Process and system for removing heavy metals from printing ink wastewater

Abstract

The invention relates to the technical field of wastewater treatment, in particular to a process and a system for removing heavy metals from printing ink wastewater. Comprising the following steps: coagulating printing ink wastewater by using a metal composite coagulant, adsorbing sludge removal wastewater by using a printing ink sludge-based adsorbent, filtering the wastewater by using a catechol-based modified polyether sulfone membrane, and detecting. According to the method, the high-iron-content copper slag, titanium tetrachloride and acetylacetone are used for preparing the metal composite coagulant, the copper slag is converted into a water treatment agent main body with the high additional value, the production cost of the coagulant is greatly reduced, and through collaborative leaching of dilute sulphuric acid and hydrogen peroxide, the water treatment efficiency is greatly improved; the iron element in the copper slag is efficiently extracted and oxidized into Fe < 3 + > with a strong coagulation effect, and the dissolved trace copper and other metal ions also provide a basis for the subsequent composite reaction, so that the treatment efficiency of the oil sludge sewage and the effluent quality are integrally improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wastewater treatment, in particular to a process and system for removing heavy metals from ink wastewater. BACKGROUND

[0002] Ink wastewater is a kind of industrial wastewater with complex composition, containing a large amount of heavy metal ions, organic pigments, resins, solvents and stable emulsions. In the prior art, chemical precipitation, adsorption, ion exchange, membrane separation and other methods are often used to remove heavy metals. However, a single method often cannot cope with the complex system of ink wastewater, and there are problems such as limited adsorbent capacity, serious membrane pollution, large sludge production, and non-recovery of heavy metal resources.

[0003] In the pretreatment stage, coagulation and sedimentation methods are often used, but traditional coagulants have limited effect on the treatment of soluble heavy metals and stable emulsion systems. Although adsorption method is widely used, the cost of commercial adsorbent is high, and the adsorbent has poor tolerance to the coexisting organic matter in ink wastewater. Membrane technology can achieve deep purification, but membrane pollution and concentrated water treatment problems restrict its wide application. In addition, the existing process focuses on the simple removal of pollutants, and cannot realize the resource utilization of waste, resulting in high treatment cost.

[0004] Therefore, it is urgent to develop an efficient, economical and resource recycling ink wastewater treatment process and system with the functions of deep removal of heavy metals and resource recovery. Therefore, the present application aims to overcome the shortcomings of the prior art, and to provide a process and system for removing heavy metals from ink wastewater by converting iron and copper-containing slag into efficient composite coagulant and further recycling the sludge generated in the treatment into high-performance adsorbent material. SUMMARY

[0005] In view of the shortcomings of the prior art, the present application aims to provide a process and system for removing heavy metals from ink wastewater.

[0006] A process for removing heavy metals from ink wastewater, comprising the following steps: S1: coagulating ink wastewater with metal composite coagulant The ink wastewater is collected in a collection tank, and the ink wastewater is pumped into a coagulation tank by a vacuum pump. 0.2-0.4 g / L of metal composite coagulant is added to the coagulation tank, and stirred uniformly. The temperature is heated to 70-80℃ and kept for 30-40 min, and then cooled to room temperature for sludge-water separation. The sludge-free wastewater and ink sludge are obtained, the ink sludge is filtered out for preparing ink sludge-based adsorbent, and the sludge-free wastewater enters the sludge adsorption tank; S2: adsorption of sludge-free wastewater by ink sludge-based adsorbent In the sludge adsorption tank, 10-12 g / L of ink sludge-based adsorbent is added, and adsorption is carried out for 60-70 min, during which the sludge adsorption tank is stirred by pumping oxygen into the sludge adsorption tank, and the amount of oxygen pumped is 1.5-2.5 kg O2 / m 3 , and then standing for 30-40 min, removing the sediment by filtration, and the filtrate enters the membrane filtration tank; S3: catechol group modified polyether sulfone membrane filters wastewater and detects The catechol group modified polyether sulfone membrane is arranged in the membrane filtration tank, and the filtrate is filtered through the catechol group modified polyether sulfone membrane. The filtered liquid enters the detection tank to detect whether the heavy metal content meets the standard. If it does not meet the standard, the filtered liquid is returned to the sludge adsorption tank to repeat the above steps. After meeting the standard, it can be discharged.

[0007] Further, the preparation method of the metal composite coagulant in step S1 specifically includes the following steps: Grind the copper slag through a 200-mesh sieve to obtain fine copper slag. Mix 100-110 parts by mass of fine copper slag, 300-310 parts by mass of dilute sulfuric acid, and 5-9 parts by mass of hydrogen peroxide, and stir and leach at 80-90°C for 2-3 hours. Then, remove the filter residue by filtration to obtain a copper slag leaching solution. Slowly add 60-70 parts by mass of TiCl4 to 100-110 parts by mass of anhydrous ethanol to form a dispersion system, and then slowly add 40-48 parts by mass of acetylacetone. React in a 60-70°C water bath for 1-2 hours to obtain a titanium complex solution. Mix the copper slag leaching solution and the titanium complex solution in a volume ratio of (3-4):1, and adjust the pH to 2.5-3. React for 1-2 hours. The resulting product is aged at 60-64°C for 24-30 hours to obtain a metal composite coagulant.

