Ca/Pyro-Hydrochar Derived from Invasive Species for Enhanced Removal of Cadmium and Phosphate

Anthropogenic contamination of Cd(II) and phosphate becomes a crucial environmental issue on a global scale. In the current study, a promising Ca/pyro-hydrochar (Ca/Py-HyC) was fabricated based on invasive species biomass of Amaranthus retroflexus and Pomacea canaliculata shell to remove Cd and phosphate. According to the non-linear fitting results of Langmuir isotherm model, the adsorption capacity of Cd(II) and phosphate achieved 717.77 mg/g and 623.37 mg/g, respectively, which greatly exceeded the documented biochar/hydrochar based materials. Ca/Py-HyC showed an excellent adsorption performance in a wide range of pH (4.0 – 8.0) and ionic strength (0 – 0.5). Precipitation was the primary adsorption mechanism, which may further reduce the bioavailability of the contaminants and facilitate their recyclability and regeneration of the metal and nutrient resources. According to life cycle assessment, in comparison with Ca/PyC, and Ca/HyC, Ca/Py-HyC exhibited the lowest overall environmental impacts in term of per kg adsorbent, particularly in the categories related to ecosystems. Economic analysis suggested that the removal costs were 0.02 $/Cd kg and 0.05 $/P kg. Thereby, as a sustainable and eco-friendly functional material, Ca/Py-HyC may provide a strategy which can not only create net revenue, but also achieve optimization benefits in both eco-environmental and economic aspects.