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Abstract We report a synthesis strategy for pure hydroxyapatite (HAp) using an amorphous calcium carbonate (ACC) colloid as the starting source. Room-temperature phosphorylation and subsequent calcination produce pure HAp via intermediate amorphous calcium phosphate (ACP). The pre-calcined sample undergoes a competitive transformation from ACC to ACP and crystalline calcium carbonate. The water content, ACC concentration, Ca/P molar ratio, and pH during the phosphorylation reaction play crucial roles in the final phase of the crystalline phosphate compound. Pure HAp is formed after ACP is transformed from ACC at a low concentration (1 wt%) of ACC colloid (1.71

Degradation of low-density polyethylene (LDPE) containing small amounts of other plastics, which are polyvinyl chloride (PVC), polyamides 66 and 6 (PA66 and PA6), polyethylene terephthalate (PET) and polystyrene (PS), has been investigated using gallium zeolite catalysts. Gallium silicate catalyst showed a high activity for converting LDPE into aromatic hydrocarbons, and its catalytic activity was hardly influenced by the presence of PET and PS in the plastic mixtures. However, PVC and PA66 mixed with LDPE caused significant reduction of the catalytic performance probably because of deposition of Cl- and N-containing compounds and more formation of coke on the catalyst surface. Ga,H-ZSM-5, newly prepared in this work, was found to be promising as a catalyst for producing aromatics from degradation of PVC- and PA66-containing LDPE. The catalyst has a high potential for use in advanced chemical recycling of waste polyolefins. [ABSTRACT FROM AUTHOR]

The effect of precursors on the active phase formation and hydrodesulfurization activities of noble metal phosphide catalysts was examined. The maximum activities of Pd--P and Rh--P catalysts prepared from acetylacetonato (acac) complex were observed at lower reduction temperatures than those for catalysts prepared from chlorides (Cl). The Pd--P catalyst prepared from acac also showed higher activity than that obtained from Cl. However, this trend was not observed in the Rh--P catalyst. The characterization results revealed that the higher activity of the Pd--P catalyst prepared from the acac is due to the highly dispersed Pd4.8P. [ABSTRACT FROM AUTHOR]