Research Progress on the Applications of Seashell Adsorption Behaviors in Cement-Based Materials

The use of seashells to replace traditional cement-based materials and study their adsorption capacity for pollutants can expand the functional engineering application range of cement-based materials. A large amount of seashell waste is produced in coastal areas every year. How to deal with and utilize this seashell waste is a common problem faced by coastal countries and regions. This paper first reviews the principles of adsorption kinetics and adsorption isotherms to demonstrate the adsorption mechanism of shell materials. Then the effects of pH, contact time, temperature, pollutant concentration and other factors on the adsorption of heavy metal ions and basic dyes to seashells are discussed. Finally, the relevant applications of seashells in the construction field are reviewed. The results showed that the optimal pH value in the process of seashell adsorption was 5-7, the active site on the surface of the seashell particles was limited, and that it would reach saturation at a certain concentration, but would not further increase with the increase of time. The active site area of the seashell would increase with the decrease of particle size, so the selection of seashell powder with small particle size was conducive to enhancing the absorption capacity and removal efficiency. The experimental use of seashells instead of cementitious materials or natural aggregates in cement-based materials showed good adsorption capacity and would have a wide range of application prospects in permeable concrete and architectural coatings. By analyzing the research progress on factors influencing seashell adsorption performance and the applications of seashell adsorption behaviors in cement-based materials, this paper could provide ideas and methods for the design of functional cement-based adsorption materials from multiple angles.