Transforming oyster shell and rice husk biowaste into functional calcium silicate board with highly-efficient photo-enhanced antimicrobial activities

Green construction materials based on biomass waste are attracting tremendous research attention in recent years as a means to satisfy the low-cost and sustainable construction requirements in the modern building industry. In this work, the use of oyster shell and rice husk biowaste as raw materials for the environment-friendly preparation of calcium silicate boards is presented. To endow the calcium silicate boards with an antimicrobial functionality, CuSe/CaCO3 is incorporated. The antimicrobial effect is credited to the presence of CuSe nanoparticles, which are capable of inhibiting microbial growth through light-induced generation of radicals, release of copper ions, and photothermal heating. The fabrication process of the antimicrobial calcium silicate boards is optimized by studying the effect of different loading amounts and processing conditions. It was determined that the calcium silicate board that exhibits the most satisfying flexural strength and antimicrobial efficacy can be prepared using the following parameters: Ca/Si ratio of 0.83, molding pressure of 30 MPa, curing temperature of 180 celcius, curing time of 10 h, and 10 wt% of CuSe/CaCO3. Our work might shed light on the sustainable preparation of functional calcium silicate boards through valorization of biowaste. The utilization of biowaste as building materials can significantly aid in mitigating environmental pollution and in lowering the overall cost of construction.