Removal Of Heavy Metal Cations Research Articles

The Effect of Lithium Ion Leaching from Calcined Li-Al Hydrotalcite on the Rapid Removal of Ni2+/Cu2+ from Contaminated Aqueous Solutions.

A layered double hydroxide (LDH) calcined-framework adsorbent was investigated for the rapid removal of heavy metal cations from plating wastewater. Li-Al-CO3 LDH was synthesized on an aluminum lathe waste frame surface to prepare the sorbent. The calcination treatment modified the LDH surface properties, such as the hydrophilicity and the surface pH. The change in surface functional groups and the leaching of lithium ions affected the surface properties and the adsorption capacity of the heavy metal cations. A zeta potential analysis confirmed that the 400 °C calcination changed the LDH surface from positively charged (+10 mV) to negatively charged (-17 mV). This negatively charged surface contributed to the sorbent instantly bonding with heavy metal cations in large quantities, as occurs during contact with wastewater. The adsorption isotherms could be fitted using the Freundlich model. The pseudo-second-order model and the rate-controlled liquid-film diffusion model successfully simulated the adsorption kinetics, suggesting that the critical adsorption step was a heterogeneous surface reaction. This study also confirmed that the recovered nickel and/or copper species could be converted into supported metal nanoparticles with a high-temperature hydrogen reduction treatment, which could be reused as catalysts.

Modified fly ash as an effect adsorbent for simultaneous removal of heavy metal cations and anions in wastewater

A novel fly ash-based composite material with multiple adsorption sites was synthesized to remove Pb2+, Cd2+ and AsO33− from wastewater. In a single pollutant system, when pH = 6, the initial pollutant concentration was 100 mg/L, and the dosage was 4 g/L, the removal rates of Pb2+, Cd2+ and AsO33− by modified DTCH-MFA were increased by 54.4 %, 2.14 % and 6.44 % compared with the unmodified FA. For DTCH-MFA, the maximum adsorption capacities of Pb2+, Cd2+ and AsO33− were 15.86 mg/g, 3.74 mg/g and 5.63 mg/g, which increased by 14.04 mg/g, 0.28 mg/g and 1.87 mg/g than FA. In the actual wastewater system, DTCH-MFA could simultaneously remove Pb2+, Cd2+ and AsO33− with removal rates of 85.31 %, 95.98 % and 47.57 %. The relevant adsorption mechanisms were studied via XRD, FTIR, VSM and XPS, which revealed electrostatic interaction, and chelation reaction played important roles to the efficient adsorption. Besides, the adsorption processes were consistent with the Pseudo-second-order Kinetics and Freundlich isothermal model. DTCH-MFA could simultaneously adsorb Pb2+, Cd2+ and AsO33− within 2–8 h, which extended the related studies on the removal of heavy metal cations and anions by FA-based adsorbents.

Adsorption of Pb(II) on Calix[4]arene Derivatives: Kinetics and Isotherm Studies

This study aims to investigate the application of two calix[4]arene derivatives named 5,11,17,23-tetra-(t-butyl)-25,26,27,28-tetrahydroxycalix[4]arene (TBCA) and 5,11,17,23-tetra-(t-butyl)-26,27,28-tribenzoyloxycalix[4]arene (TBMTCA) as adsorbents of Pb(II) from aqueous solution in a batch system. Adsorption was carried out by varying pH solution, exposure time, and concentration. The kinetics was evaluated based on the adsorption in various exposure times using the Lagergren and Ho equations, while the isotherms were analyzed based on the adsorption in various Pb(II) concentrations using the Langmuir and Freundlich equations. Furthermore, the isotherm model showed the Pb(II) adsorption of TBCA and TBMTCA followed Langmuir model with a capacity of 137.29 and 128.46 mg/g, respectively. Based on the adsorption capacity, both adsorbents are the potential for the removal of heavy metal cations from polluted water.

