Arsenic is a toxic metal that has long polluted water bodies, posing potential human and aquatic health concerns even when present in low concentrations. Prolonged consumption of arsenic-contaminated groundwater can cause cancer and other health diseases. In groundwater, arsenic is typically present in two forms – trivalent and pentavalent where the latter is less toxic and easier to remove through conventional processes such as coprecipitation, adsorption etc. Conversion of trivalent arsenic to pentavalent arsenic can be done with a photocatalyst i.e., when photocatalyst is irradiated by UV light, OH radicals are generated by which trivalent arsenic will be oxidized into pentavalent arsenic.This technology offer is a new structure of photocatalytic particle with improved activity and reusability which is especially useful to effectively treat trivalent arsenic polluted water.
The photocatalyst particle of this technology offer consists of zeolite particles and titanium dioxide (TiO2) particles coated thereon. This structure enables the TiO2 particle to possess a larger surface-area to volume-ratio than conventional particulate TiO2. By applying the photocatalytic particles to polluted water treatment, it can enhance the efficiency of detoxification of trivalent arsenic. Furthermore, since the new photocatalyst particles are of micrometers size, the photocatalysts can be separated by sedimentation from the post-treated water and can be collected to be reused. Throughput of water treatment is thoroughly enhanced by this photocatalyst by 50 times in the case of arsenic pollutants and by 100 times in the case of persistent organic materials.
Synthesis of the photocatalyst particle utilizes the inherent electrostatic interaction between nanoparticulate TiO2 photocatalyst and a particular type of microparticulate zeolite. By eliminating the use of binders between them, this maintains the inherent amount of photocatalytic active site since there is no inhibitor at the interface between the two particles. Since the TiO2 photocatalyst is weakly bonded to the surface of the zeolite, TiO2 could be desorbed from the surface of the zeolite by a simple agitation of the solution. When the agitation is stopped, TiO2 bonds to the surface of the zeolite again, allowing the feasibility of separation from post-treated water and reusability.
Some features of the photocatalyst particles include:
The technology can be used for the removal of arsenic in the following areas:
The global water and wastewater treatment market is estimated to value at USD 26 million in 2021 with a projected CAGR of 4.2% over the next 10 years. Increased demand and shortage of clean drinking water in developing countries has highlighted the need for new technologies to remove organic/toxic matter and impurities more efficiently. Since this photocatalytic water treatment technology efficiently reduces the toxicity of harmful pollutants (trivalent arsenic and hexavalent chromium), it has potential to resolve problems that occur particularly in contaminated groundwater.
The technology owner is keen to out-license this patented technology to chemical manufacturers and companies producing water purification equipment/systems.