Adsorption Removal of Humic Acid from Micro-Polluted Water Using in Situ Manganese Dioxide

The adsorption removal of humic acid (HA) from micro-polluted water using manganese dioxide (MnO2 ) formed in situ, which was prepared through the oxidation of MnSO4 using KMnO4 ,was investigated through batch experiments including kinetics, thermodynamics and isothermal adsorption models with online dosing mode. The results of analysis by the UV254 and permanganate index CODMn methods indicates that HA removal reach 29.82% and 49.99%, respectively at amount of in situ MnO2 8 mg/L and contact time 2h. The kinetics data proves a closerfit to the pseudo-second order model.The isotherm data can be fit with Langmuir isotherm model well, and maximum adsorption capacity achieved 27.20 mg/g which is near to the experimental value 26.38 mg/g. Moreover, the thermodynamic analysis shows the HA adsorption on in situ MnO2 is a spontaneous and exothermic process. The excellent adsorption performance and low cost of the in situ MnO2 can be considered as one of the effective options to remove HA from micro-polluted water.