Adele Bellis had "life changing injuries" after the assault in Lowestoft, Suffolk in August.
Leon Thompson, 38, of Alma Road, Lowestoft has pleaded not guilty at Ipswich Crown Court to assault and wounding.
Anthony Riley, 25, of Raglan Street, denied conspiracy to wound and false imprisonment.
The attack happened in the London Road South area on 14 August.
Mr Thompson has also been charged with possessing a knife.
Both defendants have been remanded in custody and their trial is due to take place in March.
A Suffolk Police spokeswoman said Ms Bellis was continuing to undergo treatment for "serious, life-changing injuries".
Two men have denied charges relating to an attack where a 22-year-old woman had corrosive liquid sprayed in her face.