Agro-industrial wastes as precursors for adsorbent synthesis

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Microextraction techniques can be considered within the Green Chemistry framework as they reduce the amount of materials and organic solvents required for the development of an analytical methodology. This green character is more marked when the microextraction technique is employed to the resolution of an environmental analytical problem. This post is focused on another green concern: the use of wastes for the fabrication of sorbent materials for analytical purposes. Researchers from the Federal University of Rio Grande do Sul (Brazil) have already proposed, in an article published in Journal of Hazardous Materials, the use of coffee grounds and eucalyptus sawdust for the preparation of activated carbon. According to the authors, these agro-industrial wastes are quite problematic since their natural degradation favors the proliferation of some harmful microorganisms.

The synthesis of the activated carbon just involves various simple processes. First of all, the coffee grounds and the eucalyptus sawdust are place in the reactor and mixed with calcium hydroxide (oxidation catalyst), soybean oil and water, the latter two being used to homogenize the mixture. After a drying and purge step (argon atmosphere) the reactor is heated at 800 ºC for 30 min. As a result, a sorbent material with exceptional properties is obtained. These properties (e.g. specific area, porosity) are extensively discussed in the article. From the chemical point of view and according to the infrared measurement, the activated carbon present different functional groups (carboxylic, carbonyl, aromatic structures) that may interact with target analytes by hydrogen bonding an π-stacking.

Synthesis of activated carbon for the extraction of endocrine disruptors

The sorbent has been evaluated for the extraction of two potential endocrine disruptors from waters, namely: 17-estradiol (E2) and 17-ethinylestradiol (EE2). Both compounds may develop hydrogen bonding an π-stacking interactions which make their extraction feasible an efficient. In fact, the extraction recoveries are higher than 95%.

In the original article, the readers will find an interesting and complete characterization of the sorbent and the full description of the syntethis. The kinetic and the thermodynamic (evaluated in the form of adsorption isotherm) studies of the extraction are strongly recommended.

Reference:
(1) Development of a new adsorbent from agro-industrial waste and its potential use in endocrine disruptor compound removal. Link to the article



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