Activated carbon from avocado seeds for the removal of phenolic compounds from aqueous solutions

Abstract

a b s t r a c tAvocado seed activated carbon (ASAC) was synthesized by microwave-heating process using ZnCl 2 as an activating agent. The adsorbent ASAC was characterized using analytical techniques namely N 2 isotherms, Fourier transform infrared spectroscopy, and scanning electron microscopy. The surface area of ASAC was 1,432 m 2 g -1 . The ASAC prepared was used for adsorption of resorcinol and 3-aminophenol from aqueous solutions. Kinetic models namely pseudo-first order, pseudo-second order, and Avrami fractional order and isotherms (Freundlich, Langmuir, and Liu) were applied to the experimental adsorption data. The results demonstrate maximum adsorption capacity for resorcinol (406.9 mg g -1 ) and 3-aminophenol (454.5 mg g -1 ) at 50°C. The thermodynamic analysis of data and the effect of temperature studies revealed that the adsorption processes of resorcinol and 3-aminophenol onto ASAC were temperature dependent. The adsorption processes were exothermic and spontaneous. The avocado carbon displayed excellent adsorption properties for the simulated effluents containing phenolic compounds.

Conversion of Eragrostis plana Nees leaves to activated carbon by microwave-assisted pyrolysis for the removal of organic emerging contaminants from aqueous solutions

“…While the images of the surface of MWEPN (Fig. 4b) were irregular with large holes that are compatible with a material with high rugosity in its surface (Leite et al, 2017b, Puchana-Rosero et al, 2016. These channels present on the surface of activated carbon allow the passage of the liquid solution through the carbon surface, allowing the mass transfer of the adsorbates from the bulk solution to the surface of the activated carbon (dos Santos et al, 2014;dos Reis et al 2016).…”

“…After this temperature, an oxidising atmosphere was imposed with synthetic air from 700°C (biomass) or 800°C (activated carbon) up to 1000°C at a heating rate of 10°C min −1 . This strategy of using a flow of synthetic air for the higher temperature aims to obtain the contents of ash of the samples during the TGA analysis, as early reported in the literature (Thue et al, 2016, Leite et al, 2017b. Besides, the pyrolysis of biomass and activated carbon also can be studied, up to 700°C (biomass) and 800°C (activated carbon), since for this temperature interval, N 2 is used as purge gas.…”

“…Afterwards, the chemically treated carbon material is pyrolysed between 500-850°C under a nitrogen atmosphere (Thue et al, 2016(Thue et al, , 2017b. After the pyrolysis, the obtained material is a composite of carbon and mixture of inorganics, and it is necessary to leach out the inorganic components to achieve the activated carbon with an excellent developed pore structure (Leite et al, 2017b).…”

“…The production of activated carbon using different agricultural residues as carbon precursor has drawn the attention of many researchers (Du et al, 2017;Yahya et al, 2015aYahya et al, , b, 2016Leite et al, 2017b;Namazi et al, 2016;Yahya et al, 2015a, b). In this focus, the present work investigated the applicability of Eragrostis plana Nees leaves as carbon precursor for preparation of activated carbon using microwaveassisted pyrolysis.…”

Electrocoagulation coupled adsorption for anaerobic wastewater post-treatment and reuse purposes

“…After EC optimal conditions, were found adsorption experiments were carried out with the purpose of polishing the final effluent. The granular activated carbon (VETEC) was previously treated with 6 mol/L HCl at open reflux (at boiling temperature) with a volumetric ratio of 1.5:1 (HCl:activated carbon) for 60 min, washed with distilled water and dried at 60°C for 24 h. This process was carried out to remove the inorganic material present in the activated carbon, thus causing an increase in the surface area and activation of the adsorption sites [35,36]. The surface area of the activated carbon was determined at 856.4 m 2 /g through adsorption isotherms of N 2 (BET method).…”