Adsorption Of Cadmium Ions Research Articles

Potential of waste mangosteen shell in the removal of cadmium ions: Effects of pH, contact time, and temperature

In this study, waste biomass adsorbents produced from mangosteen shells (MGS) were prepared (denoted as MGS500 and MGS1000). The physical and chemical characteristics, such as scanning electron microscopy, thermogravimetric-differential thermal analysis, specific surface area, pore volumes, surface functional groups, and point of zero charge of the prepared MGS samples were determined, and the adsorption capacity of cadmium ions from aqueous media was assessed. The effects of pH, adsorption time, temperature, and coexistence on adsorption were carefully assessed using an inductively coupled plasma optical emission spectrometer under several experimental conditions. The adsorption capacity decreased in the order, MGS < MGS500 < MGS1000. The optimal pH for cadmium ion removal was 5.0. The amount of cadmium ions adsorbed gradually increased with time, and adsorption equilibrium was achieved within 24 h after adsorption. Additionally, the amount of adsorbed cadmium ions increased with increasing adsorption temperature. To elucidate the adsorption mechanism in detail, the elemental distribution and X-ray photoelectron spectra of the prepared adsorbents were analyzed. Finally, desorption solutions such as HNO3, H2O, and NaOH were used to desorb the absorbed cadmium ions from MGS1000. Under our experimental conditions, the desorption percentage of cadmium ions was approximately 98.8% using HNO3. In conclusion, MGS1000 exhibited a good adsorption capacity of 12.0 mg/g for adsorbing cadmium ions from aqueous media and desorption capacity with HNO3 at 1000 mmol/L.

Adsorption of Arsenic, Lead, Cadmium, and Chromium Ions from Aqueous Solution Using a Protonated Chabazite: Preparation, Characterization, and Removal Mechanism

The adsorption of As(V), Pb(II), Cd(II), and Cr(III) ions from aqueous solutions on natural and modified chabazite was studied. The functionalization of chabazite was performed via a protonation and calcination with the aim of generating Lewis acid sites to improve its anion exchange properties. The surface and physicochemical properties of both adsorbents were studied and compared. The adsorption isotherms of tested heavy metal ions were quantified and modeled to identify the best isotherm equation. Steric parameters for the adsorption of these ions were also calculated with a monolayer statistical physics model. Natural chabazite showed the maximum adsorption capacity for Pb(II), while the modified zeolite improved its As(V) properties in 79%. These results showed that the modified zeolite was able to remove both cations and anions from aqueous solution. The application of this functionalized chabazite can be extended for the removal of other anionic pollutants from water, thus opening the possibility of preparing new adsorbents with tailored properties for water treatment.

Utilizing of sunflower seed husk through production of biochar and its application in systems for purification of water contaminated with cadmium

The pollution of water streams is one of the most spread environmental problem whole the world due to its permanently increasing from one part, and the importance of water for the human health from the other. An approach for decontamination of polluted waters based on the ideology of the circular economy is investigated in this study. The wasted sunflower seed husks obtained during the cooking oil production were subjected to gasification process in pilot plant installation. Three biochar samples were obtained and characterized regarding main properties like carbon content, moisture, ash, volatile compounds, and specific surface area at different experimental conditions. For all samples was possessed high carbon content of 69-75 wt. % and well developed surface area of 262-321 m2/g. The biochar materials were subjected to experimental procedure for evaluation of their potential for adsorption of cadmium (Cd) ions from water solution with different concentration of the pollutant. The obtained reduction coefficient for all biochar samples reached up to 99.97 % for the initial concentration of Cd-ions from 1.1 mg/l to 562 mg/l. For the higher Cd concentrations in the range of 1124-11240 mg/l, the reduction decreased to 11-24 %. The highest adsorption capacity of 289.99 mg/g is obtained for the biochar sample subjected to gasification for 2 minutes.

Studies of Adsorption of Cadmium Ions by Biowaste Adsorbent from Aqueous Solutions with Ion-Selective Electrodes and ICP-OES

Studies of Adsorption of Cadmium Ions by Biowaste Adsorbent from Aqueous Solutions with Ion-Selective Electrodes and ICP-OES

Preparation of nZVI/MCM-41/rGO for efficient adsorption of cadmium ions from aqueous solution

Preparation of nZVI/MCM-41/rGO for efficient adsorption of cadmium ions from aqueous solution

Preparation of a novel hydrogel of sodium alginate using rural waste bone meal for efficient adsorption of heavy metals cadmium ion

Adsorption has been an important method for removing heavy metals from industrial wastewater. However, there has been a lack of an environmentally friendly, low-cost, biodegradable and easily recyclable material. China produces bones are not fully utilized leads to a waste of resources Therefore, efficient application of bone meal (BM) for remediation of contaminants in water would provide a promising alternative for resource utilization of bones. In this paper, we use a combination of BM and sodium alginate (SA) to prepare a novel BM/SA/calcium ion (BM/SA/Ca2+) double cross-linked composite hydrogel (BMSAH). Enhance the mechanical structure of SA while making the BM easy to recycle and reuse. The morphology and structure of the BMSAH were characterized using FT-IR spectroscopy and SEM-EDS. suggesting that the BMSAH can provide a larger specific surface area and high number of adsorption sites. The effects of the solution pH, ionic strength and contact time on the adsorption capacity of the BMSAH were investigated in depth, Under different conditions, BMSAH has a strong adsorption capacity of >90 %. XPS and FT-IR analysis showed that Cd2+ was adsorbed mainly via coordination interactions and hydrogen bonds with the carboxyl groups and nitrogen atoms in the BMSAH. A pseudo-second-order kinetic model, particle diffusion model and Isothermal adsorption lines indicate that the surface of the BMSAH is non-uniform suggesting that the adsorption of heavy metal ions by the BMSAH involves a combination of surface adsorption and intraparticle diffusion mechanisms, which is an overall chemical-physical adsorption process. In addition, the adsorption capacity of BMSAH remained above 90 % after three desorption cycles. Our work provides a new method for the preparation of a low-cost, high mechanical performance, biodegradable and easily recyclable physical hydrogels used for the removal of heavy metal ions.

