TWI570063B - Composite particle and method for treating heavy metal contaminants by using the same - Google Patents

Description

Composite particle for remediating heavy metal pollutants and method thereof

The invention relates to a composite particle for treating heavy metal pollutants and a method thereof, in particular to a composite particle for remediating heavy metal pollutants which can adsorb and further reduce heavy metal ions and a method for using the same.

With the rapid development of the industry, the excessive use of heavy metals has caused the industrial waste liquid and the effluent from the unidentified waste dump site to contain heavy metals that cannot be loaded by the environment. The use of different raw materials and power in various industrial processes, the amount of wastewater generated and the type of water is extremely complex, especially the wastewater containing heavy metals, which will cause the ecological impact of the water after being discharged into the river, further affecting the agricultural irrigation water and People's livelihood. If people drink water containing heavy metals for a long time, they will cause cumulative poisoning. If the wastewater penetrates into the surface layer of the soil, it is possible to allow the wastewater to enter the underground aquifer after leaching, causing pollution of the groundwater source. Taking Taiwan as an example, the middle and lower reaches of the river are generally polluted, but many irrigation roads still use contaminated water sources. Among the sources of heavy metal wastewater, electroplating wastewater is a well-known source. In other industrial productions such as fertilizer plants, the catalyst used in the production of nitrogen fertilizer contains zinc, copper, cobalt, nickel, chromium, molybdenum and other metal substances. Or discard, it will pollute the environment.

There are many kinds of heavy metals, some of which are biological growth and physiological functions. Necessary, called essential elements, such as zinc, iron, copper, manganese, and cobalt. In addition, what is not required for biological life is called non-essential elements such as cadmium, lead and mercury. The characteristic of heavy metals is that once they enter the environment, they are permanently present in the environment without being naturally decomposed. In addition, heavy metals present in the environment may enter the human body in various ways. For example, heavy metals in the atmosphere may enter the body directly through the respiratory tract, or may indirectly contaminate food and enter the human body through diet. If the heavy metal is excessive, the organism will cause toxicity and even death.

Taking chromium as an example, it is a common heavy metal pollutant in groundwater. Chrome is often used in the industrial and industrial processes such as paint, alloy, electroplating, photographic, alkali chloride, petrochemical, paper, textile and leather. Therefore, process control Loss or improper disposal of waste may cause leakage and cause serious impacts and impacts on the health and ecological environment of people in the vicinity of the leak through various exposure routes such as drinking water. The main forms of chromium in the water environment include trivalent chromium and hexavalent chromium. Among them, the chemical properties of trivalent chromium are relatively stable, the permeability to biological cell membranes is weak and easy to fix in tissues; hexavalent chromium is very Strong oxidizing power has a large toxic effect on organisms, and hexavalent chromium species are often listed as control items in safety, health and environmental protection regulations.

Although there have been many studies on groundwater or soil remediation of heavy metal pollution, green remediation technology has the greatest potential for development under the awareness of environmental protection. However, there is still a need for a better solution in terms of maintaining the composition of the environment such as the local soil and groundwater, the stability of the use of the matrix itself, the length of time for controlling the treatment, the diffusion of pollutants or the simplification of the remediation steps.

Therefore, it is necessary to provide a composite particle for remediation of heavy metal pollutants and The method is to solve the problems of the conventional technology.

An object of the present invention is to provide a composite particle for remediating heavy metal contaminants, which has a multi-layer structure in which an inner layer structure is composed of metal nanoparticles contained in a plurality of crusts, and iron nanoparticles are mainly used. For reducing heavy metal ions, while using the aid of other metal nanoparticles to enhance the stability of the iron nanoparticles and reduce the rate of consumption, the life of the composite particles can be extended.

