Chemically modified silica gel with aminothioamidoanthraquinone for solid phase extraction and preconcentration of Pb(II), Cu(II), Ni(II), Co(II) and Cd(II)

Silica gel chemically bonded with aminothioamidoanthraquinone was synthesized and characterized. The metal sorption properties of modified silica were studied towards Pb(II), Cu(II), Ni(II), Co(II) and Cd(II). The determination of metal ions was carried out on FAAS. For batch method, the optimum pH ranges for Pb(II), Cu(II) and Cd(II) extraction were ≥3 but for Ni(II) and Co(II) extraction were ≥4. The contact times to reach the equilibrium were less than 10 min. The adsorption isotherm fitted the Langmuir's model showed the maximum sorption capacities of 0.56, 0.30, 0.15, 0.12 and 0.067 mmol/g for Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), respectively. In the flow system, a column packed modified silica at 20 mg for Pb(II) and Cu(II), 50 mg for Cd(II), 60 mg for Co(II), Ni(II) was studied at a flow rate of 4 and 2.5 mL/min for Ni(II). The sorbed metals were quantitatively eluted by 1% HNO₃. No interference from Na⁺, K⁺, Mg²⁺, Ca²⁺, Cl⁻ and SO₄²⁻ at 10, 100 and 1000 mg/L was observed. The application of this modified silica gel to preconcentration of pond water, tap water and drinking water gave high accuracy and precision (%R.S.D. ≤ 9). The method detection limits were 22.5, 1.0, 2.9, 0.95, 1.1 μg/L for Pb(II), Cu(II), Ni(II), Co(II) and Cd(II), respectively.     

Removal of Cu(II) and Zn(II) from industrial wastewater by acid-activated montmorillonite-illite type of clay

An acid-activated montmorillonite-illite type of clay collected from the Gulbarga region of Karnataka, India was examined for removing copper and zinc ions from industrial wastewater containing Cu(II), Zn(II) and minor amounts of Pb(II). Langmuir, Freundlich, Brunauer-Emmett-Teller (BET), and competitive Langmuir (two competing ions) isotherms were fitted to experimental data and the goodness of their fit for adsorption was compared. The shapes of isotherms obtained indicated multilayer adsorption of Cu(II) and monolayer adsorption of Zn(II) on the acid-activated clay. Competitive adsorption was found to be significant due to the presence of Cu(II) in the wastewater.     

Kinetics and equilibrium adsorption of Cu(II), Cd(II), and Ni(II) ions by chitosan functionalized with 2[-bis-(pyridylmethyl)aminomethyl]-4-methyl-6-formylphenol

Chitosan biopolymer chemically modified with the complexation agent 2[-bis-(pyridylmethyl)aminomethyl]-4-methyl-6-formylphenol (BPMAMF) was employed to study the kinetics and the equilibrium adsorption of Cu(II), Cd(II), and Ni(II) metal ions as functions of the pH solution. The maximum adsorption of Cu(II) was found at pH 6.0, while the Cd(II) and Ni(II) maximum adsorption occurred in acidic media, at pH 2.0 and 3.0, respectively. The kinetics was evaluated utilizing the pseudo-first-order and pseudo-second-order equation models and the equilibrium data were analyzed by Langmuir and Freundlich isotherms models. The adsorption kinetics follows the mechanism of the pseudo-second-order equation for all studied systems and this mechanism suggests that the adsorption rate of metal ions by CHS-BPMAMF depends on the number of ions on the adsorbent surface, as well as on their number at equilibrium. The best interpretation for the equilibrium data was given by the Langmuir isotherm and the maximum adsorption capacities were 109 mg g-1 for Cu(II), 38.5 mg g-1 for Cd(II), and 9.6 mg g-1 for Ni(II). The obtained results show that chitosan modified with BPMAMF ligand presented higher adsorption capacity for Cu(II) in all studied pH ranges.     

