RU2252818C1 - Method of preparation of vegetable-based sorbents - Google Patents

Abstract

FIELD: production of sorbents used for cleaning aqueous solutions from heavy metals.

SUBSTANCE: peel of citrus plants, orange or lemon for example is cut in pieces, 4-5 mm thick and 30-40 mm long which are washed in water, dried at temperature of 60-65 °C and then 100-105 °C, after which they are ground, dispersed and fraction of 0.2-2 mm is separated.

EFFECT: enhanced efficiency of cleaning aqueous solutions from heavy metals, from copper and cadmium for example.

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Description

The invention relates to a technology for producing sorbents, and specifically to methods for producing sorbents that can be used to purify heavy metals from aqueous solutions.

Sorption purification is one of the effective ways to remove contaminants from aqueous solutions.

A method for producing a sorbent based on sawdust that is treated with a chemical agent - 1 (2-hydroxyethyl) -4,5,6,7 tetrahydroindole in an acetone solution at a ratio of 1: 0.01 and incubated for 12 hours is described [1].

The sorption capacity of the sorbent in static conditions for heavy metals is 0.8-1.4 mg / g.

The disadvantage of this method is the complexity of the technology, low sorption capacity.

A known method of producing a sorbent on a plant basis, which is used as a cake from the processing of watermelon seeds for vegetable oil [2].

Oilcake is washed with water (after crushing), dried to constant weight, sifted, 0.2-2 mm fraction is taken. The sorption capacity of the sorbent for copper is up to 3.9 mg / g, for zinc - up to 2.6 mg / g.

The disadvantages of the method is the limited ability to clean aqueous solutions and the resource of sorbents.

The technical result is the expansion of sorption capabilities, resource and assortment of sorbents. This is achieved by the fact that the peel of citrus crops (the outer shell of the fruit) is used as a plant base, for example, orange and lemon, which contain up to 80% moisture, the rest is dry matter, mainly containing fiber and a protein-carbohydrate component (complex). The peel is a waste from the processing of citrus juices and is partially used [3]. The peel is cut into slices 4-5 mm thick and 30-40 mm long, poured with water in a ratio of 1: 4-5, mixed, aged for 40-60 minutes, the aqueous layer is separated, water is added again, mixed, aged, the aqueous layer is drained and etc. until colorless, clear wash water is obtained. The residues are dried first at a temperature of 60-65 ° C, then at 100-105 ° C to constant weight, crushed, sieved, a fraction of 0.2-2 mm is selected - a sorbent with a bulk density of 0.45-0.55 g / cm ³ containing at least 1 wt.% Kjeldahl nitrogen characterizing a protein-carbohydrate component and at least 16 wt.% fiber. The prepared sorbent makes it possible to purify aqueous solutions of heavy metals, for example, copper and cadmium, with a sorption capacity of 3.5-3.8 mg / g.

Example 1. 50 g of cut orange peel with a moisture content of 80 wt.% In a flask is filled with 200 ml of water, stirred, kept for 50 minutes, the aqueous layer is separated, again filled with water, stirred, kept for 40 minutes, the aqueous layer is separated, etc. until colorless, clear wash water is obtained. The residues are dried first at a temperature of 60-65 ° C (1 h), then at 100-105 ° C to constant weight, crushed, sieved, a fraction of 0.2-2 mm is taken. Get 9.5 g of sorbent - a yellowish powder with a bulk density of 0.51 g / cm ³ , nitrogen content according to Kjeldahl 1.1 wt.% And fiber 18.1 wt.%.

Similarly, the sorbent is obtained by processing the peel of a lemon with a yield of 9.0 g, a bulk density of 0.45 g / cm ³ , a nitrogen content of Kjeldahl of 1.2 wt.% And fiber 17.0 wt.%.

Example 2. Tests for sorption capacity. In a flask with a capacity of 100 ml add 1 g of sorbent from the peel of an orange and 40 ml of an aqueous solution containing 100 mg / l of copper in the form of sulfate, mix, incubate at room temperature until the end of sorption (by chemical analysis of copper). After 3.5 hours in the aqueous layer, the copper content is 6.4 mg / l, the sorbent capacity of 3.7 mg / g, the degree of purification of 93.6%.

Example 3. In the flask of example 2 add 1 g of sorbent from the peel of an orange, 40 ml of an aqueous solution containing 134 mg / l of cadmium in the form of sulfate, mix, incubate for 4 hours, in the aqueous layer the content of cadmium is 39 mg / l, sorption capacity 3.8 mg / g, 71% purity.

Similarly, they test the sorption capacity of the sorbent from the peel of a lemon.

It was found that its sorption capacity for copper is 3.8 mg / g, for cadmium - 3.5 mg / g, with a purity of 96.9% and 65%, respectively.

Thus, the proposed method allows you to clear aqueous solutions of heavy metals, to expand the resource and range of sorbents on a plant basis.

Sources of information

1. SU 1498551, 1987.

2. RU 2212931, 2002.

3. Karchava M.S. Pectin-containing raw materials of Georgia and prospects for its use // Storage and processing of agricultural raw materials. 2004, No. 1, p. 42.

Claims (1)

A method of producing a plant-based sorbent for cleaning aqueous solutions of heavy metals, characterized in that the peel of citrus crops, for example, orange and lemon, is used as a plant base, the waste of their processing into juices, which are washed with water, dried in two stages, first at at a temperature of 60-65 ° C for 1 h, then at 100-105 ° C to constant weight, crush, disperse, select a fraction of 0.2-2 mm.