ALLOPHANE OF GAMALAMA VOLCANIC SOIL SURFACE MODIFICATION USING SULFURIC ACID: STUDY OF THE EFFECT OF SULFURIC ACID CONCENTRATION. Advanced Research & Development Journal, [S. l.], v. 2, n. 1, 2026. Disponível em: https://www.ardjournal.com/index.php/ard/article/view/71. Acesso em: 12 sep. 2026.