@article{barros_machado_alves_sousa-aguiar_1997,  title={ION EXCHANGE MECHANISM OF Cr+3 ON NATURALLY OCCURRING CLINOPTILOLITE},  volume={14},  ISSN={0104-6632},  url={https://doi.org/10.1590/S0104-66321997000300006},  DOI={10.1590/S0104-66321997000300006},  number={3},  journal={Brazilian Journal of Chemical Engineering},  publisher={Brazilian Society of Chemical Engineering},  author={Barros, M.A.S.D. de and Machado, N.R.C.F. and Alves, F.V. and Sousa-Aguiar, E.F.},  year={1997},  month={Sep} }