Abstract: In order to further improve students' innovative consciousness and active learning ability, colleges and universities have strengthened the construction of open experimental teaching. In view of some potential safety hazards exposed in the open teaching process of materials chemistry laboratory, some experiences of safety construction of materials chemistry laboratory were discussed from four aspects: training and assessment of safety knowledge, filing and safety management of chemicals, maintenance and safety education of common instruments and equipment, and formulation and exercise of emergency plans, so as to escort the smooth development of open experimental teaching and provide support for cultivating more scientific research reserve talents with self-learning, self-improvement and innovation ability.
Keywords: open experimental teaching, hidden dangers, safety construction of material chemistry laboratory
In recent years, in order to further improve students' innovative consciousness and active learning ability, colleges and universities have strengthened the construction of open experimental teaching. Based on the experimental course of inorganic materials engineering in our school, the author offers comprehensive and research-oriented experimental projects, which is beneficial to enhance students' ability to discover and solve problems independently [1]. However, in the process of opening teaching of materials chemistry laboratory, some hidden dangers have been exposed, and some new situations and problems have also appeared [2,3]. First of all, the materials chemistry laboratory involves mechanical equipment and various dangerous chemicals needed for material synthesis. Equipment includes agitator, ball mill, high-pressure reaction kettle, oven, muffle furnace, etc. Chemicals include corrosive strong acids and alkalis, flammable and explosive organic solutions, highly toxic gases (such as hydrogen sulfide) or heavy metal powders. Secondly, students are the main part of open teaching, but some students have weak safety awareness and poor practical ability and professional foundation, which challenges the smooth development of open experimental teaching. Finally, in the process of opening the laboratory, due to the increase of experimental items and contents, the utilization rate of instruments and equipment is high, and the number of instructors is limited, which greatly increases the possibility of safety and environmental accidents. Therefore, it is particularly important to strengthen the safety education and guidance of university laboratories, especially the open materials chemistry laboratory.
The author went to the City University of Hong Kong to study in July, 20 14. During this period, he had a deep understanding of the open teaching and laboratory safety and environmental protection, and also learned advanced concepts and practices. This paper combs the author's knowledge and experience in the safety construction of material chemistry laboratory, and puts forward the key points of safety management of open material chemistry laboratory. That is, it mainly focuses on the training and assessment of safety knowledge, the filing and safety management of chemicals, the maintenance and safety education of commonly used instruments and equipment, and the formulation and exercise of emergency plans.
1, laboratory safety knowledge
In view of the particularity of materials chemistry laboratory, students must pass the safety and basic skills training organized by safety management personnel before entering the laboratory, and strictly abide by the laboratory safety system during the experimental operation.
1. 1 Good laboratory habits
Attitude is everything. To obtain reliable experimental data, we must establish a scientific and rigorous attitude and develop good laboratory habits. Laboratory personnel should keep the workbench and floor clean and dry. They shouldn't eat, drink or play in the laboratory. They shouldn't run in the laboratory. Before you leave the lab, you should take off your lab coat and wash your hands thoroughly. During the experimental operation, only the required amount of chemicals is extracted. Don't leave during the experiment, and clean up the leakage in time. Before working at night, you must get the approval of the department/department head.
1.2 personal protection
Health is the capital of revolution, so personal protection should be done. Laboratory personnel should wear gloves and lab coats to protect their hands and bodies from direct contact with chemicals and overheated surfaces. Use safety glasses, goggles or face mask to prevent injury from spilled liquid, debris and strong light. Girls should tie up their long hair and hide it in their lab clothes. Students who use contact lenses must wear goggles.
1.3 Treatment of glassware
Laboratory personnel are not allowed to use broken glassware. When removing or inserting the rubber hose from the rubber plug, please wear cut-resistant gloves. Be careful with hot glass containers to avoid scalding. Understand the use of various glassware, such as beaker, flask, conical flask, measuring cylinder, pipette, etc. , and select the appropriate glassware to operate.
1.4 Use of power supply equipment
Laboratory personnel should use electrical appliances and plugs equipped with grounding wires. Never use adapters or adapters to avoid overloading the circuit. When unplugging the power plug of the tool, be sure to unplug it, not the wire. Check the wires and plugs regularly for damage. Do not operate electrical appliances if they are wet, their hands are wet or they stand on wet ground. In areas where flammable gases (such as hydrogen and acetylene) are used, explosion-proof equipment should be used. Live working alone is not allowed. When working in a live electronic circuit, you should not touch the grounded metal objects.
2. Chemical safety
2. 1 Safe use of chemicals
Laboratory personnel should know the nature and potential dangers of chemicals used. When handling chemicals, please observe the relevant preventive measures and instructions. When conducting chemical reaction experiments, don't point the test tube or bottle with chemical substances at yourself or others. Pay attention to unstable chemicals, some of which can spontaneously ignite or explode under proper conditions, such as lithium and sodium, which will burn quickly after contacting with water at room temperature. Large bottles of chemicals should be placed no higher than the shoulder height. Be alert to the activities in the laboratory room, lest others suddenly change their moving direction. If you accidentally fall down with glassware or chemicals in your hand, try to throw the glassware or chemicals away from yourself and others. In addition, all containers in the laboratory must be covered and marked with ingredients, names, date of configuration, owner's name and laboratory room number. Chemicals without ingredients and names cannot be used. Never use your sense of smell to distinguish between chemicals.
