TW201914953A - Method for preparing high specific surface area sewage sludge carbon material, active carbon material and the use thereof - Google Patents

Abstract

A method for preparing high specific surface area sewage sludge carbon material, active carbon material and the use thereof, the method for preparing the active carbon material includes the following steps: providing activating agent, mixing sludge, dehydrating, calcining and drying, by this method, the active carbon material with high specific surface area is prepared to deal with heavy metals in air and water, so as to achieve the objects of treating of wastes, effectively adsorbing heavy metals in solution and environmental protection.

Description

Preparation method of high specific surface area domestic sludge raw carbon material, active biomass carbon material and use thereof

The invention relates to the technical field of sludge treatment, in particular to a preparation method of a high specific surface area domestic sludge raw carbon material proposed by reusing domestic sludge, an active biomass carbon material and a use thereof.

In recent years, environmental awareness has gradually risen, and Chinese people pay more and more attention to the environment, especially heavy metals are most concerned about environmental impact. If not handled properly, it will have a great impact on the ecosystem and the human body.

At present, one of the biggest environmental problems in the world is sludge treatment in sewage treatment plants. Since sludge contains a large amount of harmful pollutants and pathogenic bacteria, if it cannot be effectively improved, it will pose a serious threat to the environment and public health. The traditional treatment method of sludge is direct burial, and the land required for direct burial is large, and it is easy to cause groundwater pollution. Other sludge methods (such as drying and combustion) can stabilize the properties of the sludge and reduce the volume of the sludge. However, after treatment, the residue still needs further treatment, and the ash contains too much heavy metal after combustion, which is hazardous waste. , need to add cement to cure.

A large number of factories (such as suede, tanning, gold plating, dyeing, etc.) are prone to lead emissions of heavy metals (such as hexavalent chromium) due to process relationships. The hexavalent chromium in the wastewater must be reduced to the allowable range before being discharged to avoid environmental damage. Pollution. Hexavalent chromium is so toxic that if the human body consumes more than 0.1 mg/L of hexavalent chromium, it will cause acute kidney failure and liver damage. The traditional method for treating heavy metal-containing sewage is preferred by the chemical precipitation method. However, although the chemical precipitation method is simple and effective, it will produce a large amount of sludge, and the sludge generated is unfavorable for transportation and treatment. . In addition, chemical coagulation and sedimentation method must add a large amount of chemicals to remove heavy metals in water, resulting in the production of a large amount of heavy metal sludge, which is easy to increase sludge treatment, and if heavy metal sludge contains acid, it will release heavy metals again and cause secondary pollution. .

It is also worth noting that the current rational and feasible treatment of heavy metals in wastewater is the use of activated carbon for the adsorption of heavy metal-containing wastewater, mainly because activated carbon has a very high specific surface area, a very rich microporous structure and a functional group, which can be used for heavy metals. Good adsorption.

In view of the above technical problems and the development trend of waste resource utilization, the present invention provides a method for preparing a high specific surface area domestic sludge raw carbon material, an active biomass carbon material and a use thereof for treating heavy metals in air and water, The high specific surface area domestic sludge raw carbon material prepared by the invention is used for treating heavy metals in the solution, so as to achieve waste treatment, effective adsorption of heavy metals in the solution, environmental protection and the like.

To achieve the foregoing objective, the present invention provides a method for preparing a high specific surface area domestic sludge raw carbon material, wherein the steps of the method include:

Activator providing step: dissolving zinc oxide (ZnCl ₂ ) and distilled water at a weight ratio of 1:30 to 1:7.5 to prepare an activator;

Sludge mixing step: adding sludge to the activator, mixing and mixing to obtain a mixture, the weight ratio of zinc oxide to sludge in the mixture is 1:3 to 2:3;

Dehydration step: the mixture is placed in an oven for dehydration to obtain a preliminary product;

The calcining step: calcining the preliminary product to obtain a medium-porosity raw carbon material;

Washing and drying step: the medium pore raw material carbon material is washed until the pH is neutral, and then dried to obtain an active raw carbon material.

In an embodiment of the method for preparing a high specific surface area domestic sludge raw carbon material of the present invention, the activator provides a step of adding zinc oxide to distilled water in a weight ratio of 1:30, 1:20, 1:15, 1:10 or 1:7.5; In the sludge mixing step, the weight ratio of zinc oxide to sludge is 1:3, 1:1, 3:5 or 2:3.

In the embodiment of the method for preparing a high specific surface area domestic sludge raw carbon material, the washing and drying step is to first wash the medium pore biomass carbon material with an acid solution, and then, after heating, filter and wash with distilled water. The active raw carbon material was obtained by drying until the pH was neutral.

