Overview of various commonly used water treatment agents
The Yancheng water crisis following the blue-green algae outbreak in Taihu Lake has once again sounded the alarm for environmental protection. At present, the cause of the pollution has been initially identified. Small chemical plants are scattered around the water sources on which 300,000 citizens depend. The chemical wastewater discharged by them has seriously polluted the drinking water sources. If it is urgent to solve this major water pollution problem in the chemical industry, reporters recently learned that water treatment agent companies used for chemical wastewater treatment and various water source treatment are experiencing a sales boom. According to the reporter's investigation, there is a busy scene at the entrance of Henan Huaquan Tap Water Materials General Factory. It is understood that due to continuous orders, currently Gongyi City's Fuyuan Water Purification Materials Co., Ltd., Songxin Filter Material Industry Co., Ltd., Hongfa Net Water treatment agent companies such as Water Materials Co., Ltd. and Xinhuayu Water Purification Agent Factory that produce water purification agents, activated carbon, and papermaking flocculants are operating at full capacity. Let the editor take you to the water treatment agent and learn about this bright sword for treating chemical water pollution.
Water treatment agents refer to chemicals used for water treatment. They are widely used in chemical industry, petroleum, light industry, daily chemicals, textiles, printing and dyeing, construction, metallurgy, machinery, medicine and health, transportation, urban and rural environmental protection and other industries to achieve water conservation. and the purpose of preventing water pollution.
Water treatment agents include agents required for cooling water and boiler water treatment, seawater desalination, membrane separation, biological treatment, flocculation and ion exchange and other technologies. Such as corrosion inhibitors, scale inhibitors and dispersants, bactericidal and algaecidal agents, flocculants, ion exchange resins, purifiers, cleaning agents, pre-film agents, etc.
According to different uses and treatment processes, the main types of water treatment agents are:
Reverse osmosis pure water system water treatment preparation: Using a compound preparation with good synergistic treatment effect, it can effectively prevent the formation of scale and microbial slime, improve the desalination rate and water production of the system, and extend the service life of the RO membrane.
Special anti-scaling, special cleaning agent
Circulating cooling water treatment: ensure that cooling water towers, chillers and other equipment are in optimal operating condition, effectively control microbial flora, inhibit the generation of scale, and prevent corrosion of pipeline equipment. To achieve the purpose of reducing energy consumption and extending the service life of equipment. Develop a water treatment plan for the project, using professional compound water treatment preparations and a complete technical service system.
Bactericidal algaecide
The boiler water treatment preparation adopts a compound preparation with good synergistic treatment effect to prevent corrosion and scaling of the boiler, stabilize the boiler Water Quality, ensure the normal operation of the boiler, reduce the consumption of the boiler body, and extend its service life.
Compound boiler water treatment preparation
Can cleaning agent
Alkalinity adjuster
Spray room circulating water treatment preparation: The agent is a compound preparation with broad dispersion ability. The paint residue it treats has good dehydration properties. The treated paint residue is in a non-sticky mass, which is convenient for salvage and other processing in the next stage. The pharmaceutical environment has a friendly interface and stable processing performance. It can effectively prevent the trouble caused by paint adhering to pipeline equipment, while reducing the COD content in the water, removing odors, improving the environment, and extending the service life of circulating water.
Machine paint resin dispersant (paint mist coagulant)
suspending agent
Wastewater treatment preparations: Using reasonable water treatment technology, combined with deep water treatment, the treated water can meet the GB5084-1992, CECS61-94 reclaimed water standards, etc., and can be recycled for a long time, saving a lot of water resources.
Environmentally friendly COD special remover
heavy metal capture agent
Water treatment agents and water conservation
To save water, we must first seize the industrial water that is used more intensively. Among industrial water, cooling water accounts for the largest proportion, accounting for about 60% to 70%. Therefore, saving cooling water has become the most urgent task of industrial water conservation.
