Removal of nitrophenol pesticides from aqueous solutions by layered double hydroxides and their calcined products

The ability of MgAl layered double hydroxides (LDHs) and their calcined products to adsorb the water contaminants 2,4-dinitrophenol (DNP) and 2-methyl-4,6-dinitrophenol (DNOC) was assessed. Adsorption tests were conducted on LDHs with variable Mg/Al ratios (and variable layer charge), pH values, contact times and initial pesticide concentrations to identify the optimum conditions for the intended purpose. Adsorbents and adsorption products were characterized by X-ray diffraction and FT-IR spectroscopy as well as atomic absorption spectroscopy and thermal analyses. The amounts of pesticides removed from water were determined by UV–Vis spectrophotometry. All adsorbents except the carbonate-containing hydrotalcite possessed a very high adsorption capacity for both contaminants.