Removing nitrate with coconut activated carbon, tailored with quaternary ammonium epoxide compounds: Effect of base or acid carbon pretreatment

摘要: Abstract The authors tailored coconut-based activated carbons with a quaternary ammonium epoxide (QAE) surfactant that greatly increased the carbon's capacity for sorbing nitrate from water. This QAE-tailored carbon processed deionized water spiked 50 mg/L NO3− through rapid small scale column tests; and achieved half-breakthrough at 477 bed volumes. favorably compared to 52 volumes pristine coconut carbon. QAE employed herein was QUAB 360. Most favorable pretreatment of via NaOH immersion, which created extensive phenolic functionality on graphene edges, raised slurry pH 9.3–9.6. These phenolics served as anchor QUAB's reactions. offered highest loading onto carbon, in turn netted most removal. Per X-ray photoelectron spectroscopy, QUAB360 preloading incurred 1.62% increase N content these carbons. followed discerned by Boehm titrations; mathematically matched Gaussian-based models were fitted incremental titration data. QUAB-loaded variants ones whose pretreated precursors had exhibited peak 9.3–10.4 range—corresponding pKa phenolics. If precursor below 9.3–9.6 range—as induced acids or H2O2, then intermediate apparently over-reacted hydroxylated other molecules, rather than edge sites.