2.2 Disposal of hazardous wastes
Materials chemistry laboratory produces a large amount of chemical waste every day. If these chemical wastes are dumped into washbasins or toilets at will, it will inevitably cause environmental pollution and endanger human health. According to the document of State Environmental Protection Administration 15? Notice on strengthening the supervision of environmental pollution in laboratories? In China, laboratory pollution has been brought into the scope of environmental supervision. According to the characteristics and present situation of laboratory waste discharge, a small amount of toxic gas can be diluted by fume hood and discharged outdoors. A large number of toxic gases must be absorbed or fully burned before they can be discharged outdoors. Chemical waste liquid should be treated in the designated container, indicating the type and storage time of waste, and filling in relevant records. The waste liquid containing heavy metal ions (chromium, germanium, copper, manganese) must be treated to meet the standard before it can be discharged. Scrapping of unstable chemicals should follow the operating instructions. For example, waste lithium tablets can be destroyed in water, but if the input speed is too fast, the reaction may be too violent and an explosion may occur. Glass fragments should be discarded in the designated trash can to prevent cutting hands.
3, the use of several commonly used equipment in materials chemistry laboratory
Laboratory personnel should understand the dangers of commonly used mechanical equipment, master its operation methods, and regularly check and maintain the equipment.
3. 1 Centrifuge and planetary ball mill
Comply with the operating instructions, such equipment must be firmly in its position to ensure that its vibration will not cause the object to collapse. Don't wear a tie, gloves or loose clothes. Ensure that the load is evenly distributed. Please lock the cover before operating the equipment. Don't turn on the equipment until it stops completely.
3.2 High pressure reactor
Only trained personnel can operate the autoclave. Please understand the operating instructions before operating the high pressure reactor. Do not open the autoclave until the temperature and pressure in the autoclave have cooled down and returned to normal. When opening the autoclave, you should stand on the hinged side and wear heat-insulating gloves when operating.
3.3 compressed gas tank
Use a suitable pressure reducing valve to prevent the pressure reducing valve from being contaminated by grease or lubricant. The gas tank should be kept upright and firmly fixed to prevent it from falling over. Don't forcibly open the valve of the gas tank, especially when the valve is stuck. Before transporting the gas tank by cart, the valve of the gas tank must be closed and the pressure reducing valve removed. Keep the gas tank away from the fire source. When handling and using compressed gas, goggles must be worn.
3.4 fume hood
All processes involving volatile chemicals should be carried out in a fume hood. Each fume hood has its specific purpose, so we should choose the appropriate fume hood according to the needs of the experiment. Chemicals should be placed in the depth of fume hood, and the glass cabinet should be pulled as low as possible to effectively exhaust smoke. Never use a fume hood for storage. Try to experiment with the least chemicals and slow reaction speed to reduce the generation of smoke.
4. Emergency response measures
The laboratory should establish an emergency plan and conduct regular drills to improve the resilience of laboratory personnel and reduce disaster losses.
4. 1 fire alarm
In case of a fire, the laboratory staff kept calm and shouted? Fire alarm? To warn people nearby. Evacuate the fire scene immediately. Break the fire glass. Close all self-closing doors, doors and smoke doors to prevent fire and smoke from spreading. Leave the building according to the evacuation procedure.
4.2 Electric shock injury
If someone is injured by electric shock, don't touch the electrocuted person, and cut off the current at the first time (stand on a wooden board, thick newspaper or plastic mat, and push the electrocuted person away from the conductor with a non-conductive wooden stick). If you have received relevant training and confirmed that the victim's breathing and heartbeat have completely stopped, perform cardiopulmonary resuscitation immediately. Contact the hospital, school security office and other relevant departments in time.
4.3 Emergency treatment of general injuries
If harmful gases (such as hydrogen sulfide or carbon monoxide, etc. ) if inhaled, the injured person should be immediately removed from the infected area, moved to a fresh air place, removed from the patient's mouth and nose, unbuttoned, and kept warm. Conditional oxygen or artificial respiration can be carried out. If chemicals enter the eyes, immediately rinse the eyes with plenty of clean water for at least 15 minutes, and then do the following treatment according to two different substances: rinse the eyes with 3% sodium bicarbonate solution for acid burns; The alkali burning is washed with 3% boric acid solution and then with water. If you are burned by chemicals, treat the wound under the water throat as soon as possible and rinse it for at least 15 minutes. Take off the clothes stained with chemicals, and then treat them according to two different substances: acid burn is washed with saturated sodium bicarbonate solution, and alkali burn is washed with acetic acid solution or 3% boric acid solution. Finally, gently cover the wound with sterile gauze and send the injured person for treatment as soon as possible.
5. Conclusion
The above supplementary safety construction contents are all put forward in view of the unique safety hazards of the open material chemistry laboratory. By popularizing safety knowledge, help laboratory personnel develop good scientific habits; Strengthening professional education will help laboratory personnel to understand the potential dangers of chemicals and their protection methods; Through equipment training and emergency measures, the operation and reaction ability of laboratory personnel can be enhanced. These measures can effectively reduce the accidents in materials chemistry laboratory, which is a powerful guarantee for the smooth development of open experimental teaching and provides support for cultivating more scientific research reserve talents with self-study, self-improvement and innovation ability.
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