The starch modified montmorillonite for the removal of Pb(II), Cd(II) and Ni(II) ions from aqueous solutions

In the present study, we attempted to synthesize a novel sorbent from the starch modified montmorillonite for the removal of Pb(II), Cd(II), and Ni(II) ions from aqueous solutions. Structure and properties of the adsorbent were characterized by Fourier-transformed infrared(FT-IR) spectroscopy, X-ray diffraction (XRD), and Field emission scanning electron microscopic (FE-SEM) techniques. Batch experiments were confirmed through the effect of different conditions including pH, contact time, initial metal concentration and adsorbent dose. Specifically, the optimum value of adsorbent dose was achieved as 20 g/l for the removal of almost metal ions. The adsorption data was fitted with the optimum pH value as 5 for all experiments. The contact time at which the uptake of maximum metal adsorption was observed within 45 min for Pb(II), 90 min for Cd(II), and 60 min for Ni(II). In addition, it was revealed in our study that the equilibrium data obeyed the Langmuir model, and the adsorption kinetic followed a pseudo second-order rate model. Obtained results were noticeable for a modified phyllosilicate adsorbent, and with such a simple and low-cost modification for montmorillonite, the potential of this material as an economical and effective adsorbent for the removal of metal ions from aqueous solution was considerably elevated.     

Adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II), and As(V) on bacterially produced metal sulfides

The adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II) and As(V) onto bacterially produced metal sulfide (BPMS) material was investigated using a batch equilibrium method. It was found that the sulfide material had adsorptive properties comparable with those of other adsorbents with respect to the specific uptake of a range of metals and, the levels to which dissolved metal concentrations in solution can be reduced. The percentage of adsorption increased with increasing pH and adsorbent dose, but decreased with increasing initial dissolved metal concentration. The pH of the solution was the most important parameter controlling adsorption of Cd(II), Cu(II), Fe(II), Ni(II), Pb(II), Zn(II), and As(V) by BPMS. The adsorption data were successfully modeled using the Langmuir adsorption isotherm. Desorption experiments showed that the reversibility of adsorption was low, suggesting high-affinity adsorption governed by chemisorption. The mechanism of adsorption for the divalent metals was thought to be the formation of strong, inner-sphere complexes involving surface hydroxyl groups. However, the mechanism for the adsorption of As(V) by BPMS appears to be distinct from that of surface hydroxyl exchange. These results have important implications to the management of metal sulfide sludge produced by bacterial sulfate reduction.     

Removal of Cd(II) and Pb(II) from aqueous solution by modified attapulgite clay

Three low-cost adsorbents (purified raw attapulgite (A-ATP), high-temperature-calcined attapulgite (T-ATP), and hydrothermal loading of MgO (MgO-ATP)) were prepared as adsorbents for the removal of Cd(II) and Pb(II). By evaluating the effect of the initial solution pH, contact time, initial solution concentration, temperature and coexistence of metal ions on Cd(II) and Pb(II) adsorption, the experimental results showed that MgO-ATP was successfully prepared by hydrothermal reaction and calcination as well as appearing to be a promising excellent adsorbent. At an initial pH of 5.0, A-ATP, T-ATP and MgO-ATP reached maximum adsorption amounts of 43.5, 53.9 and 127.6 mg/g for Pb(II) and 10.9, 11.2, and 25.3 mg/g for Cd(II) at 298 K, respectively. The Cd(II) adsorption on A-ATP was fitted by the Freundlich model, while the adsorption of Pb(II) and Cd(II) on T-ATP and MgO-ATP as well as Pb(II) adsorption on A-ATP agreed with the Langmuir model. All kinetic experimental data favored pseudo second-order model. The calculated thermodynamic parameters suggested that Pb(II) adsorption onto MgO-ATP was spontaneous and exothermic. When considering foreign metal ions, the three adsorbents all presented preferential adsorption for Pb (II). Chemical adsorption had a high contribution to the removal of Cd(II) and Pb(II) by modified attapulgite. In summary, the adsorption was greatly enhanced by the hydrothermal loading of MgO. It aimed to provide insights into the MgO-ATP, which could be able to efficiently remove Cd(II) and Pb(II) and serve as an economic and promising adsorbent for heavy metal-contaminated environmental remediation.     

