Colored pigment Photo: IC

Chinese scientists have developed a low-cost, eco-friendly rare-earth pigment that addresses problems associated with traditional pigments, such as toxicity and environmental pollution, and is expected to lead the next generation of pigment technology, the Science and Technology Daily reported on Monday. 

In order to enhance color durability, industrial pigments may contain trace heavy metals such as lead, cadmium and mercury. Even with protective coatings, these metals may leach out under certain conditions and enter the human body through contact, inhalation, or accidental ingestion, potentially harming the human nervous system, blood and kidney. 

Based on China’s abundant rare-earth resources, a research team led by Dong Bin, a professor at Dalian Minzu University, has successfully developed low-cost, heavy-metal-free rare-earth pigments that contain no toxic heavy metals, while achieving highly saturated colors across four major color families – green, yellow, orange and red. 

The team was originally focused on fundamental research in rare earths. While reviewing literature on rare-earth applications, they found that the traditional inorganic pigment industry is facing an irreconcilable dilemma: most bright yellow-to-red pigments rely on heavy-metal compounds. Although these substances offer excellent coloring performance, they are highly toxic and prone to bioaccumulation. The team then made a serendipitous discovery that rare-earth ions can produce strong coloration while avoiding the toxicity associated with heavy metals.

According to Luo Xixian, a key member of the research team, as a major holder of rare-earth resources, China’s abundant reserves of rare-earth resources provide a uniquely advantageous resource base for the development of low-cost, environmentally friendly pigments. 

During the research and development process, the biggest challenge the team faced was achieving precise control over the optical behavior of rare-earth ions and efficiently optimize color saturation. The researchers found that aluminosilicates are environmentally friendly during both preparation and use, making them well suited to the requirements of ideal coloring pigments. 

The team also achieved a breakthrough in cost control. Aluminosilicates are among the most abundant minerals in the Earth’s crust, with wide availability and low prices. In addition, the rare-earth ions required to produce the pigment are mostly elements with relatively low market demand, giving the technology a clear cost advantage. 

“The low cost of these materials, combined with the marginal efficiency gains from large-scale production, gives us confidence that the selling price can be reduced by more than 60 percent compared with existing high-end environmentally friendly pigments,” Dong Bin told the Science and Technology Daily. 

Xu Hongxing, an academician of the Chinese Academy of Sciences, commented that the new rare-earth pigment overcomes the limits of traditional pigments, eliminating toxicity and pollution while delivering greater stability and lower costs, paving the way for next-generation pigment technology, according to the Science and Technology Daily. 

At present, the team has achieved stable production of pigments in four major color families including green, yellow, orange, and red, and has reached a preliminary cooperation agreement with Jinpu New Area in Dalian, Northeast China’s Liaoning Province, to establish a 500-ton pilot production line through collaboration to realize mass production. 

Next, the team plans to achieve full-spectrum color coverage. In terms of application, they aim to enter areas closely related to daily life, such as building exteriors, runways, ceramics, and automotive coatings, bringing “non-toxic alternative pigments” into ordinary consumer products. In addition, the team is also exploring applications of rare earths in medical fields, such as X-ray detection, striving to solve more technical challenges. 

Global Times