Treatment process of emulsified oil wastewater for oil removal before plating of electronic product

Abstract

The invention belongs to the technical field of electroplating wastewater treatment, and particularly relates to a treatment process of emulsified oil wastewater for oil removal before plating of electronic products. A chemical demulsification and membrane separation technology is adopted to carry out demulsification separation on the emulsified oil wastewater, demulsifier molecules adsorb oil drops, a separation interface is promoted to be broken, and finally flocculation is carried out to form clusters, so that the demulsification effect is achieved, a clarified water sample can be obtained, and the ion content is reduced; the demulsified and separated wastewater is flocculated by adopting PAC + PAM, and the sedimentation of organic matters and metal ions in the wastewater is promoted by virtue of the properties of charge neutralization and colloid adsorption, so that the flocculation effect is achieved, a water sample is clear and transparent, the metal ions and COD (Chemical Oxygen Demand) values are reduced after flocculation separation, COD and heavy metal ions are removed, and the aim of treating the emulsified oil wastewater is fulfilled.

Description

Technical Field

[0001] The invention belongs to the technical field of electroplating wastewater treatment, and specifically relates to a treatment process for deoiling and emulsified oil wastewater before electronic product plating. Background Art

[0002] Since the 21st century, the electroplating industry has developed rapidly. Along with it, the amount of electroplating wastewater has increased dramatically. Once the harmful substances and heavy metals in the electroplating wastewater flow into the soil, on the one hand, it will cause serious damage to the ecological environment of the discharge area, and on the other hand, heavy metals will accumulate in the human body through the food chain, causing irreversible damage to human health.

[0003] The common wastewater produced by electroplating pretreatment is the deoiled emulsified oil before electroplating. This wastewater is very common in the electroplating industry. This wastewater contains a large amount of oil and chemicals. Once it flows into the soil, it will affect the growth of surrounding vegetation and further damage the surrounding ecosystem. The chemicals contained in it may increase the risk of cancer, cause deformities in infants and young children, and cause great harm to human health.

[0004] Due to the limitation of the interfacial film formed by its own surfactant, emulsified oil wastewater will stably exist and be highly evenly dispersed in water, forming O / W type emulsified oil or W / O type emulsified oil. Industrial emulsified oil wastewater is different from oily wastewater in life. Its large volume and high oil content must be considered when treating it. The difficulty in treating emulsified oil lies in oil-water separation. At present, demulsification as the pretreatment of emulsified oil and then oil-water separation are the main development directions for treating emulsified oil. Through continuous efforts, researchers have developed many methods to treat emulsified oil: natural sedimentation method, filtration method, membrane separation method, adsorption method, etc. Many of these methods are already mature and common processes. At present, researchers mainly tend to prepare new adsorbents with low cost, green and environmentally friendly modification methods, and easy recycling and reuse.

[0005] Faced with the severe environmental pollution problem today, it is urgent to effectively treat electroplating wastewater and reduce environmental pollution. In recent decades, due to the rapid growth of the global population, water resources have been seriously insufficient. If electroplating wastewater can be effectively treated and utilized, and purified water can be obtained from it, the current situation of water resource tension can be alleviated to a great extent. Therefore, the present invention explores the treatment of emulsified oil wastewater for degreasing before electronic product plating, and studies demulsification separation and flocculation separation. It is hoped that it can provide some inspiration for the process of treating emulsified oil wastewater for degreasing before electroplating in industry, and contribute to the governance of environmental pollution. Summary of the invention

[0006] In view of the above problems, the object of the present invention is to provide a treatment process for deoiling and emulsifying oil wastewater before plating electronic products.

[0007] The technical contents of the present invention are as follows:

[0008] The present invention provides a treatment process for deoiling emulsified oil wastewater before electronic product plating, comprising the following steps:

[0009] 1) Demulsification and separation: Take the emulsified oil wastewater for pH adjustment, then add a demulsifier for demulsification, let it stand after the demulsification reaction, obtain a precipitate and an aqueous phase, and filter and separate them through a membrane;

[0010] The reagent used for pH adjustment includes glacial acetic acid, which adjusts the pH value to 6-10;

[0011] The demulsifier includes one or more of the models WDP1, WDP3, and WDP5 produced by Guangdong Shanmei Environmental Technology Co., Ltd.;

