsorption is relatively a physiochemical technique widely used for stabilized landfill leachate treatment. Adsorption is basically a process of mass transferring substance from liquid to solid surface and to become bounded by physical-chemical interactions. Nowadays, focus have been increasing since the usage of low cost material (e.g., natural polymer or agricultural waste and industrial process by product) to achieve adequate leachate treatment as an alternative approaches to the conventional adsorbent for the treatment of water because of its availability locally and eco-friendly material. Application of zeolite (ZEO)-based adsorbents has certain advantages over conventional method used for treating the water. ZEO typically hydrated mineral aluminosilicate that belong to tectosilicates minerals and porous material (Latiff and Rahman 2016). ZEO has an advantage of natural – VE charge which allows it to adsorb cation. ZEO have potential as an efficient adsorbent in various treatment process of drinking water (Lakdawala and Patel 2015), reduction of ammoniacal nitrogen, color, dissolved organic matter, heavy metal from landfill leachate (Aziz et al. 2010; Rosli et al. 2017), and many others.
Determination of activated carbon fiber adsorption capacity for several common organic vapors: applications for respiratory protection
Published in Journal of the Air & Waste Management Association, 2021
Margaret Summers, Jonghwa Oh, Claudiu T. Lungu
GAC removes contaminants from the air through adsorption. Adsorption occurs as the result of a weak physical attraction (Van der Waals force) between a gas-phase molecule (adsorbate) and a solid surface (adsorbent). Because adsorption is a physical process, it is highly dependent on the surface characteristics of the adsorbent, and particularly on surface area (Webb and Orr 1997). The high surface area of GAC stems from the activation process, which imparts an extensive pore structure to the adsorbent. Within the resulting pore structure, pores less than 2 nm in width (micropores) are the most favorable sites for adsorption, due in large part to the combined attractive force exerted by the narrow pore walls of micropores on the adsorbate molecule (Hayes 1994). Both the total surface area and the microporosity of the adsorbent are indications of the total volume available for adsorption and can be directly related to the overall performance of the adsorbent (Lillo-Ródenas, Cazorla-Amorós, and Linares-Solano 2005). Conventional organic vapor respirators that rely on GAC adsorbents are effective, but may pose drawbacks in the form of weight and bulk of the assembly. These properties have an impact on the wearer’s perception of comfort; user comfort is strongly associated with consistent and proper respirator use (Gutierrez et al. 2014; Shaffer and Janssen 2015).