After the cooling water is recycled, water consumption is greatly saved. However, due to the continuous evaporation of the cooling water, the salts in the water are concentrated, and the contact between the cooling water and the atmosphere greatly increases the content of dissolved oxygen and bacteria, resulting in serious scaling, corrosion and bacterial and algae growth in the circulating cooling water, which makes the heat The exchange rate is greatly reduced and maintenance is frequent, threatening the normal production. For this reason, scale inhibitors, corrosion inhibitors, bactericidal algaecides and their supporting cleaning agents, pre-filming agents, dispersants, defoaming agents, flocculants, etc. must be added to the cooling water. This set of technology that adds chemicals to prevent scaling, corrosion, and bacterial and algae growth in circulating water is called chemical water treatment technology. It includes pretreatment, cleaning, pickling, pre-filming, normal dosing, sterilization and other processes. The use of coagulants and flocculants in the primary treatment of sewage treatment is also an important means of recycling sewage. Chemical water treatment technology is currently recognized at home and abroad as the most common and effective means of industrial water conservation.
chemical water treatment agent
Chemical treatment is a treatment technology that uses chemicals to eliminate and prevent scaling, corrosion, bacterial and algae growth, and to purify water. It uses coagulants to remove mechanical impurities in raw water, uses scale inhibitors to prevent scaling, uses corrosion inhibitors to inhibit corrosion, uses bactericides to prevent the growth of harmful microorganisms, and uses cleaning agents to remove rust residue, old scale, oil stains, etc.
There are three types of water treatment agents that are used in large amounts: flocculants; bactericidal and algaecidal agents; and scale and corrosion inhibitors. Flocculant is also called coagulant. Its function is to clarify suspended matter in water and reduce the turbidity of water. Usually, inorganic salt flocculant is used to add a small amount of organic polymer flocculant, which is dissolved in water and mixed evenly with the treated water to make it suspended. Most of the objects subsided. Bactericidal and algaecidal agents, also known as biocides, are used to control or remove bacteria and algae in water. Scale and corrosion inhibitors are mainly used in circulating cooling water to increase the concentration factor of water, reduce sewage discharge to achieve water conservation, and reduce scaling and corrosion of heat exchangers and pipes.
Let’s focus on a few of these water treatment agents.
1. Flocculant
1. Starch derivative flocculant
In recent years, starch flocculants have also been widely used in printing and dyeing wastewater. Li Xuxiang and others used ammonium persulfate as the initiator to graft and copolymerize water chestnut powder and acrylonitrile. The modified starch prepared was combined with the coagulant basic aluminum chloride to treat printing and dyeing wastewater, and the turbidity removal rate could reach more than 70%. Zhao Yansheng et al., based on the two-step synthesis of cationic starch flocculant by copolymerization of starch and acrylamide, conducted a one-step synthesis and performance study of starch-acrylamide graft copolymer modified cationic flocculant CSGM. Good results have been obtained for printing and dyeing wastewater from woolen mills. Chen Yucheng et al. used the leftovers from the production of konjac powder, used urea as a catalyst, and made flocculant No. 1 through phosphate esterification to treat printing and dyeing wastewater containing sulfur dyes. When the dosage was 120 mg/L, the COD removal rate was 68.8%, and the chroma removal rate reaches 92%. Yang Tongzai et al. synthesized a cationic modified polymer flocculant using starch as the raw material, and used it to treat light industrial wastewater such as printing and dyeing. The research results showed that the removal rate of suspended solids, COD, and chroma was high and the sludge was produced. The quantity is small, and the quality of the treated wastewater is greatly improved.
2. Lignin derivatives
Since the 1970s, foreign countries have studied the synthesis of quaternary ammonium cationic surfactants using lignin as raw materials, and used them to treat dye wastewater and achieved good flocculation effects. Zhu Jianhua and others in my country used lignin in papermaking cooking waste liquid to synthesize cationic surfactants to treat printing and dyeing wastewater. The results showed that lignin cationic surfactants have good flocculation properties and the decolorization rate exceeds 90%. Zhang Zhilan et al. extracted lignin from straw pulp black liquor as a flocculant, and compared the effects with aluminum chloride and polyacrylamide, confirming the superiority of lignin in treating printing and dyeing wastewater. Lei Zhongfang et al. studied the extraction of lignin from alkali straw pulp black liquor before and after anaerobic treatment as a flocculant to treat printing and dyeing wastewater, and achieved good results. On this basis, Lei Zhongfang et al. also studied the flocculation effect of lignin. The mechanism proves that lignin flocculant is a water treatment agent with special effects on high turbidity and acidic waste liquid.