A graphene-based porous composite hydrogel for efficient heavy metal ions removal from wastewater

A graphene-enhanced supramolecular hydrogel containing poly(acrylic acid)(PAA) and poly(4-vinylpyridine) (P4VP) was fabricated for the wastewater remediation. In this work, P4VP brushes were grown from functionalized graphene oxide (GO) through surface-initiated atom transfer radical polymerization. Then, the P4VP-grafted GO (i.e., GO-g-P4VP) was integrated into PAA matrix to form GO-g-P4VP@PAA hydrogel as a highly efficient adsorbent for extraction of toxic metal ions from wastewater. Due to the introduction of GO-g-P4VP, the GO-g-P4VP@PAA composite hydrogel exhibited good compressive strength, and a special interconnected 3D porous network was formed in the hydrogel. The effect of pH, initial heavy metal ion concentration, contact time, and adsorbent dosage regarding the adsorption capacity and removal efficiency of Pb2+ and Cd2+ on the hydrogel was examined. Under appropriate conditions, the GO-g-P4VP@PAA hydrogel can achieve maximum adsorption capacities of 257.28 mg/g for Pb2+, 175.79 mg/g for Cd2+. The adsorption kinetics of Pb2+ and Cd2+ on the GO-g-P4VP@PAA hydrogel followed a pseudo-second order model and the adsorption isotherms were more consistent with the Langmuir isotherm model. In addition, the GO-g-P4VP@PAA hydrogel exhibited good reusability. After five cycles, the removal efficiency of both Pb2+ and Cd2+ still remained above 80 %. These results demonstrate the GO-g-P4VP@PAA hydrogel serves as a desirable adsorbent in removal of heavy metal cations from wastewater.

Enhanced removal of heavy metals by α-FeOOH incorporated carboxylated cellulose nanocrystal: synergistic effect and removal mechanism.

Simultaneous and highly efficient removal of heavy metal cations and oxyanions is significant for both water and soil remediation, but it remains a major challenge due to the complexity. In this work, a novel hybrid of α-FeOOH incorporated carboxylated cellulose nanocrystal (Fe/CNC) is synthesized via a hydrothermal process, which shows improved α-FeOOH dispersion and heavy metal removal capacity. In single adsorbate system, maximum adsorption capacities toward Pb(II), Cd(II), and As(V) by Fe/CNC reach 126.06, 53.07, and 15.80mgg-1, respectively, and the Fe leaching is much lower than that of α-FeOOH. In binary and ternary adsorption systems, simultaneous removal of Pb(II), Cd(II), and As(V) is proved, and the competition and synergy coexist among heavy metals. FTIR and XPS spectra have revealed the synergistic removal mechanism: Pb(II) and Cd(II) are mainly removed by surface complexation with oxygen-containing functional groups on C-CNC and α-FeOOH, and precipitation on the surface of α-FeOOH, while ligand exchange with Fe-OH is responsible for As(V) removal. The soil incubation experiments show that exchangeable and carbonate-bound Pb, Cd, and As are transformed into more stable forms in contaminated soil containing Fe/CNC composites. This work provides a novel composite material for remediation of heavy metal-contaminated environments.

Еfficiency of azorubin adsorption on polyaniline adsorbent

Polymer adsorbents based on composites of conjugated polymers (polyaniline, polypyrrole) show very good adsorption capacity when used for extraction of noble metal ions from aqueous media, for removal of heavy metal cations and various anions, as well as for purification of water from synthetic organic dyes. good solubility in water and resistance to natural biological decomposition. We synthesized samples of powdered polyaniline during oxidative polycondensation of aniline under the action of ammonium peroxide disulfate and investigated the processes of adsorption of synthetic dye on the polymer surface from aqueous solutions on the example of azorubine, which is of practical importance for cleaning water resources. The intensity of peaks of the characteristic absorption bands of azorubine solutions under conditions of equilibrium adsorption of the dye on macromolecular polyaniline chains with a change in the mass of the adsorbent in the studied systems was measured by UV spectroscopy. The change in the concentration of azorubine during adsorption was evaluated by measuring the optical density of the solutions using a UV spectrophotometer Specord M40. It is shown that with an increase in the amount of adsorbent (PAN) in the initial solutions of azorubine, a decrease in the absorption intensity of the characteristic dye band in the UV region (λ≈515 nm) is observed, which is obviously due to an increase in the equilibrium adsorption of azorubine from its aqueous solution. on polyaniline powder. It is shown that the adsorption efficiency of the anionic dye increases up to 90 % with increasing mass of polyaniline in the adsorption mixture from 0.005 to 0.1 grams, which can be explained by the contribution of intermolecular interactions between the functional groups of the adsorbent and the substrate. Some decrease in the color intensity of azorubine solutions may also be due to the participation of redox groups of macromolecules of polyaniline and air oxygen in the oxidation of the adsorbed dye and the formation of colorless reaction products. Keywords : polyaniline, dye, adsorption, azorubine.