[0012] The demulsifier also includes one or more of the models L-20 and Y-50 produced by Zibo Wanjing Water Treatment Technology Co., Ltd.;

[0013] The amount of the demulsifier added is 0.2 to 2 wt% (mass percentage);

[0014] The temperature of the demulsification separation is 25 to 65°C;

[0015] The time for demulsification and separation is 20 to 100 minutes;

[0016] The pore size of the membrane is 0.2 to 10 μm;

[0017] Preferably, a WDP1 type demulsifier is used, and the demulsification conditions are: demulsification temperature 35°C, demulsifier addition amount 1.8wt%, demulsification time 20min, and filtration using a membrane with a pore size of 0.45um;

[0018] 2) Flocculation separation: Add flocculant to the water sample after demulsification separation for flocculation separation;

[0019] The flocculant includes one or more of PAC and PAM;

[0020] The PAC includes one or more of the models PAC-SJ and PAC-SJ30% produced by Wuxi Lanbo Chemical Co., Ltd.;

[0021] The PAM includes one or more of cationic polyacrylamide, anionic polyacrylamide and nonionic polyacrylamide;

[0022] The cationic polyacrylamide includes one or more of the cationic polyacrylamide C20 and cationic polyacrylamide C10 produced by Wuxi Lanbo Chemical Co., Ltd.;

[0023] The anionic polyacrylamide includes anionic polyacrylamide 1825 produced by Wuxi Lanbo Chemical Co., Ltd.;

[0024] The nonionic polyacrylamide includes nonionic polyacrylamide 680 produced by Wuxi Lanbo Chemical Co., Ltd.;

[0025] The dosage of the flocculant is 5 to 5000 ppm;

[0026] The temperature of the flocculation separation is 25 to 65°C;

[0027] The flocculation separation time is 10 to 40 minutes;

[0028] Preferably, the flocculant comprises a composition of 5000 ppm PAC+1250 ppm APAM, the flocculation temperature is 35°C, the PAC flocculation time is 20 min, and the PAM flocculation time is 10 min.

[0029] The beneficial effects of the present invention are as follows:

[0030] The invention discloses a treatment process for emulsified oil wastewater after deoiling before electronic product plating. The chemical demulsification and membrane separation technology is used to demulsify and separate the emulsified oil wastewater. A WDP1 type demulsifier is selected to have a demulsification capacity of 0.59 mL / g and no oil droplets float. For the water sample after demulsification, a membrane with a pore size of 0.45 μm is used for filtration to obtain a clear water sample with reduced ion content. The wastewater after demulsification and separation is clarified and transparent by a PAC+PAM flocculation method, and the average particle size is reduced from 1497 nm to 294.4 nm. After flocculation and separation, the metal ions and COD values ​​are reduced, COD and heavy metal ions are removed, and the purpose of treating the emulsified oil wastewater is achieved. The present invention achieves the effect of demulsification by adsorbing oil droplets through demulsifier molecules, promoting the rupture of the separation interface, and finally flocculating into agglomerates. The flocculation process mainly uses polyaluminium chloride (PAC) and polyacrylamide (PAM) as flocculants, and promotes the sedimentation of organic matter and metal ions in the wastewater through the properties of charge neutralization and colloid adsorption, thereby achieving the effect of flocculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The water samples of the five demulsifiers in Example 1 at different pH values ​​(a, b, c, d, and e are demulsifiers WDP1, WDP3, L-20, WDP5, and Y-50, respectively, and the pH values ​​are 6, 7, 8, 9, and 10 from left to right);

[0032] Figure 2 The relationship between different pH values ​​and demulsifier types and demulsification capabilities in Example 1;

[0033] Figure 3The flocculation separation of different COD removal schemes in Example 1 (from left to right: H2O, serial number 1, 2, 3, 4, 5, 6, 7, 8);

[0034] Figure 4 Comparison of COD values ​​of water samples obtained from different schemes in Example 1;

[0035] Figure 5 The water samples at different demulsifier addition amounts in Example 2 (0.2%, 0.6%, 1.0%, 1.4%, 1.8% from left to right);

[0036] Figure 6 is the relationship between the amount of demulsifier added and the demulsification capacity in Example 2;

[0037] Figure 7 The different types of PAC+PAM water samples in Example 2 (from left to right: 1, 2, 3, 4, 5, 6, 7, 8);

