The environmental risks inherent in the surging graphene boom – pollution during the manufacturing process
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Once graphene is no longer just a display item but is produced on an industrial scale, concerns regarding pollution could become a real issue. According to the records from factories that have already started the industrial production of graphene, 40 to 50 tons of sulfuric acid and 120 to 150 tons of fresh water are required to produce one ton of graphene. “The question of whether graphene (production) causes environmental pollution is a false premise. Any chemical product inevitably generates waste; the key is whether it can be repurposed into something useful. Discharging wastewater secretly into the river – that’s what true pollution is. ” ““A hallmark of future cities, an industry worth tens of billions, a ‘Changzhou Graphene Sector’ in the capital market, a benchmark for the graphene industry…” These were the bold statements made on the local website in December 2014, after the first graphene industrialization base with a national-level status was established in a certain economic development zone. This is a scene from the graphene boom. According to the plan of the China Graphene Industry Technology Innovation Alliance (hereinafter referred to as the Alliance), 100 graphene application industrial bases are to be established across the country during the 13th Five-Year Plan period, aiming to create an industry scale of 100 billion yuan. However, on the eve of the Great Leap Forward, the environmental risks underlying that prosperity were rarely mentioned. “It is hoped that graphene will not repeat the same mistakes as lead-acid batteries. ”As early as 2011, a university professor in Shandong raised alarms about the overly aggressive graphene industry in his blog. But now, he only wishes to be interviewed anonymously: “**Strong support; everyone is talking about development. ” “This industry is relatively cutting-edge, and there are no specific reports of pollution incidents, so we haven’t paid that much attention to it yet. ”Li Xiaoliang, an associate researcher at the Environmental Planning Institute of the Ministry of Ecology and Environment, said frankly.
Although the environmental concerns associated with graphene materials themselves receive little attention, the environmental issues arising from their industrial production have come to light. Will the large-scale production of graphene have an impact on the ecosystem, and how can the resulting pollution be recovered? — These are the issues we discuss when we get together. ”said Fang Chongqing, operations director of Xiamen Kaina Graphene Technology Co., Ltd. The results of the discussion were highly divided. Feng Guanping, honorary president of the Jiangnan Graphene Research Institute, a **scientific research institution in Changzhou, Jiangsu Province, believes that the graphene industry is an environmentally friendly industry. However, anonymous industry insiders take an extreme view, arguing that some graphene manufacturers \"simply cannot pass the environmental impact assessments strictly speaking.\" Currently, the chemical vapor deposition (CVD) and redox methods are widely used in the industry to produce graphene, although these processes are not yet fully developed. Chemical vapor deposition uses carbon-containing gases such as methane as raw materials; at high temperatures, carbon atoms arrange themselves one by one on a metal substrate, thereby \"growing\" graphene films measured in square meters. The industry generally believes that this method of preparation does not place a burden on the environment. Environmental risks mainly exist in the redox method. This preparation method involves reacting graphite with a strong acid to produce graphite oxide, which is then dispersed to form graphene oxide, and a reducing agent is added to obtain graphene powder. The redox method requires large amounts of water and sulfuric acid, while generating a significant amount of acidic wastewater and waste acid. The graphene powder produced generally contains multiple layers of carbon atoms, and its properties are compromised compared to single-layer graphene in the strict sense. There is currently no authoritative statistic on the exact number of graphene manufacturing companies in the country, and some of these companies do not disclose their production capacity or methods to the public. According to Li Yichun, the secretary-general of the alliance, there are currently 3 companies that are capable of producing graphene films at an industrial scale. Five companies can produce graphene powder at such a scale (with a production capacity of 10 tons per year), and one company in Dongguan is able to produce graphene slurry on an industrial scale. In addition, twenty to thirty more enterprises have established pilot-scale production lines for graphene. The vast majority of companies that produce graphene powder use the redox method. “Expansive graphite is produced by adding two tons of sulfuric acid to one ton of graphite, which is already sufficient to cause pollution. If you keep using this thing (the redox method), won’t it cause even more pollution? ”Hongna (Dongguan) New Materials Technology Co., Ltd. produces graphene pastes, said Li Qi, the company’s chairman. The company’s manufacturing process is different from the two mentioned above; it “is a trade secret and cannot be disclosed”. However, the actual pollution is not significant. In addition to the small number of enterprises and low production capacity, another reason is that most enterprises do not operate on a daily basis. Li Yichun said that the downstream applications of graphene are not keeping up, which is restricting the production of graphene and the development of its related industries. “(Many