A new chelating resin for preconcentration and determination of Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) by flame atomic absorption spectrometry

A new polychelatogen, AXAD-16-1,2-diphenylethanolamine, was developed by chemically modifying Amberlite XAD-16 with 1,2-diphenylethanolamine to produce an effective metal-chelating functionality for the preconcentration of Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) and their determination by flame atomic absorption spectrometry. Various physiochemical parameters that influence the quantitative preconcentration and recovery of metal were optimized by both static and dynamic techniques. The resin showed superior extraction efficiency with high-metal loading capacity values of 0.73, 0.80, 0.77, 0.87, 0.74, and 0.81 mmol/g for Mn(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II), respectively. The system also showed rapid metal-ion extraction and stripping, with complete saturation in the sorbent phase within 15 min for all the metal ions. The optimum condition for effective metal-ion extraction was found to be a neutral pH, which is a great advantage in the preconcentration of trace metal ions from natural water samples without any chemical pretreatment of the sample. The resin also demonstrated exclusive ion selectivity toward targeted metal ions by showing greater resistivity to various complexing species and more common metal ions during analyte concentration, which ultimately led to high preconcentration factors of 700 for Cu(II); 600 for Mn(II), Ni(II), and Zn(II); and 500 for Cd(II) and Pb(II), arising from a larger sample breakthrough volume. The lower limits of metal-ion detection were 7 ng/mL for Mn(II) and Ni(II); 5 ng/mL for Cu(II), Zn(II), and Cd(II), and 10 ng/mL for Pb(II). The developed resin was successful in preconcentrating metal ions from synthetic and real water samples, multivitamin-multimineral tablets, and curry leaves (Murraya koenigii) with relative standard deviations of < or = 3.0% for all analytical measurements, which demonstrated its practical utility.     

麦麸对重金属离子的吸附性能研究

以麦麸为天然吸附剂,从水溶液中去除重金属离子.实验表明,麦麸对重金属离子有优良的吸附性能.在约10min内达到吸附平衡,吸附容量分别为:Hg2 70mg/g、Pb2 63mg/g、Cd2 21mg/g、Cu2 15mg/g、Ni2 13mg/g及Cr3 9.3mg/g;吸附速率很快,并且对上述金属离子有良好的选择性.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Adsorption of Ni(II), Cu(II) and Cd(II) from aqueous solutions by amino modified nanostructured microfibrillated cellulose

The aim of the present study was to investigate the adsorption properties of aminopropyltriethoxysilane (APS) modified microfibrillated cellulose (MFC) in aqueous solutions containing Ni(II), Cu(II) and Cd(II) ions. The modified adsorbents were characterized using elemental analysis, Fourier transform infrared spectroscopy, SEM and zeta potential analysis. The adsorption and regeneration studies were conducted in batch mode using various different pH values and contact times. The maximum removal capacities of the APS/MFC adsorbent for Ni(II), Cu(II), and Cd(II) ions were 2.734, 3.150 and 4.195 mmol/g, respectively. The Langmuir, Sips and Dubinin-Radushkevich models were representative to simulate adsorption isotherms. The adsorption kinetics of Ni(II) Cu(II), and Cd(II) adsorption by APS/MFC data were modeled using the pseudo-first-order, pseudo-second-order and intra-particle diffusion kinetics equations. The results indicate that the pseudo-second-order kinetic equation and intra-particle diffusion model were adequate to describe the adsorption kinetics.     