In an embodiment of the method for preparing a high specific surface area domestic sludge raw carbon material of the present invention:

The sludge mixing step, the sludge is added to the activator, and then stirred at 85 ° C for 2 hours;

In the dehydration step, the mixture is placed in an oven and dehydrated at 110 ° C for 24 hours;

In the calcining step, the preliminary product is prepared by placing in a high-temperature furnace and calcining at a temperature of 450 ° C for 3 hours to prepare the medium-pored raw carbon material;

In the washing and drying step, the medium pore raw carbon material is washed with a 3M HCl solution, heated at 90 ° C for 30 minutes, filtered and washed by distilled water until the pH reaches neutral, and finally dried in an oven at 105 ° C. The active biomass carbon material was obtained in about 12 hours.

In the embodiment of the method for preparing a high specific surface area domestic sludge raw carbon material according to the present invention, the domestic sludge is taken from the sludge of the domestic sewage treatment plant, and is dried to form a block shape and ground into a powder form. .

The present invention further provides an active biomass carbon material which is produced by a method for preparing a high specific surface area living sludge raw carbon material as described above.

In an embodiment of the active biomass carbon material of the present invention, the active biomass carbon material has a specific surface area of 305 to 490 m ² /g; and the active raw carbon material has an average pore volume of 0.16 to 0.8 cm ³ /g; The active biomass carbon material has a pore size of 3.05 to 9.39 nm.

The invention further provides the use of an active biomaterial carbon material as described above for treating heavy metals in a solution.

In an embodiment of the use of the active biomass carbon material of the present invention, the active biomass carbon material is used in a method for treating heavy metals in a solution, and the steps thereof include:

Providing a chromium-containing solution to a adsorbent material reactor;

The active raw carbon material is adsorbed to the chromium ion in the chromium-containing solution at a temperature of 15 to 45 °C.

In the use examples of the active biomass carbon material of the present invention, the chromium-containing solution has a chromium concentration of 15 to 120 ppm, and the active biomass carbon material has a dose of 1 g/L.

The preferred embodiments of the present invention are set forth in the accompanying drawings.

To facilitate the understanding of the present invention, the following description is made in conjunction with the drawings and the embodiments.

Some embodiments of the features and advantages of the present invention are described in detail in the following description. It is to be understood that the invention is capable of various modifications in the various aspects of the invention this invention.

The invention provides a preparation method of a high specific surface area domestic sludge raw carbon material, an active biomass carbon material and a use thereof. The invention mainly re-uses domestic sludge to prepare a medium-porosity raw carbon material adsorbing material with high surface area, thereby obtaining a porous, high specific surface area, uniform pore size distribution and good adsorption capacity. Active biomaterial carbon material.

The preparation method of the high specific surface area domestic sludge raw carbon material of the present invention is described below, and the sludge in the raw material for preparing the active biomass carbon material is taken from the sludge of the domestic sewage plant, dried to form a lump, and ground. After being powdered, the steps of the method include:

(1) Activator providing step: Depending on the type of raw carbon material required, different amounts of zinc oxide (ZnCl ₂ ) are used and dissolved in 150 ml of distilled water as an activator. In the embodiment of the present invention, the weight ratio of zinc oxide to distilled water is 1:30 to 1:7.5; preferably, the weight ratio of zinc oxide to distilled water includes 1:30, 1:20, 1:15, 1:10 or 1. :7.5.

(2) Sludge mixing step: The sludge is added to the activator of the step (1) and stirred at about 85 ° C for 2 hours to obtain a mixture. In the embodiment of the present invention, the weight ratio of zinc oxide to sludge in the mixture is 1:3 to 2:3; preferably, the weight ratio of zinc oxide to sludge in the mixture is 1:3, 1: 1, 3: 5 or 2: 3.

(3) Dehydration step: The mixture of the step (2) is placed in an oven and dehydrated at 110 ° C for 24 hours to obtain an initial product.

(4) Calcination step: the primary product of the step (3) is subjected to high temperature calcination to remove the organic matter, thereby obtaining a medium-pores raw carbon material. In the embodiment of the present invention, the mesoporous raw carbon material of the step (4) is prepared by placing the preliminary product of the step (3) in a high temperature furnace and calcining at a temperature of 450 ° C for 3 hours.

(5) Washing and drying steps: The obtained raw carbon material is washed with 3M HCl solution and heated at 90 ° C for 30 minutes, then filtered and washed with distilled water until the pH is neutral, and finally dried in an oven at 105 ° C. Active biomaterial carbon is available in about 12 hours.

Thereby, the present invention reproduces the domestic sludge by the preparation method of the above-mentioned active biomass carbon material, thereby producing an active biomass carbon material having a high specific surface area, specifically, a specific surface area of the active biomass carbon material. It is 305 to 490 m ² /g; the active pore carbon material has an average pore volume of 0.16 to 0.8 cm ³ /g; and the active biomass carbon material has a pore size of 3.05 to 9.39 nm.

