Natural Hydroxyapatite Derived from Fishbones of Sea Bream (Pagrus major) for Metal Removal in Aqueous Transition Metals M (M = Fe, Co, Ni, Zn) Nitrates and In-Sn-Al in Factory Phosphoric Solution

The present study examined a sustainable chemical challenge involving the removal of acidic aqueous transition metals (M = Fe, Co, Ni, Zn, In, Sn, Al) using fishbone waste. The study was grounded in research findings indicating that hydroxyapatite, a mineral compound present in sea bream (Pagrus major) fishbones, can effectively remove these metals. The relationship between removal efficiencies and time profiles was observed to vary, and classified as follows: a gradual reaction obeying quasi-first-order kinetics and a very fast reaction following a constant uptake versus time. The Fe, Co, Ni, and Zn cation removal performance was found to be superior for fishbones, dried > 600 °C > 900 °C, depending on the treatment of raw fishbone. The metals were taken up in the order Fe > Zn > Ni > Co and the results of the 6-day removal experiment showed capacities ranging from 1.1 to 2.0 mmolg−1. The mechanism is regarded as the combined process of the ion-exchange and dissolution–precipitation reactions. For the waste 64 wt% phosphoric acid solution from the liquid crystal display (LCD) production processes in the industrial factory, In, Sn and Al removals were conducted within the first 3 min, resulting in efficiencies of 30–50%. These results demonstrated the efficacy of a cost-effective technique for metal removal, as indicated by the experimental results using fishbone hydroxyapatite.