At the same pH value, the minerals with more negative charge sites are easier to adsorb protons (H +) in the solution, and each Mg-OH (Mg-O) has less charge than Al-OH (Al-O), so the net charge of ChNTs after adsorption of H + is more likely to be positive. Therefore, in the weakly acidic MO solution with pH close to 7, HNTs have the negative charges and ChNTs have the positive charge.