The above is a high specific surface area active biomass carbon material and an embodiment thereof. The following describes a method for treating heavy metals in a solution by using the active biomass carbon material; the method steps include:

(1) Providing a chromium-containing solution to an adsorption reactor. In the embodiment of the present invention, the solution has a chromium-containing concentration of 15 to 120 ppm, and the active biomass carbon material for adsorbing chromium metal has a dose of 1 g/L;

(2) The active raw carbon material is adsorbed to the chromium-containing solution through the adsorbent material at a temperature of 15 to 45 °C.

Hereinafter, the present invention will be described in detail with reference to the drawings and embodiments.

Example 1: Material composition analysis

The invention adopts the inspection method "Elemental Detection Method in Business Waste Extract - Acid Digestion Method" announced by the Environmental Protection Agency of the Environmental Protection Agency of the Executive Yuan to test whether the sewage sludge and the active biomass carbon material contain harmful heavy metals. As shown in Table 1. It can be found that although the sludge of the sewage treatment plant contains a small amount of harmful heavy metals, it is considered that the six heavy metals do not exceed the specified content after comparing the standards for hazardous industrial wastes, and are general business wastes. The active biomass carbon material prepared by carbonization of the sewage treatment plant sludge can also be found to contain a small amount of harmful heavy metals, which proves that the heavy metal has been combined with the material after being carbonized, and will not be dissolved.

Please refer to Table 2 below. The present invention is to investigate the composition ratio of the active sludge carbon element in the ratio of the original sludge to the different ZnCl ₂ impregnation ratio, so the elemental analyzer (EA) is used to carry out the C, H, N, S, O and the materials. Analysis of six elements of Ash and calorific value. Wherein, the ZnCl ₂ impregnation ratio refers to a percentage calculated according to the following formula: [ZnCl ₂ weight (g) / (ZnCl ₂ weight (g) + sludge weight (g))] ✕ 100%; implementation of the present invention In the example, the ratio of the different ZnCl ₂ impregnation ratio to the active biomass carbon material element includes 33%, 50%, 60% and 67%.

As shown in Table 2, the ratios of C, H, N, S, O and Ash of the original sludge were 25.8, 3.4, 6.0, 0.4, 49.2 and 15.2%, respectively, and the calorific values were 7954, 6734, 6560, 6486m and 6358 kJ kg ^-1 . After being immersed in different proportions of ZnCl ₂ , the C element gradually increases with the content of ZnCl ₂ impregnated. The reason is that after the anaerobic calcination, the non-carbon element volatilization in the material makes the carbon content higher than the original pollution. clay; H, N, S and O elements impregnated with ZnCl ₂ more content gradually decreases; ash content was by impregnation ZnCl ₂ more content gradually decreased, but did not change. When impregnated with 50% ZnCl ₂ , the C ratio increased significantly, and the content increased from 25.8% to 41.9%, indicating that most of the non-C elements in the original sludge have been volatilized after anaerobic calcination; the N ratio decreased from 6.0% to 5.1. %, although only reduced by 0.9%, but because this carbonization temperature belongs to medium-low temperature carbonization, it can retain more N elements, and after carbonization, it can form nitrogen functional groups and amine groups; other elements such as H ratio is reduced by 3.4%. To 1.8%; the S ratio decreased from 0.4% to 0.2% with limited difference.

Note: X%-DSSC-450 refers to a ZnCl ₂ impregnation ratio of X% of the Active Sewage Sludge Carbon (DSSC), and the active biomass carbon material is formed after carbonization by calcination at 450 °C.

Example 2: Analysis of material properties

In the embodiment of the present invention, the analyzed materials include commercially available activated carbon (hereinafter referred to as AC), original sludge (Original), carbonized domestic sludge (hereinafter referred to as DSSC) and X%-DSSC-450 ( The active raw carbon material formed by ZnCl ₂ impregnation ratio of X% and carbonized by calcination at 450 ° C is hereinafter referred to as active biomass carbon material or abbreviated X%-DSSC-450).

First, the results of thermal weight loss analysis:

The present invention uses a thermogravimetric analyzer to present the change in weight loss of the material at different temperatures, as the change in weight loss represents the composition of the material ratio. Commercially available activated carbon (AC), carbonized domestic sludge (DSSC) and X%-DSSC-450 are heated in a nitrogen atmosphere at a temperature of 30 ° C to 800 ° C to observe changes in the weight loss of the material, and then evaluate and adjust The DSSC with the best ZnCl2 ratio and its thermal stability were prepared as shown in Fig. 1 and Fig. 2.

Figure 1 shows the thermogravimetric analysis curve of the original sludge. It can be seen that there are two different stages of weight loss changes. The analysis results show that when the temperature of the first stage is less than 300 °C, the change of weight loss is due to the volatilization of water and organic molecular compound in the decomposition material, and the weight loss is about 30 wt.%; after the temperature of the second stage is more than 300 °C, the weight loss changes to The decomposition of high molecular organic substances (such as tar) in the material and the release of volatile gases, the weight loss at this stage is about 20 wt.%.

