“…Leaching tests represent a common thread in the submissions to this Special Issue [ 3 , 4 , 5 , 6 , 13 , 14 , 15 , 16 ]. The underlying mass transfer principles of column leaching tests are discussed by Liu et al [ 14 ], and Sakanakura et al [ 15 ] showed that adsorption parameters can be determined in batch leaching tests with varying liquid–solid ratios.…”