[0008] Further, the preparation method of the ink sludge-based adsorbent in step S2 specifically includes the following steps: Add 20-30 parts by mass of 1,2-dichloroethane to 10-16 parts by mass of ink sludge, heat in a 70-76°C water bath for 30-40 min, then slowly add 2-4 parts by mass of glucose, keep stirring at 70-76°C for 10-20 min, then slowly add 16-20 parts by mass of concentrated sulfuric acid with a concentration of 98 wt%, and heat to 90-100°C. Stir for 3-4 hours, cool to room temperature 23-25°C, then filter, wash the filter residue with deionized water until the filtrate is neutral, vacuum filter, dry, grind through a 100-mesh sieve, and store for use. The ink sludge-based adsorbent is obtained.

[0009] Further, the preparation method of the catechol group modified polyether sulfone membrane in step S3 specifically includes the following steps: In the Tris buffer solution, 2-2.4 g / L catechol and 2-2.4 g / L tetraethylene pentamine are added, and magnetic stirring is carried out for 30-40 min until complete dissolution, and standing is carried out for 10-15 min, to obtain a catechol-based coating solution; The pretreated polyether sulfone film is completely immersed in the catechol-based coating solution, and horizontal oscillation is carried out at a speed of 60-80 rpm at room temperature of 23-25 DEG C for 4-8 hours, after the reaction, the polyether sulfone film surface is washed with deionized water for 2-3 times, then the polyether sulfone film is placed in a 60-70 DEG C oven for heat treatment for 30-40 min, and then completely dried in a 40-50 DEG C oven, to obtain a catechol-based modified polyether sulfone film.

[0010] Further, the concentration of dilute sulfuric acid is 10-15 wt%.

[0011] Further, the copper slag is a slag produced after copper refining, and contains 30-60 wt% of iron elements, and contains calcium oxide, aluminum oxide, magnesium oxide, silicon dioxide and copper.

[0012] Further, the specific steps of the pretreatment of the polyether sulfone film are as follows: the polyether sulfone film is soaked in 1M NaOH solution for 30-40 min, then taken out, and then soaked in anhydrous ethanol for ultrasonic treatment for 15-25 min, and finally soaked in deionized water for ultrasonic treatment for 15-25 min, and then taken out and completely dried in a 40-50 DEG C oven, to obtain the pretreated polyether sulfone film.

[0013] Further, the Tris buffer solution is specifically a Tris-HCl buffer solution with a pH of 8.5 and a concentration of 10 mM.

[0014] Further, the pore size of the polyether sulfone film is 0.22 mu m.

[0015] An oil ink wastewater heavy metal removal system, which can perform the above process, comprises a collection tank, a coagulation tank, a sludge adsorption tank, a membrane filtration tank and a detection tank; The collection tank is used for collecting the oil ink wastewater, the outlet of the collection tank is connected with the inlet of the coagulation tank, the outlet of the coagulation tank is connected with the inlet of the sludge adsorption tank, the outlet of the sludge adsorption tank is connected with the inlet of the membrane filtration tank, the outlet of the membrane filtration tank is connected with the inlet of the detection tank, the detection tank is provided with a first outlet and a second outlet, the first outlet of the detection tank is connected with the sludge adsorption tank, and the second outlet of the detection tank is used for discharging the liquid in the tank.

[0016] The present application has the following advantages: 1. This invention utilizes high-iron copper slag with titanium tetrachloride and acetylacetone to prepare a metal composite coagulant, transforming the copper slag into a high-value-added water treatment agent. This not only significantly reduces the production cost of the coagulant, but also, through the synergistic leaching of dilute sulfuric acid and hydrogen peroxide, efficiently extracts and oxidizes the iron element in the copper slag into Fe, which has a strong coagulation effect. 3+ The trace amounts of copper and other metal ions dissolved also provide a foundation for subsequent composite reactions. The addition of acetylacetone and titanium tetrachloride for pre-complexation generates a stable titanium complex, effectively preventing premature hydrolysis and precipitation of titanium ions before mixing. This ensures that the titanium component can participate in subsequent reactions in a controllable manner and achieve uniform molecular-level composites with components such as iron and copper. Finally, under specific pH conditions and during aging, multiple metal ions, including iron, titanium, and copper, undergo copolymerization reactions to form an inorganic-organic hybrid polymer. This polymer contains iron and titanium... The inorganic-organic hybrid polymer of copper contains highly positively charged polynuclear hydroxy iron-titanium complexes, which can efficiently neutralize the negative charge on the surface of ink wastewater, fundamentally destroying the stability of the emulsion system and achieving oil-water separation. The hydrolysis products of the titanium component have a strong adsorption bridging effect, while the iron component is used to form dense hydroxide flocs. The two work together to form flocs with a fast settling speed, effectively capturing and sweeping away the demulsified oil droplets, fine suspended solids and colloids in the water, forming co-precipitates, thus improving the overall treatment efficiency and effluent quality of oil sludge wastewater.