Removal of heavy metal cations and co-existing anions in simulated wastewater by two separated hydroxylated MXene membranes under an external voltage

The removal of heavy metal cations and co-existing anions represents one of the promising pathways to produce purified water for industry. Laminar MXene membrane has attracted tremendous research interest in the separation field in the past decade. The thermal self cross-linking MXene membrane has been proven to exhibit good anti-swelling performance. However, the decrease of negative charge during self-crosslinking leads to decreasing ion separation performance due to fading adsorption and/or weakened surface-charged controlling effect. To regenerate the surface charge, the hydroxylation of MXene membrane is adopted by substituting –F with –OH using the alkali of KOH. The resultant hydroxylated MXene membrane demonstrates overall better performance than the pristine MXene membrane in wettability and Zeta potential, promoting the rejection and separation of ions. When two selective membranes are applied to remove the heavy metal cations (Pb2+, Cu2+, and Cd2+) and co-existing anions (Cl− and/or NO3−) under the electronic field with appropriate voltage, the rejection of 99.5% can be obtained at 12 V for a 383 nm-thick hydroxylated MXene membrane, higher than that of pristine MXene membrane. As a result, the co-existing anions were also excluded at ~97% via increasing surface-charged controlling effect. Moreover, the hydroxylated MXene membrane also shows selective separation permeance on Na+/Pb2+, Na+/Cu2+, and Na+/Cd2+ pairs. By controlling the interlayer spacing through thermal self-linking route, good operational durability and reproducibility are also achieved for the hydroxylated MXene membrane during the 70-min test. These highlight the potential of developing and applying 2D laminar membrane for separation and treatment of wastewater.

Surface modified polythiophene/Al2O3 and polyaniline/Al2O3 nanocomposites using poly(vinyl alcohol) for the removal of heavy metal ions from water: kinetics, thermodynamic and isotherm studies

In this study, polythiophene/Al2O3 (PTh/Al2O3) and polyaniline/Al2O3 (PAn/Al2O3) nanocomposites in the presence of poly(vinyl alcohol) (PVA) as the surfactant were synthesized via in situ chemical oxidative polymerization method in aqueous medium. The synthesized nanocomposites were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Results indicated that the Al2O3 and poly(vinyl alcohol) influenced the properties of synthesized nanocomposites. The aim of this research was to investigate the sorption characteristics of polythiophene and polyaniline nanocomposites for the removal of heavy metal cations including Pb(II), Zn(II) and Cd(II) from aqueous solution. The factors that affected the adsorption equilibrium as well as the removal efficiency of the nanoadsorbents, i.e., contact time, metal ion concentration, pH and adsorption conditions were investigated in detail. From the kinetic results, it was concluded that the pseudo-second-order kinetic model was found to be the best at describing the adsorption process for Pb(II), Zn(II) and Cd(II) on PTh-PVA/Al2O3 and PAn-PVA/Al2O3. In addition, thermodynamic analysis suggests the endothermic and spontaneous nature of the present adsorption process with increased entropy on PTh-PVA/Al2O3 and PAn-PVA/Al2O3. The results suggest polythiophene, polyaniline and their nanocomposites have great potential to be used as efficient absorbent for the removal of heavy metal ions from water.

Removal of Heavy Metal Cations (Copper, Lead, Zinc) from Water Runoff by Calcium Silicate Hydrate: Effect of the Co-Ion and Competition of Ions in Ternary Mixtures

The sorption behavior of calcium silicate hydrate (CSH) with respect to lead, copper and zinc was studied to consider its application to remove metal from water runoff. A series of kinetics of removal and isotherms were undertaken with single metal and mixture solutions. The sorption occurred by ion exchange with calcium. Sorption kinetics were modelled using pseudo-second order model. The weight capacities of CSH were lead > copper >> zinc when studied separately. The co-ion associated to the metal ion is of importance on the removal capacities.

Carboxymethylcellulose-chitosan film modified magnetic alkaline Ca-bentonite for the efficient removal of Pb(II) and Cd(II) from aqueous solution.

