Asso., Prof., Dr. Đinh Văn Phúc. — VNA/VNS Photo

HCM CITY — Scientists from Nguyễn Tất Thành University in HCM City have developed a filtration column that adsorbs radioactive iodine using locally available materials helping hospitals filter out this radiation, without the need to build additional treatment tanks.

Associate Professor Doctor Đinh Văn Phúc and his research team have conducted a study titled Research and Development of a Filtration Column for Adsorption of Radioactive Iodine from Hospital Wastewater.

Radioactive iodine (I-131) is one of the most important radioactive substances used in the treatment of thyroid cancer.

According to the professor, patients absorb I-131 either orally in liquid form or in capsule form. Afterwards, the I-131 is excreted through bodily waste and stored in dedicated retention tanks at hospitals until it fully decays.

With the increasing number of patients in hospitals, the retention tanks for radioactive liquid waste, that are typically built from reinforced concrete and buried underground, are difficult to expand or upgrade in time, Phúc told giaoducthoidai.vn.

This raises concerns about potential leakage of radioactive waste into the surrounding environment, he said.

Various methods have been researched and implemented both domestically and internationally for treating liquid I-131 waste, including adsorption and precipitation.

Among these, adsorption using porous materials such as activated carbon and zeolite is one of the most extensively studied methods, due to its high efficiency and low investment cost.

I-131 is a common radioisotope used in medicine. — Illustration photo

However, most research efforts so far have focused on treating airborne radioactive iodine rather than its liquid form.

Additionally, existing studies have used powdered adsorbent materials, and there has been no research in Việt Nam on the application of granular adsorbents for treating liquid I-131 using a filtration column.

Using pomelo peels as a filtration column

In their latest research, Phúc and his team combined Zeolite ZSM-5 and activated carbon to investigate their ability to adsorb liquid I-131 and remove other pollutants in hospital wastewater, such as heavy metals and antibiotics.

Zeolite ZSM-5 is widely used as a catalyst and adsorbent in petrochemical and environmental applications, Phúc said.

It features a tunnel-like structure with a network of channels and cavities, providing excellent adsorption capacity.

Meanwhile, biomass charcoal is an environmentally friendly adsorbent that is simple to synthesise and cost-effective, he said.

The research team synthesised biomass charcoal from pomelo peels sourced from Tân Triều Pomelo Village in Đồng Nai Province, using a pyrolysis method.

They also synthesised Zeolite ZSM-5 from bentonite clay obtained from Lâm Đồng Province using a hydrothermal process.

The two powdered materials were then separately mixed with polyvinyl alcohol (PVA) as a binder and formed into uniformly sized spherical granules using a specialised pelletising device.

The filtration column (adsorption column) for iodine and I-131 consists of a filter housing and a filter core. Inside the core, there are layered granules of white Zeolite ZSM-5 and black biomass charcoal, with Zeolite ZSM-5 making up 40 per cent of the composition.

Experiments on the adsorption capacity of the synthesised materials revealed that a filter containing 100g of granular material could effectively remove iodine in a laboratory-scale setup.

When applied in Military Hospital 175, the adsorption column of 30cm in diameter, 40cm in length, containing 100g of granular adsorbent, successfully treated 30 litres of I-131-containing solution, achieving over 80 per cent removal efficiency in one cycle lasting 8-10 days.

The materials demonstrated a reuse efficiency of 85 per cent, with a processing capacity of 1.44cu.m per day.

These results were validated using a radiation dose meter at Military Hospital 175 and cross-checked at the HCM City Nuclear Centre.

According to the research team, biomass charcoal and Zeolite ZSM-5 are made from low-cost, locally available raw materials, making their production affordable while maintaining similar efficiency to imported materials.

This makes them highly suitable for future large-scale industrial applications.

Additionally, hospitals will not need to construct new wastewater treatment tanks for storing radioactive iodine. Instead, the filtration column can simply be integrated into the existing wastewater system with a high-pressure pump and control panel to regulate water flow, ensuring optimal adsorption efficiency, Phúc said. — VNS