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Physical Control Measures
Published in Larry W. Canter, Robert C. Knox, Ground Water Pollution Control, 2020
Larry W. Canter, Robert C. Knox
One means of reducing the threat to ground water from land disposal of waste materials is to structurally isolate the waste material in a solid matrix prior to landfilling. This process, known as stabilization/solidification, is becoming increasingly popular for hazardous and radioactive waste disposal (U.S. Environmental Protection Agency, 1979). The objective of solidification/stabilization processes is to chemically fix the waste in a solid matrix. This reduces the exposed surface area and minimizes leaching of toxic constituents. Effective immobilization includes reacting toxic components chemically to form compounds immobile in the environment and/or entrapping the toxic material in an inert stable solid. Thus stabilization and solidification have different meanings, although the terms are often used interchangeably. From a definitional perspective, stabilization refers to immobilization by chemical reaction or entrapping (watertight inert polymer or crystal lattice), while solidification means the production of a solid, monolithic mass with sufficient integrity to be easily transported. It will become apparent that these processes may overlap or take place within one operation. An example is cementation where the process both stabilizes by producing insoluble heavy metal compounds, and solidifies into a formed mass while entrapping the pollutants.
Fabrication and Functionalization of Other Inorganic Nanoparticles and Nanocomposites
Published in Vineet Kumar, Praveen Guleria, Nandita Dasgupta, Shivendu Ranjan, Functionalized Nanomaterials I, 2020
Kiranmai Mandava, Uma Rajeswari B.
Another method of photo powdered hydrolysis was reported to prepare IrOx nanoparticles and Ir/IrOx nanocomposite. A partial reduction of IrOx to iridium on the surface of IrOx nanoparticles is useful to prepare this nanocomposite (Di et al., 2015). Iridium nanoparticles can be fabricated in one phase in surfactant-free conditions using tetrahydrofuron as a solvent (Yee et al., 1999). A method was reported to synthesize stable iridium nanoparticles by employing sodium S-dodecylthiosulfate as a ligand precursor using sodium borohydride reduction (Diego et al., 2015). Recently, research has focused on the immobilization of nanomaterials. A kind of nitrogen-doped carbon nanomaterials has been explored with glucose and dicyandiamide as carbon and nitrogen sources to immobilize iridium catalyst for alcohol condensation in water (Di et al., 2016).
Role of Enzymes in Bioremediation of Organic Pollutants
Published in M.H. Fulekar, Bhawana Pathak, Bioremediation Technology, 2020
Smita Chaudhry, Rashmi Paliwal
Application of immobilized enzymes can overcome the problems associated with the long-term utilization of suspended enzymes for the degradation of toxic compounds. Immobilization is the process of confining any biological agent or enzyme to a defined support or matrix. It resists the movement of biological agents in the space while retaining their activities in the medium. Therefore, immobilized systems can offer several advantages and improve the efficiency of the decontamination process (Engade and Gupta, 2010; Chaudhry and Paliwal, 2018). Enzymes catalyze a reaction either intracellularly (i.e., within their originating cells) or extracellularly (i.e., in the environment) when released outside by the originating cells. In the free state of activity (solublein the reaction solution), the process of catalysis is homogenous, whereas in the immobilized state, when the enzymes are retained on a solid matrix, the catalysis is heterogeneous (Gianfreda and Rao, 2004). Some advantages and disadvantages of application of enzyme immobilization are summarized in Table 6.3.
Porous poly (lactic acid)/poly (ethylene glycol) blending membrane for microorganisms encapsulation
Published in Environmental Technology, 2023
Hua Li, Yafei Duan, Hongbiao Dong, Jiasong Zhang
Immobilized microorganisms technology limit cells or enzymes in a confined space, keep a high density of microorganisms, fast reaction rate, and low sludge production and reduce the toxic effect of harmful substances on microorganism [1, 2]. Immobilized microorganisms technology has been explored as a promising wastewater treatment method [3–7]. Generally, immobilization techniques include surface adsorption, entrapment in a matrix and encapsulation [8, 9]. Adsorption on a carrier surface is achieved by the physical interaction between the microbial cells and the carrier. As the interaction is weak and there is a higher risk of cells leaking [8]. Entrapment of microorganisms in alginate [10] or other polymeric matrices [11, 12], the microorganism is immobilized tightly in the matrix. Immobilized microorganism experience lower metabolic activity resulting from lower nutrient and oxygen availability due to lower diffusion rates through the matrix [13].
Effect of thiourea-modified biochar on adsorption and fractionation of cadmium and lead in contaminated acidic soil
Published in International Journal of Phytoremediation, 2020
Leila Gholami, Ghasem Rahimi, Abolfazl Khademi Jolgeh Nezhad
Heavy metals are persistent and difficult to remove or degrade once introduced into soils. During the past decades, cost-effective and environmentally friendly techniques have been developed to reduce the mobility and bioavailability of heavy metals in contaminated soils (Song et al. 2017). Situ immobilization is an economical and environmentally friendly technology, which could effectively immobilize the contaminants and reduce ecotoxicity in contaminated soil by adsorption, complexation, and precipitation processes (Liu et al. 2018). Soil amendments have been commonly used for in situ remediation of metal contaminated soil (Kumpiene et al. 2008). Biochar is the solid product from the pyrolysis of waste biomass, such as agricultural and forestry residues, sewage sludge, manure and dead animals (Mendez et al. 2012; Ok et al. 2015). Recent studies have shown that biochar also has great potential for immobilizing heavy metals in soil (Dai et al. 2018), because of its highly porous structure, active functional groups, high pH, and cation exchange capacity (CEC) (Park et al. 2011).
Improvement of lipase activity by synergistic immobilization on polyurethane and its application for large-scale synthesizing vitamin A palmitate
Published in Preparative Biochemistry & Biotechnology, 2019
Caixia Cui, Linjing Li, Mingjie Li
There are four main immobilization techniques: physical adsorption, covalent binding, cross-linking, and entrapment.[15] Each method has its strengths and weaknesses on promoting enzyme activity, stability, and selectivity.[10] Physical adsorption keeps enzyme structural conformation stable; however, the enzyme can easily leak from the support. Covalent binding and cross-linking improve enzyme stability; however, the effect on the enzyme properties was not always positive.[30,31] Entrapment retains enzyme activity; however, substrate and products diffusion efficiency was decreased. Therefore, it is impossible to promote the activity and stability of enzyme by relying on a single immobilized method.