Nematodes used as fungicides and nematicides are extremely harmful plant parasites. There are 10000 species of plant parasites that cause economic harm, of which at least 150 species are harmful to plant life. Plant parasitic nematodes have been known since 65,438+0,750 years. Most nematodes feed on the roots of plants and cause damage to crops, so these nematodes mainly exist in the roots or a few inches above the soil near the roots. Eating nematodes can lead to hypertrophy or gall formation. The signs of serious infection are slow growth of plants, gray and withered leaves, and in extreme cases, plants die. Crops and ornamental plants all over the world may be harmed by parasitic nematodes. Destructive nematodes include root-knot nematodes parasitic on tomatoes, alfalfa, cotton, corn, potatoes, citrus and many other crops. So far, there is no good method to control and eradicate nematodes, and sodium thiocarbonate has a remarkable effect on controlling nematodes and soil diseases.
Wastewater treatment
Treatment of heavy metal ions in wastewater Heavy metal wastewater comes from electroplating, mining, chemical industry and other departments. It mainly comes from mine drainage, waste rock field soaking, tailings drainage from concentrator, dust removal drainage from nonferrous metal smelter, pickling water from nonferrous metal processing plant, washing water from electroplating plant, pickling drainage from steel plant, electrolysis, pesticide, medicine, paint, pigment and other industrial wastewater [1]. The types, contents and existing forms of heavy metal ions in wastewater vary with different production types. Generally, the toxic range of heavy metals is about 1.0 mg/L ~ 10 mg/L, and the toxic concentration of heavy metals with strong toxicity, such as cadmium and mercury, is 0.001mg/L ~ 0.1mg/L. Take chromium as an example, Cr3+ is human. However, excessive Cr3+ is easy to accumulate in alveoli, causing lung cancer, and entering the blood will cause liver and kidney dysfunction. Cr6+ is very irritating and corrosive, which can cause ulcers, laryngitis and enteritis. Epidemiological studies show that Cr6+ compounds are common carcinogens. When inhaled into blood, they capture part of O2 and convert hemoglobin into methemoglobin. Red blood cells have gas-carrying dysfunction, which leads to internal breathing. Hermann studied the toxicity of Cr6+ and discussed the effect of Cr6+ concentration on the gas-carrying function of red blood cells. Compared with Cr3+, Cr6+ is much more toxic than Cr3+[2]. Therefore, the pollution of heavy metal wastewater must be strictly controlled. The methods of treating heavy metal wastewater can be roughly divided into physical method, chemical method, physical and chemical method, biological method and efficient integration method. Among them, the most important methods are chemical methods and physical and chemical methods. Taking sulfide precipitation method as an example, heavy metal ions are precipitated in the form of sulfide by adding vulcanizing agent. Commonly used vulcanizing agents are sodium sulfide, sodium sulfide and H2S. The precipitation solubility of heavy metal sulfide is small, and the water content of sediment is low, so it is not easy to dissolve and precipitate again. But sulfide itself is toxic and expensive. If the vulcanizing agent is excessive, H2S will easily be produced in acid wastewater, and the drainage water must be treated again. Therefore, the wastewater treatment process is long, the operation is complicated and the treatment cost is high, which limits the application of sulfide precipitation method [1]. In view of the low concentration, complex composition and strict treatment requirements of heavy metal wastewater, the shortcomings of traditional wastewater treatment technology are large dosage of treatment agent, high price, difficult control of reaction, slow reaction, unsatisfactory effect, poor water quality, unstable residue and difficult recovery of precious metals. In the field of heavy metal wastewater treatment, it is of great significance to develop and utilize chemical substitutes that have no impact on the environment, non-toxic and harmless new water treatment chemicals, and strengthen the comprehensive application of various water treatment technologies to ensure environmental safety and realize circular economy. Sodium thiocarbonate (that is, sodium thiocarbonate, Na2CS3) has a structure that can precipitate with heavy metal ions. It has been used in the treatment of heavy metal wastewater and commercialized abroad. Tao Changyuan and others used microwave method to synthesize sodium percarbonate quickly and efficiently, and applied for an invention patent. 3. Used as a collector in pyrite flotation.
The results of electrochemical control contact angle measurement show that sodium percarbonate is more easily oxidized to the corresponding dithiocarbamates than dithiocarbonate. The results of conventional adsorption capacity analysis of collectors show that sodium thiocarbonate collector can be effectively used for mixed flotation of sulfide ores. The flotation test shows that the sodium thiocarbonate collector is effective for the flotation of copper sulfide minerals and platinum group metal sulfide minerals.
4. Main technical indicators:
(1) Total sodium sulfide solution: concentration 40% ~ 60%, residual sodium sulfide 5% ~ 8%, residual carbon disulfide 3% ~ 5%. Avoid light or store in a dark bottle. Toxic chemicals can be used as pesticides. Contact with oxidizing substances is strictly prohibited.
(2) Sodium percarbonate crystals: each molecule of sodium percarbonate contains 1 ~ 3 molecules of crystal water, which is easy to absorb moisture and soluble in water. Avoid light and transport at low temperature. No fireworks.