Acid washing was carried out using acids in the order HCl-HF-HCl, the washing time was two hours .
The content of REEs in oil shale samples after acid washing
For the Huadian oil shale the ash content declined from 50.28% (HOS) to 4.13% (HAW) after acid washing. In contrast, for the Luozigou oil shale the ash content reduced from 72.24% (LOS) to 5.43% (LAW) after acid washing.
Acid washing has been widely used for studying soil organic matter (Cooke et al.
The atomic percentage of C, O and N obtained by XPS analysis was used to assess surface recoveries of C, O and N after acid washing; this was calculated following Dai and Johnson (1999) as follows:
The usual techniques of deep cleaning include steam cleaning, tile and grout cleaners, pressure washing and acid washing
but these techniques seldom bring the floor back to the ae1/4oebrand newae1/4A[yen] look.
imagine not having to scrub tile, or pay for expensive acid washing
and glass beading that can ruin tile's original luster.
The filter media is then further processed by acid washing
using 1N HN[O.sub.3], as described in EPA Method 1311.
"There is a difference between acid washing
and acid etching," says Suzanne Smallwood, vice president of marketing at Sau-Sea Swimming Pool Products, a pool coatings manufacturer based in Southampton, N.J.