What are the precautions for soil lyophilization before the soil lyophilization?

The soil is cultivated all year round, and the pesticides applied to the crop, part of which is attached to the crop, part of it is scattered in the soil, atmosphere and water, and some of the pesticides remaining in the soil are absorbed
by the plant.

Residual pesticides reach people and animals directly through plant fruits, water, and atmosphere, or are transmitted to humans and livestock
through the environment and food chain.

Therefore, pesticide residues in the soil pose a major threat
to people's food safety and even life and health.

Soil remediation refers to the use of physical, chemical and biological methods to transfer, absorb, degrade and transform pollutants in the soil, reduce their concentration to acceptable levels, or convert toxic and harmful pollutants into harmless substances
.

The premise of restoration is to analyze the composition of the soil and prescribe the right medicine
.

The principle of soil lyophilizer is to prepare soil samples in a low temperature vacuum environment, because the freeze-drying temperature is low, the elements are not easy to volatilize
.

And in a closed environment, it is not easy to re-pollute
.

Lyophilized soil is also beneficial for the determination of organic matter, which can effectively prevent the volatilization of organic matter, and is conducive to maintaining soil prototypes, compositions, microorganisms, sediments, etc
.

The lyophilizer first turns the liquid water in the soil sample into amorphous ice in the low temperature environment without volume expansion, and then allows the water to be sublimated and discharged under the low temperature vacuum condition, so that the soil sample is dried
.

The microstructure and volume of the lyophilized sample do not change, 95-99% of the water can be removed, and the moisture content of the soil sample after lyophilization is about
5%.

The pre-treatment operation of the soil lyophilization machine is first placed in the ultra-low temperature refrigerator for 4 hours or more to ensure that the sample is frozen, and then taken out and placed in the drying room of the lyophilizer, and vacuumed and dried
at low temperature.