The aim of this work is to present a zero-waste process for storing CO2 in a stable and benign mineral form while producing zeolitic minerals with sufficient heavy metal adsorption capacity. To this end, blast furnace slag, a residue from iron-making, is utilized as the starting material. Calcium is selectively extracted from the slag by leaching with acetic acid (2 M CH3COOH) as the extraction agent. The filtered leachate is subsequently physico-chemically purified and then carbonated to form precipitated calcium carbonate (PCC) of high purity (<2 wt% non-calcium impurities, according to ICP-MS analysis). Sodium hydroxide is added to neutralize the regenerated acetate. The morphological properties of the resulting calcitic PCC are tuned for its potential application as a filler in papermaking. In parallel, the residual solids from the extraction stage are subjected to hydrothermal conversion in a caustic solution (2 M NaOH) that leads to the predominant formation of a particular zeolitic mineral phase (detected by XRD), namely analcime (NaAlSi2O6∙H2O). Based on its ability to adsorb Ni2+, as reported from batch adsorption experiments and ICP-OES analysis, this product can potentially be used in wastewater treatment or for environmental remediation applications.
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机译:这项工作的目的是提出一种零废物的过程,以稳定且良性的矿物形式存储CO2,同时生产具有足够重金属吸附能力的沸石矿物。为此,将高炉炉渣(炼铁的残渣)用作起始原料。通过用乙酸(2 M CH3COOH)浸提作为浸出剂,选择性地从矿渣中提取钙。随后对过滤出的渗滤液进行物理化学纯化,然后进行碳酸化,以形成高纯度(根据ICP-MS分析,<2 wt%的非钙杂质)沉淀的碳酸钙(PCC)。加入氢氧化钠以中和再生的乙酸盐。调整了所得碳酸钙PCC的形态学性能,使其有可能在造纸中用作填料。同时,将萃取阶段的残留固体在苛性碱溶液(2 M NaOH)中进行水热转化,从而导致主要形成特定的沸石矿物相(通过XRD检测),即Analcime(NaAlSi2O6∙H2O)。根据批次吸附实验和ICP-OES分析报告的吸附Ni 2 + sup>的能力,该产品可潜在地用于废水处理或环境修复应用。
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