Di ammonium hydrogen orthophosphate nh4 2hpo4

All
chemicals were of analytical
grade and used without further purification. Ammonium hydroxide [NH₄OH] solution (25%, Sigma-Aldrich), calcium nitrate tetrahydrate
[Ca(NO₃)₂·4H₂O] (98%, Sigma-Aldrich),
and di-ammonium hydrogen orthophosphate [(NH₄)₂HPO₄] (98%, Sigma-Aldrich) were used to synthesize neat
HAP. Chitosan (85%, deacetylated medium molecular weight, Sigma-Aldrich),
carboxymethyl cellulose (low viscosity, Sigma-Aldrich), sodium alginate
(low viscosity, Sigma-Aldrich), and gelatin type B (medium bloom,
SRL) were used in the synthesis process of HAP-biopolymer nanocomposites.
Cadmium nitrate (Sigma-Aldrich), lead nitrate (Merck), sodium fluoride
(99.5%, Merck), and sodium arsenate (99%, Merck) were used to prepare
the pollutant stock solutions.

All the chemicals used were analytical grade and used without further purification. Ammonium hydroxide (NH₄OH solution, 25%, Sigma Aldrich), calcium nitrate tetrahydrate (Ca(NO₃)₂·4H₂O, 98% Sigma Aldrich), di-ammonium hydrogen orthophosphate ((NH₄)₂HPO₄, 98% Sigma Aldrich) were used to synthesis neat HAP. Montmorillonite (Sigma Aldrich) was used to synthesis HAP-MMT nanocomposites and sodium fluoride, 99.5% (Merck) was used to prepare the fluoride stock solutions.