[0038] Figure 8 The water samples at different demulsification temperatures in Example 3 (from left to right are 25°C, 35°C, 45°C, 55°C, and 65°C);

[0039] Fig. 9 is the relationship between demulsification temperature and demulsification capacity in Example 3;

[0040] Fig.10 The water samples at different PAC contents in Example 3 (Note: 5ppm, 50ppm, 500ppm, 5000ppm from left to right);

[0041] Fig.11 is the relationship between PAC content and COD removal rate in Example 3;

[0042] Fig.12 The water samples under different PAM contents in Example 3 (Note: from left to right are H2O, 1, 2, 3, 4);

[0043] Fig.13 The relationship between PAM content and COD removal rate in Example 3;

[0044] Fig.14 The water samples at different demulsification times in Example 4 (from left to right: 20min, 40min, 60min, 80min, 100min);

[0045] Fig.15 is the relationship between demulsification time and demulsification capacity in Example 4;

[0046] Fig.16The water samples at different flocculation temperatures in Example 4 (from left to right are 1, 2, 3, 4, 5);

[0047] Fig.17 is the relationship between flocculation temperature and COD removal rate in Example 4;

[0048] Fig.18 The water samples after filtration with different pore sizes in Example 5 (from left to right: 0.2 μm, 0.45 μm, 10 μm);

[0049] Fig.19 The relationship between PAC flocculation time and COD removal rate in Example 5;

[0050] Fig. 20 The water samples under different PAC flocculation times in Example 5;

[0051] Fig.21 The water samples before and after demulsification in Example 6 (from left to right are water sample before demulsification, water sample after demulsification, and distilled water);

[0052] Fig. 22 The morphology of the water samples before and after treatment in Example 6 (a and b are the original waste liquid, c and d are the water samples after demulsification and filtration);

[0053] Fig.23 The particle size distribution of the water sample before and after demulsification and separation in Example 6 (the left figure is the particle size distribution of the original waste liquid; the right figure is the particle size distribution of the water sample after demulsification and separation);

[0054] Fig.24 The water samples under different PAM flocculation times in Example 6 (from left to right: H2O, 1, 2, 3, 4);

[0055] Fig.25 This is the relationship between PAM flocculation time and COD removal rate in Example 6. DETAILED DESCRIPTION

[0056] The present invention is further described in detail below through specific implementation cases and accompanying drawings. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art are all within the scope of the claims attached to this application.

[0057] Unless otherwise specified, all raw materials and reagents of the present invention are raw materials and reagents from the conventional market.

[0058] Materials used in the present invention:

[0059] Demulsifiers WDP1, WDP3, and WDP5 were purchased from Guangdong Shanmei Environmental Technology Co., Ltd.;

[0060] Demulsifiers L-20 and Y-50 were purchased from Zibo Wanjing Water Treatment Technology Co., Ltd.;

[0061] Glacial acetic acid was sourced from Guangdong Guanghua Technology Co., Ltd.;

[0062] Microporous filtration membranes 0.2 μm and 0.45 μm were purchased from Tianjin Jinteng Experimental Equipment Co., Ltd.; high-efficiency decolorizing flocculant CW-08 was purchased from Yixing Qingtai Purifying Agent Co., Ltd.

[0063] Polyaluminium chloride (PAC) PAC-SJ, PAC-SJ 30% (solid content 30%), cationic polyacrylamide (CPAM) C10, C20, anionic polyacrylamide (APAM) 1825, and nonionic polyacrylamide (NPAM) 680 were purchased from Wuxi Lanbo Chemicals Co., Ltd.

[0064] Example 1

[0065] A treatment process for degreasing emulsified oil wastewater before electronic product plating

[0066] 1) Demulsification and separation: 20 g of emulsified oil wastewater was taken and pH was adjusted with glacial acetic acid, and then 1.8 wt% of demulsifier was added to demulsify at 25°C for 20 min. After the demulsification reaction, the mixture was allowed to stand for 24 h to obtain a precipitate and an aqueous phase, which were filtered and separated through a 0.45 μm membrane;

[0067] Five demulsifiers were selected to conduct demulsification and separation studies at different pH values:

[0068] Table 1 Demulsification effect of different demulsifier types and pH values

[0069]

[0070]

[0071] Note: The interface condition is divided into three levels, namely, smooth, slightly smooth, and uneven, corresponding to 3, 2, and 1 respectively; the wall adhesion condition is divided into three levels, namely, no wall adhesion, slight wall adhesion, and severe wall adhesion, corresponding to 3, 2, and 1 respectively; the water phase cleanliness is divided into three levels, namely, clear, slightly turbid, and turbid, corresponding to 3, 2, and 1 respectively.

