PL233341B1 - Method for sorption of heavy metals from water solutions - Google Patents

Description

Description of the invention

The subject of the invention is a method of sorption of heavy metals from aqueous solutions, especially lead, cadmium and cobalt.

The currently growing awareness of the dangers of environmental pollution makes it necessary to regularly control the content of elements and toxic substances in the air, soil and food, which also results from the publication of the authors Kocjan R., Kot A. and Ptasiński H. entitled "The content of chromium, zinc, copper, nickel, cadmium and lead in vegetables and fruit from Stalowa Wola", Bromatol. Chem. Toxicol. 2002, (1), pp. 31-38. Nowadays, human activity leads to the generation of significant amounts of waste, which is one of the greatest threats to the natural environment, including natural waters. These are mainly industrial, agricultural and household sewage. Heavy metals, such as lead, cadmium, mercury and others are among the pollutants that get into water. They pose a great threat to the health and life of organisms, due to their high toxicity and the ability to bioaccumulate, as it is confirmed in its publication entitled "Toxicology" W. Seńczuk, Warsaw, PZWL Medical Publishing, 1999.

Conventional techniques for the removal of heavy metals from water and wastewater include chemical precipitation, reverse osmosis, evaporation, and ion exchange, among others, as reported in Al-Qodah Z. "Biosorption of heavy metals ions from aqueous solutions by activated sludge" Desalination, 196, 2006, 164-176.1, as well as Uluozlu O.D., Sari A., Tuzen M., Soylak M. pt. "Biosorption of Pb (II) and Cr (III) from aqueous solution by lichen (Parmelina tiliaceae) biomass", Bioresource Technology, 99, 2008, 2972-2980. These methods have many advantages, but often prove to be ineffective at low concentrations, generate toxic deposits and are expensive, as shown in the publications of Gupta S., Kumar D., Gaur J.P. Fri "Kinetic and isotherm modeling of lead (II) sorption onto some waste plant materials", Chemical Engineering Journal, 148, 2009, 226-233.

In her speech on the elimination of lead ions with the use of natural sorbents at the international conference on environmental management in terms of sustainable development of industrialized areas, Sanak-Rydlewska assessed the selected, so far used methods of metal separation from aqueous solutions, which shows that:

• chemical precipitation and filtration is characterized by low cost and simplicity, but the disadvantages of this method include the possibility of using it at high concentrations, low efficiency, difficult separation and the fact that the final result is a sediment;

• electrochemical methods recover the metal but can be used for high concentrations and are very expensive;

• reverse osmosis allows to obtain clean water for reuse, but requires the use of high pressures and there is also difficulty in obtaining process continuity due to clogging of the membranes;

• ion exchange is one of the effective methods, it is also possible to recover metals, but it is sensitive to suspended solids. Besides, there is a high cost due to the use of suitable resins;

• Evaporation produces clean water for reuse, but is energy-consuming and costly, and sludge remains.

In turn, from the Polish patent application no. P.327273 entitled "Preparation for the treatment of wastewater containing heavy metals and the method of producing a preparation for the treatment of wastewater containing heavy metals" shows that the preparation for the treatment of wastewater containing heavy metals is formed as a result of reactions taking place in the reactor as a result of mixing ground hard coal and / or lignite with ground stone lime in the temperature zone 527 K to 1327 K. Additionally, the preparation may contain modifiers in the form of quicklime or hydrated lime, sodium carbonate or potassium carbonate. The preparation method is based on the fact that hard coal and / or brown coal dust is fed through one nozzles in the reactor wall, and ground limestone with a grain size of 0-30 mm and CaCO3 content is fed to the temperature zone 527 through the other nozzles. K to 1327 K and the mixture is mixed and reacted.

Also in the Polish patent description of the application no. P.336188 entitled "Silica sorbents that bind effectively heavy metals" presents new silica sorbents that effectively bind heavy metals from water. Sorbents are characterized by containing an amino alcohol, preferably ethanolamine or 3-amino-1-propanol, bonded to the silica gel in an amount of 3.5-4.5% by weight of the amino alcohol, or containing an ethanolamine-acetate or magnesium chloride complex bonded to the surface of silica gel.

They contain 4.5-5% by weight of ethanolamine-magnesium salt complex, or contain an ethanolamine aluminum chloride complex surface bonded to silica gel in an amount of 4.7-5% by weight of ethanolamine-aluminum chloride complex. The new silica sorbents are characterized by very good sedimentation properties. They are easy to make and use. They can be used as column filling, and when packed with a fabric of appropriate density and immersed in a liquid, they effectively clean it. They can be used for the treatment of industrial wastewater from heavy metals as well as radioactive waste.

Gorkem Degirmen et al. In the article "Removal of copper (II) and cadmium (II) ions from aqueous solutions by biosorption onto pine cone (Water Science & Technology 66 (3): 564-72) states that heavy metals can be removed from water solutions using pine cones. Such a sorption method, eg Cu, Cd, consists in introducing crushed pine cones in the form of a powder into aqueous solutions in the amount of 1-10 g / liter.

An alternative to the existing solutions may be the use of the biosorption process. Various organic materials can play the role of natural sorbents. These can be waste from the food and wood industries and residues from the agricultural industry. This group of waste includes: fruit and vegetable peelings, nut husks, seeds, straw and tree bark, etc.