[0017] 2. This invention reacts ink sludge containing an iron-titanium-copper metal composite coagulant with 1,2-dichloroethane, glucose, and concentrated sulfuric acid. 1,2-dichloroethane acts as an extractant and pore-forming agent, removing organic impurities from the ink sludge and constructing a porous framework for subsequent reactions. Glucose, as an auxiliary carbon source, cokes in an acidic environment to form an amorphous carbon matrix, further optimizing the pore structure. Subsequently, concentrated sulfuric acid acts as a dehydrating agent to carbonize the organic matter, and a sulfonating agent introduces high-density hydrophilic sulfonic acid groups onto the formed carbon framework. The iron-titanium-copper composite coagulant pre-existing in the ink sludge acts as a highly efficient catalyst, significantly promoting the sulfonation reaction and ensuring more complete and robust grafting of the sulfonic acid groups. Simultaneously, the metal oxides / hydroxides formed by its hydrolysis constitute a robust inorganic framework, effectively preventing the collapse of the carbon framework during high-temperature acid treatment and ensuring the formation of a well-developed and stable pore structure. By utilizing the built-in metal component as a catalyst and structural enhancer, a highly efficient adsorbent with both well-developed pores and abundant functional groups is successfully prepared, improving the adsorption capacity for heavy metals.

[0018] 3、The application constructs a functional coating layer capable of adsorbing heavy metal ions on the surface of the polyether sulfone membrane through the synergistic effect of catechol and tetraethylenepentamine, in a weakly alkaline Tris buffer solution, catechol is oxidized to high-reactivity o-benzoquinone, and is combined with the amine group in the tetraethylenepentamine molecule through an addition reaction, this process not only forms a stable three-dimensional cross-linked network on the membrane surface, but also introduces a high-efficiency heavy metal adsorption functional group, the catechol group has complexing and reducing ability for heavy metal ions, and the multiple amine groups of tetraethylenepentamine can strongly chelate with heavy metal ions, and the two work together to build a functional layer on the membrane surface to capture heavy metals. The polyether sulfone membrane is changed from passive screening to active adsorption, which can efficiently and targetedly remove various heavy metal ions in wastewater, in addition, the introduced large number of hydrophilic groups enhance the hydrophilicity of the membrane, which helps to slow down the membrane pore blockage caused by organic pollutants in ink wastewater, improves the anti-pollution ability, and ensures that the catechol group modified polyether sulfone membrane can maintain efficient operation for a longer time in the complex ink wastewater environment, prolonging the service life. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A process flow diagram for removing heavy metals from ink wastewater of the application.

[0020] Figure 2 A system schematic diagram for removing heavy metals from ink wastewater of the application. DETAILED DESCRIPTION

[0021] In order to enable those skilled in the art to better understand the technical solutions in the application, the technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application.

[0022] Example 1: A process for removing heavy metals from ink wastewater, as shown in Figure 1 , comprising the following steps: S1: coagulating ink wastewater with a metal composite coagulant Grind the copper slag through a 200-mesh sieve to obtain fine copper slag, mix 100 parts by mass of the fine copper slag, 300 parts by mass of 10wt% concentrated sulfuric acid and 5 parts by mass of hydrogen peroxide, stir and leach at 80℃ for 2 hours, then filter to remove the filter residue to obtain a copper slag leaching solution; Slowly add 60 parts by mass of TiCl4 to 100 parts by mass of anhydrous ethanol to form a dispersion system, then slowly add 40 parts by mass of acetylacetone, and react in a 60℃ water bath for 1 hour to obtain a titanium complex solution; The copper slag leaching solution and titanium complex solution are mixed in a volume ratio of 3:1, the pH is adjusted to 2.5, and the reaction is carried out for 1 hour, and the obtained product is aged at 60°C for 24 hours to obtain a metal composite coagulant, wherein the copper slag is a slag produced after copper refining, containing 30wt% of iron elements, and containing calcium oxide, aluminum oxide, magnesium oxide, silicon dioxide and copper; The ink wastewater is collected in a collection tank, and the ink wastewater is pumped into a coagulation tank by a vacuum pump. 0.2 g / L of the metal composite coagulant is added to the coagulation tank, and stirred uniformly. The temperature is heated to 70°C and kept for 30 min. After cooling to room temperature, sludge-water separation is carried out to obtain sludge-free wastewater and ink sludge. The ink sludge is filtered out for preparing an ink sludge-based adsorbent, and the sludge-free wastewater enters a sludge adsorption tank.