Another object of the present invention is to provide a composite particle for remediating heavy metal contaminants, the outer structure of which contains a functional group capable of binding with heavy metal ions, thereby improving the chance of contact of heavy metal ions with the composite particles, and promoting the efficiency of remediation, and Heavy metal ions can settle with the weight of the composite particles, thereby reducing the re-release of heavy metal ions and limiting their diffusion range. In addition, its outer structure also has bio-available components that promote the growth of existing micro-organisms and strengthen and link bioremediation projects for other pollutants.

A further object of the present invention is to provide a method for remediating heavy metal contaminants, which utilizes mixing or contact of the above composite particles with heavy metal contaminants, which simplifies the remediation process and does not change the existing soil during and after remediation. The composition of groundwater is extremely environmentally friendly.

To achieve the above object, an embodiment of the present invention provides a composite particle for remediating heavy metal contaminants, comprising a nano metal core comprising iron nano particles, aluminum nanoparticles, and nickel nanoparticles; A modified surface layer surrounds the nano metal core, the modified surface layer having at least one coordination functional group for forming a metal complex with a heavy metal ion to adsorb the heavy metal ions on the modified surface layer.

In an embodiment of the present invention, in the nano metal core, the nickel nanoparticle occupies less than the weight of the aluminum nanoparticle, and the aluminum nanoparticle occupies less than the iron. The weight of the nanoparticles.

In one embodiment of the invention, the iron nanoparticle comprises at least 65% by weight of the nanometal core.

In one embodiment of the invention, the aluminum nanoparticle comprises up to 25% by weight of the nanometal core.

In one embodiment of the invention, the nickel nanoparticles comprise up to 10% by weight of the nanometal core.

In one embodiment of the invention, the coordinating functional group is a hydroxyl group (-OH), an ether group (-O-), an aldehyde group (-CHO), a keto group (-CO-), a carboxyl group (-COOH), Ester group (-COO-), amine group (-NH ₂ ) or guanamine group (-CO-NH ₂ ).

In an embodiment of the invention, the heavy metal ion is a hexavalent chromium ion.

In one embodiment of the invention, the modified surface layer comprises citric acid, an amino acid, a multivitamin, a biodegradable surfactant, and an organic solvent.

In one embodiment of the invention, the weight ratio of the citric acid, the amino acid, the multivitamin, the biodegradable surfactant, and the solvent is 10:5:5:30:50.

In one embodiment of the invention, the biodegradable surfactant comprises lecithin, and the lecithin is at least 15-30% by weight of the modified surface layer.

Furthermore, another embodiment of the present invention provides a method of remediating heavy metal contaminants, comprising the steps of: (1) providing composite particles for remediating heavy metal contaminants as described above; and (2) causing the composite particles Contact with a heavy metal contaminant.

In an embodiment of the invention, the heavy metal contaminant is a heavy metal containing soil or a heavy metal containing water body.

In an embodiment of the invention, the heavy metal contaminant comprises a heavy metal ion that is a hexavalent chromium ion.

In one embodiment of the invention, the modified surface layer forms an emulsified colloid layer with water.

10‧‧‧Composite particles

11‧‧‧Nano Metal Core

12‧‧‧Modified surface

20‧‧‧Local microorganisms

Fe‧‧‧Tennel particles

Ni‧‧‧Nylon nanoparticles

Al‧‧‧Alumina Particles

Cr ⁶⁺ ‧‧‧hexavalent chromium ion

Cr(OH) ₃ ‧‧‧Chromium Hydroxide

Fig. 1 is a schematic view showing the structure of a composite particle according to an embodiment of the present invention.

Fig. 2 is a bar graph showing the ratio of iron/aluminum/nickel metal components in the composite particles according to an embodiment of the present invention.

Fig. 3 is a view showing the total reduction efficiency of hexavalent chromium ions in the case where the composite particles according to an embodiment of the present invention continuously injects hexavalent chromium ions.

Fig. 4 is a chart showing the spectrum of the composite particles after the reduction of hexavalent chromium ions according to an embodiment of the present invention by X-ray photoelectron spectroscopy (XPS).