In order to endow alkaline Ca-bentonite (ACB) with magnetic separation ability, simultaneously obtain better magnetic stability and stronger removal capacity of heavy metal cations; magnetic alkaline Ca-bentonite/carboxymethylcellulose-chitosan film (MACB/C-C) was prepared by organic modification of magnetic alkaline Ca-bentonite (MACB) using non-toxic carboxymethylcellulose and chitosan. Textural characterization results revealed that magnetic Fe3O4 nanoparticles were successfully immobilized on ACB and modified with C-C. The functionalized layer of C-C concurrently enhanced the stability of Fe3O4 and removal performances of heavy metal cations. Adsorption results indicated that MACB/C-C exhibited thorough separation from aqueous solution and greater uptake ability for Pb(II) and Cd(II) (483 mg·g-1 and 123 mg·g-1) than the nascent MACB (335 mg·g-1 and 76 mg·g-1), respectively, at pH 5 and 25 °C temperature. The adsorption of Pb(II) and Cd(II) on MACB/C-C mainly occurred via surface precipitation and complexation when pH > 2. MACB/C-C could be efficiently recycled with marginal decrease in adsorption capacity. The current approach credited to the convenient operation, simplified synthesis, and high efficiency of MACB/C-C could be deemed as a promising alternative for the removal of heavy metal cations from wastewater.

Effect of Chelating Agents on Removal of Heavy Metal Cations of Cellulose-based Ion Exchange Resins from Water Hyacinth

Presently, heavy metal pollution in natural water resources is considered very hazardous. The purpose of this research is to develop the novel cellulose-based ion exchange resins from water hyacinth and the effect of chelating agents on the removal of heavy metal cations from single-metal aqueous solutions has been investigated. Cellulose was prepared from the stem of water hyacinth by alkaline treatment process then cellulose-based ion exchange resins were prepared via esterification reaction between cellulose with two different chelating agents such as pyromellitic dianhydride and 3,3’,4,4’- benzophenone tetracarboxylic dianhydride. The chemical structure, crystallinity index, surface morphology, and thermal stability of resins were characterized and analyzed with FTIR, XRD, SEM, and TGA, respectively. The results confirmed the esterification reaction between anhydride groups of chelating agents with hydroxyl groups of celluloses due to the apparent peak of the ester group. Heavy metal cations adsorptions were studied in optimum conditions and the residual concentration of heavy metal cations was measured by ICP. These resins showed high adsorption capacities of more than 98 mg/g for Pb2+, Cd2+, Cu2+, and Ni2+. Moreover, the adsorption process was controlled by the ion exchange mechanism. Therefore, the novel cellulose-based ion exchange resins could be suitable for the removal of pollutants from wastewater.

CHITIN MATERIALS: OBTAINING; CLEANING OF DRAINS

The properties of chitin and its derivatives, chitosan and chitosan-melanin complexes, are considered. Their possible sources are analyzed, as well as the possibilities of their use for wastewater treatment, including removal of heavy metal cations and suspended solids, including microplastic particles.

Phosphate modified magnetite@ferrihydrite as an magnetic adsorbent for Cd(II) removal from water, soil, and sediment

This work successfully fabricated a novel magnetic adsorbent, i.e., phosphate modified magnetite@ferrihydrite (Mag@Fh-P), and explored its potential application for Cd(II) removal from water, soil, and sediment. To synthesize the adsorbent, ferrihydrite-coated magnetite (Mag@Fh) was firstly developed with partially acid-dissolved natural magnetite particles, followed by in-situ synthesis of ferrihydrite on magnetite surface via alkali addition. Selection of natural magnetite as iron source for ferrihydrite synthesis and as magnetic core is believed to save the cost of adsorbent. Then, phosphate was loaded on Mag@Fh by impregnation-heating treatment to produce Mag@Fh-P. Batch adsorption experiments revealed that the Cd(II) adsorption on Mag@Fh-P could reach equilibrium within 60 min, and the calculated adsorption capacity using Langmuir model was 64.1 mg/g, which was significantly higher than that on magnetite (0.44 mg/g) and Mag@Fh (23.9 mg/g). The results from X-ray photoelectron spectroscopy analysis and batch adsorption experiments confirmed that both ligand exchange and electrostatic attraction contributed to Cd(II) adsorption. Besides, Mag@Fh-P can also be an efficient amendment for soil and sediment remediation. The spent Mag@Fh-P could be easily recovered via magnetic separation, accompanied by the significant decrease in total Cd(II) concentration in soil/sediment. At an adsorbent dosage of 2 wt%, 0.82 and 0.74 mg/kg of total Cd(II) in soil and sediment was removed, respectively. In all, the synthesized Mag@Fh-P as adsorbent has the merits of cost effectiveness, fast adsorption rate, high adsorption capacity, and easy separation, and thus it has promising application for the removal of heavy metal cations from water, soil, and sediment.

