RU2637436C1 - Sorbent based on kelp fiber - Google Patents

Abstract

FIELD: pharmacology.

SUBSTANCE: sorbent based on kelp fiber, possessing a sorption activity in relation to the heavy metal salts and MMW liquid toxicants, is algulose, cleaned from water-soluble components, with a particle size of 0.05-0.2 mm, with a mesoporous structure, the main components of which are algal cellulose and hardly hydrolysable proteins, which is obtained by supercritical fluid extraction of air-dry kelp, under certain conditions.

EFFECT: sorbent possesses high sorption capacity to salts of heavy metals and MMW toxicants of liquid media.

1 dwg, 2 tbl, 3 ex

Description

The invention relates to the pharmaceutical industry, in particular to a sorbent based on brown algae fiber. The sorbent can be used as a means with adsorption activity with respect to medium molecular toxins and heavy metal ions.

Brown algae are used worldwide as a raw material for the production of biologically active substances such as mannitol, fatty acids, chlorophyll, and salts of alginic acid. In the process of obtaining alginates at one of the technological stages, algal fiber (VK) is formed from algal raw materials, which is a complex polymer structure based on a cellulose matrix.

The main component of algal fiber is cellulose, which contains residual amounts of components: insoluble proteins, salts, alginic acids, insoluble forms of laminiran and fucoidan, low molecular weight degradation products of algal components, as well as trace amounts of chlorophyll and carotenoids, which determine the color of the drug.

Algal cellulose is somewhat different from cellulose of higher plants, therefore it is called “eucellulose” or “algulosis” [Podkorytova A.V., Kladnikova I.A. Quality, safety and analysis methods of products from aquatic organisms. Vol. 3. A guide to modern research methods for algae, herbs and their processed products. - M.: Publishing House VNIRO. - 2009. - 108 p., Pan L.S., Bakhireva O.I., Balabenko E.A., Anshkenis A.I., Volkhin V.V. The synthesis of biosorbents based on seaweed for the extraction of cesium from aqueous media // Bulletin of the Perm National Research Polytechnic University. Chemical technology and biotechnology. - 2010. - No. 11. P. 143-149] and is characterized by the predominance of the crystalline fraction Iα [Aleshina L.A. Modern views on the structure of cellulose (review) / L.A. Aleshina, S.V. Glazkova, L.A. Lugovskaya, M.V. Podoynikova, A.D. Fofanov, E.V. Silina. // Chemistry of plant materials. - 2001. - No. 1. - S. 5-36]. Its usual content in brown algae does not exceed 2-5% of the mass.

It has been established that algal fiber has a complex structure based on a cellulose matrix, representing a natural polysaccharide [Plechova, 2002]. Also, due to the presence of residual amounts of alginic acid, lignin-like substances, VK has multifunctional properties. The ion-exchange mechanism of sorption is carried out due to the presence of carboxyl groups, as well as sulfate, carbonyl, and hydroxyl groups. Complex formation processes involving the above groups also have an effect. Due to their presence, fiber is capable of cation exchange and sorption of heavy metals by algae biomass.

Currently known sorbents with a similar effect: carbon sorbents based on activated carbon (Patent Ru No. 2180231, IPC A61K 35/78, A61K 33/44, 2002), sorbents based on lignin, for example polyphepan (Patent Ru No. 2440125 , IPC A61K 36/00, A61K 31/715, A61P 33/00 2010) and others. The disadvantages of such sorbents include the fact that additional processing of raw materials using caustic reagents and elevated temperatures is required.

Ion-exchanged sorbents from wood can be obtained by treatment with sulfuric acid [Kraynova EA, Rodionov AI, Kim A.V. Obtaining carbon sulfocationite by sulfuric acid charring from cellulose-containing waste // Ecology and Industry of Russia. - 2008. - No. 3. - S. 21-23]. In this process, sulfonation of the feed occurs, which gives the matrix additional cation exchange capacity. The disadvantage is the decomposition and carbonization of biomass under the action of acid.

