Luong, H. V. T., L. N. H. Cao, N. P. L. Tran, T. B. Q. Tran, and Q. N. Ha. “Adsorption of Chromium (VI) Ion Using Adsorbent Derived from Lignin Extracted Coir Pith”. CTU Journal of Innovation and Sustainable Development , vol. 12, no. 3, Nov. 2020, pp. 54-65, doi:10.22144/ctu.jen.2020.024.