Figure 2 is a thermogravimetric analysis curve of DSSC (X%-DSSC-450), original sludge and AC impregnated with different ZnCl ₂ ratios. It can be seen that the original sludge is divided into two types after activation and anaerobic calcination. The change of weight loss at different stages, the analysis results show that when the temperature of the first stage is less than 100 °C, the change of weight loss is due to the volatilization of water in the decomposition material, and the weight loss is about 5 wt.%; and when the temperature of the second stage is greater than 500 °C, The change in weight loss is due to the decomposition and release of a small amount of high molecular organic matter and volatile gases in the material after medium and low temperature calcination. In the embodiment of the present invention, since the organic matter in the original material is to be retained to form a functional group after carbonization, the calcination temperature of the preparation material is selected when the carbonization temperature is 450 ° C.

Second, nitrogen isothermal absorption / desorption instrument analysis results

The following is an example showing the influence of BET surface area, pore volume and pore size distribution of different materials by the examples, so that commercially available activated carbon, carbonized domestic sludge and X%-DSSC-450 (33%, 50%, 60% and 67) %) Perform N ₂ absorption/desorption analysis to understand whether the isothermal absorption/desorption curve, BET specific surface area, average pore volume, and pore size distribution have a certain influence due to the amount of ZnCl2 added; the results of the examples are shown in Table 3. The N ₂ absorption/desorption curve is shown in Figure 3; the pore size distribution curve is shown in Figure 4.

It can be seen from Fig. 3 that the N ₂ absorption/desorption curve of AC and X%-DSSC-450 is more than the isothermal absorption/desorption curve of the hole material in the fourth type (Type IV). According to the hysteresis loop type classification, it can be known that the adsorption/desorption behavior has four stages: the first stage is that when the relative pressure is low, the N ₂ adsorption capacity increases slowly, which is consistent with the pore wall single layer-multilayer adsorption; the second stage is When the relative pressure rises, the nitrogen adsorption capacity increases sharply, indicating that the capillary in the middle hole has condensation phenomenon; in the third stage, when the relative pressure rises (when the relative pressure is high), the adsorption capacity of N ₂ increases again slowly, indicating that the crystal has external Multilayer adsorption phenomenon. The fourth stage is characterized by a pressure increase near saturation (P/P0 = 1.0) and a significant increase in N ₂ adsorption capacity, at which point N ₂ fills all other holes.

As shown in Fig. 4 and Table 3, the specific surface area of AC is 901 m ² g ^-1 , and the specific surface area of X%-DSSC-450 when the proportion of DSSC-impregnated ZnCl ₂ is 33%, 50%, 60% and 67%, respectively. They are 305, 490, 459 and 435 m ² g ^{-1 respectively} . It can be seen that the impregnation ratio rises to a certain extent and then decreases slightly. It may be because the ability of ZnCl _{2 to} erode the material is limited, so that immersion of too much proportion of ZnCl ₂ can not produce more specific surface area on the surface of the material, or even break the cross-linked structure between the pores, resulting in The pore wall collapses during carbonization.

The average pore volume of the DSSCs with ZnCl ₂ ratios of 33%, 50%, 60% and 67%, respectively, differed by the impregnation ratio, which were 0.16, 0.80, 0.70 and 0.67 cm ³ g ^-1 , respectively. The pore size distributions were 3.05, 9.39, 8.48, and 7.14 nm, respectively. It is known that the best impregnation ratio in the examples of the present invention is impregnation of 50% ZnCl ₂ .

Third, FT – IR analysis results

The following is an illustration of an embodiment of the invention for analyzing the functional sludge species of a sewage treatment plant raw sludge and impregnating different ZnCl ₂ content DSSC (X%-DSSC-450) by FT-IR. As shown in Fig. 5A, the sludge is at 3400 cm ^-1 , corresponding to the bending vibration of the O - H bond and the N - H bond, which is a characteristic peak of the amine group, and DSSC (X%-DSSC- in different ratios of ZnCl ₂ ) 450) can also be found, and there is a clear trend of enhancement; sludge at 2930 cm ^-1 and 2849 cm ^-1 , the bending vibration corresponding to the C - H bond is the characteristic peak of the CH ₂ functional group, in different proportions of ZnCl ₂ DSSC can be found to indicate that the CH ₂ functional group retains the surface of the material after carbonization. The sludge at 1653 cm ^-1 corresponds to the bending vibration of C = C bond, and DSSC in different proportions of ZnCl ₂ can also be found, and there is a tendency to increase significantly. These characteristic peaks all show that the surface of the material has the same surface characteristics as the amine modified material. The sludge is at 1245 - 1155 cm ^-1 , corresponding to the hydrogen bonded P = O bond, O - C bond, P - O - C bond and P = OOH bond, DSSC (X%) in different proportions of ZnCl ₂ -DSSC-450) It can also be found that the peak of the hydrogen bonding bond has a significant tendency to increase; the sludge at 1020 cm ^-1 can correspond to the C-O bond. After using 50% -DSSC-450 adsorption Cr (VI) ions, the observed at 1172.97 cm ^-1 is shifted to 1163.54 cm ^-1, 1008.50 cm ^-1, and at a shifted to 1022.47 cm ^-1. As shown in Figure 5B. Probably due to the hydroxyl groups on the surface of the material, the carboxyl and amine groups and the Cr(VI) ions are attracted to each other, resulting in a characteristic peak shift, ie, the Cr(VI) ion has bound to the 50%-DSSC-450 surface. The sludge has a weak vibration zone between 765 - 530 cm ^-1 , which is judged to be an aromatic structure. Because of the large amount of organic matter in the sludge, its chemical structure is composed of a large number of different atoms, so there are more The functional group is produced.