Spectrophotometric study of Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) complexes with some crown ethers in dimethylsulphoxide solution using murexide as a metallochromic indicator

The complexation reactions between Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Pb(II) ions and benzo-15-crown-5, dicyclohexyl-18-crown-6, dibenzo-18-crown-6 and 1,10-diaza-18-crown-6 have been studied in dimethylsulphoxide solution at 25 degrees by means of a competitive spectrophotometric method using murexide as a metallochromic indicator. With the exception of Pb(II)(benzo-15-croqn-5)(2) the stoichiometry of the resulting complexes was found to be 1:1. The formation constants of the complexes were determined, and found to follow the Irving-Williams rule for the cations of the first transition series. It was found that the metal ion-18-crown interactions are strongly dependent on the nature of the substituents on the ring.     

Solid phase extraction of lead (II), copper (II), cadmium (II) and nickel (II) using gallic acid-modified silica gel prior to determination by flame atomic absorption spectrometry

The immobilization of gallic acid on the surface of amino group-containing silica gel phases for the formation of a newly chelating matrix (GASG) is described. The newly synthesized extractant, characterized by the diffuse reflectance infrared Fourier transformation spectroscopy and elemental analysis, was used to preconcentrate Pb(II), Cu(II), Cd(II) and Ni(II). The pH ranges for quantitative sorption and the concentrations of HCl for eluting Pb(II), Cd(II), Cu(II) and Ni(II) were opimized, respectively. The sorption capacity of the matrix has been found to be 12.63, 6.09, 15.38, 4.62mg/g for Pb(II), Cd(II), Cu(II) and Ni(II), respectively, with the preconcentration factor of approximately 200 ( approximately 100 for Cd(II)). The effects of flow rates, the eluants, the electrolytes and cations on the metal ions extraction, as well as the chelating matrix stability and reusability, were also studied. The extraction behavior of the matrix was conformed with Langmuir's equation. The present preconcentration and determination method was successfully applied to the analysis of synthetic metal mixture solution and river water samples. The 3sigma detection limit and 10sigma quantification limit for Pb(II), Cu(II), Cd(II) and Ni(II) were found to be 0.58, 0.86, 0.65, 0.92microg/L and 1.08, 1.23, 0.87, 1.26microg/L, respectively.     

Isotherm Model Analysis for the Adsorption of Cd (II), Cu (II), Ni (II), and Zn (II) on Anaerobically Digested Sludge

Adsorption of Cd (II), Cu (II), Ni (II), and Zn (II) from aqueous solutions on anaerobically digested sludge has been investigated. Experimental data has been fit to Langmuir, Freundlich, and Redlich-Peterson isotherms to obtain the characteristic parameters of each model. Based on the maximum adsorption capacity obtained from the Langmuir and the Redlich-Peterson isotherm the affinity of the studied metals for the sludge has been established as Cu (II)>Cd (II)>Zn (II)>Ni (II). Adsorption tests from multimetal systems confirm the affinity order obtained in the individual metal tests. The adsorption capacity for Cu (II) measured in individual tests is not reduced by the presence of the other above referred metals. Desorption of Zn (II) and Cd (II) previously bound to the sludge in front of Cu (II) and HCl solutions is also reported. Copyright 2000 Academic Press.     

Removal of Cd(II), Cu(II), and Pb(II) by adsorption onto natural clay: a kinetic and thermodynamic study

In this work, we study the elimination of three bivalent metal ions (Cd²⁺, Cu²⁺, and Pb²⁺) by adsorption onto natural illitic clay (AM) collected from Marrakech region in Morocco. The characterization of the adsorbent was carried out by X-ray fluorescence, Fourier transform infrared spectroscopy and X-ray diffraction. The influence of physicochemical parameters on the clay adsorption capacity for ions Cd²⁺, Cu²⁺, and Pb²⁺, namely the adsorbent dose, the contact time, the initial pH imposed on the aqueous solution, the initial concentration of the metal solution and the temperature, was studied. The adsorption process is evaluated by different kinetic models such as the pseudo-first-order, pseudo-second-order, and Elovich. The adsorption mechanism was determined by the use of adsorption isotherms such as Langmuir, Freundlich, and Temkin models. Experiments have shown that heavy metals adsorption kinetics onto clay follows the same order, the pseudo-second order. The isotherms of adsorption of metal cations by AM clay are satisfactorily described by the Langmuir model and the maximum adsorption capacities obtained from the natural clay, using the Langmuir isotherm model equation, are 5.25, 13.41, and 15.90 mg/g, respectively for Cd(II), Cu(II), and Pb(II) ions. Adsorption of heavy metals on clay is a spontaneous and endothermic process characterized by a disorder of the medium. The values of ΔH are greater than 40 kJ/mol, which means that the interactions between clay and heavy metals are chemical in nature.     