3. Other natural polymer flocculants
Miya Shiguo and others used natural resources as the main raw materials, and after physical and chemical processing, they made a new amphoteric composite coagulation decolorizing agent ASD-Ⅱ to flocculate the dyeing wastewater of reduction, vulcanization, naftol, cationic and reactive dyes in printing and dyeing plants. In the decolorization experiment, the average decolorization rate was greater than 80%, with a maximum of more than 98%, and the COD removal rate was an average of greater than 60%, with a maximum of more than 80%. Zhang Qiuhua et al. used the developed carboxymethyl chitosan flocculant to treat printing and dyeing wastewater from a towel factory. The experimental results showed that the carboxymethyl chitosan flocculant was superior to other commonly used high-quality wastewater decolorization and COD removal effects. Molecular flocculants.
2. Bactericidal and algaecide
It can effectively dig out algae reproduction and slime growth. It has good sterilization and algae killing capabilities in different pH value ranges, and has dispersion and penetration effects. It can penetrate and remove slime and peel off attached algae.
In addition, it has oil removal capabilities. It is widely used in circulating cooling water systems, oil field water injection systems, and chilled water systems. It can be used as a non-oxidative sterilizing and algaecide agent and a slime stripper. It can also be used as a leveling agent for acrylic fiber dyeing and smoothening before textile processing. and antistatic treatment.
3. Scale and corrosion inhibitors
Hydroxyethylidene diphosphonic acid HEDP
characteristic:
HEDP is an organic phosphoric acid scale and corrosion inhibitor that can form stable complexes with various metal ions such as iron, copper, and zinc, and can dissolve oxides on metal surfaces. HEDP can still play a good role in corrosion and scale inhibition at 250°C, is still very stable under high pH values, is not easy to hydrolyze, and is not easy to decompose under general light and heat conditions. Its acid and alkali resistance and chlorine oxidation resistance are better than other organic phosphates (salts). HEDP can form a six-ring chelate with metal ions in water, especially calcium ions. Therefore, HEDP has a good scale inhibition effect and an obvious solubility limit effect. When used in combination with other water treatment agents, it shows ideal Synergy. HEDP solid is a high-purity product suitable for use in areas with severe cold winters; it is especially suitable for cleaning agents and daily chemical additives in the electronics industry.
HEDP application scope and usage
HEDP is widely used in industrial circulating cooling water systems such as electric power, chemical industry, metallurgy, and fertilizers, as well as in medium and low-pressure boilers, oil field water injection, and oil pipelines for scale and corrosion inhibition. HEDP can be used as a cleaning agent for metals and non-metals in the light textile industry. , peroxide stabilizer and color-fixing agent in the bleaching and dyeing industry, and complexing agent in the cyanide-free electroplating industry. HEDP is usually used in conjunction with polycarboxylic acid-type scale inhibitor and dispersant.
The water treatment agent market is booming in 2009
Nowadays, sewage treatment is receiving increasing attention from domestic enterprises. In addition, downstream enterprises have started operations after the beginning of spring, and the demand for water treatment agents is increasing day by day. The overall situation of activated carbon enterprises at the beginning of the year is better than last year. The reporter learned that the annual output of water purification agent products in Gongyi City, Henan Province accounts for 1/3 of the country's total, and there are 70 or 80 water purification agent factories.
Our country attaches great importance to water source protection and sewage treatment, and has continuously increased the support of preferential policies. Even when the global financial crisis had a serious impact on the chemical industry, the country did not relax its environmental governance and resolutely shut down chemical companies with serious pollution emissions. At the same time, it encouraged the investment and establishment of non-polluting and low-emission chemical projects. . Therefore, water treatment agent companies will usher in new development opportunities in 2009.
Last year, due to reduced orders for water treatment agent companies, the overall operating rate was only around 50% for the whole year. Especially in the months after the financial crisis broke out, the operating rate was even lower. However, judging from the current production situation, many companies are gradually resuming production and gradually emerging from the shadow of the financial crisis.
