Characterization of activated carbons for water treatment using TGA-FTIR for analysis of oxygen-containing functional groups

Abstract

Water treatment with activated carbon (AC) is an established method for the removal of organic micropollutants and natural organic matter. However, it is not yet possible to predict the removal of individual pollutants. An appropriate material characterization, matching adsorption processes in water, might be the missing piece in the puzzle. To this end, this study examined 25 different commercially available ACs to evaluate their material properties. Frequently reported analyses, including N$$_2$$ 2 adsorption/desorption, CHNS(O), point of zero charge (PZC) analysis, and X-ray photoelectron spectroscopy, were conducted on a selected subset of powdered ACs. Inorganic elements examined using X-ray fluorescence and X-ray diffraction spectroscopy revealed that relative elemental contents were distinctive to the individual AC’s raw material and activation procedure. This study also is the first to use thermogravimetric analysis (TGA) coupled to Fourier-transform infrared spectroscopy (FTIR) to conduct quantitative analyses of functional surface oxygen groups (SOGs: carboxylic acid, anhydride, lactone, phenol, carbonyl, and pyrone groups) on such a large number of ACs. The comparably economical TGA method was found to provide good surrogates for the PZC by pyrolytic mass loss up to 600 $$^{\circ }$$ ∘ C (ML$$_{600}$$ 600 ), for the oxygen content by ML$$_{1000}$$ 1000 and for the carbon content by oxidation. Mass loss profiles depict the AC’s chemistry like fingerprints. Furthermore, we found that SOG contents determined by TGA-FTIR covered a wide individual range and depended on the raw material and production process of the AC. TGA and TGA-FTIR might therefore be used to identify the suitability of a particular AC for a variety of target substances in different target waters. This can help practitioners to control AC use in waterworks or wastewater treatment plants.

Batch and Packed Bed Column Studies of Azo Dyes Adsorption from the Aqueous Solutions Using Activated Sugarcane Bagasse Charcoal Adsorbent: Isotherm and Kinetic Studies

“…When the band level reduces from 1000 cm -1 , the presence of C-H functional groups was identified because of the aromatic vibrations (Kepenek et al, 2020). The -CH2 vibration stretching disappeared at 2860 cm -1, and -OH stretching was formed at lower frequency levels (Dittmann et al, 2022). Hence, the FTIR studies confirm the availability of functional groups in the adsorbent and their role in azo dye uptake during the experimental studies.…”

Equilibrium, Kinetics and Thermodynamic studies of Cr (VI), Pb (II) & Zn (II) biosorption using Sargassum Wightii

“…Similarly, the -CH 3 group's stretch and twisting vibrations moved to a lower frequency. This demonstrates metal ion binding onto the binding sites of SW (Dittmann et al, 2022). 3.3 Effect of pH on metals adsorption -Adsorption tests were carried out at various pH levels (2.0 to 7.0).…”

„Die Aktivkohle“ gibt es nicht – die physikochemische Vielfalt von Aktivkohleprodukten zur Wasseraufbereitung

“…Zu den umfangreichen Informationen, die mittels TGA-FTIR gewonnen werden können, zählen bereits temperaturabhängige Massenverluste der TGA. So erzeugt diese eine Art "Fingerabdruck" der Oberflächenchemie frischer AK, der den Vergleich mit einer Musterkohle zulässt [5]. Die so stark vereinfachte Gerätekonfiguration würde für die Betriebsmittelüberwachung bereits ausreichen und bietet zudem weitere Anwendungsmöglichkeiten, zum Beispiel für die Verfahrensüberwachung oder Schlammanalytik [7].…”

“…This resulted in the monitoring of perfluoroacetic acids (PFAA) C 2 -C 14 , perfluorosulfonic acids (PFSA) C 1 -C 12 , and seven other fluorinated chemicals (3,3,4,4,5,5,6,6,7,7,8,8,8tridecafluorooctane-1-sulfonic acid (6:2 FTS), 2,3,3,3-Tetrafluoro-2-(heptafluoropropoxy)-propanoic acid (HFPO-DA), Trifluoromethanesulfinic acid (triflinate), N-(3-(Dimethylamino)propyl)-3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctanesulphonamide N-oxide (DPOSA), Tris(pentafluoroethyl)trifluorophosphate (FAP), Bis(trifluoromethylsulfonyl)imide (NTf2), and 1,1,1,3,3,3-Hexafluoropropan-2-ol (HFIP)) in 46 surface water, bank filtrate, and ground water samples. This data and corresponding total oxidizable precursor (TOP) assay and absorbable organic fluorine (AOF) measurements were used to investigate the occurrence and distribution of ultra-short chain and legacy PFAS in the sources of German drinking water [5].…”

“…Aufgrund der erhöhten Temperaturen während des Herstellungsprozesses der AK spaltet frische AK während der Pyrolyse nur CO 2 , CO und eventuell H 2 O ab. Diesen Gasen können durch Entfaltung (deconvolution) der temperaturabhängigen Freisetzungsraten[5] bis 1000 °C funktionelle Gruppen zugeordnet werden, welche die Oberflächenchemie unbeladener Aktivkohlen prägen und die Adsorption organischer Spurenstoffe beeinflussen können.…”