Fourth, SEM - EDS analysis results

The invention adopts the sludge of the domestic sewage treatment plant and uses different proportions of ZnCl ₂ as the interface active agent to obtain the active biomass carbon material by the procedures of impregnation, drying and anaerobic calcination (X%-DSSC-450, X= 33%, 50%, 60%, 67%). The aforementioned X%-DSSC-450 and commercially available activated carbon were analyzed by SEM-EDS. It can be seen from Fig. 7 that the X%-DSSC-450 and the outer surface of the AC material have pores of different sizes, and the appearance of the surface is uneven. Among them, as shown in the small figure (f) of Figure 7, the volume of 67%-DSSC-450 is compared with other proportions of DSSC (X%-DSSC-450, X=33%, 50%, 60%). The small surface has no pores, which may be caused by excessive impregnation rate, which leads to excessive erosion of ZnCl _{2 on the} surface of the material, and collapse of the pore wall of the material after carbonization.

The invention further uses EDS to qualitatively analyze the chemical element composition of the material, as shown in the EDS elemental analysis chart of Fig. 8, it is known that the carbon content of AC is the largest, and the carbon content of X%-DSSC-450 is also quite high, which proves to be successful. Biomass carbon is prepared. The rest of the trace metal elements should be the dust on the road when it rains and the particles in the air are washed by the rainwater into the sewage treatment plant, and then the sludge contains trace elements of metal.

As a result of analyzing the material by SEM according to the present invention, as shown in FIG. 9, it can be seen that the material having a relatively smooth surface and having pores becomes rough after adsorption, and produces a phenomenon similar to columnar crystal, and transmits the EDS component. As shown in Figure 10, it can be seen that there is more peak of Cr(VI). In the present invention, EDS mapping is used to observe the distribution of Cr(VI) on the surface of the material. As shown in the figure on the right side of Figure 9, it can be seen that Cr(VI) is uniformly distributed on the surface of the material, thus proving Cr(VI). The ions have indeed been adsorbed to the surface by the material.

Example 3: Adsorption test results of Cr(VI) ions in water

First, the effect of different concentrations on the adsorption of Cr(VI) ions

As shown in FIG. 11A to FIG. 11D, the present invention shows that the temperature of the adsorption reactor is fixed to 25 ° C, and when the pH value is fixed at 2, the ratio of four ZnCl ₂ is impregnated with DSSC (X%-DSSC-450, X=33%, 50%, 60%, 67%) and AC adsorption materials on the adsorption capacity of Cr (VI) experimental results, showing that when the Cr (VI) ion concentration is 15, 30, 60 and 120 ppm of the initial concentration, DSSC The adsorption capacities were 15.1, 28.9, 48.3 and 68.8 mg g ^-1 , respectively, and the adsorption capacities of AC were 0.04, 0.07, 0.12 and 0.17 mg g ^{-1 , respectively} . It can be seen from the above results that although there is no significant effect at an initial concentration of 120 ppm, there are some effects at 15 ppm, 30 ppm and 60 ppm because of the limited activation zone of the adsorbent material. Among them, when the concentration of Cr(VI) ions is high, it is necessary to compete for a limited activation zone, resulting in higher concentration and lower efficiency; and the surface of the sludge raw carbon contains C = O. In addition, H ₂ O adsorbed on the surface of the adsorbent. Bending vibrations are generated and therefore contribute to the adsorption of the material.

In addition, the adsorption capacity of the Cr(VI) ion concentration is 120 ppm, which is up to 68.8 and 0.17 mg g ^{-1 respectively} ; but the Cr(VI) ion concentration is 15 ppm, the adsorption capacity is the lowest, only 15.1 and 0.04 mg respectively. g ^-1 , because of the higher concentration, the driving force between Cr(VI) ions and the adsorbent material is large. When the concentration of ions is poor, the ions moving in the direction of high concentration collide with other ions, and the concentration is higher than the concentration. The opportunity for the ions moving in the low direction to be bounced back is large, resulting in a higher concentration and a greater adsorption capacity. It can be seen from the above that since the AC surface does not contain an oxygen-containing functional group, it is impossible to adsorb Cr(VI) ions in water, and the adsorption capacity of X%-DSSC-450 is much larger than that of the existing materials, so X%-DSSC-450 is one. Feasible adsorbent material.