At present, the operating rates of several manufacturers of papermaking flocculants in Guangdong are increasing. Recently, the orders given to us by environmental protection companies have also been increasing. The operating rates of enterprises have increased. This is mainly due to the following reasons: First, the downstream printing and dyeing, printing and dyeing, Papermaking companies have started operations one after another. Because such enterprises will produce a large amount of wastewater after operation, the demand for water treatment agents such as papermaking flocculants will increase, which will lead to an increase in orders for water treatment agents; second, various basic chemical industries caused by the financial crisis The price of raw materials has dropped significantly, while the decline in end consumer products such as papermaking, dyes, clothing, etc. has not been significant, which has reduced the production costs of water treatment agent companies and increased their profit margins; third, since last year, the country’s environmental protection requirements have become more stringent. Strictly, all chemical, printing and dyeing, and paper-making enterprises have increased their efforts in the construction of sewage facilities. Many enterprises are in the construction stage of facilities and have not really formed actual demand for water treatment agents. However, at the beginning of this year, the construction of the projects was basically completed. Meeting the standards has created a demand for water treatment agents. In addition, after the financial crisis broke out in September last year, investment in environmental protection management also entered a low-cost period. Driven by these dual benefits, this year will form a period of high demand for water treatment agents; fourth, it is based on the current good investment environment. In order to overcome the financial crisis, the state has continuously introduced preferential support policies, especially in wastewater treatment. Therefore, new growth points for water treatment agent companies will gradually form.
A dealer who has been engaged in the sales of polyaluminum chloride for many years reported that the current increase in market demand, reduction in production costs, and preferential policy support are good for the company, but at the same time, they feel unprecedented pressure. Because when downstream companies place orders now, their requirements for both product quality and after-sales service are higher than before. This forces relevant companies to not only seize development opportunities, but also update concepts in a timely manner and increase technological transformation. Improve product quality and increase investment in the research and development of new water treatment agent products to lay a solid foundation for the healthy and long-term development of the entire water treatment agent industry.
The development of water treatment agents tends to be green
At the turn of the century, major revolutionary changes took place in the development direction of the world's chemistry and chemical engineering disciplines, which was marked by the introduction of the concept of "green chemistry". As a water treatment agent for specialty chemicals, its development strategy is closely related to green chemistry.
The pursuit of greening of water treatment agents starts from the sustainable development strategy to achieve the greening of water treatment agent products, the greening of raw materials and conversion reagents used in water treatment agent production, the greening of water treatment agent production reaction methods, and the greening of water treatment agent production reactions. The greening of environmental conditions has become the subject frontier and key research and development direction of natural sciences.
The most important issue at present is the greening of target molecule water treatment agent products, because without the target molecule, its production process would be impossible. Starting from the concept of green chemistry, according to the author's practice and experience, the greening of water treatment agents can start from the following aspects. Designing safer water treatment agents The concept of green chemistry is reshaping the development direction of water treatment technology and water treatment chemicals. Biodegradability, that is, substances can be decomposed by microorganisms into simple, environmentally acceptable forms, is an important mechanism to limit the accumulation of chemical substances in the environment. Therefore, when designing new water treatment agents that are more environmentally friendly and safer for humans, biodegradability should be a primary consideration.
The synthesis experiments we conducted show that linear polyaspartic acid with high relative molecular weight has excellent dispersion, corrosion inhibition, chelation and other functions, and can be used as a scale inhibitor, corrosion inhibitor and dispersant. Re-evaluation of existing water treatment agent products Since my country began the research and development of modern water treatment technology and water treatment agents in the early 1970s, many important results have been achieved. Especially during the "Eighth Five-Year Plan" and "Ninth Five-Year Plan" periods, the state gave key support to the research and development of water treatment agents, which greatly promoted the progress of water treatment science and technology and formed a series of technologies and products with independent intellectual property rights.
At present, our water treatment chemicals mainly include corrosion inhibitors, scale inhibitors, biocides and flocculants. Among them, corrosion inhibitors and scale inhibitors are close to the international advanced level in terms of variety development. At present, the formulas of Water Quality stabilizers used in industrial circulating cooling water are mainly phosphorus-based, accounting for about 52~58%, molybdenum-based formulas account for 20%, silicon-based formulas account for 5%-8%, and tungsten-based formulas account for 5% %, other formulas account for 5%~10%. The concept of green chemistry is re-evaluating the role and performance of existing water treatment chemicals. For products whose functions are already well known, biodegradability is the most important evaluation indicator.
Although phosphorus-based corrosion and scale inhibitors, polyacrylic acid and other polymers and copolymer scale inhibitors that are now widely used on the market have made breakthroughs in cooling water treatment technology, they have played an important role in solving the problem of water resource depletion faced by mankind. plays an important role.