A sorbent based on dried sphagnum plants is known (Patent Ru No. 2183501, IPC B01J 20/24 of 1996). Sorbent is mainly applicable for water purification from oil spills and hydrophobic compounds. Its disadvantage is the lack of information on its applicability to heavy metal ions.

Known fibrous sorbent based on cellulose-containing products, modified by compounds of the type of polydienes (Patent Ru 2152250, IPC B01J 20/00, B01J 20/22, B01J 20/26, 1999). The sorbent is mainly applicable for cleaning soil and water from oil spills. The disadvantage of the sorbent is the need for additional processing of cellulose-containing products with compounds such as polydienes, as well as the lack of information on the ability to absorb molecular toxicants and heavy metals.

Some authors propose using algae directly purified by distilled water to remove salts and sand as a sorbent of metal ions [Romera E., Gonzalez F., Ballester A., Blazquez M.L., Munoz J.A. Comparative study of biosorption of heavy metals using different types of algae // Bioresource Technology. - 2007. - Vol. 98. - P.3344-3353, Montazer-Rahmati M.M., Rabbani P., Abdolali A., Keshtkar A.R. Kinetics and equilibrium studies on biosorption of cadmium, lead, and nickel ions from aqueous solutions by intact and chemically modified brown algae // Journal of Hazardous Materials. - 2001 .-- Vol.185. - P.401-407] or after extraction with organic solvents (hexane) [Klochkova N.G., Berezovskaya V.A. Kamchatka shelf algae. Distribution, biology, chemical composition. - Vladivostok; Petropavlovsk-Kamchatsky: Dalnauka. - 1997. - 155 p.]. The disadvantage of these sorbents is the presence in algae of large quantities of water-soluble components, which makes it difficult to separate the sorbent from the sorbate.

Closest to the proposed invention is a method for producing a cellulose semi-finished product from brown algae (RF patent No. 2556115, IPC С08В 15/02, 2014), which consists in sequential processing of raw materials with 5-6% sulfuric acid at a boiling point and subsequent boiling of the solid residue with 2.5-5.0% potassium hydroxide, washing and drying the target product. The disadvantage of this method is the significant hydrolytic destruction of the cellulosic component of the raw material due to the use of elevated temperatures and aggressive environments. Lack of prospects for using products as a sorbent. The destruction of other algal biologically active substances, which calls into question the economic efficiency of obtaining this product.

The aim of the invention is the development of a sorbent with high sorption characteristics, while simple and cheap, without the use of expensive materials.

The tasks are to clean and increase the adsorption capacity of the sorbent to heavy metal ions.

The technical result of this invention is achieved by cleaning VK from water-soluble components and revealing the porous structure of this plant matrix by multi-stage treatment with water at a temperature of 100 ° C. The advantage of this sorbent is that VK is used as a raw material, which is formed during the processing of brown algae biomass, which allows us to solve the problem of VK utilization, which is a large-tonnage waste.

Technical result: 1) the ability of the proposed sorbent to effectively bind heavy metal ions and medium molecular weight toxicants from liquid media; 2) a solution to the problem of the disposal of large-tonnage waste from the integrated chemical processing of brown algae biomass.

The sorbent is a brown powder with a particle size of 0.05-0.2 mm, obtained as a result of purification of algal fiber (VC), formed during the complex chemical processing of brown algae. The sorbent has a mesoporous structure and a high sorption capacity with respect to salts of heavy metals.

The proposed sorbent is prepared as follows.

For extraction, air-dried brown algae is used, crushed to a particle size of 0.1-0.3 mm.

In the first stage, the algae is subjected to supercritical fluid extraction with a binary solvent: supercritical carbon dioxide - ethanol (10: 1) (Fig. 1, block 1). At this stage, the lipid-pigment complex containing fatty acids, chlorophyll and carotenoids is released. Extraction parameters: fraction size 0.2-0.03 mm, raw material humidity 9% by mass, temperature 60 ° C, pressure 300 atm, extraction time 60 min, carbon dioxide consumption 5.4 ml / min, ethanol consumption 0.6 ml / min

At the second stage of extraction, a complex of water-soluble substances (mannitol, laminaran, fucoidan, polyphenols, proteins and amino acids) is extracted. The biomass is treated with 0.1 N HCl at 60 ° C in three stages of 60 minutes, a water module of 1:20 (Fig. 1, block 2).

