POLY(2-ACRYLAMIDOGLYCOLIC ACID-CO-2-ACRYLAMIDE-2-METHYL-1-PROPANE SULFONIC ACID) AND POLY(2-ACRYLAMIDOGLYCOLIC ACID-CO-4-STYRENE SODIUM SULFONATE): SYNTHESIS, CHARACTERIZATION, AND PROPERTIES FOR USE IN THE REMOVAL OF CD(II), HG(II), ZN(II), AND PB(II) Artículo académico