[0072] Figure 1 The water samples of 5 kinds of demulsifiers at different pH values ​​are shown in Table 1. Combined with the results in Table 1, the demulsifiers suitable for emulsified oil wastewater are WDP1, WDP3, and Y-50. The demulsification abilities of these three types of demulsifiers at 5 different pH values ​​are plotted to obtain Figure 2As a surface active substance, demulsifier can destroy the emulsified liquid structure to achieve the purpose of two-phase separation. WDP1 and WDP3 types of demulsifiers are water-soluble reverse demulsifiers, suitable for water-in-oil emulsions. The relative molecular mass of this type of demulsifier is small, the steric hindrance is small, the interface adsorption capacity is increased, and the emulsified oil colloid in the water can be flocculated and precipitated. At the same time, heavy metal ions and color in the water are removed to increase its demulsification effect.

[0073] Compared with acidic and neutral conditions, slightly alkaline conditions are more conducive to demulsification. The above-mentioned demulsifiers are inorganic polymers, composed of aluminum salts and iron salts. Under alkaline conditions, the number of hydroxyl groups increases, which is conducive to the hydrolysis process to produce more aluminum hydroxide or iron hydroxide colloids. The colloids have the properties of adsorption and flocculation to adsorb suspended matter in the water. The decrease in pH value will make the H in the system + As the ion concentration increases, it is very easy to combine with certain alkaline functional groups or polar groups in the oil to form positively charged functional groups or groups, which makes the surface of the oil droplets carry positive charges. Due to repulsive forces, it is difficult for the oil droplets to combine with each other and between the oil droplets and the demulsifier molecules, resulting in a decrease in demulsification ability. Under alkaline conditions, the charge of the polymer is opposite to the charge of the oil droplets in the emulsion. The oil droplets are easy to adsorb polymer molecules, thereby generating a coagulation effect for precipitation, which promotes the demulsification of the emulsion.

[0074] 2) Flocculation separation: Add one or more of decolorizing agent, flocculant and water purifier to the water sample after demulsification separation, with PAC added in an amount of 5000ppm and APAM added in an amount of 1250ppm, and perform flocculation separation at 35°C for 10 minutes;

[0075] Research on flocculation separation under different types of flocculants:

[0076] Table 2 Flocculation separation effect under different reagent types

[0077]

[0078]

[0079] Note: The viscosity of water samples is divided into three levels, namely viscous, slightly viscous, and non-viscous, corresponding to 3, 2, and 1 respectively.

[0080] Combine Table 2 Figure 3 , Figure 4, and considering the cost, the method of using PAC+PAM flocculants to remove COD is better. PAC+PAM is often used as a group of coagulants to synergistically treat sewage. Polyaluminium chloride (PAC) acts as a coagulant, which plays a role of connection and wiring. It can provide a bridge between polymers and suspended particles, promote the polymerization of the two, and thus have the effect of flocculation and precipitation. Polyacrylamide (PAM) is a flocculant. Its positively charged nature can be well used to neutralize the negative charge on the surface of particles in wastewater, promote the flocculation and sedimentation of polymers and suspended particles, and reduce COD and metal content.

[0081] The above-mentioned decolorizing flocculant (CW-08, Yixing Qingtai Purifying Agent Co., Ltd.) is mainly a dicyandiamide formaldehyde condensation product, which can provide a large amount of cations to neutralize the negative charge carried by the dye molecules and destabilize them. At the same time, the flocculant will generate floccules due to the hydrolysis reaction, and achieve the effect of decolorization and flocculation by adsorbing the dye molecules; the water purifier is a high-efficiency biological water purifier, and the activated carbon in its components can remove part of the chromaticity, heavy metals, etc. through physical adsorption. The porous structure of the carrier can allow microorganisms to form a film quickly, which is conducive to the existence of aerobic bacteria and reduces the COD content. However, the price of the water purifier is relatively high and is not suitable for large-scale use.