In the third stage, alginic acids are extracted from the residue after acid extraction by treatment with alkali (1.5% NaHCO ₃ ) at 50 ° C in 2 stages, each stage for 60 minutes, water module 1:20 (Fig. 1, block 3).

When brown algae is extracted according to the complex processing scheme we propose, cellulose is formed containing cellulose and residual amounts of components contained in the algae biomass (insoluble proteins, alginic acids, insoluble forms of laminirane and fucoidan, low molecular weight degradation products of algae components).

VC cleaning is carried out by quadrupling with water at boiling point with a water module of 1:20, each stage for 60 minutes. Thus, the removal of low molecular weight hydrolyzable carbohydrates and residual alginic acids occurs.

The resulting preparation, purified VK, is a brown fibrous mass. The mass is crushed to a particle size of 0.05-0.2 mm This substance has high sorption characteristics with respect to heavy metal ions and has a mesoporous structure (Table 1).

It should be noted that the use of the proposed VK purification method to obtain the sorbent is not limited to the application within the framework of the scheme proposed above (Fig. 1).

As test objects used purified VK.

Dried VK is a brown-green powder with a specific odor. The chemical composition of VK is presented in table 1.

As a comparison object, a Medisorb activated carbon sample was used. The tabletted sample was ground and fractionated. For analysis, particles of 0.08-0.25 mm in size were used.

Methylene blue dye and heavy metal salts (using the example of Cd ²⁺ and Pb ^{2+ ions} ) were used as markers to determine the effectiveness of the action of sorbents against medium molecular toxins and heavy metals.

To determine the brightening ability by methylene blue, we used the standard method according to GOST 4453-74, based on the photocolorimetric determination of the light transmission of a methylene blue solution before and after treatment with a sorbent. The result was expressed in mg / g of air-dried fiber.

The experiments on determining the sorption capacity with respect to heavy metal ions were carried out with solutions of the salts Cd (NO ₃ ) ₂ H 4H ₂ O and Pb (NO ₃ ) with metal ion concentrations of 35-700 mg / L and 300-4800 mg / L, respectively.

During the experiment, weighed samples of 0.1 g of sorbents were added to the flask and 100 ml of salt solution was added. The flasks were placed in a thermostatic device with magnetic stirring. At the end of the sorption time, a sample of the solution was taken from the settled sorbent. The equilibrium concentration of metal ions was determined on an atomic absorption spectrometer.

Dependence of sorption ability on time

In the experiment, solutions with a concentration of metal ions of Cd ²⁺ 35 mg / L and Pb ²⁺ 600 mg / L were used.

A weighed sample of a sorbent weighing 0.5 g was added to the flasks, and 500 ml of salt solution was added. Sorption was carried out in a thermostatic device (27 ± 1 ° C) with magnetic stirring. The pH of the sorbate solution corresponded to the pH of the aqueous solution of the test salt. Sorption time: 2.5, 5, 10, 15, 60, 240, 480, 1440 minutes. At the end of time, a sample of the solution was taken, further analyzed for the residual content of metal ions by atomic absorption spectroscopy.

Temperature dependence of sorption capacity

To a sample of the sorbent weighing 0.1 g, 100 ml of salt solution was added and the flask was placed in a mixing device with thermostating. The experiments were carried out at temperatures of 27 ± 1, 37 ± 1, 47 ± 1 ° C. Sorption time is 2 hours. The pH of the sorbate solution corresponded to the pH of the aqueous solution of the test salt.

The dependence of sorption ability on the pH of the solution

In 100 ml of a salt solution, the pH was set (1.5-5) by the addition of concentrated nitric acid. The upper pH level corresponds to an aqueous solution of salt.

