Study on the Adsorption of Heavy Metals in Sludge by Calcium Alginate Cross-Linked Zeolite Microspheres

Abstract

This study successfully prepared a calcium alginate cross-linked zeolite microsphere, a heavy metal adsorbent, to reduce the harmful heavy metal content in sludge and improve the efficiency of sludge resource utilization. The effects of temperature, dosage, and stirring time on the adsorption effect were investigated by atomic absorption spectrophotometry and BCR (European Community Bureau of Reference) method, and the ecological risk of heavy metals in sludge before and after treatment was evaluated via the geoaccumulation index. The following results were obtained: after the sludge was treated with calcium alginate cross-linked zeolite microspheres, the total amount of heavy metals decreased, and the proportion of stable state increased. At temperatures within 10ºC-25ºC, the following trend was observed: the higher the temperature, the higher the adsorption efficiency. When the dosage was controlled at 0.5-2 g/500 ml and the stirring time was 2-3 h, a good adsorption effect was achieved. The pollution level of Pb and Zn in the sludge was reduced after adsorption treatment from unpolluted to moderately polluted to unpolluted, and that of Cd and Cu was reduced from moderately to heavily polluted to moderately polluted.

Investigation of the Adsorption Properties of a New Biopolymer Created Using Brown Algae Powder

“…This bioplymer is very interesting due to its capability to create porous gels, especially in the presence of divalent cations, particularly calcium ions. The fixation of pollutants occurs through ion exchange at the carboxylate functions of the alginate (Esmat et al, 2017;Ren et al, 2021;Wang et al, 2018;Suresh et al, 2022). However, the sodium alginate is soluble in water and presents low stability, which limits its direct use as an adsorbent.…”