(Key Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, Beijing 100083, Beijing 100083)
1. Introduction
Oil well drilling and refinery Sewage discharge contains a large amount of oil and organic molecules, causing harm to the environment. In recent years, the "red tide" phenomenon caused by too many planktonic microorganisms in the ocean has become another extremely threatening source of environmental pollution. This is mainly caused by humans discharging too much organic matter rich in phosphorus and nitrogen into rivers, lakes and seas. . The key to solving the above pollution problems is to develop an effective oil absorbent.
Expanded graphite is produced from natural flake graphite through chemical or electrochemical intercalation treatment, washing and drying, and high-temperature expansion. The expanded graphite is worm-shaped, and the graphite wafers expand dozens to hundreds of times along the C-axis direction, and have a large number of unique network-like microporous structures in form. Therefore, in addition to retaining some of the properties of flake graphite (such as high chemical stability, resistance to high and low temperatures, corrosion resistance, electrical and thermal conductivity) and being safe and non-toxic, it also has a large specific surface area, high surface activity, and a lot of With strong adsorption performance, it can be widely used in environmental protection projects to adsorb and separate oil and organic macromolecules from water.
The New Carbon Materials Research Laboratory of the Department of Materials Science and Engineering of Tsinghua University first carried out a large amount of research work on the pore structure, surface state, liquid phase adsorption behavior and mechanism of expanded graphite, and proposed the "parallel plate" Model" and "Twining Adsorption Space" model to describe the microscopic model of the pore structure of expanded graphite and the structure of expanded graphite when adsorbing oil substances; the impact of the preparation conditions of expanded graphite on the pore structure was studied; the effect of expanded graphite on sulfur dioxide, The adsorption performance and mechanism of various substances such as heavy oil, polar compounds and biological macromolecules; the treatment of the oil-water mixture in the advection tank of the steel rolling mill and the printing and dyeing wastewater of the textile factory was studied. The International Conference on Carbon Materials and Interlayer Compounds has listed expanded graphite liquid phase adsorption and other oil-absorbing materials as a discussion topic.
The Tsinghua University project team was the first to conduct systematic research on the liquid phase adsorption characteristics of porous (expanded) graphite at home and abroad, and the research results are leading at home and abroad. Due to its hydrophobic and lipophilic properties and porous structure, porous graphite has a large adsorption capacity for oils and macromolecular organic substances. The adsorption capacity of dispersed porous graphite for heavy oil in water is >80 g/g, which is unmatched by other oil-absorbing materials.
2. Promotion and application
Porous graphite low-density boards prepared by intercalation and de-intercalation control technology are used to remove oil from the cooling pool of Baogang Steel Strip Plant and to remove printing and dyeing wastewater from Qinghe Woolen Mill. In engineering application experiments for COD removal, its decontamination effect is far better than that of activated carbon. Porous graphite has good prospects as a material for water pollution control.
3. Identification, Awards, and Patent Information
This technology has applied for an invention patent "Preparation of Oil Pollution Adsorbent and Its Recovery and Regeneration Method" (Application No. 200410037978.1).