Formation of Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Cd(II) hexacyanocobaltates

A study is reported of the formation of Fe(II), Co(II), Ni(II), Cu(II), Zn(II), Ag(I) and Cd(II) hexacyanocobaltates. The results show that the precipitates form by reaction of the metal ions with KCo(CN)(6)(2-) ion-pairs in 1:1 ratio, followed by solid phase transformations.     

Removal of As(V) by Cu(II)-, Ni(II)-, or Co(II)-doped goethite samples

The present study reports removal of As(V) by adsorption onto laboratory-prepared pure and Cu(II)-, Ni(II)-, and Co(II)-doped goethite samples. The X-ray diffraction patterns showed only goethite as the crystalline phase. Doping of ions in the goethite matrix resulted in shift of d-values. Various parameters chosen for adsorption were nature of adsorbent, percentage of doped cations in goethite matrix, contact time, solution pH, and percentage of adsorbate. It was observed that the pH(pzc) of the goethite surface depended on the nature and concentration of metal ions. The surface area as well as the loading capacity increased with the increase of dopant percentage in goethite matrix. A maximum loading capacity of 19.55 mg/g was observed for 2.7% Cu(II)-doped goethite. The adsorption kinetics for Ni(II), Co(II) and for undoped goethite attained a quasi-equilibrium state after 30 min with almost negligible adsorption beyond this time. In case of Cu(II)-doped goethite samples, the quasi-equilibrium state for As(V) adsorption was observed after 60 min. At each studied pH condition, it was observed that the percentage of adsorption of As(V) decreased in the order Cu(II)-doped goethite > or = Ni(II)-doped goethite > Co(II)-doped goethite > pure goethite. The adsorption followed: Langmuir isotherm, indicating monolayer formation.     

Adsorption behavior of Pb(II) on montmorillonite

The present work investigated the adsorption and desorption behaviors of Pb(II) on montmorillonite. The adsorption experiments were carried out using batch process. The results show that the adsorption is dependent on the pH value of the medium, and the uptake of Pb(II) increases with the pH increasing in the pH range of 2.0–10.0. The adsorption kinetics is in better agreement with pseudo-second order kinetics, and the adsorption data is a good fit with Langmuir isotherm. The presence of EDTA may result in a decrease of the amount of Pb(II) adsorbed. The presence of electrolyte and EDTA may enhance the desorption of Pb(II) ions adsorbed. The adsorption mechanism of Pb(II) on montmorillonite may be explained in two aspects: the chemical binding between Pb(II) ions and surface hydroxyl groups; and the electrostatic binding between Pb(II) ions and the permanent negatively charged sites of montmorillonite.     

Amberlite XAD-7 impregnated with Xylenol Orange: a chelating collector for preconcentration of Cd(II), Co(II), Cu(II), Ni(II), Zn(II) and Fe(III) ions prior to their determination by flame AAS

