Application of diatomite for sorption of Pb, Cu, Cd and Zn from aqueous solutions: kinetic, thermodynamic studies and application of response surface methodology (RSM)

Abstract

Contamination of water and soil with toxic metals is a serious environmental issue. To study the Pb, Cu, Cd, and Zn sorption behavior by diatomite, batch experiments were carried out with increasing levels of initial concentration (0–200 mg/L) under different contact times (0–360 min) and temperatures (283, 293, 303, and 313 K). The effects of concentration (0–200 mg/L), pH (3–6), and ionic strength (0.01–0.06 mol/L) on the sorption were modeled using response surface methodology (RSM). Results showed that adsorption data were well‐fitted by the Langmuir equation. The sorption of metals intensified by increasing initial concentration and pH but ionic strength had inverse effect. High value for R2 (0.99) and adjusted R2 (0.99) showed that the removal of ions can be described by response surface method. One‐way ANOVA showed (p‐value < 0.0001) that quadratic model is the best model for determining the interaction of variables. The values of the sorption energy parameter from Dubinin–Radushkevich model (E < 8 kJ K−1 mol−1) and negative values of ∆G showed that the sorption of the metals was physical and spontaneous. The positive values of enthalpy (ΔH) indicated that the sorption reaction of metals was endothermic at 283–313 K. Practitioner points Applications of diatomite increased the sorption of Pb, Cd, Zn, and Cu from aqueous solutions. Diatomite, as low‐cost adsorbent, had significant potential to sorption of ions. The sorption of heavy metals by adsorbent intensified by increasing initial concentration and pH but ionic strength had inverse effect. High value for R2 (0.99) and adj‐R2 (0.99) showed that removal of metals can be described by response surface method (RSM) and the initial concentration of metal was the most significant factor.

Adsorption and Release Kinetics, Equilibrium, and Thermodynamic Studies of Hymexazol onto Diatomite

“…It can carry out single-molecule adsorption and multimolecular layer adsorption as well . Diatomite can be widely used in metal ion adsorption − and dye adsorption − and can also function as a carrier for high content powder, especially suitable for processing liquid pesticides into a carrier of high content powder. Therefore, diatomite as a carrier of pesticides has high research value.…”

Preparation of biochar by mango peel and its adsorption characteristics of Cd(ii) in solution

“…Piri et al reported that diatomite could adsorb Cd, Cu and Pb successfully. 11 Pu et al found the adsorption capacity of NaP zeolite for Cu(II) in solution was 62.3 mg g À1 . 12 Adsorbents, especially prepared from renewable sources, brought about the widespread attention in wastewater treatment recent years.…”

Adsorption Characteristics and Charge Transfer Kinetics of Fluoride in Water by Different Adsorbents

“…The surface of CB has an irregular pore structure but a rough surface; while for BC and RHB, they have relatively few pores, showing the presence of dispersed particulate matter as well as a plate-like structure. The granular material on their surface could be crystals formed by some mineral elements ( Piri et al, 2020 ). Overall, DA has a relatively well-developed pore structure and a high specific surface area for better absorption.…”