Acidic buffer is solution which containing high concentration of weak acid and its conjugate base. Its pH would remain relatively constant when adding small amount of acid or base.i.e. CH3COOH = H+ + CH3COO-It works as Ka stay constant under certain temperature. Therefore, as the pH changes( change of H+ concentration in the solution), buffer would try to produce H+ as pH goes up or consume H+ as pH goes down in order to remain equilibrium. Meaning acidic buffer works better if it has high and similar amount of concentration of weak acid and its conjugate base.