Removal of heavy metal ion cobalt (II) from wastewater via adsorption method using microcrystalline cellulose–magnesium hydroxide

Abstract

Microcrystalline cellulose (MCC), magnesium sulfate hexahydrate, and trisodium citrate were reacted in ammonia bath in an aqueous solution to prepare a MCC–magnesium hydroxide (MH) composite adsorbent, which was used to adsorb heavy metal Co(II) ion. The method of using MCC–MH to adsorb and remove Co(II) was studied under different pH values, adsorbent dosages, contact times, initial Co(II) ion concentrations, and temperatures. The optimal process parameters include an MCC–MH dosage of 2.5 mg/mL, a contact reaction equilibrium time of 50 min, a Co(II) solution pH of 6.0–8.0, an initial Co(II) concentration of 300 mg/L, and a temperature of 303 K. The removal rate of Co(II) solution by MCC–MH was as high as 97.67%, and the maximum adsorption capacity of MCC–MH reached 153.84 mg/g under these optimal conditions. The adsorption isotherm of Co(II) conformed to the Langmuir model, the kinetic data of Co(II) conformed to the pseudo-second-order kinetic model, and the adsorption of Co(II) by MCC–MH was a spontaneous endothermic reaction under the optimized conditions. Analytical studies showed that Co(II) adsorption on MCC–MH composites is affected by chemical adsorption and involves the influence of intraparticle diffusion to a certain extent.