Preparation of ultrahigh-surface-area sludge biopolymers-based carbon using alkali treatment for organic matters recovery coupled to catalytic pyrolysis

In this work,we employed waste activated sludge(WAS)as carbon source to prepare ultrahigh specific surface area(SSA)biopolymers-based carbons(BBCs)through alkali(KOH)treatment coupled to pyrolysis strategy.Before the pyrolysis process,the involvement of KOH made a great recovery of soluble biopolymers from WAS,resulting in highly-efficient catalytic pyrolysis.The Brunner-Emmett-Teller and pore volume of BBCs prepared at 800℃(BBC800)reached the maximum at 2633.89 m2·g-1 and 2.919 m3·g-1,respectively.X-ray photoelectron spectroscopy suggested that aromatic carbon in the form of C=C was the dominant fraction of C element in BBCs.The N element in BBCs were composed of pyrrolic nitrogen and pyridinic nitrogen at 700℃,while a new graphitic nitrogen appeared over 800℃.As a refractory pollutant of wastewater treatment plants,tetracycline(TC)was selected to evaluate adsorption performance of BBCs.The adsorption behavior of BBCs towards TC was conformed to the pseudo-second-order kinetic and the Langmuir models,signifying that chemisorption of monolayers was dominant in TC adsorption.The adsorption capacity of BBC800 reached the maximum at 877.19 mg·g-1 for 90 min at 298 K.Thermodynamic analysis indicated that the adsorption process was endothermic and spontaneous.Hydrogen bonding andπ-πstacking interaction were mainly responsible for TC adsorption,and interfacial diffusion was the main rate-control step in adsorption process.The presence of sol-uble microbial products(SMPs)enhanced TC removal.This work provided a novel strategy to prepare bio-carbon with ultrahigh SSA using WAS for highly-efficient removal of organic pollutants.