[0023] S2: ink sludge-based adsorbent adsorbs sludge-free wastewater To 10 parts by mass of ink sludge, 20 parts by mass of 1,2-dichloroethane is added, heated in a water bath at 70°C for 30 min, then 2 parts by mass of glucose is slowly added, and stirring is continued at 70°C for 10 min. Then 16 parts by mass of concentrated sulfuric acid with a concentration of 98wt% is slowly added, and the temperature is raised to 90°C. Stirring is carried out for 3 hours. After cooling to room temperature 23°C, filtration is carried out. The filter residue is washed with deionized water until the filtrate is neutral. Suction filtration is carried out, and the product is dried and ground through a 100 mesh sieve for storage. An ink sludge-based adsorbent is obtained. In the sludge adsorption tank, 10 g / L of the ink sludge-based adsorbent is added, and adsorption is carried out for 60 min. During this period, the sludge adsorption tank is stirred by pumping oxygen into the sludge adsorption tank. The amount of oxygen pumped is 1.5 kg O2 / m 3 Then, the sludge is allowed to stand for 30 min, and the sediment is removed by filtration. The filtrate enters a membrane filtration tank.

[0024] S3: catechol-based modified polyether sulfone membrane filters wastewater and detects In a Tris buffer solution, 2 g / L of catechol and 2 g / L of tetraethylenepentamine are added, and magnetic stirring is carried out for 30 min until complete dissolution. After standing for 10 min, a catechol-based coating solution is obtained. The Tris buffer solution is specifically a Tris-HCl buffer solution with a pH of 8.5 and a concentration of 10 mM; A polyether sulfone membrane with a pore size of 0.22 μm is soaked in a 1M NaOH solution for 30 min, then taken out, soaked in anhydrous ethanol for ultrasonic treatment for 15 min, and finally soaked in deionized water for ultrasonic treatment for 15 min. After taking out, it is completely dried in an oven at 40°C to obtain a pretreated polyether sulfone membrane. The pretreated polyether sulfone membrane is completely immersed in the catechol-based coating solution, horizontally shaken at a rotation speed of 60 rpm at room temperature of 23°C for 4 hours, and then washed with deionized water twice after the reaction, and then placed in an oven at 60°C for heat treatment for 30 minutes, and then completely dried in an oven at 40°C to obtain a catechol-based modified polyether sulfone membrane; The catechol-based modified polyether sulfone membrane is arranged in the membrane filtration tank, and the filtrate is filtered through the catechol-based modified polyether sulfone membrane, and then the filtered liquid enters the detection tank to detect whether the heavy metal content meets the standard, and if not, the filtered liquid is returned to the sludge adsorption tank for repeated steps, and if it meets the standard, it can be discharged.

[0025] A system for removing heavy metals from ink wastewater, which can perform the above process, as shown in Figure 2 The system comprises a collection tank, a coagulation tank, a sludge adsorption tank, a membrane filtration tank and a detection tank. The collection tank is used for collecting ink wastewater, the outlet of the collection tank is connected with the inlet of the coagulation tank, the outlet of the coagulation tank is connected with the inlet of the sludge adsorption tank, the outlet of the sludge adsorption tank is connected with the inlet of the membrane filtration tank, the outlet of the membrane filtration tank is connected with the inlet of the detection tank, the detection tank is provided with a first outlet and a second outlet, the first outlet of the detection tank is connected with the sludge adsorption tank, and the second outlet of the detection tank is used for discharging the liquid in the tank.

[0026] Example 2: A process for removing heavy metals from ink wastewater, as shown in Figure 1 The process comprises the following steps: S1: coagulating ink wastewater with a metal composite coagulant Grind the copper slag through a 200-mesh screen to obtain fine copper slag, mix 105 parts by mass of the fine copper slag, 305 parts by mass of dilute sulfuric acid with a concentration of 13wt%, and 7 parts by mass of hydrogen peroxide, stir and leach at 85°C for 2.5 hours, and then filter to remove the filter residue to obtain a copper slag leaching solution; Slowly add 65 parts by mass of TiCl4 to 105 parts by mass of anhydrous ethanol to form a dispersion system, then slowly add 44 parts by mass of acetylacetone, and react in a 65°C water bath for 1.5 hours to obtain a titanium complex solution; Mix the copper slag leaching solution and the titanium complex solution in a volume ratio of 3.5:1, adjust the pH to 2.8, and react for 1.5 hours, and then age the product at 62°C for 27 hours to obtain a metal composite coagulant, wherein the copper slag contains 45wt% of iron element, and also contains calcium oxide, aluminum oxide, magnesium oxide, silicon dioxide and copper slag produced after copper refining; The ink wastewater is collected in a collection tank, the ink wastewater is pumped into a coagulation tank by a vacuum pump, 0.3 g / L of metal composite coagulant is added into the coagulation tank, stirring is uniformly carried out, heating is carried out to 75 DEG C and heat preservation is carried out for 35 min, mud-water separation is carried out after cooling to room temperature, ink sludge and mud-removed wastewater are obtained, the ink sludge is filtered out for preparing an ink sludge-based adsorbent, and the mud-removed wastewater enters a sludge adsorption tank.

