title: Preparation of cationized pine sawdust for nitrate removal: Optimization of reaction conditions.
abstract: Anion exchange materials were prepared from pine sawdust (Pinus sylvestris, PSD) through cationizing treatment with N-(3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHMAC) in the presence of NaOH. Response surface methodology (RSM) was used to find the optimal reaction conditions. Three factors were chosen: reaction temperature (26-94 °C), reaction time (0.32-3.7 h) and NaOH/CHMAC molar ratio (0.19-2.2). Product yield (%) was used as a response. A quadratic model was fitted to the experimental data. The optimal conditions were: a reaction temperature of 57 °C, a reaction time of 1.8 h and a NaOH/CHMAC molar ratio of 1.32. A maximum nitrogen content of 2.6% was obtained at 60 °C, 3.7 h and a molar ratio of 1.2. The molar ratio had the greatest impact on the response. Regression analysis revealed that over 95% of the variance can be explained by the model. A maximum nitrate sorption capacity of 15.3 ± 1.4 mg N/g was achieved. The effect of CHMAC dose was also studied (a NaOH/CHMAC molar ratio of 1.2): 0.064 mol/g PSD was found to be near the optimum. Nitrate-contaminated groundwater (27.5 mg/l NO3) was treated with CPSD. Doses of 3-6 g/l resulted in 59-71% nitrate reduction.
authors.affiliation: University of Oulu, Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland. Electronic address: anni.keranen@oulu.fi.
authors.forename: Anni
authors.initials: A
authors.lastname: Keränen
authors.affiliation: University of Oulu, Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland. Electronic address: tiina.leiviska@oulu.fi.
authors.forename: Tiina
authors.initials: T
authors.lastname: Leiviskä
authors.affiliation: University of Oulu, Department of Physics and Chemistry, P.O. Box 3000, FIN-90014 University of Oulu, Oulu, Finland. Electronic address: osmo.hormi@oulu.fi.
authors.forename: Osmo
authors.initials: O
authors.lastname: Hormi
authors.affiliation: University of Oulu, Chemical Process Engineering, P.O. Box 4300, FIN-90014 University of Oulu, Oulu, Finland. Electronic address: juha.tanskanen@oulu.fi.
authors.forename: Juha
authors.initials: J
authors.lastname: Tanskanen
mesh_terms: D000327:Adsorption; D006801:Humans; D009566:Nitrates / Q000737:chemistry*; D028223:Pinus; D013499:Surface Properties; D013696:Temperature; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical
keywords: Cationization; Ion exchange; Lignocellulose; Nitrate; Response surface methodology; Sorption capacity