Four tricks to solve chemical testing laboratory problems

Today's global environmental pollution problem has become increasingly serious, and the development of the chemical industry is an important reason. It has brought surprise to people, but also brought about annoying chemical environmental problems. Therefore, in the process of managing environmental pollution, chemistry Workers have an unshirkable responsibility for this. In addition to the pollution of large industrial and mining enterprises, a large number of students in tens of thousands of colleges and middle schools every day are doing a variety of chemical experiments, and many of them discharge little waste. Although each discharge is not large, the pollution component of this “sand accumulation tower” is complicated. The cumulative effect should not be ignored.

We know that chemistry is a central science. This science is inseparable from experiments. Experiments are the foundation of chemical theory. The laws and results of chemistry are based on experiments. Chemical experiments are also the only criterion for the correctness of test chemistry theory.

Chemical laboratory pollution has the following characteristics:

1. Concentrations of pollutants are large and concentrated. For example, inorganic acids and alkalis are almost necessary for each experiment. If these materials are discharged without treatment, they will corrode the sewage pipelines and contaminate the nearby soil.

2, more types, not as single as the factory.

3, organic laboratory volatile, toxic substances and more.

The chemistry departments of universities in developed countries all attach great importance to the issue of waste disposal. In general, professors are responsible for handling the three wastes of this department. The cost of processing is also relatively large, but our country is lagging behind in this respect. Therefore, it is quite necessary to change the traditional experimental settings and modes. At present, green chemistry has become the hot spot and frontier of current chemical research, and it is one of the important directions of chemical development in the 21st century. It provides an effective means for mankind to solve the pollution of the chemical industry to the environment and achieve sustainable economic and social development. Green chemistry requires a series of principles and methods to reduce or eliminate the use and generation of hazardous substances in the design, manufacture, and use of chemical products, making the designed chemical products or processes more environmentally friendly. In other words, it is common to say that we must control pollution at the source and design pollution-free chemical processes instead of waiting for pollution to be remedied. To achieve this process, we must first start from the laboratory in order to transition to industrial production.

I suggest starting from the following aspects:

I. Deletion and Improvement of Experiments Focusing on Very Toxic Substances We must drastically delete those experimental projects that are toxic, dangerous, and difficult to handle, and are undoubtedly in compliance with the requirements of green chemistry. Such as inorganic experiments containing cyanide electroplating, the nature of As203, the nature and preparation of N02, oxidation of C12, arsenate properties and other experiments. The third edition of the “Inorganic Chemistry Experiment” edited by the Beijing Normal University and other institutes of inorganic chemistry has been reflected in the improvement. It removed the relevant contents of the second edition. In organic chemistry experiments, for example, "cinnamic acid" experiments can be used in place of "quinoline" experiments to avoid toxic carcinogenic agents such as aniline and nitro groups. The "bromo bromide" experiment can be used instead of the "bromobenzene" experiment to avoid the experiment. Benzene, bromine and other agents that pollute the air, reduce the pollution to the environment, but also reduce the cost of low-value consumables; For the synthesis of nitrophenols, bisphenol A and phenolphthalein compounds, due to the reaction can not be complete, phenol The solubility of the genus in water is relatively large. The phenols contained in these effluents are excessive, and they can be added by bleaching to boil them so that the phenols can be oxidized and then decanted. This method is also suitable for aniline compounds.

Second, the development of micro-chemical experiments to reduce environmental pollution Micro-chemical operation technology is to use as few reagents as possible to obtain the desired chemical information experimental methods. The amount of reagent used is one-tenth to one-thousandth of the corresponding number of routine experiments. Developing micro-chemical experiments is conducive to cultivating students' rigorous scientific attitudes and enhancing environmental awareness. Its advantages include the following:

1. Micro-chemical experiments, especially micro-preparation methods, are not a simple reduction of conventional chemical experiments, a considerable part of which is the simulation of modern research methods (in the recent large amount of literature, organic synthesis is mostly in the millimolar scale). It integrates synthesis and identification, and uses infrared instruments, chromatography, nuclear magnetic resonance and other modern instruments to test the composition and structure of a small amount of products produced in the experiment. Through the evolution from a constant to a micro-experiment, students have learned how to use the basic principles of chemistry to redesign, modify, and combine various instrumentation devices to meet the experimental requirements of different specifications. This process of flexible application of knowledge will play an active role in stimulating students' ideas and inspiring their creativity.

In addition, the minipreparation experiment controls the amount of synthetic product to not exceed the required amount for subsequent testing as a principle. In this way, the economic benefits of the chemical reaction are obvious, as it not only meets the requirements of the chemical information required for the experiment, but also drastically reduces the amount of raw material reagents and reduces the environmental pollution caused by chemical reactions. At the same time, the amount of reagents can reduce the reaction time, some experimental phenomena are easier to observe, and there are good teaching effects.

2. The use of micro-chemical experiments to reform teaching methods for teachers is a promotion, especially for high school chemistry laboratories. Due to tight funding, fewer experiments are conducted. Some schools simply do not open student experiments, but only teachers demonstrate. The safety of micro-chemical experiments saves a lot of trouble for the experimental teachers. They can be more willing to teach students in accordance with their aptitude by using open and exploratory experimental teaching methods. For the same experimental project, several different materials or several different dosages can be designed and selected by the students. To change the experimental content and experimental requirements of the past is too uniform pattern, fully mobilize the students' enthusiasm for learning, so that they do a good job of micro-chemical experiments in the atmosphere of active exploration.

Micro-chemical experiment instruments, medicines, and drop bottles are small and portable, providing convenience for the classroom. In some schools, in the teaching of elements and compounds, each classroom conducts several micro experiments in conjunction with the content of the lectures, thereby changing the boring and nasty situation of narrative content in the past and receiving good results. The micro-chemistry experiment also added new contents and means for the extracurricular chemical science and technology activities.

Third, the use of closed-circuit operation or recycling and other experimental methods 1, the laboratory should set acid tanks and spent caustic tanks, after a period of time, will be carried out to achieve the required PH value of 6-9 and then discharged.

2. The waste liquid of valuable drugs must also be recycled after chemical treatment.

3. Some toxic organic insolubles should be recycled after distillation recovery.

These methods can enhance students' awareness of environmental protection, make them aware of the principle of use of chemical reagents, and make it clear that even chemical products with a small amount of drops can react significantly, so they cannot be discharged at will and pollute the earth on which we depend.

Fourth, increase design, comprehensive experiments, improve scientific and technological content In today's era, the rapid development of science and technology, promote inter-infiltration between various disciplines, the boundaries between disciplines will become more and more blurred. Therefore, how to cultivate students' ability to apply the theoretical knowledge and experimental skills of various chemical disciplines to solve practical chemical problems has become an urgent issue.

In short, the world needs to be green, and scientific experiments, which are an important part of human civilization, will be green first, which will play an important role in promoting the development of nanotechnology, experimental methods and technological improvement.