Adsorption mechanism of shell powders on heavy metal ions Pb2+/Cd2+ and the purification efficiency for contaminated soils

Abstract

The adsorption capacity of oyster shell powders (SPs) and the adsorption mechanism of heavy metal ions (HMs; i.e., cadmium ions Cd2+ and lead ions Pb2+) on SPs are discussed by means of adsorption kinetics tests, adsorption-desorption tests, scanning electron microscopy and Fourier transform infrared spectroscopy. The influences of seepage velocity, heavy metal types, and SP addition amount/concentration on the adsorption effect of SPs in the treatment of HMs in laterite as well as quartz sand were analyzed. Studies have shown that i) the adsorption of HMs on SPs can be divided into three stages, i.e., the surface adsorption stage, the internal pore diffusion stage, and the equilibrium stage; ii) with the increase in seepage velocity, the effluent concentration of HMs will slightly increase, and the residual amounts at each section of the column generally decrease rapidly with the increase in migration distance; iii) the increase in the concentration of SP solution provides more adsorption points for the adsorption of HMs, and finally, the amount of HMs desorbed from quartz sand is reduced, which also reduces the concentration of HMs in the effluent. Overall, SPs possess high purification efficiency for the HMs of contaminated soils.

Synthesis and Characterization of Biodegradable Poly(vinyl alcohol)-Chitosan/Cellulose Hydrogel Beads for Efficient Removal of Pb(II), Cd(II), Zn(II), and Co(II) from Water

“…Experimental data were modeled by pseudo-first-order and pseudo-second-order kinetic models. The linear forms of both models are explained in Equations (8) and (9) [ 73 ]: where q t and q e (mg/g) are the amount of metal removed per unit mass of adsorbent (mg/g) at a certain time t and at equilibrium, respectively. K 1 (1/min) is a pseudo-first-order rate constant, and K 2 (g/mg·min) is the rate constant of a pseudo-second-order reaction…”

Unveiling the Role of Dissolved Organic Matter on the Hg Phytoavailability in Biochar-Amended Soils

“…We observed a negative correlation of P-Hg with pH (r s = −0.644, p < 0.01) and DOC (r s = −0.692, p < 0.01), respectively. At higher pH (alkaline conditions), metals tend to produce more stable forms, while at lower pH (acidic conditions) they tend to occur as soluble organometallic or free ionic species with high availability [ 57 , 58 ]. In addition, an increase in soil pH can also cause an increase in the net negative charge of soil surfaces, promoting the adsorption of metals on the soil surface and reducing metal utilization [ 59 ].…”

Investigation of the viable role of oil sludge-derived activated carbon for oily wastewater remediation

“…Then the mixture was placed on the hotplate and boiled for 30 s. After the Erlenmeyer flask was cooled, 100 mL of standard iodine solution was immediately added to the solution and was shaken vigorously for 30 s. After this period of time, the solution was filtered quickly and 50 mL of the solution was separated for titration with 0.1 normal sodium thiosulfate. Finally, the amount of adsorbed iodine can be determined by measuring the amount of consumed thiosulfate (Bai et al, 2023). Iodine adsorption number (mg/g) Efficiency (%)…”