[0082] Example 2

[0083] A treatment process for degreasing emulsified oil wastewater before electronic product plating

[0084] 1) Demulsification and separation: 20 g of emulsified oil wastewater was taken and the pH was adjusted to 8 with glacial acetic acid, and then demulsifier WDP1 was added to demulsify at 25°C for 20 min. After the demulsification reaction, it was allowed to stand for 24 h to obtain a precipitate and an aqueous phase, which were filtered and separated through a 0.45 μm membrane;

[0085] Research on demulsification and separation at different demulsifier dosages:

[0086] Table 3 Demulsification effect under different demulsifier addition amounts

[0087]

[0088] Note: The color of the water phase is divided into four levels, namely colorless, slightly yellow, light yellow, and yellow, corresponding to 4, 3, 2, and 1 respectively.

[0089] Combine Table 3 Figure 5 , Figure 6 It can be seen that the amount of demulsifier added is roughly proportional to the demulsification ability. When the demulsifier molecules increase, the molecules will be continuously adsorbed on the oil-water interface film, achieving the effect of multi-layer adsorption, reducing the strength of the oil-water interface film, and increasing the strength of the interface film formed by the demulsifier molecules themselves. At the same time, the tension of the separation interface will also decrease with the increase of the amount added, thereby improving the demulsification ability.

[0090] 2) Flocculation separation: Add flocculants to the water sample after demulsification separation, with PAC added at 5000ppm and APAM added at 1250ppm, and perform flocculation separation at 35°C for 10 minutes;

[0091] Study on flocculation separation under different flocculant types:

[0092] Table 4 Flocculation separation effect under different PAC+PAM types

[0093]

[0094]

[0095] Figure 7 From left to right, they correspond to the numbers 1-8 in Table 4.

[0096] Table 5 Differences between different PAC types

[0097]

[0098] The degree of hydroxylation or alkalinity in a certain form of PAC is called basicity, which is generally expressed by the hydroxyl-aluminum molar ratio. Basicity is an important indicator of polyaluminium chloride and has an important relationship with the flocculation effect. Generally, the higher the basicity, the better the flocculation effect, but at the same time the price will be slightly higher.

[0099] Table 6 Differences between different PAM types

[0100]

[0101] There are three main types of PAM: cationic, anionic, and nonionic. Since the charged structural units of polyacrylamide are different when ionized or hydrolyzed in water, there are cationic, anionic, and nonionic types. However, their functions are to adsorb solid particles suspended in water through polar groups in the molecular chain, bridge the particles or condense the particles through charge neutralization, thereby achieving the effect of flocculation and sedimentation. Since the wastewater particles are mainly positively charged after demulsification, anionic polyacrylamide has a better effect.

[0102] Combine Table 4, Table 5, and Table 6 Figure 7 It can be seen that the effect is better when PAC-SJ30% and APAM are used together as flocculants.

[0103] Example 3

[0104] A treatment process for degreasing emulsified oil wastewater before electronic product plating

[0105] 1) Demulsification and separation: 20 g of emulsified oil wastewater was taken and the pH was adjusted to 8 with glacial acetic acid, and then 1.8 wt% of demulsifier WDP1 was added to demulsify for 20 min. After the demulsification reaction, the mixture was allowed to stand for 24 h to obtain a precipitate and an aqueous phase, which were filtered and separated through a 0.45 μm membrane;

[0106] Study on demulsification and separation at different demulsification temperatures:

[0107] Table 7 Demulsification effect at different demulsification temperatures

[0108]

[0109] Combine Table 7 Figure 8 , Fig. 9 It can be seen that at a certain temperature, the demulsification ability increases with the increase of demulsification temperature. This is because as the temperature increases, the thermal motion of the demulsifier molecules intensifies, accelerating the adsorption on the oil droplets. At the same time, the temperature increase makes the viscosity of the emulsion oil decrease, which can effectively reduce the resistance to the movement of the demulsifier molecules, enhance the fluidity of the oil-water interface film, reduce the mechanical strength, and gradually thin the oil film. The strength decreases, accelerates the sedimentation of water droplets, and achieves the effect of water-oil separation. When destroying the oil-water separation interface, a shear force is required, that is, the tendency of "tearing" the film. When the temperature rises, the shear force increases, and the oil drop surface film is more easily destroyed, which promotes the aggregation of droplets. However, the demulsification ability does not keep increasing with the increase of temperature. When exceeding a certain temperature, the demulsification ability decreases with the increase of the demulsification temperature. This is because when the temperature rises to a certain value, the critical shear strength is reached, that is, the shear force at this time is the largest. If the temperature is increased, the separation efficiency will be reduced, and the demulsification situation will not be ideal.

