Hybrid porous phosphate heterostructures as adsorbents of Hg(II) and Ni(II) from industrial sewage

Porous phosphate heterostructures (PPH), functionalized with different ratios of aminopropyl and mercaptopropyl groups, labelled as N-x=5,N-25,N-50-PPH and S-x=5,S-25,S-50-PPH, respectively, were tested as adsorbents for Ni(II) and Hg(II) found in industrial sewage from electroplating processes and button battery recycling. X-ray diffraction was used to study the structures. The specific surface area of the pristine material (PPH) was 620 m(2) g(-1), whereas the specific surface areas of the modified mercaptopropyl (S-5-PPH) and aminopropyl (N-5-PPH) were 472 and 223 m(2) g(-1), respectively. The adsorption data were fitted to a Langmuir isotherm model. The S-5-PPH material was saturated by 120 mmol Hg(II) per 100 g of material, whereas for Ni(II) adsorption, N-25-PPH material displayed the highest adsorption with a saturation value of 43.5 mmol per 100 g. These results suggest that functionalized PPH materials may be promising toxic metal scavengers and that they may provide an alternative environmental technology. (C) 2011 Elsevier B.V. All rights reserved.