Physicochemical properties and sorption capacities of sawdust-based biochars and commercial activated carbons towards ethoxylated alkylphenols and their phenolic metabolites in effluent wastewater from a textile district

Massimo Del Bubba; Beatrice Anichini; Zaineb Bakari; Maria Concetta Bruzzoniti; Roberto Camisa; Claudia Caprini; Leonardo Checchini; Donatella Fibbi; Ayoub El Ghadraoui; Francesca Liguori; Serena Orlandini

doi:10.1016/j.scitotenv.2019.135217

Physicochemical properties and sorption capacities of sawdust-based biochars and commercial activated carbons towards ethoxylated alkylphenols and their phenolic metabolites in effluent wastewater from a textile district

Sci Total Environ. 2020 Mar 15:708:135217. doi: 10.1016/j.scitotenv.2019.135217. Epub 2019 Nov 22.

Affiliations

¹ Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3 - 50019 Sesto Fiorentino, Florence, Italy. Electronic address: delbubba@unifi.it.
² Publiacqua S.p.A., Via Villamagna 90/c 50126 Florence, Italy.
³ Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3 - 50019 Sesto Fiorentino, Florence, Italy; National Engineering School of Sfax, Route de la Soukra km 4 3038 Sfax, Tunisia.
⁴ Department of Chemistry, University of Turin, Via Pietro Giuria 5 - 10125 Turin, Italy.
⁵ GIDA S.p.A., Via di Baciacavallo 36, 59100 Prato, Italy.
⁶ Department of Chemistry "Ugo Schiff", University of Florence, Via della Lastruccia 3 - 50019 Sesto Fiorentino, Florence, Italy.
⁷ Institute for the Chemistry of Organometallic Compounds, National Research Council (ICCOM-CNR), Via Madonna del Piano 10 - 50019 Sesto Fiorentino, Florence, Italy.

PMID: 31810702
DOI: 10.1016/j.scitotenv.2019.135217

Abstract

Three biochars were produced using sawdust from waste biomass, via a simple pyrolysis thermal conversion at 450, 650, and 850 °C (BC450, BC650, and BC850), without any activation process. These materials, together with vegetal and mineral commercial activated carbons (VAC and MAC), were characterized for their elemental composition, Brunauer-Emmett-Teller surface area, t-plot microporosity and Barrett-Joyner-Halenda mesoporosity. Moreover, iodine, phenol and methylene blue porosity indexes were measured. The materials were also evaluated for their pH of the point of zero charge, as well as near-surface chemical composition and surface functionality by means of X-ray photoelectron and Fourier-transform infrared spectroscopy. Ash content, water-extractable metals and polycyclic aromatic hydrocarbons (PAHs) were also determined. BC650 showed a much higher surface area (319 m² g^-1) compared to BC450 (102 m² g^-1), as well as an increase in aromatization and the residual presence of functional polar groups. BC850 exhibited a loss of polar and aromatic groups, with the dominance of graphitic carbon and the highest value of surface area (419 m² g^-1). Biochars comply with the EN 12915-1/2009 limits for metal and PAH release in water treatment. Biochars and MAC were tested using Langmuir and Freundlich isotherms for the sorption in real effluent wastewater of a mixture of 14 branched ethoxylated 4-t-octyl and 4-nonylphenols, as well as 4-t-octyl and 4-nonylphenol, the latter representing persistent, endocrine disrupting contaminants, widespread in the effluents from wastewater treatment plants and listed as priority/priority hazardous substances in the Directive 2013/39/EU. Biochars showed a lower sorption efficiency compared to MAC. The best performance was found for BC650 towards the alkylphenols (9-13 times less efficient than the MAC). Considering the lower market price of biochar compared to MAC (estimated as at least 16 times less expensive by a small market survey), the former can be considered more competitive than the latter.

Keywords: FTIR; Heavy-metal release; PAH release; Porosimetry analyses; Priority substances; XPS.

MeSH terms

Adsorption
Charcoal*
Chemical Phenomena
Phenols
Textiles
Wastewater

Substances

Phenols
Waste Water
biochar
Charcoal