▁Director ▁of ▁ ▁the ▁Andre ▁Ag ass i ▁Foundation ▁for ▁Education , ▁an ▁organization ▁dedicated ▁to ▁transform ing ▁U . S . ▁public ▁education ▁for ▁unders erved ▁youth . ▁ ▁References ▁ ▁Category : 1 9 4 4 ▁birth s ▁Category : L iving ▁people ▁Category : American ▁air line ▁chief ▁execut ives ▁Category : New ▁York ▁Racing ▁Association ▁execut ives ▁Category : Pol y techn ic ▁Institute ▁of ▁New ▁York ▁University ▁al umn i <0x0A> </s> ▁Sp ent ▁ca ust ic ▁is ▁a ▁waste ▁industrial ▁ca ust ic ▁solution ▁that ▁has ▁become ▁exha usted ▁and ▁is ▁no ▁longer ▁useful ▁( or ▁spent ). ▁Sp ent ▁ca ust ics ▁are ▁made ▁of ▁sod ium ▁hydro x ide ▁or ▁pot ass ium ▁hydro x ide , ▁water , ▁and ▁cont amin ants . ▁ ▁The ▁cont amin ants ▁have ▁consum ed ▁the ▁majority ▁of ▁the ▁sod ium ▁( or ▁pot ass ium ) ▁hydro x ide ▁and ▁thus ▁the ▁ca ust ic ▁liqu or ▁is ▁spent , ▁for ▁example , ▁in ▁one ▁common ▁application ▁H 2 S ▁( gas ) ▁is ▁scr ub bed ▁by ▁the ▁Na OH ▁( aque ous ) ▁to ▁form ▁Na HS ▁( a q ) ▁and ▁H 2 O ▁( l ), ▁thus ▁cons uming ▁the ▁ca ust ic . ▁ ▁Types ▁ ▁Eth yl ene ▁spent ▁ca ust ic ▁comes ▁from ▁the ▁ca ust ic ▁scr ub bing ▁of ▁crack ed ▁gas ▁from ▁an ▁eth yl ene ▁cra cker . ▁ ▁This ▁liqu or ▁is ▁produced ▁by ▁a