Nanocomposite for wastewater treatment

A method of immobilizing contaminants disposed in an aqueous medium, the method comprising:

• contacting the aqueous medium with a particulate crystalline nanocomposite for a sufficient contact time to permit adsorption of the contaminants, the particulate crystalline nanocomposite comprising:
• a tetragonal CaMoO4 crystalline phase;
• a CaSiO3 crystalline phase;
• and,
• a graphitic-C3N4 crystalline phase,
• wherein at least a fraction of the graphitic-C3N4 is in the form of mesoporous nanosheets,
• further comprising preparing the particulate crystalline nanocomposite by:
• forming a solution of a calcium salt and an alkali metal silicate in a solvent comprising water and a C1-C4 alkanol;
• heating the solution at a temperature of from about 150 to about 250° C. to form a dry product of CaSiO3;
• forming graphitic-C3N4 by heating urea in a closed vessel at a temperature of about 500 to about 700° C.;
• forming an acidified solution in a polar protic solvent of a molybdenum salt and a reducing sugar;
• heating the acidified solution at a temperature of from about 150 to about 250° C. for a sufficient duration to carbonize the reducing sugar to form a carbonized product;
• comminuting the carbonized product of the heating stage;
• calcining the comminuted carbonized product at a temperature of from about 500 to about 1200° C. for a duration of from about 1 to about 5 hours to form MoO3;
• dispersing the CaSiO3, graphitic-C N4 and MOO3 in a polar protic solvent and heating the dispersion at a temperature of from about 150 to about 250° C. at a pressure of from about 2 to about 8 Bar;
• and,
• separating the solid particulate crystalline nanocomposite from the heated dispersion to form the particulate crystalline nanocomposite.