Adsorption Properties of Activated Carbons Prepared from Recycled PET in the Removal of Organic Pollutants from Aqueous Solutions

Abstract

Activated carbons (ACs) were prepared from recycled polyethylene terephthalate (PET) by chemical activation with KOH and used successfully for the removal of 4-chloro-2-methylphenoxyacetic acid (MCPA) and Methylene Blue (MB) from aqueous media. In order to improve the adsorption capacity towards pollutant removal, the AC was submitted to different post-treatments. After oxidation, the sample exhibited an increase in MB adsorption capacity but showed a decreased MCPA adsorption removal extent. High-temperature treatment was not favourable for increasing the MB or MCPA adsorption capacity. However, after treatment with sodium hydroxide or urea, the samples showed a significant increase in their MCPA adsorption capacities. Normalisation of the MB and MCPA adsorption data with respect to the micropore volume led to a clearer understanding of the influence of the textural and chemical characteristics of the AC on the removal of MB and MCPA. The MB and MCPA adsorption isotherms were analysed via the Langmuir and Freundlich models, with the calculated parameters accurately fitting the experimental data and exhibiting good agreement between them.

The influence of the activated carbon post-treatment on the phenolic compounds removal

“…In the present study, the FTIR spectra were interpreted using the OMNIC application from the Thermo Nicolet Corporation together with information already published by several authors [1,[37][38][39][40][41]. In general all the spectra of ACs from charcoal cloth, PET and cork show some different absorption peaks with variable intensity.…”

“…Phenols are typically considered as one of the important organic pollutants discharged into the environment causing unpleasant taste and odour and are also toxic, even at low concentrations. The phenolic compounds present in liquid effluents are generated from paper and pulp, chemical, paint, resin, pesticides, gas and coke manufacture and dyeing industries [1][2][3][4][5]. Their determination and removal from wastewater is therefore imperative.…”

“…Concerning the liquid phase adsorption, various kinetic models have been reported in the literature to describe this process [1][2][3][4][5][26][27][28][29][30]. The most widely used isotherm equation for modelling equilibrium is the Langmuir equation.…”

Adsorption of MCPA, 2,4-D and diuron onto activated carbons from wood composites

“…A complete characterization of the AC was achieved through different methods, normally used for this purpose, such as N 2 adsorption at 77 K, CHNS-O elemental analysis, point of zero charge and thermogravimetrical analysis of the precursors. The detailed description of the experimental procedure is given elsewhere [4,7,8].…”

“…Adsorption is considered an attractive method for removing pollutants and in particular pesticides from dilute solutions which involve the previous determination of the adsorptive behaviour on various adsorbents. Activated carbon (AC) materials have an important place among the adsorbents tested as they can be prepared from a wide variety of relatively low cost, natural or synthetic precursors, as largely described in the literature, and their improved properties allow them to adsorb various organic and inorganic compounds for a long time, being able to be regenerated and reused for several times [4][5][6][7][8][9][10][11]. The industries are still looking for environmentally friendly and cheaper AC retaining or increasing the adsorption capacities when compared with those often used for the same purpose.…”