Study On Adsorption Effect Of Phosphogypsum Whisker On Phosphorus And Heavy Metal Ions In Wastewater

Adsorption is one of the basic processes in nature. Materials used for adsorption include artificially synthesized and naturally existing matter. They can also be divided into organic and inorganic substances which are widely used in fields of biomedicine, chemistry and chemical engineering, and environmental control. In the field of environmental control, these materials are mainly applied in sewage disposal, drinking cleaning and waste gas treatment, etc. However, to date, little adsorbent gain popularity in the environment domain, activated carbon, activated alumina and resin are the most common adsorbents. Therefore, developing high efficient adsorbent becomes a hot issue.In this study, we prepared the phosphogypsum whisker as the adsorbent by using the phosphogypsum as the raw material and tested its adsorption capacity for P, Pb and Cu in water, as well as the influence factors including pH, initial concentration and the adding amount. The kinetic adsorption characteristic was also examined. It was found that phosphogypsum whisker had good adsorption effect on heavy metals and P with high concentrations.Phosphogypsum whisker showed higher retention ability at alkali pH values than acidic values, for Cu and Pb, the best pH values ranged between 6.0 and 7.0. Langmuir and Freundlich isotherm equations were applied to fit the adsorption data and the adsorption characteristics of all the three materials could be better described by Langmuir model. The obtained saturate adsorption amounts of P, Pb and Cu were 140.4 mg/g, 66.02mg/g and 39.93 mg/g, respectively. The adsorption process tended to be single monolayer adsorption reaction. Pseudo-first, Pseudo-second and Elovich equations were applied to fit the date in kinetic adsorption experiments. Pseudosecond equation was better than Pseudo-first and Elovich equations in describing the kinetic adsorption process. The determination coefficients were all above 0.97.When the initial pH of the sewage was 10.0, the adding amount of the phosphogypsum whisker was 1.0 g/L and initial P concentrations were 5~100 mg/L, the removal rates of P were all above 93% after 1.0h of reaction. When the initial pH of the sewage was 7.0, the adding amount of the phosphogypsum whisker was 5.0 g/L and initial Pb concentrations were 10~200mg/L, the removal rate of Pb were above 91% after 3.0h of reaction. When the initial pH of the sewage was 7.0, the adding amount of the phosphogypsum whisker was 5.0 g/L and initial Cu concentrations were 10~100mg/L, the removal rate of Cu were above 84.3% after 3h of reaction. The adsorption capacity of phosphogypsum whisker for these three materials followed the order: P>Pb>Cu.