From the publication by Agnieszka Gola and Stanisława Sanak-Rydlewska entitled "Sorption of toxic metal ions from aqueous solutions on natural waste", Mining and Geoengineering, 34, 4 / 1.2010 shows that the functions of natural sorbents can also be successfully fulfilled by waste from other industries. This is confirmed by tests performed on waste tobacco dust. This material was used to separate heavy metal ions from aqueous solutions, such as: Pb2 +, Cu2 +, Cd2 +, Zn2 + and Ni2 +. Additionally, experiments were performed for single and multi-component systems. In this case, dust with a grain size of 1: 2 mm was used, the tests were carried out at pH 6.5: 7.2 for a sorbent concentration of 1 g / dm ³ . The maximum sorption capacity of tobacco dust in relation to Pb2 +, Cu2 +, Cd2 +, Zn2 + and Ni2 + ions in one-component systems was respectively: 39.6; 36.0; 29.6, 25.1 and 24.5 mg / g. It has also been shown that the presence of other heavy metal ions in the solution significantly affects the adsorption process. The isotherms obtained for single and multi-component systems are different. The amount of ingredients in the solution changes the selectivity of the sorbent. It was found that for multi-component systems the selectivity decreases in series, Cu2 +> Pb2 +> Zn2 +> Cd2 +> Ni2 +, while for single-component solutions the following order is maintained: Pb2 +> Cu2 +> Cd2 +> Ni2 + = Zn2 +.

It turned out that a very high degree of purification of an aqueous solution contaminated with heavy metals such as lead, cadmium and cobalt can be obtained using the sorption method according to the invention, which is characterized by the fact that the natural sorbent consists of larch cones which, after drying to an air-dry state, grind to grains with a diameter preferably less than 0.5 mm. The sorbent prepared in this way is introduced into the contaminated aqueous solution to be treated in an amount of at least 2.5 g per 1 dm ^{3 of the} solution, and after mixing, preferably after 30 minutes, the mixture is filtered, obtaining water fit for reuse.

The method of heavy metals sorption from aqueous solutions according to the invention is characterized by low costs and is also fully ecological. Larch cones are easy to obtain and the uncomplicated procedure of their use for water purification allows the use of this method in individual households, which was impossible with the methods previously described in the cited publications, as well as in patents P.327273 and P.336188. In addition, its high efficiency is worthy of special emphasis.

This method is shown in exemplary embodiments.

P r z k ł a d 1

1 kg of larch cones were collected, dried in laboratory conditions to an air-dry state, and then homogenized using a laboratory mill. A homogeneous product with a particle diameter of less than 0.5 mm was obtained.

An aqueous solution with heavy metal contamination - lead, cadmium, cobalt at the level of 1 mg * L ^{-1 was} prepared, which corresponds to extremely high contamination of the liquid occurring in nature. The solution prepared in this way with simulated heavy metal contamination was divided into 3 samples in the amount of 20 ml each and 0.05 g of powdered larch cone was added to them. Then, after successive times for the respective samples, ie 10, 20, 30 minutes, the mixture was filtered through a paper filter and the residual heavy metal content in the solution was measured. The entire procedure was carried out under laboratory conditions at room temperature.

PL 233 341 Β1

The results are as in the table below:

Sorption time [min] The amount of remaining metals in the solution [mg * L ' ^l ] Percentage of absorbed metal [%] 10 Pb - 0.1 Cd-0.15 Co - 0.30 Pb-90 Cd-85 Co-70 twenty Pb - 0.07 Cd-0.14 Co-0.28 Pb-93 Cd-86 Co-72 thirty Pb-0.05 Cd-OJ Co - 0.2 Pb-95 Cd-90 Co-80

Example 2

1 kg of larch cones were collected, dried in laboratory conditions to an air-dry state, and then homogenized using a laboratory mill. A homogeneous product with a particle diameter of less than 0.5 mm was obtained.

An aqueous solution with heavy metal contamination - lead, cadmium, cobalt at the level of 1 mg * L ' ^{1 was} prepared, which corresponds to extremely high contamination of the liquid occurring in nature. The solution prepared in this way with simulated heavy metal contamination was divided into 2 samples in the amount of 20 ml each and 0.05 g of powdered larch cone was added to them. Then, after successive times for the appropriate samples, i.e. 60, 120 minutes, the mixture was filtered through a paper filter and the residual heavy metal content in the solution was measured. The entire procedure was carried out under laboratory conditions at room temperature.

The results are as in the table below:

Sorption time [min] The amount of remaining metals in the solution [mg * L '*] Percentage of absorbed metal [%] 60 Pb-0.03 Cd-0.05 Co-0.15 Pb-97 Cd-95 Co-85 120 Pb-0.015 Cd - 0.05 Co-0.015 Pb-98.5 Cd - 95 Co-85

Patent claim

Claims (1)

Patent claim 1. Method of sorption of heavy metals from aqueous solutions, characterized in that the natural sorbent consists of larch cones, which, after drying to an air-dry state, are ground into grains with a diameter, preferably below 0.5 mm, and introduced into the contaminated aqueous solution to be treated in an amount of at least 2.5 g per 1 dm ^{3 of} solution, and after mixing, preferably after 30 minutes, the mixture is filtered, obtaining water fit for reuse.