[0027] S2: The ink sludge-based adsorbent adsorbs the mud-removed wastewater To 14 parts by mass of ink sludge, 25 parts by mass of 1,2-dichloroethane is added, heating is carried out in a 73 DEG C water bath for 35 min, then 3 parts by mass of glucose is slowly added, stirring is continuously carried out for 15 min at 73 DEG C, then 18 parts by mass of concentrated sulfuric acid with a concentration of 98 wt% is slowly added, the temperature is raised to 95 DEG C, and reaction is carried out for 3.5 hours under stirring, after cooling to room temperature 24 DEG C, filtration is carried out, the filter residue is washed by deionized water until the filtrate is neutral, suction filtration is carried out, drying is carried out, grinding is carried out through a 100 mesh sieve, and preservation is carried out for standby, and an ink sludge-based adsorbent is obtained; In the sludge adsorption tank, 11 g / L of the ink sludge-based adsorbent is added, adsorption is carried out for 65 min, during which the sludge adsorption tank is stirred by pumping oxygen into the sludge adsorption tank, the amount of oxygen pumped is 2 kg O2 / m 3 Then, standing is carried out for 35 min, the sediment is removed by filtration, and the filtrate enters a membrane filtration tank.

[0028] S3: Catechol-based modified polyether sulfone membrane filters wastewater and detection In a Tris buffer solution, 2.2 g / L of catechol and 2.2 g / L of tetraethylenepentamine are added, magnetic stirring is carried out for 35 min until complete dissolution, and standing is carried out for 13 min, and a catechol-based coating solution is obtained, wherein the Tris buffer solution is specifically a Tris-HCl buffer solution with a pH of 8.5 and a concentration of 10 mM; A polyether sulfone membrane with a pore size of 0.22 μm is soaked in a 1M NaOH solution for 35 min, then taken out, soaked in anhydrous ethanol for ultrasonic for 15-25 min, and finally soaked in deionized water for ultrasonic for 20 min, and after taking out, completely dried in an oven at 45 DEG C, and a pretreated polyether sulfone membrane is obtained; The pretreated polyether sulfone membrane is completely immersed in the catechol-based coating solution, horizontal oscillation is carried out at a speed of 70 rpm at room temperature of 24 DEG C for 6 hours, after the reaction is completed, the surface of the polyether sulfone membrane is washed with deionized water for 2-3 times, then the polyether sulfone membrane is placed in a 65 DEG C oven for heat treatment for 35 min, and finally completely dried in a 45 DEG C oven, and a catechol-based modified polyether sulfone membrane is obtained; The membrane filtration tank is provided with a catechol-based modified polyether sulfone membrane, the filtrate is filtered through the catechol-based modified polyether sulfone membrane, the filtered liquid enters a detection tank, whether the heavy metal content meets the standard is detected, if not, the filtered liquid is returned to the sludge adsorption tank to repeat the above steps, and after meeting the standard, it can be discharged.

[0029] A system for removing heavy metals from ink wastewater, which can perform the above process, such as Figure 2 As shown, the system comprises a collection tank, a coagulation tank, a sludge adsorption tank, a membrane filtration tank and a detection tank; The collection tank is used to collect ink wastewater, the outlet of the collection tank is connected with the inlet of the coagulation tank, the outlet of the coagulation tank is connected with the inlet of the sludge adsorption tank, the outlet of the sludge adsorption tank is connected with the inlet of the membrane filtration tank, the outlet of the membrane filtration tank is connected with the inlet of the detection tank, the detection tank is provided with a first outlet and a second outlet, the first outlet of the detection tank is connected with the sludge adsorption tank, and the second outlet of the detection tank is used to discharge the liquid in the tank.

