This study focused on the adsorptive behaviors of humic acid onto freshly prepared hydrous MnO_(2)(s)(δMnO_(2)),and investigated the feasibility of employingδMnO2 for humic acid removal from drinking water.Effects of such parameters as molecular mass of humic acid,kinds of diva-lent cations on adsorptive behaviors and possible mechanisms involved were investigated.This study indicated that humic acid with higher molecular mass exhibited more tendency of adsorbing ontoδMnO2 than that with lower molecular mass.Ca^(2+)facilitated more humic acid adsorption than Mg^(2+);UV-Vis spectra analysis indicated higher capabilities of Ca^(2+)coordinating with acidic functional groups of humic acid than that of Mg2+.Additionally,ζpotential characterization indicated that Ca^(2+)showed higher potential of increasingζpotential ofδMnO_(2) than Mg^(2+).Ca^(2+)of 1.0 mmol/L increasedζpotential ofδMnO2 from−37 mV(pH 7.9)to+7 mV(pH 7.2),while 1.0 mmol/L Mg^(2+)^increased to lower value as−9 mV(pH 6.5),correspondingly.Fourier transform infrared(FTIR)spectra demonstrated the adsorption of humic acid ontoδMnO_(2),showing the important roles of-COO−function-al groups and surface Mn-OH in the adsorption of humic acid ontoδMnO_(2).
LIU RuipingYANG YanlingLI GuibaiHE WenjieHAN Hongda
Iron-manganese composited oxide(FeMnO) was prepared with potassium permanganate and ferrous salt. Interface performance, charge property and structure topography of the FeMnO were investigated. Coagulation efficiency and pollution removal mechanism of the FeMnO were approached. Results show that the main compositions of the FeMnO are δ-manganese dioxide and ferric hydroxide. The specific surface area is about 146.22 m2/g. The FeMnO contains rich hydroxyl with extremely strong adsorption action and chemical adsorption activity. The zero charge point of the oxide in pure water is about 8.0 of pH value. Under neutral pH value conditions, the FeMnO particle surface carried positive charges. The FeMnO particles are quasi-spherical micro-particles with irregular sizes adjoined each other to form net construction. Phosphorus removal efficiency of the FeMnO is remarkable, the total dissoluble phosphorus of settled water can be reduced below detecting level(0.3 μg/L) at a FeMnO dosage of 6 mg/L, and total phosphorus below detecting level at a FeMnO dosage of 10 mg/L, for water samples containing total phosphorus of 1281.70 μg/L and total dissoluble phosphorus of 1187.91 μg/L. The mechanism of effective coagulation for phosphorus removal is combined results of multiple actions of adsorption, charge neutralization, adsorption/bridging and so on.
YANG Yan-lingLI XingGUO Can-xiongZHAO Fu-wangJIA Feng
