Earlier, only natural polymer substances were used as flocculants. Such as sodium alginate, Alkaline starch, gelatin, tannic acid, etc. In recent years, various polymer flocculants have been synthesized, such as sodium polyacrylate, polyacrylamide, etc. Compared with previous inorganic flocculants or natural water-soluble polymers. Synthetic polymer flocculants are characterized by high molecular weight. Because there are many functional groups in the molecular chain, it is used in small amounts in wastewater treatment; at the same time, it is used in solid-liquid separation operations such as flocculation filtration and dehydration. It has superior performance in all aspects.
Among the synthetic polymer flocculants, the acrylamide type is the most commonly used. According to the charge, polymer flocculants can be divided into cationic There are three categories: anionic, anionic and non-ionic.
1, cationic polymer
Cationic polymers commonly used as water treatment agents include dimethylamine ethyl methacrylate Polymers or copolymers of cationic monomers, condensates of polyacrylamide and formaldehyde, etc. The flocculation properties of cationic polymers are not only reflected in their ability to flocculate suspended colloidal particles through charge neutralization. Moreover, it can react with negatively charged dissolved substances to form insoluble salts.
YangIonic polymers are used as flocculants, ukiIt has the function of removing turbidity or decolorizing. It is suitable for wastewater containing a lot of organic colloids, such as industrial wastewater from dyeing, papermaking, pulp, food, aquatic product processing and fermentation.
Compared with inorganic flocculants with the same charge neutralization performance, cationic polymers have excellent water treatment agent properties because they have more adsorption active points in the molecules. But so far, its demand is not as large as that of anionic and nonionic polymers. In practice, anionic or nonionic polymer flocculants are used in combination with inorganic flocculants.
2. Anionic polymer
The main varieties are sodium polyacrylate , polyacrylamide partially hydrolyzed, sulfonmethaneBased polyAcrylamide, etc. Compared with cationic polymers, anionic polymers have high molecular weight, and due to the interaction between polymeric groups within the same molecule Repellent, the molecular stretch in water is relatively large, so it has good particle flocculation function.
Polypropyleneamide departmentThe application range of water separation and disintegration flocculant, for the water being treatedpH valueIt is suitable for suspensions that are neutral to alkaline and contain a lot of inorganic matter. In addition to being used in wastewater treatment in iron-making blast furnaces, aluminum processing, papermaking, river gravel washing and other production processes, it can also be used in the primary treatment of urban groundwater.
Sodium polyacrylate Highly charged suspended particlesare not Applicable, while for metal Positively charged suspended particles such as hydrogen oxide Good flocCoagulation performance. Suitable for recycling wastewater treatmentobtained琍与Use it Productionfeed.
3. Non-ionic polymer
non The main varieties of ionic polymers are polypropyleneenamide and polyoxyethylene, condensed urea-formaldehyde resin. Nonionic polyacrylamide high molecular flocculant due to its Ionic functional groups, in phase with anionic highmolecular flocculantsIt has the following characteristics:
①Flocculation performance is affected by wastewater PHValue and SaltThe impact of the class is small;
②Wastewater flocculates under neutral and alkaline conditionsEffect(Settlement Speed)thanAnionic polymer flocculant is poor, but under acidic conditions it scores higher than anionic type子flocculationGood agent;
③ The floc strength is stronger than that of anionic polymer flocculant.
This type of flocculant is mainly used to treat aluminum processing and papermaking , comprehensive wastewater from pulp and other production processes.
�Ruanyahei; color: #323232; letter-spacing: 0px; font-size: 14px;”>② Wastewater flocculates under neutral and alkaline conditionsEffect(Settling speed)ratioAnionic polymer flocculant is poor, but under acidic conditions it scores higher than anionic type 子flocculationJihao;
③The floc strength is stronger than that of anionic polymer flocculant.
This type of flocculant is mainly used to treat comprehensive wastewater from aluminum processing, papermaking, pulp and other production processes.