The removal of heavy metal cations by sulfidated nanoscale zero-valent iron (S-nZVI): The reaction mechanisms and the role of sulfur

In this study, the reaction between sulfidated nanoscale zero-valent iron (S-nZVI) and heavy metal cations as well as the role of sulfur were investigated. The results showed the corrosion products of S-nZVI were lepidocrocite (γ-FeOOH) or/and magnetite (Fe3O4), depending on heavy metal species. While the removal of Hg(II), Ag(I), Cu(II), and Pb(II) by S-nZVI was rapid and could achieve over 99% within 5 mins, the removal of Ni(II) and Zn(II) was low in efficiency and unstable. Sulfur was existed as iron sulfides at fresh S-nZVI, but was displaced by the heavy metals and formed the related sulfide compound, or oxidized to S0 and SO42-. The removal mechanisms are strongly dependent on the solubility product constant (Ksp) of metal sulfides. For Hg(II) and Ag(I), with Ksp of corresponding metal sulfides much lower than that of iron sulfide, the removal mechanism is the displacement reaction. For Cu(II) and Pb(II), with Ksp of corresponding metal sulfides moderately lower than that of iron sulfide, the removal mechanisms are the displacement reaction and complexation with surface groups of S-nZVI. For Zn(II) and Ni(II), whose Ksp of corresponding metal sulfides slightly lower than that of iron sulfide, are mainly removed by complexation with surface groups of S-nZVI.

Layer-by-layer assembly of layered double hydroxide/histidine/δ-MnO2 nanosheets: Synthesis, characterization, and applications

In this work, layered double hydroxide (LDH) nanosheets, manganese dioxide (δ-MnO2) nanosheets, and amino acid as organic molecules were selected as the building blocks for the fabrication of organic-inorganic nanohybrids. Layer-by-layer LDH/histidine/MnO2 (LDH/His/MnO2) nanohybrids were synthesized by self-assembly between oppositely charged 2D nanosheets of LDH and δ-MnO2 nanosheets in presence of zwitterionic histidine biomolecules. Single-layer LDH and δ-MnO2 nanosheets were prepared by exfoliation of highly crystalline MgAl-LDH and bulk MnO2, respectively. To investigate the efficiency of the prepared structure, LDH/His/MnO2 was used for removal of heavy metal cations of Pb(II) and oxyanions of As(V) from aqueous solutions. The enormous capacities for Pb(II) (584.8 mg g−1) and As(V) (632.9 mg g−1) and very high distribution coefficients (Kd) of 7.2 × 104 mL g−1 for Pb(II) and 9.2 × 104 mL g−1 for As(V) clearly demonstrate the performance of the proposed strategy for the layer-by-layer synthesis of LDH/His/MnO2 materials. The present findings clearly show that the layer-by-layer assembly between inorganic 2D nanosheets and organic molecules is quite effective to improving the simultaneous removal of heavy metal ion Pb(II) and oxyanion of As(V).

INFLUENCE OF pH AND PRECIPITATING AGENT ON THE REMOVAL OF HEAVY METAL CATIONS FROM INDUSTRIAL SAMPLES

The purpose of this research was to examine the influence of pH and type of precipitating agent on the removal of heavy metal cations from industrial wastewater samples by method of chemical precipitation. Three precipitating agents were used: Na2CO3, NaOH and waste sludge from the Solvay process. Samples of industrial wastewater, in which the presence of Cu (II) and Ni (II) was determined, have been taken from the electroplating process, and samples in which the presence of Zn (II) was determined, have been taken from the galvanizing process. The experimental results showed that the highest percentage of removal of these cations was at pH > 7 for each precipitant used, with NaOH proving to be the best precipitating agent, followed by Solway waste sludge and Na2CO3.