[0110] In addition, since the flocculation process is a reversible process, when the temperature rises, the Brownian motion of the liquid molecules intensifies, causing the oil droplets that have aggregated into clusters to collide. The oil droplets are constantly broken up, affecting the coagulation process, and the flocculation proceeds in the reverse direction, which will also reduce the demulsification effect.

[0111] 2) Flocculation separation: Add flocculant PAC-SJ 30% + APAM to the water sample after demulsification and perform flocculation separation at 35°C for 10 minutes;

[0112] Study on flocculation separation at different flocculant addition amounts:

[0113] Table 8 Flocculation separation effect under different flocculant addition amounts

[0114]

[0115] Note: ppm is the concentration expressed as the mass of the solute as parts per million of the total solution mass.

[0116] Combined with Table 8 Fig.10 , Fig.11 It can be seen that when the APAM content is 1250ppm, the COD removal rate is the highest and the flocculation effect is the best. This is because there are active groups on the carbon chain of APAM, which can adsorb on the particle surface, increase the floc volume, increase the COD removal rate, and enhance the flocculation ability. However, as the APAM content increases, the COD removal rate gradually decreases. The reason for the decrease in flocculation effect is that APMA is a high molecular organic matter. When the APMA input is too much, it will constitute a part of COD, resulting in a decrease in COD removal rate and a weakened flocculation effect as the APMA input increases.

[0117] Example 4

[0118] A treatment process for degreasing emulsified oil wastewater before electronic product plating

[0119] 1) Demulsification and separation: 20 g of emulsified oil wastewater was taken and the pH was adjusted to 8 with glacial acetic acid, and then 1.8 wt% of demulsifier WDP1 was added to demulsify at 35°C. After the demulsification reaction, the mixture was allowed to stand for 24 hours to obtain a precipitate and an aqueous phase, which were filtered and separated through a 0.45 μm membrane;

[0120] Research on demulsification and separation at different demulsification times:

[0121] Table 9 Demulsification effect at different demulsification time

[0122]

[0123] Combine Table 9 Fig.12 , Fig.13 It can be seen that within a certain range, the increase in demulsification time will cause more demulsification molecules to adsorb onto the interfacial membrane, thereby improving the demulsification ability. However, beyond a certain range, the increase in demulsification time, that is, the increase in stirring time, will cause the originally flocculated small droplets to be broken up, thereby destroying the flocculation and aggregation process in the demulsification process and reducing the demulsification ability.

[0124] 2) Flocculation separation: Add flocculants to the water sample after demulsification separation, PAC-SJ30% addition amount 5000ppm, APAM addition amount 1250ppm, and perform flocculation separation at 35°C for 10 minutes;

[0125] Study on flocculation separation at different flocculation temperatures:

[0126] Table 10 Flocculation separation effect at different flocculation temperatures

[0127]

[0128]

[0129] Combine Table 10 Fig.14 , Fig.15 It can be seen that the increase of flocculation temperature will intensify the thermal movement of flocs and promote colloidal flocculation, thereby reducing the organic matter content, increasing the COD removal rate, and enhancing the flocculation effect. However, if the flocculation temperature is too high, the flocs formed will be small and the filtration will be incomplete, resulting in a decrease in COD removal rate and a weakened flocculation effect. Therefore, too high or too low flocculation temperature is not good for flocculation.

[0130] Example 5

[0131] A treatment process for degreasing emulsified oil wastewater before electronic product plating

[0132] 1) Demulsification and separation: 20 g of emulsified oil wastewater was taken and the pH was adjusted to 8 with glacial acetic acid, and then 1.8 wt% of demulsifier WDP1 was added to demulsify at 35°C for 20 min. After the demulsification reaction, the mixture was allowed to stand for 24 h to obtain a precipitate and an aqueous phase, which were separated by filtration through a membrane;

[0133] Study on separation at different membrane pore sizes:

[0134] Table 11 Demulsification effect under different membrane pore sizes

[0135]

[0136] Combine Table 11 Fig.16 It can be seen that the size of the membrane pore size directly affects the water quality after demulsification and separation. The smaller the membrane pore size, the larger molecules are filtered out, and only a very small number of small molecules can pass through the membrane, making the filtered water sample clear. However, the size of the membrane pore size will also affect the filtration rate. When the membrane pore size is larger, the resistance of the water sample through the membrane is smaller, the easier it is to filter, and the filtration rate is faster; but when the membrane pore size is smaller, the resistance of the water sample through the membrane increases, the more precipitation is produced, and the filtration rate is slower.