Fig. 5 is a view showing the mechanism for rectifying hexavalent chromium ions by composite particles according to an embodiment of the present invention.

The above and other objects, features and advantages of the present invention will become more <RTIgt; Furthermore, the directional terms mentioned in the present invention, such as upper, lower, top, bottom, front, rear, left, right, inner, outer, side, surrounding, central, horizontal, horizontal, vertical, longitudinal, axial, Radial, uppermost or lowermost, etc., only refer to the direction of the additional schema. In addition, the singular forms "a", "an" set. The range of values (such as 10% to 11% of A) includes upper and lower limits (ie, 10% ≦A ≦ 11%) unless otherwise specified; if the value range does not define a lower limit (such as less than 0.2% B) , or B) below 0.2%, the lower limit may be 0 (ie 0% ≦ B ≦ 0.2%). The above terms are used to illustrate and understand the present invention and are not intended to limit the invention.

Referring to FIG. 1 , an embodiment of the present invention provides a composite particle 10 for remediating heavy metal contaminants, which mainly comprises a nano metal core 11 and a modified surface layer 12 . The composite particle 10 has a particle diameter of about 80 to 100 nm.

The nano metal core 11 can be composed of a plurality of metal nanoparticles, including iron nanoparticles, aluminum nanoparticles, and nickel nanoparticles. In the nano metal core 11, the weight of the nickel nanoparticle is less than the weight of the aluminum nanoparticle, and the weight of the aluminum nanoparticle is less than the weight of the iron nanoparticle. The iron nanoparticle accounts for at least 65% by weight of the nanometal core 11 by weight. The aluminum nanoparticle accounts for up to 25% by weight of the nano metal core 11 by weight. The nickel nanoparticles account for up to 10% by weight of the nano metal core 11 by weight. Preferably, the iron nanoparticle is 65 to 80 wt% (ie, 65% ≦Fe ≦ 100%) relative to the weight of the nano metal core 11, and the aluminum nanoparticle is 15 to 25 wt% (ie, 15%). ≦Al≦ 25%), and the nickel nanoparticles are 5 to 10% by weight (i.e., 5% ≦Ni ≦ 10%), and the total of the above iron, aluminum, and nickel nanoparticles is 100% by weight.

Furthermore, the modified surface layer 12 is formed on the outer layer of the nano metal core 11 and surrounds the nano metal core 11. The modified surface layer 12 comprises at least one coordination functional group, which can form a metal complex with a heavy metal ion, so that the heavy metal ions are adsorbed on the modified surface layer 12, and the heavy metal ions and the composite particle 10 are increased. The contact opportunity makes it easy to carry out a reduction reaction with the nano metal core 11. The coordination functional group may, for example, be selected from the group consisting of hydroxyl (-OH), ether (-O-), aldehyde (-CHO), keto (-CO-), carboxyl (-COOH), ester (-COO-) a group consisting of an amine group (-NH ₂ ) and a guanamine group (-CO-NH ₂ ). The heavy metal ion may be, for example, a hexavalent chromium ion (Cr ⁶⁺ ), but is not limited thereto.

Further, the modified surface layer 12 contains components for growth of microorganisms such as citric acid, amino acids, multivitamins, biodegradable surfactants, and an organic solvent. Preferably, the weight ratio of the citric acid, the amino acid, the multivitamin, the biodegradable surfactant, and the solvent may be 10:5:5:30:50, but is not limited thereto. The multivitamin comprises, for example, at least one of vitamin B group, vitamins A, C, D, E, and K, or any combination thereof, to promote microbial growth. The biodegradable surfactant can improve the mutual solubility of oil and water, and can be naturally decomposed in the environment, and does not leave harmful substances in the environment, and meets environmental protection requirements. The biodegradable surfactant may be, for example, lecithin, a natural vegetable oil derivative (such as coconut oil, palm oil derivative) or natural sapindus extract saponin, but is not limited thereto. Preferably, the biodegradable surfactant comprises lecithin, and the lecithin is at least 15-30% by weight of the modified surface layer, and may be, for example, 15, 16, 17, 18 or 20%. Not limited to this. The organic solvent is preferably a solvent which is compatible with water, such as ethanol.