[0030] Example 3: A process for removing heavy metals from ink wastewater, such as Figure 1 As shown, the process comprises the following steps: S1: coagulating ink wastewater with a metal composite coagulant Grind the copper slag to pass through a 200-mesh sieve to obtain fine copper slag, mix 110 parts by mass of the fine copper slag, 310 parts by mass of dilute sulfuric acid with a concentration of 15wt%, and 9 parts by mass of hydrogen peroxide, stir and leach at 90°C for 3 hours, then filter to remove the filter residue to obtain a copper slag leaching solution; Slowly add 70 parts by mass of TiCl4 to 110 parts by mass of anhydrous ethanol to form a dispersion system, then slowly add 48 parts by mass of acetylacetone, and react in a 70°C water bath for 2 hours to obtain a titanium complex solution; Mix the copper slag leaching solution and the titanium complex solution in a volume ratio of 4:1, adjust the pH to 3, and react for 2 hours, then age the product at 64°C for 30 hours to obtain a metal composite coagulant, wherein the copper slag is a slag produced after copper refining, containing 60wt% of iron elements, and containing calcium oxide, aluminum oxide, magnesium oxide, silicon dioxide and copper; Collect the ink wastewater in the collection tank, pump the ink wastewater into the coagulation tank by a vacuum pump, add 0.4g / L of the metal composite coagulant in the coagulation tank, stir uniformly, heat to 80°C and keep for 40min, cool to room temperature, then perform mud-water separation to obtain mud-removed wastewater and ink sludge, filter out the ink sludge for preparing an ink sludge-based adsorbent, and the mud-removed wastewater enters the sludge adsorption tank.

[0031] S2: adsorbing the mud-removed wastewater by the ink sludge-based adsorbent To 16 parts by mass of ink sludge, 30 parts by mass of 1,2-dichloroethane was added, heated in a water bath at 76°C for 40 min, then 4 parts by mass of glucose was slowly added, keep 76°C continue stirring for 20 min, then 20 parts by mass of concentrated sulfuric acid with a concentration of 98wt% was slowly added, heated to 100°C, stirred for 4 hours, cooled to room temperature 25°C, then filtered, the filter residue was washed with deionized water until the filtrate pH was neutral, suction filtered, dried, ground through a 100 mesh sieve, and stored for use, to obtain ink sludge-based adsorbent; In the sludge adsorption tank, 12g / L of ink sludge-based adsorbent was added, and adsorbed for 70 min, during which the sludge adsorption tank was stirred by pumping oxygen into the sludge adsorption tank, and the amount of oxygen pumped was 2.5kg O2 / m 3 Then stand for 40 min, remove the sediment by filtration, and the filtrate enters the membrane filtration tank.

[0032] S3: catechol group modified polyether sulfone membrane filters wastewater and detects In Tris buffer solution, 2.4g / L of catechol and 2.4g / L of tetraethylene pentamine were added, and stirred magnetically for 40 min until completely dissolved, and stood for 15 min to obtain a catechol group coating solution, wherein the Tris buffer solution is specifically a Tris-HCl buffer solution with a pH of 8.5 and a concentration of 10mM; The polyether sulfone membrane with a pore size of 0.22μm was soaked in 1M NaOH solution for 40 min, then taken out, soaked in anhydrous ethanol for 25 min, and finally soaked in deionized water for 25 min, and then completely dried in an oven at 40°C to obtain a pretreated polyether sulfone membrane; The pretreated polyether sulfone membrane was completely immersed in the catechol group coating solution, and oscillated horizontally at a speed of 80rpm at room temperature of 25°C for 8 hours, after the reaction, the polyether sulfone membrane was rinsed with deionized water for 3 times, then placed in a 70°C oven for heat treatment for 40 min, and finally completely dried in a 50°C oven to obtain a catechol group modified polyether sulfone membrane; The membrane filtration tank was provided with a catechol group modified polyether sulfone membrane, and the filtrate was filtered through the catechol group modified polyether sulfone membrane, and the filtered liquid entered the detection tank to detect whether the heavy metal content met the standard, if not, the filtered liquid was returned to the sludge adsorption tank to repeat the above steps, and if it met the standard, it could be discharged.

[0033] A system for removing heavy metals from ink wastewater, which can perform the above process, as shown in Figure 2 The system comprises a collection tank, a coagulation tank, a sludge adsorption tank, a membrane filtration tank and a detection tank. The collecting tank is used for collecting ink wastewater, the outlet of the collecting tank is connected with the inlet of the coagulation tank, the outlet of the coagulation tank is connected with the inlet of the sludge adsorption tank, the outlet of the sludge adsorption tank is connected with the inlet of the membrane filtration tank, the outlet of the membrane filtration tank is connected with the inlet of the detection tank, the detection tank is provided with a first outlet and a second outlet, the first outlet of the detection tank is connected with the sludge adsorption tank, and the second outlet of the detection tank is used for discharging liquid in the tank.

[0034] Comparative Example 1: Comparative Example 1 is different from Example 1 in that the titanium tetrachloride in step S1 is replaced by titanium powder with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 1.

[0035] Comparative Example 2: Comparative Example 2 is different from Example 1 in that the copper slag in step S1 is replaced by titanium tetrachloride with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 2.

[0036] Comparative Example 3: Comparative Example 3 is different from Example 1 in that acetylacetone is not added in step S1, and anhydrous ethanol is used to replace acetylacetone with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 3.

[0037] Comparative Example 4: Comparative Example 4 is different from Example 1 in that 1,2-dichloroethane is not added in step S2, and dichloromethane is used to replace 1,2-dichloroethane with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 4.