Second, the impact of different ZnCl ₂ impregnation rate

The invention immerses the sludge of the sewage plant with 33%, 50%, 60% and 67% ZnCl _{2 respectively} , and at a pH of 2, the initial concentration is 60 ppm, and when the dosage is 1 g L ^-1 , the solution is carried out in the solution. The adsorption of Cr(VI) ions, thereby comparing the adsorption efficiencies of different ZnCl ₂ impregnation rates DSSC (X%-DSSC-450, X=33%, 50%, 60%, 67%) and AC. As shown in Fig. 12, the adsorption curve decreased rapidly in the first 30 min, but the adsorption curve gradually slowed down with time until the adsorption equilibrium was reached at 480 min. The adsorption curve of AC tends to be saturated after 60 min, and the maximum adsorption capacity is only 0.17 mg g-1, and the DSSC of different ZnCl _{2 has a} good removal effect. The lowest impregnation ratio of 33%-DSSC-450 also has a maximum adsorption capacity of 66.1 mg g ^-1 , while 50%-DSSC-450 has the best adsorption capacity, and its maximum adsorption capacity is 68.8 mg g ^-1 . However, as the impregnation ratio increases, the maximum adsorption capacity decreases until it reaches 55.9 mg g ^-1 , as shown in FIG. Since ZnCl ₂ can surface etch the DSS and form an activator for the porous cavity on the surface of the material, even if an excessive amount of activator is used, it is impossible to erode more holes on the surface of the material. Therefore, after the effectiveness evaluation, the optimum ZnCl ₂ impregnation rate was 50%. As shown in Table 4, the present invention further compares the maximum adsorption capacity of the prepared material with other materials, and it is known that the active biomass carbon material prepared by the present invention (X%-DSSC-450, X=33%, 50%, 60) %, 67%) has the highest maximum adsorption capacity.

Third, the impact of different pH values

As shown in FIG. 14, the pH value is a very important adsorption condition when the Cr(VI) ions are adsorbed, so the present invention adjusts different pHs (1.5, 2, 3, 4, 5, 6, 7, 8, 9, 10). With 11), and at an initial concentration of 60 ppm, Cr(VI) ions were adsorbed using 50%-DSSC-450, and changes in treatment efficiency at different pH values were observed. At lower pH, the adsorption efficiency can reach nearly 90%, that is, the lower the pH, the better the adsorption capacity. The reason is that H ⁺ ions strengthen the potential. If pH>3, since Cr(VI) ions are anions in aqueous solution ([HCrO4] ^- , [CrO4] ^2- or [Cr2O7] ^2- ), the proton and deprotonation process causes the surface area of carbon to decrease, and then In addition, the pH of the solution rises, so at high pH, the electrostatic repulsion hinders the removal of Cr(VI).

The present invention uses an interface potentiometer to measure the interface potential of 50%-DSSC-450 (due to the charge on the surface of the material, an electric double layer is formed in the solution, and an imaginary plane in the diffusion layer of the electric double layer is called a sliding plane. The potential on the plane is the interface potential), and the interface potential is affected by the surface properties of the nanoparticles and the pH of the solution, which is an indicator for determining the stability of the solution system. Generally, the higher the interface potential value is, the more stable the solution state is. If there is sufficient repulsive force between the particles, the particles can be prevented from being connected to each other to form agglomeration. It can be seen from Fig. 15 that the interface potential value and the Cr(VI) ion removal efficiency are both high at a low pH value, thus demonstrating that the X%-DSSC-450 of the present invention can be effectively adsorbed at a lower pH. Cr(VI) ion.

Fourth, the impact of the amount of adsorbent

As shown in Fig. 16, the present invention was applied to a 60 ppm aqueous solution of Cr(VI) ion using four different adsorbents (X%-DSSC-450), and the pH was fixed at 2 for observation. In this example, 50%-DSSC-450 was used as the adsorbent material, and the adsorption capacity effects of the dosages of 0.5, ¹ , 2 and 4 g L ^-1 were tested and analyzed. It can be seen from the experimental results that the removal efficiency of the four dosages increased significantly in the first 60 min of the experiment, but as the adsorption time increased, the adsorption efficiency gradually reached the adsorption equilibrium state. Moreover, with the increase of 50%-DSSC-450 dosage, the adsorption efficiency is getting better and better, and the adsorption efficiency can reach more than 99%. When the dosage is 1 g L ^-1 , the adsorption efficiency is about 80%, and when the dosage is 2 and 4 g L ^-1 , the treatment efficiency is 99% or more. As shown in Fig. 17, it can be seen that the more the 50%-DSSC-450 is added, the higher the removal efficiency, but the adsorption capacity is reversed, and the adsorption capacities are 67.7, 48.3, 29.9 and 15.1 mg g ^{-1 , respectively} . The reason may be that as the dosage of 50%-DSSC-450 increases, the adsorption site for Cr(VI) ion adsorption on the surface of the material increases, and the amount of Cr(VI) adsorbed by 50%-DSSC-450 increases. However, as the adsorption site increases, there are still many adsorption sites after the Cr(VI) ions are removed, thus reducing the adsorption capacity.