Another embodiment of the present invention provides a method for remediating heavy metal contaminants, comprising the steps of: (1) providing composite particles 10 for remediating heavy metal contaminants as described above; and (2) causing the composite particles 10 is in contact with a heavy metal contaminant.

A method for remediating heavy metal contaminants according to an embodiment of the present invention is first: (1) providing composite particles 10 for remediating heavy metal contaminants as described above. In this step, the nano metal core 11 can be synthesized, for example, by wet deposition, followed by immersion in ethanol 50%, lecithin 15%, citric acid 10%, comprehensive amino acid 5%, and comprehensive vitamin 5%. ,natural A 15% mixture of derivatized surfactants (such as coconut oil and palm oil derivatives) is fully vortexed to form a suspension. Then, the product powder is obtained by lyophilization to remove excess water, and the surface microscopic state can be analyzed by a scanning electron microscope additional energy dispersive spectrometer (SEM-EDS), and the material is completely dissolved into a solution state, and then inductively coupled plasma-atomic radiation is used. The composition of the metal composition was analyzed by spectroscopy (ICP-AES). According to Table 1, the analysis results of the iron/aluminum/nickel metal components of the composite particles prepared in four groups of different weights are shown in Fig. 2.

The theoretical value of Group 5 is the weight percentage of iron/aluminum/nickel in the existing crust, set to iron: aluminum: nickel = 76.6: 13.4:10, and the other four groups are analyzed by ICP-AES, as shown in Figure 2. The average value of the actual composition of the iron/aluminum/nickel metal is about iron: aluminum: nickel = 70:20.8: 9.2, so it can be confirmed that the composition of the composite particles produced is indeed iron/aluminum/nickel, and the actual value thereof Similar to the ratio of the theoretical values, it has also been confirmed that the composite particles of the present invention can adjust the proportion of the metal contained in the nano metal core in accordance with the present crustal composition.

The method of an embodiment of the invention is followed by: (2) contacting the composite particle 10 with a heavy metal contaminant. In this step, for example, water may be used as a carrier, the composite particle 10 is first suspended with water, and then the suspension is injected or mixed into the heavy metal contaminant; or the heavy metal contaminant may be directly The water and the composite particles 10 are mixed; or alternatively, the composite particles may be filled in a suitable container and used as a filter material for the passage of the heavy metal contaminant. The above method may be adjusted according to the type of the heavy metal contaminant, the scope of remediation or the need to combine with other types of remediation, and is not particularly limited. The heavy metal contaminant may be a heavy metal containing soil or a heavy metal containing water body. The heavy metal contaminant contains at least one heavy metal ion, and may be, for example, a hexavalent chromium ion (Cr ⁶⁺ ), but is not limited thereto, as long as it can form a metal complex with the above-mentioned coordination functional group, and can be used by the nano metal. The heavy metal ions reduced by the core 11 can be treated using the composite particles 10 of the present invention. The modified surface layer 12 of the composite particle 10 can form an emulsified colloid layer after interaction with water, and the emulsified colloid layer is a porous structure, so that the heavy metal ions can pass through to the nano metal core 11. Furthermore, the modified surface layer 12 contains the biodegradable surfactant, which is very advantageous for the dispersion of water (groundwater, waste water, etc.).

To verify the effectiveness of the method of the present invention for remediating heavy metal contaminants, the present invention performs laboratory simulation tests and the results are as follows.

Experiment 1: Treatment of hexavalent chromium pollutants in water

The composite particle 10 (containing about 56.0 mg of iron) was injected into a water sample containing hexavalent chromium, and a potassium chromate solution was added to provide hexavalent chromium ion (Cr ⁶⁺ ) at intervals to simulate the local environment. The state in which the hexavalent chromium contaminant is continuously injected is used to evaluate the continuous decontamination ability of the composite particle 10 after being injected into the water body. The number and timing of refills are shown in Table 2 below.