[0038] Comparative Example 5: Comparative Example 5 is different from Example 1 in that glucose is not added in step S2, and ink sludge is used to replace glucose with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 5.

[0039] Comparative Example 6: Comparative Example 6 is different from Example 1 in that tetraethylenepentamine is not added in step S3, and catechol is used to replace tetraethylenepentamine with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 6.

[0040] Comparative Example 7: Comparative Example 7 is different from Example 1 in that catechol is not added in step S3, and tetraethylenepentamine is used to replace catechol with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 7.

[0041] Comparative Example 8: Comparative Example 8 is different from Example 1 in that catechol is not added in step S3, and polydopamine is used to replace catechol with the same mass, and the remaining steps remain unchanged, which is denoted as Comparative Example 8.

[0042] The total chromium, total lead and total mercury content of the ink wastewater of Examples 1-3 and Comparative Examples 1-8 before step S1 and the total chromium, total lead and total mercury content of the filtered liquid entering the detection cell in step S3 were detected, and the results are shown in Table 1.

[0043] The total chromium content in the ink wastewater before and after use of the catechol-modified polyether sulfone membrane of Examples 1-3 and Comparative Examples 6-8 was detected after 10 times of reuse, and the results are shown in Table 2.

[0044] Table 1 (unit: mg / L)

[0045] Table 2 (unit: mg / L)

[0046] As can be seen from Table 1, the total chromium, total lead and total mercury of Examples 1-3 after the treatment process were reduced to 0.36-0.41 mg / L, 0.24-0.31 mg / L, 0.027-0.038 mg / L, respectively, while the total chromium, total lead and total mercury of Comparative Examples 1-8 were all higher than those of the examples, proving that copper-titanium bimetallic synergistic flocculation is the key to efficient capture of heavy metals in the coagulation section, and 1,2-dichloroethane and glucose together determine the number of pores and surface functional groups of the adsorbent, which directly affects the secondary adsorption effect, and the catechol-tetraethylene pentamine copolymer layer is also indispensable for chelation and interception of heavy metals.

[0047] As can be seen from Table 2, after 10 times of continuous use, the total chromium of the catechol-modified polyether sulfone membrane of Examples 1-3 after treatment was only increased from about 0.4 mg / L to about 0.6 mg / L, showing that the catechol-tetraethylene pentamine co-modified PES membrane has excellent cycle stability and anti-pollution ability, while the membrane of Comparative Example 6 lacks tetraethylene pentamine, and the total chromium after the first treatment is 1.41 mg / L, which increases to 2.37 mg / L after 10 times of recycling, the membrane of Comparative Example 7 lacks catechol, and the total chromium after the first use is as high as 1.18 mg / L, which increases to 2.08 mg / L after 10 times of recycling, and the membrane of Comparative Example 8 replaces catechol with polydopamine, and the total chromium after the first treatment is 1.13 mg / L, which increases to 2.04 mg / L after 10 times of recycling. It is proved that the lack of catechol or tetraethylene pentamine will reduce the chelation sites of the coating and reduce the hydrophilicity, leading to more serious membrane pollution and rapid performance degradation.

[0048] It should be understood that those of ordinary skill in the art can make improvements or changes according to the above description, and all these improvements and changes shall fall within the protection scope of the appended claims of the present application. The parts not described in detail in the specification belong to the prior art known to those skilled in the art.

Claims

1. A process for removing heavy metals from ink wastewater, characterized in that, Specifically, the following steps are included: S1: Metal composite coagulant coagulates ink wastewater Ink wastewater is collected in a collection tank and then pumped into a coagulation tank via a vacuum pump. 0.2-0.4 g / L of metal composite coagulant is added to the coagulation tank, stirred evenly, heated to 70-80℃ and kept at that temperature for 30-40 minutes, and then cooled to room temperature for mud-water separation to obtain sludge-removed wastewater and ink sludge. The ink sludge is filtered out and used to prepare ink sludge-based adsorbent, while the sludge-removed wastewater enters the sludge adsorption tank. S2: Ink sludge-based adsorbent for adsorbing and removing sludge wastewater Add 10-12 g / L of ink sludge-based adsorbent to the sludge adsorption tank and adsorb for 60-70 minutes. During this period, stir the sludge adsorption tank by pumping oxygen at a rate of 1.5-2.5 kg O2 / m³. 3 Then let it stand for 30-40 minutes, filter to remove sediment, and the filtrate enters the membrane filtration tank; S3: Catechol-modified polyethersulfone membrane filtration and detection of wastewater The membrane filtration tank is equipped with a catechol-modified polyethersulfone membrane. The filtrate is filtered through the catechol-modified polyethersulfone membrane. The filtered liquid enters the detection tank to test whether the heavy metal content meets the standard. If it does not meet the standard, the filtered liquid is returned to the sludge adsorption tank and the above steps are repeated. Once it meets the standard, it can be discharged.

