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Manufacturing Techniques for Nanoparticles in Drug Delivery
Published in Yasser Shahzad, Syed A.A. Rizvi, Abid Mehmood Yousaf, Talib Hussain, Drug Delivery Using Nanomaterials, 2022
Daniel Real, María Lina Formica, Matías L. Picchio, Alejandro J. Paredes
The preceding described methods require the use of organic solvents and surfactants that could be hazardous for the environment and physiological systems. In this sense, supercritical fluids have emerged as an interesting alternative due to the use of an ecofriendly methodology, and homogenous and easy scale-up (Adschiri and Yoko, 2018). This procedure is based on using a fluid heated and compressed above its critical temperature and critical pressure. In such conditions, the fluid behaves like a gas but with the solvating properties and density of a liquid. Supercritical carbon dioxide is the most broadly used supercritical fluid because it has mild critical conditions and is nontoxic, inexpensive, abundant, nonflammable, and environmentally benign.
Materials and Synthesis of pH-Responsive Membranes
Published in Randeep Singh, Piyal Mondal, Mihir Kumar Purkait, pH-Responsive Membranes, 2021
Randeep Singh, Piyal Mondal, Mihir Kumar Purkait
The unique properties of supercritical fluids make them desirable for many processes. Supercritical carbon dioxide is the most useful because of its properties, such as it being economical, nontoxic, and nonflammable. Also, its critical parameters are reasonable, with a critical temperature of 31.1°C and a critical pressure of 7.38 MPa. Recently, the major use of critical carbon dioxide is as a solvent in the fields of polymer processing and chemistry. It is used to develop various polymers, fine particles, fibers, polymer fractionation, and foam materials. Supercritical carbon dioxide has the ability to dissolve smaller organic compounds and swell many others. Therefore, supercritical carbon dioxide is useful for the impregnation of different additives in polymers. The properties, such as high diffusivity, low viscosity, negligible surface tension, and tunable solvent strength, help in the uniform distribution of the monomers along with initiators in a very short period of time. Also, it is easy to remove carbon dioxide from the final product because it will be in the gaseous state at ambient conditions of pressure and temperature. Thus, it is very effective and beneficial to use supercritical carbon dioxide for the modification of membranes.
Detoxification of Biomedical Waste
Published in Ram Chandra, R.C. Sobti, Microbes for Sustainable Development and Bioremediation, 2019
Bamidele Tolulope Odumosu, Tajudeen Akanji Bamidele, Olumuyiwa Samuel Alabi, Olanike Maria Buraimoh
This is a nonthermal sterilization technique used extensively for the inactivation and removal of viable microorganism for commercial purpose, especially in food and pharmaceutical industries. The technique works on the principle of solubility and diffusion of pressure through the microbial cell membrane. It avoids the use of high temperature during extraction since many supercritical fluids are best kept at low temperature in order to preserve the integrity of such products under study. Supercritical carbon dioxide (Sc-CO2) is environmentally friendly because it is nontoxic although inflammable (Zhang et al., 2008). This method is highly effective for the inactivation of infectious organisms and their spores (Banana, 2013); it is based on three principles in combination: carbon dioxide, temperature, and pressure that are all critical for the growth and development of many living cells. Sc-CO2 has been demonstrated to be effective methods for remediation of high solvent loads in the environment, e.g., toluene, IPAc, MTBE, etOAc, and so on. The major advantage of this method is in the recovery of the CO2 for reuse and further increasing the preservation of the environment and the green chemistry.
An extraction-based facile method for measuring the solubility of organic solid compounds in supercritical carbon dioxide
Published in Chemical Engineering Communications, 2023
Jian-Lei Qi, Qin-Qin Xu, Jian-Fei Sun, Dan Zhou, Jian-Zhong Yin
Supercritical carbon dioxide (scCO2) is an environmentally friendly solvent, since it is non-flammable, nontoxic, chemically inert, low-cost, and readily available, as well as having mild critical temperature and pressure (304.26 K and 7.38 MPa, respectively) (Pishnamazi et al. 2021; Rai et al. 2017; Wang et al. 2021). It has been applied widely in plant extraction, nanocomposite preparation, chemical reactions, microelectronics, and cleaning precision instruments (Putra et al. 2021; Qiao et al. 2020a, 2021; Ushiki et al. 2020; Yin et al. 2009). Especially, supercritical fluid deposition (SCFD) based on scCO2 has been used in recent years to fabricate supported nanocomposites and even single-atom catalytic materials on porous supports (Qi et al. 2021; Qiao et al. 2020a, 2020b; Yin, Xu, and Wang 2009). In the typical SCFD method, scCO2 with both liquid-like solubilization capacity and gas-like diffusion behavior can easily transport precursors into the porous supports, resulting in highly dispersed precursors on the support surface at adsorption equilibrium (Zhang et al. 2014). Furthermore, the absence of surface tension in scCO2 prevents the collapse of pore channels during the depressurization process (Bozbağ and Erkey 2015). Since the dissolution and crystallization of precursors (commonly metal salts) are very important in the SCFD process, it is essential to accurately measure the solubility of metal complexes in scCO2.
Lipase-mediated epoxidation of alkenes in supercritical carbon dioxide
Published in Green Chemistry Letters and Reviews, 2018
Jiaxin Zhang, Wenwei Qian, Chunyu Wang, Ziyi Cao, Shanshan Chen, Liu Zhang, Yang Zhang, Lei Wang
It is known that supercritical carbon dioxide (scCO2) has a prodigious potential as an environmentally benign reaction medium for sustainable chemical synthesis due to its advantages, such as low cost, nontoxicity, non-flammability, inertness, full recovery and moderate critical properties (Pc= 7.38 MPa, Tc = 304.2 K) when compared to other green solvents (19–22). Many researches showed that lipases are active and stable in scCO2, which increased the potential use of scCO2 in lipase-catalyzed reactions (23–25). For example, isoamyl acetate could successfully be synthesized from isoamyl alcohol in scCO2 by novozym 435, and an esterification extent of 100% was obtained (26). Santos et al. reported that higher esterification rates could be obtained when the esterification of oleic acid with methanol was catalyzed by lipase in scCO2 (27). These findings encourage further studies to develop scCO2 as a reaction medium in enzymatic promiscuous reactions, such as lipase-mediated epoxidation.
Mass transfer and hydrodynamic study of supercritical carbon dioxide extraction of 1,8-cineole from small cardamom seeds
Published in Chemical Engineering Communications, 2018
Kaninika Paul, Paramita Bhattacharjee
The purpose of exploration of bioactive compounds in natural sources lies in the roles of these in combating maladies as well as for their usage as food supplements (Silva et al., 2016). Supercritical carbon dioxide (sc-CO2) extraction is widely used worldwide in extraction of bioactive molecules from natural botanicals. This is a green technology of extraction in its utilization of readily available CO2 as the extracting solvent, which is nontoxic, nonflammable and exhibits high selectivity toward analytes owing to its low viscosity, high diffusivity, and liquid-like density (Reverchon et al., 1993).