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Ceramic Based Biomaterials
Published in Yaser Dahman, Biomaterials Science and Technology, 2019
Zirconia is made through the decomposition reaction of zircon (ZrSiO4) (Ayala et al., 2003). The first step of the process is called zircon disintegration; it is composed of mixing zircon with soda ash or with lime. Thermal treatment of the product is then performed, where the temperature can range from 1100 to 1600°C. It takes from 5 minutes to 3 hours to dry depending on the amount of soda ash used. The result of this step is a mixture of monoclinic zirconia, Na-silicozirconate, and amorphous silica. To remove the amorphous silica, a wet chemistry process is performed, called alkali leaching. This process consists of the mixture being treated with NaOH solution in an acid digestion bomb, which is later heated at a temperature of 200°C. Finally, the last step is acid leaching using hydrochloric acid. This is done to remove the Na-silicozirconate from the mixture leaving behind the desired zirconia product. Overall, the zirconia product created is dependent on the concentration of the soda ash, the temperature of the reaction, and the overall reaction time (Ayala et al., 2003).
Solid and Hazardous Waste
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
Incineration accounts for less than two percent of the hazardous wastes managed although it offers the advantages of (1) completely destroying many forms of hazardous waste, (2) reducing the volume of waste, (3) and recapturing energy in the form of steam or electricity. Thermal treatment may include incineration or pyrolysis. Pyrolysis combusts materials in an oxygen-starved atmosphere and is not as widely used as incineration, which is conducted in an oxygen-rich environment. Incineration is normally conducted at temperatures of 425°C to 1650°C (800°F–3000°F) in a turbulent atmosphere of sufficient duration that will ensure good mixing and effective destruction of the waste approaching levels of the USEPA current standard of 99.99 percent.36,37 Incinerators have been used successfully to treat waste paints, plastics, mineral oils, pesticides, solvents, sludge, resins, greases, and waxes. The threat of hazardous emissions, including acids, dioxin, and heavy metals, have led to strict regulations on emissions from incinerator facilities.38 The materials generated in an incinerator include carbon dioxide, water, sulfur, and nitrogen oxides, acid gases such as hydrogen chloride, and ash. Gas streams must be monitored, and hazardous materials must be removed from the emissions by various scrubbers, filters, and electrostatic precipitators. This has prompted very high construction and maintenance costs but has become a useful alternative as the options for land disposal continue to decrease.
Urban Waste (Municipal Solid Waste—MSW) to Energy
Published in Sheila Devasahayam, Kim Dowling, Manoj K. Mahapatra, Sustainability in the Mineral and Energy Sectors, 2016
Moshfiqur Rahman, Deepak Pudasainee, Rajender Gupta
WtE processing involves thermal treatment and can release particulates and toxic metals including Hg, in contrast to the other energy recovery options from natural resources. Major advantages of the thermal treatment method are that it reduces the volume of disposed waste and destroys harmful microorganisms, helping to keep society healthy. MSW treatment can be divided into two sections: (a) nonthermal treatment and (b) thermal treatment. Nonthermal treatment processes are classified as dumping and landfilling and aerobic and anaerobic composting processes (described in section “Nonthermal Conversion”). Thermal treatment methods are pyrolysis, gasification, and incineration technologies (described in section “Thermal Conversion”). It must be noted that the purpose of thermal WtE is not to produce power for the sake of producing power (electricity or fuels), rather it is a by-product of reducing the volume of MSW as well as environmental issues. WtE may produce more harmful emissions that may be expensive in terms of treatment.
Chitosan-based electrospun nanofibers mat for the removal of acidic drugs from influent and effluent
Published in Chemical Engineering Communications, 2023
Henriette Niragire, Temesgen Girma Kebede, Simiso Dube, Malek Maaza, Mathew Muzi Nindi
One of the most environmentally friendly treatment procedures is thermal treatment. Nanofibers must be insoluble in water for their intended use in water treatment. Thermal crosslinking was chosen for this study because it is environmentally benign, and it does not require the use of toxic chemicals (Tonglairoum et al. 2014). Cay et al. suggested this method above other cross-linking methods for nanofiber stabilization because it was observed to have no mass loss after water treatment (Çay et al. 2014). Following thermal treatment, FTIR and XRD were used to examine the functional groups and crystallinity of the nanofibers in order to investigate the effect of heat treatment on the treated nanofibers. The FTIR results (Figure 15) indicated the identical vibration bands before and after thermal treatment, however, there was a tiny shift of the peak to a lower intensity, which is due to the eliminated water molecule. The original form of nanofibers exhibited a superior crystalline structure than the thermally treated ones, as shown by the XRD data in Figure 16, with the diffraction pattern peaks at 2 = 10° and 20°. This can be attributed to some inter and intra-molecule hydrogen bonds that have been destroyed during the thermal treatment. These results are in agreement with the FTIR data whereby there is a shift at lower intensity after thermal treatment.
Pyrolysis kinetic study of cathode material derived from spent lithium ion batteries (LIBs): Comparison of different models
Published in Journal of the Air & Waste Management Association, 2021
Shaoqi Yu, Baogui Zhang, Jingjing Xiong, Zhitong Yao, Daidai Wu, Jie Liu, Shaodan Xu, Junhong Tang
As a comparison, thermal treatment has the advantages of simple operation and high efficiency (Cheng et al. 2019; Qi et al. 2019; Reis et al. 2019; Yu et al. 2019). Zhang et al. (2019, 2018, 2019) removed the PVDF binder using pyrolysis treatment. The optimum pyrolysis temperature of organic binders in electrode materials was determined as 500°C with a heating rate of 10°C/min and pyrolysis time of 15 min. Wang et al. (2018) removed the binder by roasting at 450°C for 15 min. Wang et al. (2019) developed a novel molten salt technique to degrade the binder. The AlCl3-NaCl system could melt PVDF efficiently at a temperature of 160°C with a holding time of 20 min. However, there are sparse researches on the thermodynamic kinetics of these treatments, which will be critical for the reactor design, optimization, and scaleup during industrial-scale treatments of spent LIBs. Therefore, in this work, the pyrolysis kinetics of cathode material was investigated by different isoconversional methods. The possible degradation mechanism of cathode material was studied as well.
Optimized protocol for the preparation of multi-walled carbon nanotube:polystyrene transducers for electrochemical sensing
Published in Instrumentation Science & Technology, 2021
Martha R. Baez-Gaxiola, Jorge A. García-Valenzuela
With this basis, in this paper is presented an optimized protocol for the preparation of CNT:PS composite transducers for electrochemical sensors, which are simple, low-cost, quick, nonpolluting, and very practical and feasible to be carried out in traditional labs. To optimize the protocol, we paid particular attention in saving processing time and energy without losing the material characteristics and desired device performance. In this sense, we varied three parameters in order to study their effect on the electrochemical performance of a Si/SiO2/Au/CNT:PS sensor. These parameters were: (a) the number of CNT:PS composite layers, (b) the thermal treatment temperature used for curing the CNT:PS composite layers, and (c) the thermal treatment duration. The results show that a CNT:PS transducer with CNTs that are not electrically insulated and that are ready to be functionalized can be fabricated in a typical lab without employing complex equipment and long duration steps. In addition, the method to prepare such a CNT:PS transducer is simple, scalable, and compatible with technology for microelectronic fabrication. An important indirect purpose of this work is to demonstrate the importance of studying the effect of the processing parameters established in a specific protocol, since these are usually not addressed or explained in the reported literature.