Recovery of calcium from maize Lime-Cooking wastewater as hydroxyapatite for biomedical applications Academic Article in Scopus uri icon

abstract

  • Cooking maize kernels with lime (Ca(OH)2) constitutes the first step in the production of maize-based products. This process produces an alkaline, Ca2+-containing, yellow-colored liquor, commonly known as maize lime-cooking wastewater (MLCWW). Vast amounts of MLCWW are produced and discarded without treatment, representing a significant environmental problem, especially in developing countries whose diets heavily rely on maize-based products. This study thoroughly evaluated a series of Ca-P mineral recovery strategies based on chemical precipitation for recovering Ca2+ from MLCWW in the form of hydroxyapatite (HAp) with suitable characteristics for biomedical applications. Results showed that over 99 % of residual Ca2+ from MLCWW was recovered by precipitation induced by a series of phosphate precursors with and without the use of chemical dispersants at pH 11. Furthermore, the formation of nano-sized HAp particles was achieved after the calcination of the Ca-P precipitates obtained, as confirmed by a well-defined crystallographic structure and the presence of the typical PO43- and ¿OH functional moieties of HAp. Bioactivity and cellular viability assays confirmed the potential of the recovered HAp for biomedical applications, as suggested by the nucleation of secondary apatite and the lack of cytotoxicity towards human fibroblast cells. Altogether, these results provide the basis for developing technologies for HAp recovery from industrial Ca2+-rich wastewater. Technical, sustainability, and economic aspects of integrating the proposed technology into MLCWW treatment train and valorization within maize-processing industries are discussed. © 2025 Elsevier B.V.

publication date

  • September 11, 2025