Trung D. Research application of K2CO3 activated coal coal and processing by HNO3 from cake shoulder to process Methylene Blue color. VNUHCM Journal of Earth Science and Environment [Internet]. 30Jun.2020 [cited 30Jan.2023];4(1):170-7. Available from: http://stdjsee.scienceandtechnology.com.vn/index.php/stdjsee/article/view/534