A weighed portion of the sorbent 0.1 g was placed in flasks and 100 ml of salt solution was added. Sorption was carried out in a thermostatic device (27 ° C) with magnetic stirring. Sorption time is 2 hours.

The results obtained are presented in table 2 and indicate that the proposed sorbent has an increased sorption capacity in relation to heavy metal ions in comparison with activated carbon.

Pore volume and surface area are comparable with the parameters of some activated carbons. VK has a high ultimate specific adsorption capacity with respect to heavy metal ions: 60 ± 3 and 60 ± 3 with respect to cadmium ions, 105 ± 5 and 128 ± 6 mg / g with respect to lead ions, 130 ± 10 mg / g and 72 ± 3 mg / g with respect to methylene blue for fiber L.digitata and F.vesiculosus, respectively, at a pH of an aqueous solution of the corresponding salts of heavy metals and a temperature of 37 ° C.

The foregoing is illustrated by the following examples.

Example 1

0.5 kg of dried thallus of vesiculosus fucus (fucus vesiculosus) (humidity 9% wt.) Is ground to a particle size of 0.03-0.2 mm, placed in a semi-preparative supercritical fluid extractor MV-10ASFE (Thar Process, USA). Process parameters: temperature 60 ° С, pressure 300 atm, extraction time 60 min, fluid composition: supercritical СО ₂ (flow rate 5.65 g / min (5.4 ml / min)) + co-solvent ethanol with a flow rate of 10% vol. from fluid (0.6 ml / min (0.47 g / min)). The result is a supercritical extract with a yield of 29 g or 6.4% of the mass. from the original algae.

I algal residue after supercritical fluid extraction was placed in a container and poured 8.5 liters of 0.1N hydrochloric acid and extracted three times at ⁶⁰ ° C for 60 minutes with constant stirring. The extracts are separated from the algae by filtration through a nylon filter.

The algal residue II is extracted with 15 l of a 1.5% solution of sodium bicarbonate in two stages of 60 minutes at a temperature of 50 ^about With stirring. The extracts are separated from the algae by filtration through a nylon filter.

Algal residue III is a brown mass - fiber. Purification of the algal residue III is carried out by quadruple extraction of 10 l of water at boiling point, with constant stirring. The extracts are separated from the algae by filtration through a nylon filter. The extracts are discarded. The algal residue IV - purified VK is a fibrous brown mass with a yield of 14 g (3.1% of the mass of the algae). Sorption characteristics of the product are shown in table 2.

Example 2

Similar to example 1, but for the extraction we took algae of the species kelp palmate (laminaria digitata). The result was 10 g of purified fiber. Sorption characteristics of the product are shown in table 2.

Example 3

A mass of Pb (NO ₃ ) ₂ salt corresponding to 100 mg of lead ions was dissolved in 100 ml of water. 500 mg of VK fucus vesiculosus was placed in a flask. The mixture was thermostated with constant stirring for 60 minutes. After an hour, the content of lead ions in the solution decreased to 40 mg.

Claims (1)

A sorbent based on brown algae fiber, which has sorption activity with respect to salts of heavy metals and medium molecular weight toxicants of liquid media, which is an algal fiber purified from water-soluble components with a particle size of 0.05-0.2 mm, with a mesoporous structure, the main components of which are algal cellulose and hardly hydrolyzable proteins, which is obtained by supercritical fluid extraction of air-dried brown algae, crushed to a particle size of 0.1-0.3 mm, binary solvent: supercritical carbon dioxide - ethanol, with a solvent ratio of 10: 1, temperature 60 ° C, pressure 300 atm, for 60 minutes, followed by purification of the residue from water-soluble substances by treatment with biomass 0.1 n HCl at 60 ° C in three stages 60 minutes each, from alginic acids - 1.5% NaHCO ₃ solution at 50 ° C in 2 stages and subsequent four-fold extraction of the residue with water at boiling point.

Images