[0137] 2) Flocculation separation: Add flocculants to the water sample after demulsification separation, PAC-SJ30% addition amount 5000ppm, APAM addition amount 1250ppm, and perform flocculation separation at 35°C;

[0138] Study on flocculation separation at different flocculation times:

[0139] Table 12 Flocculation separation effect under different PAC flocculation time

[0140]

[0141] Combine Table 12 Fig.17 , Fig.18 It can be seen that with the increase of PAC flocculation time, COD removal first increases and then remains basically unchanged. The reason is: Al 3+It can compress the double electric layer on the surface of suspended particles, thereby accelerating the flocculation of suspended particles. 3 + The longer the flocculation time in water, the more conducive it is to flocculation. However, there is also a maximum value for flocculation time. When the maximum value is reached, the flocculation effect is the best. After that, the flocculation effect remains unchanged when the time is increased. Considering the time cost and flocculation effect, the PAC flocculation time is selected as 20 minutes.

[0142] Table 13 Flocculation separation effect under different PAM flocculation time

[0143]

[0144] Combined with Table 13 Fig.19 , Fig. 20 It can be seen that APAM can adsorb suspended particles and organic matter in water through the active groups on its carbon chain, causing them to aggregate and settle. However, if the flocculation time is too long, the large particles that have been flocculated and settled will be broken into small particles, thereby reducing the flocculation effect and causing the water sample to become turbid. Therefore, the APAM flocculation time should not be too long or too short, and it is appropriate to select the APAM flocculation time of 10 minutes.

[0145] Example 6

[0146] 1) Demulsification and separation: 20 g of emulsified oil wastewater was taken and the pH was adjusted to 8 with glacial acetic acid, and then 1.8 wt% of demulsifier WDP1 was added to demulsify at 35°C for 20 min. After the demulsification reaction, the mixture was allowed to stand for 24 h to obtain a precipitate and an aqueous phase, which were filtered and separated through a 0.45 μm membrane;

[0147] Table 13 Water sample changes before and after demulsification

[0148]

[0149] Table 14 Water sample changes before and after demulsification

[0150]

[0151] Fig.21 In the figure, from left to right are the water sample before demulsification, the water sample after demulsification, and distilled water. It can be seen that the water sample after demulsification becomes clear and Fig. 22 (a and b are the original waste liquid, c and d are the water samples after demulsification and filtration) It can be seen that there are no oil drops after magnification 100 times under a fluorescence microscope. Fig.23 It can be seen that the particle size of the water sample after demulsification and filtration increases, causing the oil droplets to aggregate after demulsification, and the content of heavy metal ions is reduced compared with the original solution, among which the removal rate of Zn content reaches 76.75%, and the removal rate of P content reaches 83.15%.

[0152] 2) Flocculation separation: Add flocculants to the water sample after demulsification separation, PAC-SJ30% addition amount 5000ppm, APAM addition amount 1250ppm, and perform flocculation separation at 35°C for 10 minutes.

[0153] Table 15 Comparison of original wastewater and water samples after flocculation separation treatment

[0154]

[0155] Table 16 Comparison of metal ion content, total phosphorus value and COD value of original wastewater and treated water samples

[0156]

[0157] Fig.24 In the figure, from left to right are: original waste liquid, water sample after demulsification and separation, water sample after flocculation and separation, and distilled water. It can be seen that the water sample after demulsification and flocculation and separation of the present invention is relatively clear, and its clarity is close to that of distilled water; and Fig.25 Combined with Table 15 and Table 16, it shows that the particle size of the water sample after demulsification and flocculation separation changed from 1497nm to 294.4nm, the metal ion content, total phosphorus value, and COD value were greatly reduced, and the flocculation separation effect was relatively good.

[0158] As can be seen from the above, the emulsified oil wastewater was demulsified and separated by the chemical demulsification-membrane separation method. The results showed that the water sample changed significantly after demulsification, the water sample was clear and had no oil droplets, the content of heavy metal ions decreased, and the removal rate of Zn and P elements exceeded 80%;

[0159] The PAC+PAM coagulant was used to remove the ion content and COD value in the water sample after demulsification separation, and the particle size of the water sample after flocculation separation was reduced, and the ion content and COD value were reduced. According to the influence of various variables in flocculation separation on the flocculation separation process, the PAC+PAM flocculation process was speculated: polyaluminium chloride (PAC) was used as a coagulant, and its Al 3+ The hydrolysis product carries a positive charge and can be adsorbed and bridged with suspended particles and organic matter in the water, acting as a "bridge" to connect the two. Polyacrylamide (PAM) as a flocculant can adsorb particles and form precipitation by using the effect of charge neutralization, and finally settle down by its own gravity. This process is related to the amount of coagulant and flocculation time. Within a certain range, when the amount of coagulant increases, the COD removal rate increases; but excessive coagulant will lead to an increase in the positive charge on the surface of the colloid, and the particles will repel each other due to the same charge, and the destabilized colloid will stabilize again, making the flocculation effect worse. The length of the flocculation time is related to the size of the flocs. If the flocculation time is too short, the flocs will be too small and the effect will be poor; if the flocculation time is too long, the flocs will be broken again, which will also reduce the volume of the flocs and is not conducive to flocculation.

Claims

1. A treatment process for deoiling and emulsified oil wastewater before electronic product plating, characterized in that: The steps include: 1) Demulsification and separation: taking the emulsified oil wastewater for pH adjustment, then adding a demulsifier for demulsification, standing after the demulsification reaction, obtaining a precipitate and an aqueous phase, and filtering and separating through a membrane; the demulsifier includes one or more of the models WDP1, WDP3, and WDP5 produced by Guangdong Shanmei Environmental Technology Co., Ltd.; The demulsifier also includes one or more of the models L-20 and Y-50 produced by Zibo Wanjing Water Treatment Technology Co., Ltd.; The demulsifier is added in an amount of 0.2 to 2 wt%; 2) Flocculation separation: Add flocculant to the water sample after demulsification separation for flocculation separation; The flocculant includes one or more of PAC and PAM; The dosage of the flocculant is 5 to 5000 ppm.

2. The process for treating emulsified oil wastewater before electronic product plating according to claim 1, characterized in that: The reagent used for pH adjustment in step 1) includes glacial acetic acid, and the pH value is adjusted to 6-10.

3. The process for treating emulsified oil wastewater before electronic product plating according to claim 1, characterized in that: The temperature of the demulsification separation in step 1) is 25 to 65° C. and the time is 20 to 100 minutes.

4. The process for treating emulsified oil wastewater before electronic product plating according to claim 1, characterized in that: Step 1) The pore size of the membrane is 0.2-10 μm.

5. The process for treating emulsified oil wastewater before electronic product plating according to claim 1, characterized in that: Step 2) The PAC includes one or more of the models PAC-SJ and PAC-SJ30% produced by Wuxi Lanbo Chemicals Co., Ltd.

6. The process for treating emulsified oil wastewater before electronic product plating according to claim 1, characterized in that: Step 2) The PAM includes one or more of cationic polyacrylamide, anionic polyacrylamide, and nonionic polyacrylamide.

7. The process for treating emulsified oil wastewater before electronic product plating according to claim 6, characterized in that: The cationic polyacrylamide includes one or more of the cationic polyacrylamide C20 and cationic polyacrylamide C10 produced by Wuxi Lanbo Chemical Co., Ltd.

8. The process for treating emulsified oil wastewater before electronic product plating according to claim 6, characterized in that: The anionic polyacrylamide includes anionic polyacrylamide 1825 produced by Wuxi Lanbo Chemical Co., Ltd.

9. The process for treating emulsified oil wastewater before electronic product plating according to claim 6, characterized in that: The non-ionic polyacrylamide includes non-ionic polyacrylamide 680 produced by Wuxi Lanbo Chemicals Co., Ltd.

10. The process for treating emulsified oil wastewater before electronic product plating according to claim 1, characterized in that: Step 2) The flocculation separation is carried out at a temperature of 25 to 65°C and for a time of 10 to 40 minutes.

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