Adsorptive removal of five heavy metals from water using blast furnace slag and fly ash

Abstract

Heavy metals can be serious pollutants of natural water bodies causing health risks to humans and aquatic organisms. The purpose of this study was to investigate the removal of five heavy metals from water by adsorption onto an iron industry blast furnace slag waste (point of zero charge (PZC) pH 6.0; main constituents, Ca and Fe) and a coal industry fly ash waste (PZC 3.0; main constituents, Si and Al). Batch study revealed that rising pH increased the adsorption of all metals with an abrupt increase at pH 4.0-7.0. The Langmuir adsorption maximum for fly ash at pH 6.5 was 3.4-5.1 mg/g with the adsorption capacity for the metals being in the order Pb > Cu > Cd, Zn, Cr. The corresponding values for furnace slag were 4.3 to 5.2 mg/g, and the order of adsorption capacities was Pb, Cu, Cd > Cr > Zn. Fixed-bed column study on furnace slag/sand mixture (1:1 w/w) revealed that the adsorption capacities were generally less in the mixed metal system (1.1-2.1 mg/g) than in the single metal system (3.4-3.5 mg/g). The data for both systems fitted well to the Thomas model, with the adsorption capacity being the highest for Pb and Cu in the single metal system and Pb and Cd in the mixed metal system. Our study showed that fly ash and blast furnace slag are effective low-cost adsorbents for the simultaneous removal of Pb, Cu, Cd, Cr and Zn from water.

Estimation of equilibrium times and maximum capacity of adsorption of heavy metals by E. crassipes (review)

“…Generally, heavy metals are cations (possess a positive charge) because they have lost electrons, represented with an oxidation state (+) (Kobielska et al 2018), for example, magnesium (II), aluminum (III), lead (II), zinc (II), copper (II), mercury (II), cobalt (II), arsenic (III) and (V), chromium (III), and (VI) among others (Nguyen et al 2018), which means that these heavy metals need electrons to complete their last level of energy. These electrons are what are putting into play during the chemisorption process (Tortora et al 2018).…”

Simultaneous adsorption of heavy metals from water by novel lemon-peel based biomaterial

“…Wastewaters contain more than one metal ion that could mutually interfere affecting each other's removal [12][13] . Therefore, it is important to investigate and optimize insuffi ciently explored adsorption in multi-metal systems, which is the novelty of the present study.…”

Remediation of heavy metals using non-conventional adsorbents and biosurfactant-producing bacteria

“…For instance, the iron industry during smelting of iron in blast furnace produces slag waste whereas coal industry generates fly ash wastes that can be optimized for heavy metal removal from waste streams. Nguyen and his team assessed the removal efficiency of slag and fly ash wastes in the removal of five metals (Pb, Cu, Cd, Cr and Zn) and found the maximum adsorption capacity for Pb and Cd, when used in multiple metal system at an optimum pH 6.5 (Nguyen et al, 2018). Another mixed metal system study conducted by Ma et al, (2018) In the recent years, many researchers have worked with industrial wastes as suitable adsorbents for the heavy metal removal.…”