Removal of fluoride using quaternized palm kernel shell as adsorbents: Equilibrium isotherms and kinetics studies by Bakar, Ayu Haslija Abu, Koay, Yin Shin, Ching, Yern Chee, Abdullah, Luqman Chuah, Choong, Thomas S.Y., Alkhatib, Ma'an, Mobarekeh, Mohsen Nourouzi, Zahri, Nur Amirah Mohd