In addition, it is known from the experimental results that although the adsorption efficiency of 50%-DSSC-450 dosage 2 and 4 g L ^-1 can reach over 99%, the adsorption capacity is the largest when 0.5 g L ^-1 is added. The adsorption capacity, so in view of the above conditions, in the examples of the present invention, the optimum adsorption dosage is obtained when the selected 50%-DSSC-450 dosage is 1 g L ^-1 .

Fifth, the impact of different adsorption temperatures

As shown in FIG. 18, in the embodiment of the present invention, when 50%-DSSC-450 is used at a concentration of 60 ppm and the pH value is fixed at 2, four different temperatures are adjusted to test the adsorption of Cr(VI) ions by the adsorbent at different temperatures. Effect effect. It can be seen from the figure that as the temperature increases, the adsorption capacity gradually increases, and the removal effect is almost the same at 35 and 45 °C; the maximum adsorption capacity is shown in Fig. 19, and the maximum adsorption capacities of the four temperatures are 40.3 and 52.1, respectively. , 60.7 and 59.9 mg g ^-1 , this phenomenon may be due to the ion exchange between the surface of the material and Cr(VI) as the adsorption temperature increases, which is an endothermic process; as the temperature increases, the movement between ions will be accelerated. Bringing Cr(VI) ions closer to the surface of the material, thereby increasing the collision rate of collision between Cr(VI) ions and materials, so that the chance of 50%-DSSC-450 adsorbing Cr(VI) ions increases, and the adsorption capacity also follows On the contrary, when the Cr(VI) ion decreases at a low temperature, the ion movement rate decreases, resulting in a decrease in the chance of 50%-DSSC-450 adsorbing Cr(VI) ions.

The above results show that the living sludge active biomass carbon material prepared by the above technical solution can be used for treating heavy metals in air and water, thereby achieving waste treatment, effective adsorption of heavy metals in solution, environmental protection, etc. purpose.

It will be apparent to those skilled in the art that various changes can be made in accordance with the embodiments of the present invention without departing from the spirit of the invention. Therefore, it is to be understood that the invention is not limited by the scope of the invention, but is intended to cover the modifications of the spirit and scope of the invention.

no

Figure 1 is a thermogravimetric analysis curve of the original sludge of the present invention. 2 is a thermogravimetric analysis curve of X%-DSSC-450 (X=33%, 50%, 60%, 67%), carbonized domestic sludge (DSSC) and commercially available activated carbon (AC) of the present invention. Figure 3 is an X ₂ isothermal absorption/desorption of X%-DSSC-450 (X=33%, 50%, 60%, 67%), carbonized domestic sludge (DSSC) and commercially available activated carbon (AC) of the present invention. Attached to the graph. Figure 4 is a plot of the pore size distribution of X%-DSSC-450 (X = 33%, 50%, 60%, 67%), carbonized domestic sludge (DSSC) and commercially available activated carbon (AC) of the present invention. 5A and 5B are FT-IR analysis of X%-DSSC-450 (X=33%, 50%, 60%, 67%), carbonized domestic sludge (DSSC) and commercially available activated carbon (AC) of the present invention. Figure. (a) The curve is DSSC; (b) the zone is 33%-DSSC-450; (c) the curve is 50%-DSSC-450; (d) the curve is 60%-DSSC-450; (e) the curve is 67 %-DSSC-450. Figure 6 is a FT-IR analysis of the 50%-DSSC-450 of the present invention before adsorption and adsorption of Cr(VI). Figure 7 is an SEM image of various materials of the present invention. Among them, each of the small figures (a) to (f) are expressed as follows: (a) AC; (b) domestic sludge; (c) 33.3%-DSSC-450; (d) 50%-DSSC-450; e) 60%-DSSC-450; (f) 67%-DSSC-450. Figure 8 is an analysis of EDS elements of various materials of the present invention. Among them, each of the small figures (a) to (f) are expressed as follows: (a) AC; (b) domestic sludge; (c) 33.3%-DSSC-450; (d) 50%-DSSC-450; e) 60%-DSSC-450; (f) 67%-DSSC-450. Figure 9 is a SEM comparison and mapping diagram before and after adsorption of Cr(VI) by the DSSC of the present invention. Fig. 10 is a chart showing the EDS element analysis before and after adsorption of Cr(VI) by the DSSC of the present invention. 11A to 11E are DSSC and AC adsorption effects using different ratios of ZnCl2 at various concentrations of the present invention. 11A represents DS%-DSSC-450; FIG. 11B represents 50%-DSSC-450; FIG. 11C represents 60%-DSSC-450; FIG. 11D represents 67%-DSSC-450; and FIG. 11E represents AC. Figure 12 is an adsorption effect of different ZnCl ₂ ratios DSSC (X%-DSSC-450, X = 33%, 50%, 60%, 67%) and AC at 60 ppm of the present invention. Figure 13 is a graph showing the maximum adsorption capacity of different ZnCl ₂ ratios DSSC (X%-DSSC-450, X = 33%, 50%, 60%, 67%) and AC at 120 ppm of the present invention. Figure 14 is a graph showing the effect of the pH of the present invention on the adsorption of 60 ppm Cr(VI) ions by 50%-DSSC-450. Figure 15 is a graph showing the effect of pH on the adsorption and interface potential of 50%-DSSC-450 of the present invention. Figure 16 is a graph showing the effect of different dosages of the present invention on the adsorption of Cr(VI) ions by 50%-DSSC-450. Figure 17 is a graph showing the adsorption capacity of 50%-DSSC-450 for adsorption of Cr(VI) ions by different dosages of the present invention. Figure 18 is a graph showing the effect of different temperatures of the present invention on the adsorption of Cr(VI) ions by 50%-DSSC-450. Figure 19 is a graph showing the maximum Cr(VI) adsorption capacity of 50%-DSSC-450 at different temperatures of the present invention.

