Abstract
Nowadays the dyeing wastewater has brought about increasingly serious environmental issues, and the methods of wastewater treatment both at home and abroad mainly include the adsorption, the floccutant, photocatalytic degradation, ultrafiltration and electrochemical methods, etc. Among them, the adsorption method has been widely applied to treatment of the dyeing wastewater due to its advantages such as simple operation, low cost and no secondary pollution, etc. The diatomite, with a relatively large surface area and strong adsorption capacity, is an excellent natural environmental adsorbent with negative charge on its surface when in solution. But it needs further modified so as to strengthen its limited adsorption capacity. This paper, using the diatomite as the raw material, studies the characteristics of the Mn-modified diatomite which has been prepared with the oxidation method after precipitation and the results show that the Mn-modified diatomite is covered with Mn oxide particles. It has found the optimal adsorption condition by studying Congo red adsorption of the Mn-modified diatomite mainly with static adsorption experiment. Moreover, it studies the impact of the adsorbent quantity, solution pH value, dye concentration as well as temperature on the adsorption effect and explores the kinetic behavior in which the Mn-modified diatomite adsorbs Congo red. The study shows that Mn-modified diatomite owns excellent removal effect to Congo red. And through kinetics analysis of the adsorption process, it has been found that Congo red adsorption of the Mn-modified diatomite conforms to the Langmuir isotherm, Freundlich linear model and pseudo-second-order kinetic equation.
