[Science Column] KIST Recovers 99.9% of Palladium from Mildly Acidic Wastewater

High-Efficiency Recovery in 30 Minutes with Titanium-Based MXene Nanosheets
Recovered Metal Reused as Hydrogen Catalyst... Achieving Closed-Loop Precious Metal Recycling

A domestic research team has developed a technology that enables the high-efficiency recovery of palladium (Palladium·Pd), a critical precious metal used in various industries such as smartphones, semiconductor manufacturing, and hydrogen fuel cells, even from mildly acidic wastewater, without the need for toxic chemicals or electricity. Since the supply chain for palladium is concentrated in a few countries and resource security is a significant issue, this eco-friendly recovery and recycling method is expected to enhance the self-sufficiency of Korea's precious metal recycling technologies.

The Korea Institute of Science and Technology (KIST) announced that a research team led by Dr. Choi Jae-woo from the Water Resources Circulation Research Center and Dr. Kim Jin-young from the Hydrogen and Fuel Cell Research Center has developed an eco-friendly palladium recovery technology using titanium-based MXene material, specifically 'TiOx/Ti3C2Tx' nanosheets. Unlike existing overseas technologies, which only work in highly acidic environments and are therefore unsuitable for the mildly acidic wastewater commonly found in industrial sites, this new method overcomes that limitation.

Palladium Recovery - Upcycling - Recycling Closed Loop. Provided by KIST

99.9% Recovery in 30 Minutes Even in Mildly Acidic Conditions

The research team densely arranged 'TiOx nanoclusters' with unsaturated oxygen on the surface of the nanomaterial, enabling the recovery of palladium at an ultra-high purity level of 99.9% within just 30 minutes, even in mildly acidic environments where conventional methods struggle. No external power supply or toxic chemicals are required, and the recovered palladium is naturally reduced to its metallic state, allowing it to be separated simply through filtration.

This material demonstrated a world-class adsorption capacity of 1,983 mg/g and maintained about 90% recovery efficiency even after more than 10 cycles of reuse, confirming both its stability and reusability. Since no high-temperature treatment or strong acid processes are needed, the research team expects that carbon emissions can be reduced by more than 80% compared to conventional recovery technologies.

From Recovery to Recycling... Proposing 'Complete Precious Metal Circulation'

Notably, this technology goes beyond simple recovery. The recovered palladium-nanosheet composite can be reused as a hydrogen evolution catalyst, and the research team presented this as a case of implementing a 'complete closed-loop recycling' system for precious metals, connecting recovery, recycling, and reintegration into industrial processes.

The technology also has a wide range of applications. It can be used to recover palladium from spent catalysts generated in the refining, petrochemical, automotive, and hydrogen fuel cell industries, as well as from electronic waste such as smartphones and circuit boards. KIST plans to further develop and commercialize the technology, aiming to establish a circular resource ecosystem that enables real-time treatment of palladium-containing wastewater in industrial settings and supplies the recovered metal back as catalysts and electronic materials.

Thesis cover. Provided by KIST

Dr. Choi Jae-woo stated, "By making it easy to recover precious metals discarded in spent catalysts and electronic waste, this technology marks a turning point that can contribute to the self-sufficiency of Korea's resource circulation system and reduce dependence on imported precious metals. We will enhance the potential for commercialization with a modular recovery system." Dr. Kim Jin-young explained, "We have confirmed that the recovered palladium can be used not just for simple recycling, but also as an electrochemical electrode catalyst for high-efficiency hydrogen production. This demonstrates the potential for expansion as a circular resource supporting clean energy production."

This research was carried out as part of KIST's major projects and the Photovoltaic Panel Recycling Technology Development Project (RS-2025-02223005), with support from the Ministry of Science and ICT and the Ministry of Climate, Energy, and Environment. The results were published in the latest issue of the international journal Advanced Functional Materials.

The title of the paper is 'Protophilic TiOx/Ti3C2Tx nanosheets for hyper-efficient closed-loop Pd recycling.'