Evaluation of a novel polyamide-polyethylenimine nanofiltration membrane for wastewater treatment: Removal of Cu2+ ions

Abstract This paper describes a novel approach for enhancing membrane technology for the removal of heavy metal cations in contaminated waters. A simple method of forming a positively charged polyamide (PA) nanofiltration (NF) membrane has been developed by attaching a layer of hyperbranched polyethylenimine (PEI) to the PA surface, involving the linking of PEI amino groups to the PA surface carboxyl groups. The nature of the PEI modified PA membrane, in terms of surface morphology, zeta potential and hydrophobicity was found to depend on the PEI molecular weight (MW), and the PEI concentration and membrane exposure time during preparation. In turn, the nature of the modified membrane determined its performance in terms of hydraulic flux and metal ion rejection. In tests using a model solution of 5 mg/L Cu2+ and a 70,000 MW PEI membrane the Cu rejection was >90%, with only a modest reduction in flux compared to blank water. The Cu2+ rejection was found to be a combination of electrostatic repulsion and adsorption, with the relative proportions depending on the nature of the PEI modified PA membrane. In addition, the Cu2+ rejection and membrane flux were found to be sustainable over repeated filtration cycles, and the rejection was not adversely affected by the presence of humic acid in solution (5 mg/L).

Structural alteration within fly ash-based geopolymers governing the adsorption of Cu2+ from aqueous environment: Effect of alkali activation.

Fly-ash based geopolymers have been considered as a low-cost yet effective adsorbent for the removal of heavy metal cations, including Cu2+, from the aqueous environment. In the synthesis of geopolymers, the fly-ash needs to be alkali activated using several systems rich in either Na+ or K+. Herein, we investigate the effect of alkali activation on the structural alteration and its consequence on the adsorption capacity. Based on the series of detailed characterizations, the geopolymers formed in Na+-based alkali system is found to have more organized structure compared to that formed in K+-based alkali system. Moreover, the incorporation of additional silicate creates ancillary structure which positively contributes to the organization of the overall structure. All the samples, fly-ash and geopolymers, exhibits Cu2+ adsorption based on Langmuir isotherm and pseudo-second order kinetic. The geopolymers with more organized structure display higher Cu2+ adsorption capacity, which reaches 40 mg g-1 higher in comparison to 7 mg g-1 for fly ash sample. The structural alteration induces the formation of open-framework structure with more accessible sites which can accommodate more Cu2+. Our study provides a fundamental understanding for the design and fabrication of geopolymers as an effective adsorbent for the removal of heavy metal cations.

A positively charged tight UF membrane and its properties for removing trace metal cations via electrostatic repulsion mechanism.

The development of highly efficient membranes technology using low-pressure driven filtration process, is one of the principal challenges in the wastewater treatment field, especially those aimed at the removal of trace heavy metals. In this work, a novel positively charged tight ultrafiltration (PCTUF) membrane was developed to remove heavy metal cations (Mn2+, Co2+, Ni2+, Zn2+ and Cd2+) from contaminated waters via electrostatic repulsion mechanism. The PCTUF membrane was fabricated from a new polymer with poly (vinyl chloride co dimethylaminoethyl methacrylate), P (VC-co-DMA) via a nonsolvent induce phase separation (NIPS) process and following facile surface quaternization. The quaternization conditions, the pore structures and chemical properties of the membranes were investigated in detail. The optimally quaternized membrane possessed a positively charged surface and 3.27 nm charged channel with the water permeability of 84 L m-2 h-1 bar-1. The rejections of heavy metal cations surpassed 95% for feed solutions containing 10 ppm heavy metal. Moreover, the influences of feed concentrations and the operating condition with pressure and pH on the membrane performances were also investigated. The results revealed that the prepared PCTUF membrane with its high perm-selectivity performance provides a worthy reference for highly efficient removal of heavy metal cations.

Use of The Eggshells in Removing Heavy Metals from Waste Water - The Process Kinetics and Efficiency

Abstract Studies of the efficiency of Ni, Cu and Cd cations removal from water solutions were carried out, with the use of clay limestone, hen eggshells from eggs for consumption and hen eggshells after hatching, which main element is calcium carbonate. Hen eggshells are a waste product, which can be used as a substitute of clay limestone in removing heavy metals from wet flue gas desulphurisation installation. Mixed solutions of Ni, Cu and Cd were used in the research, with the composition similar to the waste water from wet flue gas desulphurisation installation: Ni (0.009-0.053 mmol/dm3), Cu (0.008-0.057 mmol/dm3) and Cd (0.003-0.008 mmol/dm3). The metals were determined by flame atomic absorption spectrophotometry (F-AAS). Kinetics of the process was analysed and equilibrium parameters were estimated, taking into consideration changes of the solutions pH during the process duration. It was demonstrated that the dominating mechanism of cations removal is their binding in hydroxides and carbonates. The studies demonstrated comparable characteristics of hen eggshells versus clay limestone, in the context of their application in removal of heavy metal cations from solutions.