ADSORPTION OF p-NITROPHENOL ON ACTIVATED CARBON DERIVED FROM THE LIGNIN OF CELLULOSIC ETHANOL BY-PRODUCT

Adsorption of p-nitrophenol (PNP) onto activated carbon (AC) prepared from lignin of cellulosic ethanol by-product has been experimented. Effects of contact time, AC dosage, pH, initial PNP concentration and temperature were investigated using batch experiments. Isotherm models such as Langmuir, Freundlich, Temkin and Redlich-Peterson were employed to evaluate the PNP adsorption behavior. The results indicated that Langmuir isotherm can well describe the PNP adsorption process and the maximum monolayer adsorption capacity was 1.03 mmol/g at 298 K. The PNP adsorption process followed the pseudo-first-order, suggesting that the PNP adsorption on AC may be a physical adsorption process. Brunauer-Emmett-Teller, Scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetry were used to analyze the characteristics of AC. Adsorption mechanism was discussed, and it is clear that adsorption process was influenced by the H-bonding, pi-pi interaction and electrostatic repulsion. It showed that AC derived from the lignin of cellulosic ethanol by-product was an excellent adsorbent for PNP removal.