A novel nano-sized calcium hydroxide catalyst prepared from clam shells for the photodegradation of methyl red dye

Semiconductor photocatalysis is a promising approach to combat both environmental pollution and the global energy shortage. Advanced photocatalysts with novel photoelectronic properties are benchmark materials that have been pursued for their high solar-energy conversion efficiency. Consequently, this paper discusses a new nano-sized calcium hydroxide (Ca(OH)2) photocatalyst synthesised by a precipitation method from the raw materials derived from sea shells. The as-prepared Ca(OH)2 samples were characterised by Scanning Electron Microscopy (SEM). The Ca(OH)2 samples were then immobilised in Alginate beads and they showed excellent photocatalytic degradation activities against methyl red (MR) aqueous solution under UV light radiation. Dependence of the activity on various experimental conditions was investigated, and the results showed promising utilization of the immobilised Ca(OH)2 photocatalysts. The influence of initial dye concentration and catalyst loading were studied and it was found that maximum% degradation was achieved with 20 mg/L of initial dye concentration and 3 g/L of catalyst loading. In addition, the photocatalytic degradation of MR was well fitted into pseudo first order kinetics and heterogeneous catalytic kinetic model. Studies over recyclability of immobilised catalysts were performed and the results showed that the alginate immobilised catalysts were efficient enough to reuse for several times.