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Chemistry of Wet Etch Cleaning
Published in Tadahiro Ohmi, Ultraclean Technology Handbook, 2017
Tetsuo Mizuniwa, Mitsuo Abe, Hiroyuki Mishima, Nobuhiro Miki, Hirohisa Kikuyama
Instead of HF, a mixture of ammonium fluoride and HF is used as an etching agent. This is because the photoresist is not chemically resistant to HF: it swells and peels off the wafer. In short, the photoresist film is protected by the ammonium fluoride.
Process Applications and Challenges in Mineral Beneficiation and Recovery of Niobium from Ore Deposits – A Review
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Nnaemeka Stanislaus Nzeh, Samson Adeosun, Abimbola Patricia Popoola, Abraham Adeleke, Daniel Okanigbe
Since then, various studies have improved on this method and different new methods altogether have also been investigated and developed. This involved the digestion of the Nb and Ta minerals and effecting selective/stepwise separation of Nb and Ta from the same reaction complexes, putting into consideration; the reagent and energy consumption (Ribagnac et al. 2017), the recovery, cost, economic, environmental and waste management issues. Among the processes that have been utilized by researchers to achieve simultaneous decomposition of Nb-Ta minerals is the alkali fusion process. Others include alkali fusion-acid leaching, chlorination, ammonium fluoride (NH4F) or ammonium bifluoride (NH4HF2) fusion, direct sulfuric (H2SO4) acid dissolution or in a combination with hydrofluoric (HF) acid, alkaline solution dissolution (El-hussaini and El-hakam Mahdy 2002B; Gupta and Suri 1994; Wang et al. 2009; Yang et al. 2012a; Zhou, Zheng and Zhang 2005). More recently, the most successful used methods in processing and recovering Nb and Ta from their primary sources employs the initial halogenation and decomposition/dissolution in HF acid or a combination of mineral acids with HF acid or fluoride media like fluoride salts that forms oxy-fluorides complexes (El-hussaini and El-hakam Mahdy 2002A; Nete, Purcell and Nel 2016a, 2016b; Sanchez-Segado et al. 2015; Wang et al. 2010; Yang et al. 2013b, 2012a; Zhou, Zheng and Zhang 2005).
Nanotubes TiO2 supported Pt catalyst for selective electrocatalytic oxidation of glycerol to glyceric acid
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Guoxu Qin, Xinyun Wang, Xinjun Wan, Dong Chen, Bo Qiu
Acetone, ethanediol, hydrochloric acid (HCl, 36.8%), sulfuric acid (H2SO4), hydrochloric acid (H3PO4), hydrogen fluoride (HF), and ammonium fluoride (NH4F) were provided by Sinopharm Chemical Reagent Co., Ltd. Titanium foil (99.95%), chloroplatinic acid (H2PtCl6), GLY, GLA, GALD, and OA were purchased from Alfa Aesar. Titanium foil with a nominal reaction area of 0.01 cm2 (0.05 cm × 0.2 cm) and 2 cm2 (1 cm × 2 cm) was chosen as the metal matrix. All chemical reagents were used as received.