Claims (10)

A method for preparing a high specific surface area domestic sludge raw carbon material, wherein the method comprises the steps of: an activator providing step: mixing zinc oxide (ZnCl ₂ ) and distilled water at a weight ratio of 1:30 to 1:7.5 Dissolving to make an activator; sludge mixing step: adding sludge to the activator, mixing and stirring to obtain a mixture, the weight ratio of zinc oxide to sludge in the mixture is 1:3 to 2:3 Dehydration step: the mixture is placed in an oven for dehydration to obtain a preliminary product; calcination step: calcining the preliminary product to obtain a medium-pored raw carbon material; washing and drying step: the middle hole is produced The carbonaceous material is washed until the pH is neutral and then dried to obtain an active biomass carbon material. The method for preparing a high specific surface area domestic sludge raw carbon material according to claim 1, wherein: the activator provides a step of adding zinc oxide to distilled water in a weight ratio of 1:30, 1:20, 1: 15, 1:10 or 1:7.5; The weight ratio of zinc oxide to sludge in the sludge mixing step is 1:3, 1:1, 3:5 or 2:3. The method for preparing a high specific surface area domestic sludge raw carbon material according to claim 1, wherein the washing and drying step first washes the medium pore raw material carbon material with an acid solution, and after heating, The activated biomass carbon material was obtained by filtering and washing with distilled water until the pH was neutral and then drying. The method for preparing a high specific surface area sewage sludge raw carbon material according to any one of claims 1 to 3, wherein: the sludge mixing step, the sludge is added to the activator at 85 ° C Stirring for 2 hours; in the dehydration step, the mixture is placed in an oven and dehydrated at 110 ° C for 24 hours; in the calcining step, the preliminary product is prepared by being placed in a high temperature furnace and calcined at a temperature of 450 ° C for 3 hours. The medium-porosity raw carbon material; the washing and drying step, the medium-hole raw carbon material is washed with a 3M HCl solution, heated at 90 ° C for 30 minutes, and then filtered and washed by distilled water until the pH reaches neutral Finally, it was dried in an oven at 105 ° C for about 12 hours to obtain the active biomass carbon material. The method for preparing a high specific surface area domestic sludge raw carbon material as described in claim 1, wherein the domestic sludge is taken from a sludge of a domestic sewage treatment plant, dried to form a lump, and ground. Made into powder. An active biomass carbon material produced by the method for producing a high specific surface area sewage sludge raw carbon material according to any one of claims 1 to 5. The active raw carbon material according to claim 6, wherein the active raw carbon material has a specific surface area of 305 to 490 m ² /g; and the active raw carbon material has an average pore volume of 0.16 to 0.8 Cm ³ /g; the active biomass carbon material has a pore size of 3.05 to 9.39 nm. A use of an active biomass carbon material as described in claim 6 or claim 7 for treating heavy metals in a solution. The use of the active biomass carbon material according to claim 8, wherein the active biomass carbon material is used in a method for treating heavy metals in a solution, the method comprising: providing a chromium-containing solution to a adsorbent material reactor; The active raw carbon material is adsorbed to the chromium ion in the chromium-containing solution at a temperature of 15 to 45 °C. The method for processing an active metal carbon material according to claim 9 for treating a heavy metal in a solution, wherein the chromium-containing solution has a chromium concentration of 15 to 120 ppm, and the active biomass carbon material has a dose of 1 g/L.