Synthesis and performance characterization of green desiccant from cockle shell and marble waste

As global environmental concerns intensify, the need for sustainable and green materials becomes paramount. The utilization of waste materials not only addresses environmental challenges but also offers potential economic benefits. In the realm of desiccants, there exists an opportunity to innovate using waste-derived materials, reducing both environmental footprint and production costs. This study aimed to synthesize and characterize the green desiccant calcium chloride from cockle shell and marble waste through the optimization of hydrochloric acid process parameters. Utilizing D-optimal design, experiments assessed the impact of hydrochloric acid concentration and particle size on yield and reaction time. Response Surface Methodology (RSM) revealed significant influences of these variables on both maximizing yield and minimizing reaction time. The data aligned with a second-order polynomial model equation. For cockle shell, optimal conditions were identified as 5.09 M acid concentration with a particle size range of 250–75 µm. In contrast, marble required a 6 M acid concentration within the same particle size range. Analytical evaluations confirmed that the synthesized calcium chloride matched the physicochemical properties of its commercial counterparts, positioning it as an effective green desiccant alternative. Additionally, the findings reveal that the cockle shell-derived calcium chloride exhibits superior moisture absorption capabilities at a relative humidity of 90% and a temperature of 25 °C, attributed to the synergistic effects of magnesium presence and a reduction in crystallinity structure. These characteristics, alongside enhanced dehumidification performance of up to 45.24%, underscore the potential of using waste materials for energy-efficient solutions in addressing environmental and energy challenges.