companies) just set up their production lines, produce a batch, and then produce another batch once they have downstream customers. ” However, once applications are developed, the growth of the graphene industry could accelerate rapidly. At the 2015 China International Graphene Innovation Conference on October 29, Zhou Changyi, Director of the Raw Materials Industry Department of the Ministry of Industry and Information Technology, revealed that a 13th Five-Year Plan for the development of new material industries, including graphene, is set to be released. “This year marks the beginning of the industrialization of graphene; sales are expected to reach 500 million, and next year they will be at least several billion. ”Li Yichun said, “Companies like Dongguan Hongna had a production line capable of producing 100 tons of slurry last year, but this year that capacity has risen to 10,000 tons; it’s easy to replicate such capabilities.” ”
Waste treatment accounts for 10% of the total costs. “Other graphene producers haven’t yet reached a sufficient scale, so they don’t have such an urgent need.” We get so anxious that we’re tempted to jump off a building if it (the hazardous waste disposal company) doesn’t come to collect the acidic waste even for one day. ” Standing in front of the 8 5-meter-tall reaction vessels, amid the loud roaring of the massive machines, Luo Hongzhong, the manager of Changzhou Sixth Element Materials Technology Co., Ltd. (hereinafter referred to as Sixth Element), appeared worried. The Sixth Element is one of the few companies that operate on a daily basis. With an annual production capacity of 100 tons and an average daily output of over 300 kilograms, Luo Hongzhong states that the company ranks first among those in China that use redox methods to produce graphene powder. It is an industry consensus that the redox method for producing graphene consumes water and acid. However, due to the different production processes in various factories, the specific ratios also vary. Luo Hongzhong calculated the requirements for the sixth element: to produce one ton of graphene, 40 to 50 tons of sulfuric acid and 120 to 150 tons of fresh water are needed. In the fertilizer production industry, which has the highest total sulfuric acid consumption, approximately 360 kilograms of sulfuric acid are needed to produce one ton of phosphate fertilizer. According to the \"Evaluation of Water Use Efficiency in High-Water-Consuming Industries in China\" published by the China Institute of Water Resources and Hydropower Research in 2015, the water consumption per ton of product produced in China’s petroleum industry in 2011 ranged from 1.1 to 7.3 tons. Just for the step of removing impurities, producing one ton of graphene requires approximately 30 tons of water. According to Luo Hongzhong, when the sixth element was first put into mass production in 2013, it took 50 to 60 tons of water to wash one ton of graphene; today, a water usage ratio of 1:30 is the result of optimized production processes. What troubles him even more are the high costs of treating waste acid. At least 1:40 sulfuric acid is added to the reaction vessel as an oxidizing agent; after the reaction is complete, the amount of waste acid almost doubles due to concentration dilution. According to relevant regulations, these waste acids must be handed over to companies qualified to handle hazardous waste. “One ton of sulfuric acid costs only 500 yuan when purchased, but once it becomes two tons of waste acid, the company that handles it charges me 800 yuan. The money I spent on acids amounted to 1300 yuan, which is a very high cost. ”Luo Hongzhong feels a lot of pressure. Luo Hongzhong told a reporter from Southern Weekend that currently, the cost of handling production waste in the factory accounts for 10% of the total costs. “It’s already remarkable for other chemical companies to account for 1%. The cost of producing one ton of graphene is currently between two and three million, which we consider to be still too high. ” Hou Shifeng, an associate professor in the Department of Chemistry at Montclair State University in the United States, has established a factory in Jining City, Shandong Province, where graphene is also produced using redox methods. The current annual production capacity is 2 tons, and a production line with a capacity of 30 tons has just been completed. He said that the cost of treating the three types of waste on-site is “probably even higher” than 10% of the total cost. In his factory, producing one ton of graphene generates twenty to thirty tons of waste acid. “This pressure is quite high. To be honest, this is indeed a big problem.”
If not mentioned, one would not be aware of the problems this causes to the environment; all that can be done is to hope that environmental protection will be ensured alongside development.
Seeing this reminds me of polysilicon from 10 years ago
Rule of law + morality + responsibility = clean production
In previous years, there were always many such practices of exploiting resources to the extreme regardless of the consequences. Regardless of other factors, profits in the film should have improved by now. It’s better not to do things that will bring disaster to future generations.
The current approach of going all out at this **level is likely to be applied to next-generation polysilicon as well: L
It reminds me of the photovoltaic industry in previous years! In fact, the best type of graphene powder that can be prepared at present (as of now) is one obtained through solid-phase intercalation and liquid-phase expansion; the surface of the graphene is not damaged by strong acids or bases, and it lacks functional groups. In terms of applications, various parties can independently work on modifying graphene! Feel free to communicate. WeChat ID: six_river