Wet fully bleached pulp was hydrolyzed with 64% H2SO4 acid at 45 °C for 50 min, the reaction was terminated by diluting 10 times with deionized water. After standing for 12 h, water was decanted off and solid sediment was collected with minimum amount of deionized water then divided into two portions. The first portion was neutralized by aqueous Na2CO3 solution, centrifuged at 9000 rpm for 20 min to separate CNFs from the suspension.