铅、镐在给水厂残泥免烧陶粒上的竞争吸附特性.

In order to explore the practicability of the Unburned ceramsites derived from water treatment residuals ( UCWTR ) for remediating multiple heavy metals-contaminated wastewater, a series of static adsorption experiments were carried out here to analyze the competitive adsorption performance of Pb and Cd on the surface of UCWTR and the main factor affecting its adsorption behavior for heavy metals. Results showed that the regular co-lumnar structured UCWTR particles of abundant cracks possessed large specific surface area and rich adsorption sites, which were conducive to improve the adsorption capacity for heavy metals. Meanwhile, the functional groups within UCWTR, such as-OH, Al-OH, Fe-O and C-S-H, also were beneficial to adsorbing Pb and Cd. During the competitive adsorption process of Pb and Cd, the maximum adsorption capacities of UCWTR for Pb and Cd were 0.36 mmol • g-1 and 0.25 mmol • g-1, respectively, and the adsorption kinetics were fitted better with the pseudo-second-order model (R²cd =0.963,R²pb=0.987). The presence of Cd significantly promoted the adsorption of Pb on UCWTR, and more Cd boosted the promotive effect increasingly in a certain range of concentration of Cd. On the contrary, the high concentration Pb obviously inhibited the adsorption of Cd. Competitive adsorption isotherms of Pb and Cd were fitted better by Langmuir and Freundlich models, respectively. The higher pH value led to higher adsorption capacity of UCWTR for Pb and Cd, while the increased adsorbent dosage decreased that. The dominative existence speciation of adsorbed Pb and Cd was acid-extracted state. Compared with single adsorption by UCWTR, the competitive adsorption declined the proportion of the acid-extracted state, increased reduced and residue states, and enhanced the stability of Pb and Cd. [ABSTRACT FROM AUTHOR]