After injecting the composite particles into the hexavalent chromium water sample at the beginning (0 hours), the analysis found that the Cr ⁶⁺ concentration in the solution tends to 0 mg/L, indicating that Cr ⁶⁺ in the solution is reduced when the composite particles are just put in. Is Cr ³⁺ . After 6 hours, the same solution was added for the first time Cr ^6+, Cr ⁶⁺ in the solution concentration estimated 100mg / L, and analyzed again hexavalent chromium, the concentration of Cr ⁶⁺ findings also tend 0mg /L, shows that the composite particles can still rapidly reduce Cr ⁶⁺ if the hexavalent chromium contaminants are reinjected. When the Cr ⁶⁺ was replenished to the 5th (96 hours), the Cr ⁶⁺ concentration was measured to be about 50 mg/L, and then the sixth refill of Cr ⁶⁺ was performed at the 144th hour (the sixth day) of the experiment. The residual concentration of hexavalent chromium in the water sample is about 57 mg/L. Continuing the experiment for the 216th hour (ninth day), the concentration of Cr ⁶⁺ in the water sample was measured to be 0 mg/L, indicating that the composite particles could continue to reduce the hexavalent chromium under sufficient reaction time. The total amount of hexavalent chromium which the composite particles can continuously and rapidly remove is about 49.0 mg (calculated only to the fifth replenishment), and the weight of the continuous removal of hexavalent chromium per gram of the composite particles is calculated to be about 0.875 g. Figure 3 shows the total reduction efficiency of the composite particles to hexavalent chromium during the test. It is confirmed that the reduction efficiency of the composite particles is still as high as 100% under the continuous injection of the six-time contaminant Cr ⁶⁺ , indicating that the composite particles can continuously reduce the subsequent added pollutants in addition to rapidly reducing the pollutants.

Experiment 2: After treating hexavalent chromium contaminants, observe the surface sediment type

As shown in Fig. 4, the results of the X-ray photoelectron spectroscopy (XPS) can confirm that the composite particles can effectively adsorb chromium ions in water and reduce hexavalent chromium to trivalent chromium. After the reaction, the hydroxide and oxygen functional groups on the surface of the composite particles increase, and the bond energy indicates that there is no hexavalent chromium absorption peak, and only the bond energy of trivalent chromium such as Cr ₂ O ₃ or Cr(OH) ₃ is met. (9.8eV). The analysis results confirmed that the hexavalent chromium contaminant in the aqueous phase was reduced to trivalent chromium to form a solid and adsorbed on the surface of the composite particle, so the hexavalent chromium contaminant in the aqueous phase was removed, and the water body was confirmed by the elemental analysis result. The hexavalent chromium is effectively reduced to trivalent chromium, and the formation and adsorption mechanism of chromium hydroxide (Cr(OH) ₃ ) is shown in Fig. 5.

Referring to FIG. 5, the remediation mechanism of the composite particle 10 for the hexavalent chromium ion is shown in FIG. First, the aluminum nanoparticle contained in the nano metal core 11 can coat and protect the nano metal core 11, slow down the corrosion rate, and provide electrons to the iron nanoparticles. The nickel nanoparticle is an inert metal end, which has a non-oxidizing property and can form a DC battery structure with the iron nanoparticle, so that the electron is continuously and stably released to the surface of the nano metal core 11. The coordination functional group of the modified surface layer 12 can capture the hexavalent chromium ion, and the hexavalent chromium ion (Cr ⁶⁺ ) is reduced by the modified surface layer 12 to the trivalent chromium ion (Cr ³⁺ ) by the iron nanoparticle. Then, a chromium hydroxide (Cr(OH) ₃ ) solid is formed and deposited on the nano metal core 11 while the iron nanoparticle is oxidized to ferrous ion (Fe ²⁺ ) and the hexavalent chromium ion is continuously reduced. The microorganism 20 can promote growth by using the biodegradable surfactant, vitamins and minerals contained in the modified surface layer 12. The main component of the nano-metal core 11 after total oxidation is similar to that of the earth's crust, and the current bioacceptance is high and the impact on the environment is extremely low.

