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Introduction to Nanosensors
Published in Vinod Kumar Khanna, Nanosensors, 2021
A base is a substance, such as KOH or NaOH, that dissociates in aqueous solution to produce hydroxide ions, acting as a proton acceptor. A base is a substance that can donate an electron pair to form a covalent bond. An alkali is a base that is soluble in water.
Activated Carbon/Ion Exchange
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
Bicarbonate alkalinity: The presence in a solution of hydroxyl (OH−) ions resulting from the hydrolysis of carbonates or bicarbonates. When these salts react with water, a strong base and a weak acid are produced, and the solution is alkaline.
General Princlpes
Published in Martin B., S.Z., of Industrial Hygiene, 2018
pH is used to measure the acidity or alkalinity of a solution. It uses a scale of from 1 to 14, with 7 being neutral. Acids (H3O+) have pH values of from 0 to 6, with the lowest values being more acidic. Litmus paper turns red when exposed to acids. Alkalis (bases, OH-) have pH values ranging from 8 to 14, with the highest numbers indicating the greatest alkalinity. Litmus paper will turn blue in the presence of alkalis.
Development of environmentally and economically sustainable delamination process for spent lithium-ion batteries
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Tushar Maske, Sandeep Anwani, Ravi Methekar
Solvent dissolution, heat treatment, alkali dissolution, and deep eutectic solvents are common methods used for delamination of the untreated cathode material (UCM) from the cathode electrode. In the solvent dissolution method (SDM), the UCM is delaminated from the aluminum foil by dissolving the polyvinylidene fluoride (PVDF) binder in a solvent such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylacetamide (DMAC), or N, N-dimethylformamide (DMF), etc. (He et al. 2015; Wu et al. 2023). Despite being a time-consuming process, the main advantage of this method lies in the low energy consumption for delamination of the cathode electrode materials (He et al. 2021). On applying high-temperature, PVDF gets decomposed causing the delamination of UCM in heat treatment method (Raj et al. 2022). Hydrogen fluoride (HF) and other hazardous gases are produced as a consequence of this procedure and these emissions have a negative impact on the ecosystem (Wang et al. 2019a). The inertness of NaOH toward UCM selectively dissolves the aluminum foil into the alkali solution in the alkali treatment method (Senćanski et al. 2017). It would be harmful to aquatic plants and animals if the alkaline wastewater generated after alkali treatment was discharged directly (Zhao et al. 2019). Although high temperatures are needed in the deep eutectic solvent for melting and dissolving the PVDF binder, better delamination efficiencies were achieved (Tran et al. 2019; Wang et al. 2019b). The primary detriment of this approach is the expensive nature of the solvent.
Challenge of adopting relatively low strength and self-cured geopolymer for road construction application: a review and primary laboratory study
Published in International Journal of Pavement Engineering, 2021
Peerapong Jitsangiam, Teewara Suwan, Kedsarin Pimraksa, Piti Sukontasukkul, Prinya Chindaprasirt
Theoretically, alkaline metals in the periodic table group I and II can be used as activators. However, sodium (Na) and potassium (K) are most commonly used due to strong alkaline properties, economic affordability, and availability worldwide (Hardjito et al.2004, Suwan 2016). From recent studies, widely used alkaline materials are sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium silicate (Na2SiO3), potassium silicate (K2SiO3), calcium hydroxide (Ca(OH)2), and combinations of the same. In practice, soluble sodium is frequently used as an alkaline activator, because it is widely available and less expensive than soluble potassium (Van Jaarsveld 2000, Hardjito et al.2009). The most suitable alkaline activators in geopolymer synthesis are a combination of sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions (see Figure 5). Sodium hydroxide plays a significant role in dissolving alumina-silicate minerals along with its concentration (Molar, M), while sodium silicate is responsible for binding activities and initiating geopolymeric formation from the presence of silica (Si) (Panias et al.2007). Therefore, according to the type of alkaline activator, the combination of sodium hydroxide and sodium silicate solutions would be the most appropriate activators for superior strength development of the geopolymer. Using effective alkaline activators increases the chance of achieving strength under room temperature curing conditions.
Evaluation of geochemical data of Yamuna River using WQI and multivariate statistical analyses: a case study
Published in International Journal of River Basin Management, 2019
Balwant Kumar, Umesh Kumar Singh, Sri Narayan Ojha
NH4 is commonly derived from the nitrogenous wastes during aerobic and anaerobic decomposition of organic matter. It is highly toxic for aquatic organism especially in alkaline environment (Martin et al.2007). In this study, NH4 varies from 0.2 to 20.0 mg/L in pre-monsoon, 0.4 to 13.1 mg/L in monsoon and 0.2 to 13.2 mg/L in post-monsoon with mean ± SD value of 7.2 ± 6.7 mg/L, 4.1 ± 4.6 mg/L and 4.8 ± 4.5 mg/L respectively. The result indicated that most of the sites were found with high concentration of NH4 as compared to the regulatory standard (<1.2 mg/L) prescribed by BIS (1991). The higher level of NH4 value was observed from sites S5 to S16 in the pre-monsoon season (Figure 5(a)). It may be due to high rate of industrial and domestic wastewater discharge into the river from urban and industrial centres of Delhi during low fresh water level in the river catchment (Sharma et al.2017b). NH4 concentration in the river downstream always showed higher value because the river received large amount of waste from tannery industries as well as food and beverage industries. However, paddy field is most suitable for NH4 formation due to their redox potentiality, which has ability to vanish nitrogen through denitrification process (Singh et al.2008). Therefore, significant level of NH4 at these sites is probably due to agricultural activities with the application of nitrogenous fertilizers (Kumar et al.2017).