2. The process for removing heavy metals from ink wastewater according to claim 1, characterized in that, The preparation method of the metal composite coagulant in step S1 specifically includes the following steps: The copper slag is ground through a 200-mesh sieve to obtain fine copper slag. 100-110 parts by weight of fine copper slag, 300-310 parts by weight of dilute sulfuric acid and 5-9 parts by weight of hydrogen peroxide are mixed and leached at 80-90℃ for 2-3 hours. The filter residue is then removed by filtration to obtain copper slag leachate. 60-70 parts by mass of TiCl4 were slowly added to 100-110 parts by mass of anhydrous ethanol and stirred to form a dispersion system. Then, 40-48 parts by mass of acetylacetone were slowly added and reacted in a water bath at 60-70°C for 1-2 hours to obtain a titanium complex solution. The copper slag leachate and titanium complex solution were mixed at a volume ratio of (3-4):1, and the pH was adjusted to 2.5-3. The reaction was carried out for 1-2 hours, and the resulting product was aged at 60-64℃ for 24-30 hours to obtain a metal composite coagulant.

3. The process for removing heavy metals from ink wastewater according to claim 1, characterized in that, The preparation method of the ink sludge-based adsorbent in step S2 specifically includes the following steps: Add 20-30 parts by weight of 1,2-dichloroethane to 10-16 parts by weight of ink sludge, heat in a water bath at 70-76℃ for 30-40 minutes, then slowly add 2-4 parts by weight of glucose, maintain the temperature at 70-76℃ and continue stirring for 10-20 minutes, then slowly add 16-20 parts by weight of 98wt% concentrated sulfuric acid, raise the temperature to 90-100℃, stir and react for 3-4 hours, cool to room temperature (23-25℃), filter, wash the filter residue with deionized water until the pH of the filtrate is neutral, filter by suction, dry, grind through a 100-mesh sieve, and store for later use to obtain ink sludge-based adsorbent.

4. The process for removing heavy metals from ink wastewater according to claim 1, characterized in that, The preparation method of the catechol-modified polyethersulfone membrane in step S3 specifically includes the following steps: Add 2-2.4 g / L catechol and 2-2.4 g / L tetraethylenepentamine to Tris buffer, stir magnetically for 30-40 min until completely dissolved, and let stand for 10-15 min to obtain catechol-based coating solution. The pretreated polyethersulfone membrane was completely immersed in the catechol-based coating solution and horizontally oscillated at 60-80 rpm at room temperature of 23-25℃ for 4-8 hours. After the reaction, the surface of the polyethersulfone membrane was rinsed with deionized water 2-3 times. Then, the polyethersulfone membrane was placed in an oven at 60-70℃ for 30-40 minutes for heat treatment, and then thoroughly dried in an oven at 40-50℃ to obtain the catechol-based modified polyethersulfone membrane.

5. The process for removing heavy metals from ink wastewater according to claim 2, characterized in that, The concentration of dilute sulfuric acid is 10-15 wt%.

6. The process for removing heavy metals from ink wastewater according to claim 3, characterized in that, Copper slag is the slag produced after refining copper ore, which contains 30-60 wt% iron and also contains calcium oxide, aluminum oxide, magnesium oxide, silicon dioxide, and copper.

7. The process for removing heavy metals from ink wastewater according to claim 4, characterized in that, The specific steps for pretreatment of polyethersulfone membrane are as follows: immerse the polyethersulfone membrane in 1M NaOH solution for 30-40 minutes, then remove it and immerse it in anhydrous ethanol for 15-25 minutes by sonication, and finally immerse it in deionized water for 15-25 minutes by sonication. After removal, dry it completely in an oven at 40-50℃ to obtain the pretreated polyethersulfone membrane.

8. The process for removing heavy metals from ink wastewater according to claim 4, characterized in that, The Tris buffer is specifically a 10mM Tris-HCl buffer with a pH of 8.

5.

9. The process for removing heavy metals from ink wastewater according to claim 4, characterized in that, The polyethersulfone membrane has a pore size of 0.22 μm.

10. A system for removing heavy metals from ink wastewater, characterized in that, The system is capable of performing the process described in any one of claims 1-9, and the system includes a collection tank, a coagulation tank, a sludge adsorption tank, a membrane filtration tank, and a detection tank. The collection tank is used to collect ink wastewater. The outlet of the collection tank is connected to the inlet of the coagulation tank. The outlet of the coagulation tank is connected to the inlet of the sludge adsorption tank. The outlet of the sludge adsorption tank is connected to the inlet of the membrane filtration tank. The outlet of the membrane filtration tank is connected to the inlet of the detection tank. The detection tank has a first outlet and a second outlet. The first outlet of the detection tank is connected to the sludge adsorption tank. The second outlet of the detection tank is used to discharge the liquid in the tank.

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