Method for absorbing and removing heavy metal and hexavalent chromium from waste liquid by using mangosteen slag

The invention relates to a method for absorbing and removing a heavy metal and hexavalent chromium from waste liquid by using mangosteen slag. The method comprises the following steps of washing a certain amount of mangosteen pericarp, mangosteen fruit stems or juice-squeezed solid residues, mixing the above solid residues and alkali and water according to a mass ratio of 1 : 0.05-0.2 : 0.5-2 with stirring; reacting for 0.5-48 hours; washing the solid product, drying in a vacuum oven at a temperature of 60-100 DEG C; smashing and screening to obtain an absorbent material; preparing a metal ion water solution containing lead cadmium copper iron nickel zinc and hexavalent chromium, wherein the concentration of the metal ion water solution is 0.1-10 mmol/L; and adding the absorbent material obtained from the step 3 according to a proportion of the weight of the absorbent to the volume of the solution being 0.25-20 g/L, wherein the absorbent cam absorb the hexavalent chromium ions and heavy metal ions in the wate