Compared with the prior art, the composite particles for remediating heavy metal pollutants and the method thereof according to the present invention can rapidly and continuously reduce heavy metal pollutants and improve the locality by using green physical remediation technology combined with biological re-cultivation method. The activity and quantity of microorganisms to degrade other pollutants. The composite particles of the invention have the following advantages: (1) the crust element which does not change the environmental composition such as soil groundwater after the addition, is a geochemical remediation technology; (2) the nanotechnology combined with the surface modification technology, the zero-valent iron factor The presence of aluminum and nickel can slow down the rust rate and improve the effective time, stability and transportability of the material. (3) The nanometer scale and microporosity can increase the specific surface area of the material, accelerate the heavy metal ions in the unsaturated layer and saturate. The anaerobic reduction reaction of the layer; (4) providing the substrate available for the microorganism to enhance the local biodegradability; (5) rapidly creating an anaerobic environment, promoting the reduction reaction of the pollutant, and continuously releasing the electron at the later stage of the reaction, Strengthen the degradation of residual target pollutants; (6) Avoid soil acidification and destruction.

The present invention has been disclosed in its preferred embodiments, and is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

10‧‧‧Composite particles

11‧‧‧Nano Metal Core

12‧‧‧Modified surface

Fe‧‧‧Tennel particles

Ni‧‧‧Nylon nanoparticles

Al‧‧‧Alumina Particles

Claims (12)

A composite particle for remediating heavy metal contaminants, comprising: a nano metal core comprising iron nano particles, aluminum nano particles and nickel nano particles; and a modified surface layer surrounding the nano metal core, The modified surface layer has at least one coordinating functional group for forming a metal complex with a heavy metal ion, so that the heavy metal ion is adsorbed on the modified surface layer, wherein the nickel nanoparticle in the nano metal core The weight of the particles is less than the weight of the aluminum nanoparticle, and the weight of the aluminum nanoparticle is less than the weight of the iron nanoparticle; and the modified surface layer comprises citric acid, an amino acid, A comprehensive vitamin, a biodegradable surfactant, and an organic solvent. The composite particle of claim 1, wherein the iron nanoparticle comprises at least 65% by weight of the nano metal core by weight. The composite particle of claim 1, wherein the aluminum nanoparticle accounts for up to 25% by weight of the nano metal core. The composite particle of claim 1, wherein the nickel nanoparticle comprises up to 10% by weight of the nano metal core. The composite particle according to claim 1, wherein the heavy metal ion is a hexavalent chromium ion. The composite particle of claim 1, wherein the coordination functional group is a hydroxyl group, an ether group, an aldehyde group, a ketone group, a carboxyl group, an ester group, an amine group or a decylamino group. The composite particle according to claim 1, wherein the citric acid, the The weight ratio of the amino acid, the multivitamin, the biodegradable surfactant, and the solvent is 10:5:5:30:50. The composite particle according to claim 1, wherein the biodegradable surfactant comprises lecithin, and the lecithin is 15 to 30% by weight of the modified surface layer. A method for remediating heavy metal contaminants, comprising the steps of: (1) providing composite particles for remediating heavy metal contaminants as described in claim 1; and (2) providing the composite particles with a heavy metal Contaminant contact. The method of claim 9, wherein the heavy metal contaminant is a heavy metal-containing soil or a heavy metal-containing water body. The method of claim 9, wherein the heavy metal contaminant comprises a heavy metal ion that is a hexavalent chromium ion. The method of claim 9, wherein the modified surface layer forms an emulsified colloid layer with water.