A new chelating resin, Xylenol Orange coated Amberlite XAD-7, was prepared and used for preconcentration of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) prior to their determination by flame atomic absorption spectrophotometry. The optimum pH values for quantitative sorption of Cd(II), Co(II), Cu(II), Fe(III), Ni(II) and Zn(II) are 4.5-5.0, 4.5, 4.0-5.0, 4.0, 5.0 and 5.0-7.0, respectively, and their desorptions by 2 mol L(-1) HCl are instantaneous. The sorption capacity of the resin has been found to be 2.0, 2.6, 1.6, 1.6, 2.6 and 1.8 mg g(-1) of resin for Cd, Co, Cu, Fe, Ni and Zn, respectively. The tolerance limits of electrolytes, NaCl, NaF, NaI, NaNO3, Na2SO4 and of cations, Mg2+ and Ca2+ in the sorption of the six metal ions are reported. The preconcentration factor was between 50 and 200. The t1/2 values for sorption are found to be 5.3, 2.9, 3.2, 3.3, 2.5 and 2.6 min for the six metals, respectively. The recoveries are between 96.0 and 100.0% for the different metals at preconcentration limits between 10 to 40 ng mL(-1). The preconcentration method has been applied to determine the six metal ions in river water samples after destroying the organic matter (if present in very large amount) with concentrated nitric acid (RSD < or = 8%, except for Cd for which it is upto 12.6%) and cobalt content of vitamin tablets with RSD of approximately 3.0%.     

Chemically modified multiwalled carbon nanotubes as efficient and selective sorbent for separation and preconcentration of trace amount of Co(II), Cd(II), Pb(II), and Pd(II)

Multi-walled carbon nanotubes (MWCNTs) were chemically functionalized by glutaric dihydrazide (GDH) and characterized with FT-IR technique. This new sorbent was used for enrichment and preconcentration of Co(II), Cd(II), Pb(II), and Pd(II) ions. The adsorption was achieved quantitatively on MWCNTs at pH 4.0, and then the retained metal ions on the adsorbent were eluted with 1.5 mol L^?1 HNO₃. The effects of analytical parameters including pH of the solution, eluent type, sample volume, and matrix ions were investigated for optimization of the presented procedure. The adsorption capacity of the adsorbent at optimum conditions was found to be 33.6, 29.2, 22.1, and 36.0 mg g^?1 for Co(II), Cd(II), Pb(II), and Pd(II), respectively. The LOD values of the method were 0.16, 0.19, 0.17, and 0.12 ng mL^?1 (3Sb, n = 10) for Co(II), Cd(II), Pb(II), and Pd(II), respectively. The RSDs values of the method were 0.75, 0.85, 1.16, and 1.30 ng mL^?1 for Co(II), Cd(II), Pb(II), and Pd(II), respectively. The method was applied for the determination of analytes in soil, well water, and wastewater samples with satisfactory results.     

Biosorption of Co(II), Cr(III), Cd(II), and Pb(II) Ions from Aqueous Solution Using Nonliving Neochloris Pseudoalveolaris Deason & Bold: Equilibrium,Thermodynamic, and Kinetic Study

In this study, biosorption of cobalt(II), chromium(III), cadmium(II), and lead(II) ions from aqueous solution was studied using the algae nonliving biomass (Neochloris pseudoalveolaris, Np) as natural and biological sorbents. The effect of pH, contact time, temperature, and metal concentration on the adsorption capacity of metal ions was investigated. The maximum adsorption capacities for Co(II), Cr(II), Cd(II), and Pb(II) were found to be 20.1, 9.73, 51.4 and 96.2 mg/g at the optimum conditions, respectively. The experiments showed that when pH increased, an increase in the adsorption capacity of the biomass was observed too. The kinetic results of adsorption obeyed a pseudo second-order model. Freundlich and Langmuir isotherm models were applied to experimental equilibrium data of metal ions adsorption and the value of R _L for Pb(II), Cb,(II), Co(II), and Cr(III) was found to be 0.376, 0271, 0872, and 096, respectively. The thermodynamic parameters related to the adsorption process such as E _a , ΔG ⁰, ΔH ⁰, and ΔS ⁰ were calculated. ΔH ⁰ values (positive) showed that the adsorption mechanism was endothermic. Weber-Morris and Urano-Tachikawa diffusion models were also applied to experimental equilibrium data. The algae biomass was effectively used as a sorbent for the removal of metal ions from aqueous solutions.