Cost-effective copper removal by electrosorption powered by microbial fuel cells

This work studied a cost-effective electrosorption that driven by microbial fuel cells (MFC-sorption) to remove Cu²⁺ from wastewater without an external energy supply. The impact factors, adsorption isotherms and kinetics of the novel process were investigated. It indicated that a low electrolyte concentration and a high solution pH could enhance the Cu²⁺ removal efficiency, while the adsorption capacity increased with the increase of numbers of MFCs in series and the initial Cu²⁺ concentration. The adsorption isotherms study indicated that the monolayer adsorption in MFC-sorption was dominant. The kinetics study suggested the increase of initial Cu²⁺ concentration could enhance the initial adsorption rate. The electrode characterizations verified the existence of Cu₂O and Cu on the electrode surface of active carbon fibers (ACFs), suggesting that MFC-sorption was not only an adsorption process, but also a redox reaction process.     

Adsorption of lead(II) from aqueous solution onto Hydrilla verticillata

The adsorption of Pb(II) onto Hydrilla verticillata was examined in aqueous solution with parameters of pH, adsorbent dosage, contact time and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms, and both models fitted well. The monolayer adsorption capacity of Pb(II) was found as 104.2 mg/g at pH 4 and 25°C. Dubinin–Radushkevich (D–R) isotherm model was also applied to the equilibrium data. The mean free energy of adsorption (15.81 kJ/mol) indicated that the adsorption of Pb(II) onto H. verticillata may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (ΔG ⁰), enthalpy (ΔH ⁰) and entropy (ΔS ⁰) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto H. verticillata was a feasible, spontaneous and exothermic process in nature. The influence of Cd²⁺, Cu²⁺ and Ni²⁺ on adsorption of Pb²⁺ onto H. verticillata was studied, too. In the investigated range of operating conditions, it was found that the existence of Cd ²⁺, Cu ²⁺ and Ni ²⁺ had no impact on the adsorption of Pb²⁺.     

Oscillatoria anguistissima: A Promising Cu2+ Biosorbent

Oscillatoria anguistissima rapidly adsorbs Cu²⁺ from aqueous solution. The adsorption of Cu²⁺ followed Freundlich Isotherm, and the amount of Cu²⁺ removed from solution increased with increasing Cu²⁺ concentration. The adsorption is pH dependent, and maximum Cu²⁺ removal occurs at pH 5. Of the various pretreatments, HCl treatment of the biomass increased the capacity for Cu²⁺ removal. Presence of Mg²⁺ and Ca²⁺ resulted in decline in the Cu²⁺ adsorption capacity of Oscillatoria cells. This species could also effectively remove Cu²⁺ from mine water containing 68.4 μg/ml of Cu²⁺ at pH 3.45. Received: 23 December 1996 / Accepted: 20 February 1997     

Adsorption of Ni2+ and Cu2+ using Bio-Mineral: Adsorption Isotherms and Mechanisms

Heavy metal pollution has become one of the most serious environmental pollution problems. This study aimed to determine the adsorption and desorption characteristics of Ni²⁺ and Cu²⁺ by bio-mineral which was induced by Bacillus subtilis, and to explore the effect of pH on adsorption characteristics. The results showed that the Langmuir model gave a better fit to the experimental data than the Freundlich model, which demonstrated the adsorption was of a single-molecule layer form. The maximum adsorption capacities of the bio-mineral for Ni²⁺ and Cu²⁺ were determined as 67.114 mg/g and 69.930 mg/g, respectively. The desorption rates of Ni²⁺ and Cu²⁺ were very low, especially for Ni²⁺ which was almost 0. Besides, the bio-mineral maintained high adsorption capability for metals ions within a wide pH range (pH ≥ 3). It did not show any new phases after adsorption of Ni²⁺ and Cu²⁺ tested by FTIR, indicating that the bio-mineral and heavy metal ions might mainly physically be adsorbed. The bio-mineral has a larger internal and external specific surface area, pore volume and colloidal properties which are beneficial for the adsorption of metals ions, but shows limits in desorption. This study provides a theoretical basis for the utilization of bio-mineral and opens a new perspective for the remediation of heavy metals pollution.     

Copper biosorption in an aerobic bioreactor

Abstract

This study evaluates the biosorption of copper by aerobic biomass that was selected from surface waters of the San Pedro River in Sonora, Mexico. Using a batch system, 73% biosorption of copper was obtained in 75 minutes. Continuous biosorption assays were carried out for 133 days in an ascending flow aerobic reactor packed with zeolite (AFAR-PZ) that was inoculated with a bacterial consortium. Strains were grown until 1g L^?1 of biomass was obtained. Tests using continuous biosorption were performed as follows: (i) the addition of 50 mg Cu²⁺ L^?1 without recirculation of biomass; (ii) the addition of 20 mg Cu²⁺ L^?1without recirculation of biomass; and (iii) the biomass were recirculated with the addition of 20 mg Cu²⁺ L^?1 to pH 3 to 4. The fourth and fifth assays varied pH between 4 and 5, with 20 mg Cu²⁺ L^?1and the biomass recirculated. Biosorption capacity of the first and second assays was 96% on the first day of experimentation. During the third trial 97% of biosorption was obtained during 6 days and the process was improved by varying the pH. Copper biosorption equilibrium was investigated under the same operating conditions. Langmuir adsorption isotherms were used to fit experimental data. The biosorption capacity of aerobic biomass was 3.08 mmol g^?1. It was demonstrated that this biomass is capable of biosorbing copper and this method has potential for the treatment of industrial effluents contaminated with heavy metals.     

Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity

To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH₂) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES_1.0CEC-Mt, APTES_2.0CEC-Mt, APTES_3.0CEC-Mt, APTES_4.0CEC-Mt) with enhanced adsorption capacity for Co²⁺. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co²⁺ by APTES-Mt was evaluated. The results indicated that adsorption of Co²⁺ onto Ca-Mt, APTES_1.0CEC-Mt and APTES_2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co²⁺ onto APTES_3.0CEC-Mt and APTES_4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES_1.0CEC-Mt, APTES_2.0CEC-Mt, APTES_3.0CEC-Mt and APTES_4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g^-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co²⁺ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co²⁺-rich wastewater.     

Study of multicompound sorption of Lead and Pyrene on a reconstituted soil: batch and fixed bed column tests

Many polluted sites are simultaneously contaminated with polycyclic aromatic hydrocarbons and heavy metals. In the present study, batch and continuous column experiments were performed utilizing self-composition soil to describe the sorption behavior of two contaminants: lead (Pb²⁺) and pyrene (PYR). Operational conditions such as contact time, bed depth, and flow rate were optimized. The effect of soil organic matter content on the process of adsorption of both contaminants was investigated. The presence of PYR in solution at neutral pH (6.0–7.5) decreased Pb²⁺ sorption. Similar behavior was observed for PYR in the presence of Pb²⁺ in solution. At room temperature, batch experimental data conducted as a function of contact time were analyzed using the Langmuir and Freundlich isotherms. Results revealed that Pb²⁺ sorption isotherms were fitted better by the Langmuir model and PYR sorption isotherms were fitted better by the Freundlich model. Column adsorption experiments were carried out at room temperature and under operating parameters (bed depth, flow rate, and initial contaminant concentration). Breakthrough curves were well fitted to the two-site first-order kinetic model with a sum of square errors less than 0.14. The Pb²⁺ adsorption kinetic data were processed also for the Thomas model with a good accuracy.     

Biosorption of copper by fungal melanin

Summary Melanin obtained from Aureobasidium pullulans and Cladosporium resinae was an efficient biosorbent for copper. Copper uptake could be expressed using various adsorption isotherms; melanin from A. pullulans obeyed Freundlich and Langmuir isotherms whereas C. resinae melanin followed the BET isotherm indicating a more complex type of adsorption than in A. pullulans. In general, uptake capacities of melanin were greater than for intact biomass and the higher uptake by pigmented rather than albino biomass could be correlated with the presence of melanin. Cu²⁺ was less readily desorbed from melanin by dilute mineral acids than from intact biomass and again, the relative ease of Cu²⁺ desorption from pre-loaded pigmented or albino biomass was correlated with the presence or absence of melanin. Mg²⁺ and Zn²⁺ appeared to be the most effective cations for desorption with Na⁺ and K⁺ the least effective. The addition of melanin to a coppercontaining culture of the albino strain of A. pullulans resulted in some reduction of toxicity.     

Biosorption of copper(II) from aqueous solutions by green alga <Emphasis Type="Italic">Cladophora fascicularis</Emphasis>

Biosorption is an effective means of removal of heavy metals from wastewater. In this work the biosorption behavior of Cladophora fascicularis was investigated as a function of pH, amount of biosorbent, initial Cu²⁺ concentration, temperature, and co-existing ions. Adsorption equilibria were well described by Langmuir isotherm models. The enthalpy change for the biosorption process was found to be 6.86 kJ mol⁻¹ by use of the Langmuir constant b. The biosorption process was found to be rapid in the first 30 min. The presence of co-existing cations such as Na⁺, K⁺, Mg²⁺, and Ca²⁺ and anions such as chloride, nitrate, sulfate, and acetate did not significantly affect uptake of Cu²⁺ whereas EDTA substantially affected adsorption of the metal. When experiments were performed with different desorbents the results indicated that EDTA was an efficient desorbent for the recovery of Cu²⁺ from biomass. IR spectral analysis suggested amido or hydroxy, C=O, and C–O could combine strongly with Cu²⁺.     

Methacryloylamidohistidine in affinity ligands for immobilized metal-ion affinity chromatography of ferritin

A new metal-chelate adsorbent utilizing 2-methacryloylamidohistidine (MAH) was prepared as a metalchelating ligand. MAH was synthesized using methacryloly chloride and histidine. Monosize nanospheres with an average diameter of 450 nm were produced by emulsion polymerization of 2-hydroxyetylmethacrylate (HEMA) and MAH. Then, Fe³⁺ ions were chelated directly onto the monosize nanospheres. Mon-poly(HEMA-MAH) nanospheres were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and elemental analysis. Fe³⁺ chelated monosize nanospheres were used in ferritin adsorption from an aqueous solution. The maximum ferritin adsorption capacity of Fe³⁺-chelated mon-poly(HEMAMAH) nanospheres was 202 mg/g at pH 4.0 in acetate buffer. The non-specific ferritin adsorption on the monpoly( HEMA-MAH) nanospheres was 20 mg/g. The adsorption behavior of ferritin could be modeled using both Langmuir and Freundlich isotherms. The adsorption capacity decreased with increasing ionic strength of the binding buffer. High desorption ratios (> 95% of the adsorbed ferritin) were achieved with 1.0 M NaCl at pH 7.0. Ferritin could be repeatedly adsorbed and desorbed with the Fe³⁺-chelated mon-poly(HEMA-MAH) nanospheres without significant loss of adsorption capacity.     

Stability of Ca2+-, Cd2+-, Cu2+-[illite-humic] complexes and pH influence

Decomposition of fresh plant residues in soil is expected to produce humic fractions varying in molecular size. It was hypothesized that metal adsorption by soil, to some degree, will depend on humic acid content and molecular size. The latter is expected to vary in number and type of functional groups. In this study, illite-humic complexes were used to evaluate Ca²⁺, Cd²⁺, and Cu²⁺ adsorption and how this adsorption was affected by humic acids, differing in molecular size, under various pH values. Potentiometric titration using ion-selective electrodes with a stop-and-go procedure was employed to evaluate metal-[illite-humic] complex formation. The results showed that illite-humic complexes exhibited at least two types of metal-ion adsorption sites (low and high affinity) and molecular size of humic fractions had a large potential influence on total metal adsorption but a relatively smaller influence on metal-complex stability. Relative strength of metal-ion-[illite-humic] complexes followed the order of Cu²⁺>Cd²⁺>Ca²⁺ and were affected by pH, especially for low metal-ion affinity sites. Magnitude of metal-[illite-humic] stability constants, depending on molecular size of humic fraction and pH, varied on a log-scale from 3.52 to 4.21 for Ca²⁺, 4.38 to 5.18 for Cd²⁺and from 5.23 to 5.83 for Cu²⁺. There was an approximate 5-fold difference in these stability constants between the three different sizes of humic fractions. The larger the humic fraction, the lower the metal-[illite-humic] stability constant. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date. This revised version was published online in June 2006 with corrections to the Cover Date.     

Studies of biosorption of Pb2+, Cd2+ and Cu2+ from aqueous solutions using Adansonia digitata root powders

The potentials of Adansonia digitata root powders (ADRP) for adsorption of Pb²⁺, Cd²⁺ and Cu²⁺ from aqueous solutions was investigated. Physico-chemical analysis of the adsorbent (ADRP) shows that hydroxyl, carbonyl and amino groups were predominant on the surface of the adsorbent. Scanning Electron Microscope (SEM) image revealed its high porosity and irregular pores in the adsorbent while the Energy Dispersive X-ray Spectrum showed the major element with 53.0% Nitrogen, 23.8% carbon, 9.1% calcium, 7.5% potassium and 6.6% magnesium present. The found optimal conditions were: initial concentration of the metal ions = 0.5 mg/L, pH = 5, contact time = 90 min, adsorbent dose = 0.4 g and particle size = 32 µm. Freundlich isotherm showed good fit for the adsorption of Pb²⁺, Cd²⁺ and Cu²⁺. Dubinin-Radushkevich isotherm revealed that the adsorption processes were physisorption Cd(II) and Cu(II) but chemisorption with respect to Pb(II) ions. The kinetics and thermodynamic studies showed that Pseudo-second order and chemisorptions provided the best fit to the experimental data of Pb (II) ions only. Batch desorption result show that desorption in the acidic media for the metal ions were more rapid and over 90% of the metal ions were recovered from the biomass.     

Bioactive and metal uptake studies of carboxymethyl chitosan-graft-d-glucuronic acid membranes for tissue engineering and environmental applications

Carboxymethyl chitosan-graft-d-glucuronic acid (CMCS-g-d-GA) was prepared by grafting d-GA onto CMCS in the presence of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and then the membranes were made from it. In this work, the bioactivity studies of CMCS-g-d-GA membranes were carried out and then characterized by SEM, CLSM, XRD and FT-IR. The CMCS-g-d-GA membranes were found to be bioactive. The adsorption of Ni²⁺, Zn²⁺and Cu²⁺ ions onto CMCS-g-d-GA membranes has also been investigated. The maximum adsorption capacity of CMCS-g-d-GA for Ni²⁺, Zn²⁺and Cu²⁺ was found to be 57, 56.4 and 70.2 mg/g, respectively. Hence, these membranes were useful for tissue engineering, environmental and water purification applications.     

Identification of fiber types in rat skeletal muscle based on the sensitivity of myofibrillar actomyosin ATPase to copper

Summary Experiments are reported demonstrating that differential rates of inactivation of the histochemical staining for myofibrillar actomyosin ATPase in rat skeletal muscle fibers exist following inclusion of low concentrations of Cu²⁺ in the preincubation medium. This response of rat muscle occurs at near neutral (7.40), acid (4.60), and alkaline (10.30) pH. The response to Cu²⁺ appears to result from a binding of Cu²⁺ onto the myofibrillar complex, probably on myosin itself, as it can be reversed by soaking of the pretreated muscle sections in sodium cyanide or the Cu²⁺ chelator diethyldithiocarbamate. The pattern of modification of the staining pattern following pretreatment with Cu²⁺ is the mirror image of that produced by pretreatment with acid. The results demonstrate that the inclusion of Cu²⁺ in the preincubation media for the myofibrillar actomyosin ATPase can be a useful tool to differentiate fiber types. They also support the earlier conclusion that three distinct types of type II fibers can be identified in rat skeletal muscle based on the histochemical staining for myofibrillar actomyosin ATPase.     

Removal of Ca(II) and Mg(II) from aqueous single metal solutions by mercerized cellulose and mercerized sugarcane bagasse grafted with EDTA dianhydride (EDTAD)

In a previous work, chemically modified cellulose (EMC) and sugarcane bagasse (EMMB) were prepared from mercerized cellulose (MC) and twice-mercerized sugarcane bagasse (MMB) using ethylenediaminetetraacetic dianhydride (EDTAD) as modifying agent. In this work we described in detail the modification of these materials in function of reaction time and EDTAD amount in the reaction media. The resistance of ester bond at pH 1, 2, 11, and 12 was also evaluated by FTIR. The results were used to model the hydrolysis process and a kinetic model was proposed. The modified materials (EMMB and EMC) were used to adsorb Ca²⁺ and Mg²⁺ ions from aqueous single solutions. The adsorption isotherms were developed at two pH values. These materials showed maximum adsorption capacities for Ca²⁺ and Mg²⁺ ions ranging from 15.6 to 54.1 mg/g and 13.5 to 42.6 mg/g, respectively. The modified material from sugarcane bagasse (EMMB) showed larger maximum adsorption capacities than modified material from cellulose (EMC) for both metals.     

Reversible immobilization of invertase on Cu-chelated polyvinylimidazole-grafted iron oxide nanoparticles

Polyvinylimidazole (PVI)-grafted iron oxide nanoparticles (PVIgMNP) were prepared by grafting of telomere of PVI on the iron oxide nanoparticles. Different metal ions (Cu²⁺, Zn²⁺, Cr²⁺, Ni²⁺) ions were chelated on polyvinylimidazole-grafted iron oxide nanoparticles, and then the metal-chelated magnetic particles were used in the adsorption of invertase. The maximum invertase immobilization capacity of the PVIgMNP–Cu²⁺ beads was observed to be 142.856 mg/g (invertase/PVIgMNP) at pH 5.0. The values of the maximum reaction rate (V _max) and Michaelis–Menten constant (Km) were determined for the free and immobilized enzymes. The enzyme adsorption–desorption studies, pH effect on the adsorption efficiency, affinity of different metal ions, the kinetic parameters and storage stability of free and immobilized enzymes were evaluated.     

Adsorption of Cu(II), Cd(II), and Pb(II) from aqueous single metal solutions by succinylated mercerized cellulose modified with triethylenetetramine

This study describes the preparation of two new chelating materials derived from succinylated mercerized cellulose (cell 1). Cell 1 was activated through two different methods by using diisopropylcarbodiimide and acetic anhydride (to form an internal anhydride) and reacted with triethylenetetramine in order to obtain cell 2 and 4. New modified celluloses were characterized by mass percent gain, concentration of amine functions, elemental analysis, and infrared spectroscopy. Cell 2 and 4 showed degrees of amination of 2.8 and 2.3 mmol/g and nitrogen content of 6.07% and 4.61%, respectively. The capacity of cell 2 and 4 to adsorb Cu²⁺, Cd²⁺, and Pb²⁺ ions from single aqueous solutions were examined. The effect of contact time, pH, and initial concentration of metal ions on the metal ions uptake was also investigated. Adsorption isotherms were well fitted by the Langmuir model. The maximum adsorption capacity of cell 2 and 4 were found to be 56.8 and 69.4 mg/g for Cu²⁺; 68.0 and 87.0 mg/g for Cd²⁺; and 147.1 and 192.3 mg/g for Pb²⁺, respectively.     

Preparation,characterization, bioactive and metal uptake studies of alginate/phosphorylated chitin blend films

Alginate/phosphorylated chitin (P-chitin) blend films were prepared by mixing of 2% of alginate and P-chitin in water and then cross-linked with 4% CaCl₂ solution. The blended films were characterized by FT-IR. Then, the bioactivity of blend films was studied by biomimetic method in simulated body fluid solution (SBF) for 7, 14 and 21 days. After 7, 14 and 21 days and films were characterized by FT-IR and SEM studies. The SEM and FT-IR studies showed that the hydroxyapatite was formed on the surface of the blend films after 7, 14 and 21 days in the SBF solution. These studies confirmed that the alginate/P-chitin blend films are bioactive. Furthermore, the adsorption of Ni²⁺, Zn²⁺and Cu²⁺onto alginate/P-chitin blend films has been investigated. The parameters studied include the pH, contact time, and initial metal ion concentrations. The maximum adsorption capacity of alginate/P-chitin blend films for Ni²⁺, Zn²⁺and Cu²⁺ at pH 5.0 was found to be 5.67, 2.85 and 11.7 mg/g, respectively. These results suggest that alginate/P-chitin blend films-based technologies may be developed for water purification and metal ions separation and enrichment.     

Toxic metal biosorption by macrocolonies of cyanobacterium <Emphasis Type="Italic">Nostoc sphaeroides</Emphasis> Kützing

The cyanobacterium Nostoc sphaeroides Kützing is expected to be effective in toxic metal adsorption as it produces abundant exopolysaccharides with functional groups. Therefore, the adsorption properties of Cu²⁺, Cd²⁺, Cr³⁺, Pb²⁺, Ni²⁺, and Mn²⁺ on fresh macrocolonies and algal powder of N. sphaeroides were compared at pH 5 and 25 °C. The adsorption capacity of fresh biomass for Pb²⁺ and of algal powder for Pb²⁺ and Cr³⁺ were highest in single metal solutions. Compared to the fresh biomass, the metal adsorption capacities of algal powder were similar for Ni²⁺, Cd²⁺, and Pb²⁺ and slightly greater for Cr³⁺, but they were markedly smaller for Mn²⁺ and Cu²⁺. Coexisting ions (in tap water or in multiple solutions) significantly decreased the metal adsorption capacity, except for Cr³⁺ in tap water. The Pb²⁺ and Cr³⁺ adsorption dynamic process fitted the pseudo-second-order model well, showing fast adsorption at the first stage in 10 and 20 min, respectively. Higher pH in acidic ranges favored the adsorption greatly. The Langmuir isotherm model was suitable for explaining the adsorption, and the maximum adsorption capacities were 116.28 and 22.37 mg g^?1 for Pb²⁺ and Cr³⁺, respectively. The adsorption process was endothermic, confirmed by the significantly higher adsorption capability at higher temperature. Hydroxyl, amino, and carboxyl groups were the main functional groups based on Fourier transform infrared spectroscopy analysis, and they bind to metal ions via ion exchange. The results suggest that fresh macrocolonies of N. sphaeroides can be used as an effective biosorbent for metal ion removal, especially for Pb²⁺ and Cr³⁺.     

Unexpected Thiocyanate Adsorption onto Ferrihydrite Under Prebiotic Chemistry Conditions

The most crucial role played by minerals was in the preconcentration of biomolecules or precursors of biomolecules in prebiotic seas. If this step had not occurred, molecular evolution would not have occurred. Thiocyanate is an important molecule in the formation of biomolecules as well as a catalyst for prebiotic reactions. The adsorption of thiocyanate onto ferrihydrite was carried out under pH and ion composition conditions in seawater that resembled those of prebiotic Earth. The seawater used in this work had high Mg²⁺, Ca²⁺ and SO₄^2? concentrations. The most important result of this work was that ferrihydrite adsorbed thiocyanateata pH value (7.2?±?0.2) that usually does not adsorb thiocyanate. The high adsorptivity of Mg²⁺, Ca²⁺ and SO₄^2?onto ferrihydrite showed that seawater ions can act as carriers of thiocyanate to the ferrihydrite surface, creating a huge outer-sphere complex. Kinetic adsorption and isotherm experiments showed the best fit for the pseudo-second-order model and an activation energy of 23.8 kJ mol^?1forthe Langmuir-Freundlich model, respectively. Thermodynamic data showed positive ΔG values, which apparently contradict the adsorption isotherm data and kinetic data that was obtained. The adsorption of thiocyanate onto ferrihydrite could be explained by coupling with the exergonic SO₄^2? adsorption onto ferrihydrite. The FTIR spectra showed no difference between the C≡N stretching peaks of adsorbed thiocyanate and free thiocyanate, corroborating the formation of an outer-sphere complex. All the results demonstrated the importance of the artificial seawater composition for the adsorption of thiocyanate and for understanding prebiotic chemistry.