Carbonated nanohydroxyapatite from bone waste and its potential as a super adsorbent for removal of toxic ions
Yurina Sekine, Takuya Nankawa, Teppei Yamada, Daiju Matsumura, Y. Nemoto, Masaki Takeguchi, Tsuyoshi Sugita, Iwao Shimoyama, Naofumi Kozai, Satoshi Morooka
Abstract
The effective, low-cost decontamination of toxic metals is critical for addressing global health risks, reducing environmental pollution, and building a sustainable future. Here, we developed an eco-friendly hydroxyapatite nanocrystal adsorbent made from bone waste that can effectively capture 90Sr. Highly carbonated nanohydroxyapatite (C-NHAP) crystals with a negatively charged surface were obtained by simply immersing pig bone in an aqueous solution of sodium hydrogen carbonate (NaHCO3). Fourier transform infrared spectra showed that the C-NHAP was highly carbonated and that the amount of introduced carbonate ions (CO32−) increased with increasing NaHCO3 concentration in the immersion solution. With increasing amount of CO32− ions introduced into the C-NHAP, it exhibited a greater ion-adsorption performance. The distribution coefficient (Kd = 24,780 mL g−1) of the C-NHAP for Sr2+ was approximately 20 and 250 times greater than those of clinoptilolite and untreated bone, respectively. The C-NHAP also exhibited high adsorption capacity (Qe = 125 mg g−1) for Sr2+. The extended X-ray absorption fine structure spectra showed that the CO32− sites in C-NHAP played an important role in its high adsorption performance. The C-NHAP exhibited high adsorptivity for Cd2+, Pb2+, and Cu2+. The C-NHAP prepared from bone waste is an eco-friendly, high-performance, low-cost material that should be useful in environmental pollutant removal and food waste disposal.