{TAIL ~ A method} 13 wherein the aqueous acid solution contains about 0.01% to about 1.0% by weight of {HEAD ~ the surfactant} based on the amount of acid 
{ TAIL ~ A method } 13 wherein the aqueous acid solution contains about 0.01 % to about 1.0 % by weight of { HEAD ~ the surfactant } based on the amount of acid
TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH