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Microwave Method for Regeneration of Spent-Activated Carbon from Pharmaceutical Industries
Published in Kailas L. Wasewar, Sumita Neti Rao, Sustainable Engineering, Energy, and the Environment, 2022
Sumita N. Rao, Aditi S. Pandey, Mangesh S. Dhore, Pradeep P. Pipalatkar, Babubhai C. Patel
In paracetamol industries, removal of impurities and color is done by Activated carbon. The use of granular activated carbon for the removal of organic impurities is considered economical owing to its reuse during several adsorption-regeneration cycles. These industries generate a few 100 metric tons of spent activated carbon (SAC) annually, awaiting either regeneration or disposal. The ‘spent’ carbon, whose adsorptive capacity is diminished and it can no longer be used for the intended application without regeneration, is regarded as hazardous waste and sent either to landfill or incinerator. In most of the cases, the cost of replacing the saturated carbon would be prohibitive. Hence, it should be regenerated. The conventional methods of regeneration of SAC includes steam regeneration [3], thermal regeneration [4], chemical/solvent regeneration and biological regeneration [5]. Although, thermal regeneration method regenerates the carbon very well but has several drawbacks. The alternative carbon reactivation/regeneration methods that can be used are Ex-situ/In-situ wet oxidations, Wet air oxidation [6, 7], Ultrasonic regeneration [8], Supercritical regeneration and Electrochemical regeneration. It has been reported that electrochemical regeneration process is more effective and economical as compared to thermal, ultrasonic, and base washing regeneration processes [9].
Kinetic, Isotherm, and Thermodynamic Studies for Batch Adsorption of Metals and Anions, and Management of Adsorbents after the Adsorption Process
Published in Deepak Gusain, Faizal Bux, Batch Adsorption Process of Metals and Anions for Remediation of Contaminated Water, 2021
Deepak Gusain, Shikha Dubey, Yogesh Chandra Sharma, Faizal Bux
The adsorbent after its use can be managed by various means such as regeneration, reuse, and safe disposal (Figure 8.2). The regeneration can be done by various methods such as acid desorption agent, chelating desorbing agent, alkali desorbing agent, alkali desorbing agent, salt desorbing agent (Vakili et al. 2019), thermal regeneration (Yang et al. 2020), and electrochemical regeneration (Ding et al. 2020). The organic pollutants can also be regenerated in addition to the earlier methods, such as ultrasonic regeneration (Naghizadeh et al. 2017), microbial regeneration, microwave-assisted regeneration, thermal regeneration, chemical regeneration, ozonation, photoassisted oxidation, and electrochemical oxidation (Omorogie et al. 2016).
Evaluation of efficiency and capacity of thermal, chemical and ultrasonic regeneration of tetracycline exhausted activated carbon
Published in Environmental Technology, 2022
Letícia Reggiane de Carvalho Costa, Luana de Moraes Ribeiro, Gelsa Edith Navarro Hidalgo, Liliana Amaral Féris
Several studies in the literature report techniques of regeneration of adsorbent solids. Guo et al. [22] studied different solvents for the chemical regeneration of exhaust activated charcoal used in coke oven wastewater treatment. At the end of the study, the authors reported that n-pentane showed the best regeneration efficiency, at 98.27%, for depleted activated carbon compared to other solvents. By studying the electrochemical regeneration of activated carbon from grape stalk, Zanella [26] concluded that the regeneration process developed in the study presented 100% regeneration capacities when the best process conditions were used. Cazetta et al. [27] and Marques et al. [28], during the regenerative heat treatments, they obtained, respectively, an adsorption capacity of the studied pollutants in 57% and 50%, when compared with the initial capacity. By comparing thermal regeneration with microwave-induced regeneration of phenol-polluted activated carbon, Ania and his collaborators [29] found that both the porous structure and the adsorbent capacity of the material are much higher when regeneration is performed in the microwave device compared to those obtained in the conventional oven. Regeneration by ultrasound was studied by Lim and Okada [30] by analysis of activated carbon trichlorethylene desorption (TCE). About 64% of TBI was desorbed from 5g of CAG loaded with 6.5mg TCE within 1 h in the ultrasonic field.
Design, Fabrication, and Testing of Electrolytic Cell for Minimizing Simulated Active Waste
Published in Nuclear Technology, 2019
R. Puspalata, S. Sumathi, V. Balaji, S. Rangarajan, S. Velmurugan
However, radioactive and other metallic contamination forms only a fraction of the total spent resin volume. In recent years, there has been more and more concern about the future availability of waste disposal sites. Hence, alternative methods are being developed with the objective to minimize the resin volume requirement. Proposals such as using metal ion–impregnated polymer to selectively remove only radioactive metal ions9 or DCD with electrochemical regeneration, i.e., continuous application of a suitable potential during the process of decontamination to remove these metal ions by electrodeposition, were explored.10,11 This will extend the operational life of the resin bed, reduce the total volume of the resin requirement, and generate active waste in a more compact inorganic form and minimum activity level in spent resin that can be handled and disposed of with more ease. After they are removed/released from the electrolytically regenerated resin, the captured radionuclides and heavy metals either deposit on the cathode or precipitate out if the metal ion concentration increases above the solubility product. In any case, this becomes a more compact inorganic activity.
A review of posttreatment technologies for anaerobic effluents for discharge and recycling of wastewater
Published in Critical Reviews in Environmental Science and Technology, 2018
D. T. Mai, C. Kunacheva, D. C. Stuckey
Electrochemical processes to treat anaerobic effluents were studied with different electrodes such as; titanium/platinum-iridium oxide (Ti/Pt-IrO2) anode (Dai et al., 2011; Lei and Maekawa, 2007) or Ti/Ru0.3Ti0.7O2 dimensionally stable anode (Buzzini et al., 2007) and aluminum and stainless-steel cathode. It was observed that electro-flotation was the main mechanism for turbidity, TOC and inorganic carbon removals (Lei and Maekawa, 2007). Electrochemical treatment with stainless-steel electrodes had higher COD removals (82%) than aluminum electrodes (67%) (Buzzini et al., 2007). In addition, electrochemistry can be used to regenerate adsorbents such as activated carbon (Zanella et al., 2016) and graphite-based adsorbents (Asghar et al., 2012; Brown et al., 2004). However, the regeneration of activated carbon usually required an electrolyte, took a long time with high energy but low regeneration efficiency (<100%), whereas the electrochemical regeneration of a nonporous and low-cost carbon powder with no internal surface was quick, easy and cheap (Brown and Roberts, 2007). The charge required to achieve 100% regeneration efficiency was found to be around 36–80 Coulombs/g, with the higher charge required for the higher adsorptive capacity adsorbent (Asghar et al., 2012; Brown et al., 2004), which is much lower than that reported for GAC of 1,500 C g−1 for 95% regeneration (Narbaitz and Cen, 1994). With regard to economic costs, the treatment process using a nonporous graphite-based adsorbent had significantly lower operational costs (42%) than using fresh GAC, although the operational costs were still higher (12%) than using GAC with regeneration (Jeswani et al., 2015). Nevertheless, because of the fast regeneration time of the nonporous adsorbent, a continuous process with adsorption and electro-regeneration was developed in the same device (Mohammed et al., 2011). This provided a promising process for the posttreatment of anaerobic effluent, as well as other wastewaters.