Functionalized Bentonite Clay Composite with NiAl-Layered Double Hydroxide for the Effective Removal of Cd(II) from Contaminated Water

In this study, the efficiency of functionalized bentonite (F-bentonite) and NiAl-layered double hydroxide (LDH), as well as their nanocomposites, was explored regarding the adsorption of cadmium ions (Cd2+) in batch tests. Surface characterization using SEM, EDX, and FTIR analyses confirmed the successful loading of LDH (NiAl) onto the F-bentonite and the adsorption of Cd2+ onto the F-bentonite, LDH (NiAl), and LDH/F-bentonite composite adsorbent, suggesting ion exchange and surface precipitation as the main controlling mechanisms of the formation of adsorbent. An equilibrium contact period of 60 min was suggested, with the LDH/F-bentonite composite presenting the highest adsorption capacity and removal effectiveness as compared to the other adsorbents. The LDH/F-bentonite composite also presented the highest removal efficiency and maximum adsorption capacity at an optimum pH value of 7.0. A steady increase in the uptake capacity of Cd2+ was observed by increasing the dosage of the adsorbents, with the LDH/F-bentonite composite having the best adsorption capacity. The fitting of the pseudo second-order kinetic model to the adsorption data of Cd2+ suggested chemisorption on the adsorbents’ surfaces as the controlling mechanism. The Langmuir isotherm with a near-perfect fitting revealed a monolayer adsorption, while physical adsorption of Cd2+ onto all the adsorbents is proposed using the D–R isotherm. Finally, both homogeneous and heterogeneous adsorption systems are proposed for all the adsorbents due to the satisfactory fitting of the Sips and R–P isotherm models.

Preparation and characterization of sodium polyacrylate grafted montmorillonite nanocomposite for the adsorption of cadmium ions form aqueous solution

High-efficiency adsorbents made from clay minerals have a wide application in remediation of soil and water pollution, especially in the treatment of refractory and highly toxic heavy metals. Montmorillonite itself has a good adsorption capacity and a large modification space for its layered structure. Therefore, carboxylate polymer grafted montmorillonite was developed to improve the adsorption capacity of heavy metals in this paper. Two kinds of modified preparation routes were compared, and a series of batch adsorption tests were conducted to evaluate the influence degree of parameters (contact time, pH, temperature, and cadmium concentration). The structural changes of montmorillonite samples before and after modification were characterized by a series of microscopic analyses and measurement techniques. The results show that the silicon hydroxyl produced by the hydrolysis of silane coupling agent can indeed be grafted by dehydration condensation with Si/Al-OH on clay surface. The grafting chain can be greatly increased by C=C double bond breaking polymerization. The polycarboxylate group can effectively improve the adsorption performance of modified montmorillonite for cadmium ions. The maximum adsorption capacity of modified montmorillonite increased by about 224.75%, reaching 63.49 mg/g. The adsorption model of montmorillonite conforms to Langmuir monolayer adsorption model, while modified montmorillonite samples exhibit Freundlich adsorption model and S-type isothermal adsorption curve characteristics of resin. The preparation method of neutralizing after polymerization of acrylic acid was proposed to be better, which provides technical guidance for scientific and efficient application.

Adsorption of Heavy Metal Ions Copper, Cadmium and Nickel by Microcystis aeruginosa.

To investigate the treatment effect of algae biosorbent on heavy metal wastewater, in this paper, the adsorption effect of M. aeruginosa powder on heavy metal ions copper, cadmium and nickel was investigated using the uniform experimental method, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and TG-DSC comprehensive thermal analysis. The experimental results showed that the initial concentration of copper ion solution was 25 mg/L, the temperature was 30 °C, the pH value was 8 and the adsorption time was 5 h, which was the best condition for the removal of copper ions by algae powder adsorption, and the removal rate was 83.24%. The initial concentration of cadmium ion solution was 5 mg/L, the temperature was 35 °C, the pH value was 8 and the adsorption time was 4 h, which was the best condition for the adsorption of cadmium ion by algae powder, and the removal rate was 92.00%. The initial nickel ion solution concentration of 15 mg/L, temperature of 35 °C, pH value of 7 and adsorption time of 1 h were the best conditions for the adsorption of nickel ions by algae powder, and the removal rate was 88.67%. The spatial structure of algae powder changed obviously before and after adsorbing heavy metals. The functional groups such as amino and phosphate groups on the cell wall of M. aeruginosa enhanced the adsorption effect of heavy metal ions copper, cadmium and nickel. Additionally, M. aeruginosa adsorption of heavy metal ions copper, cadmium, nickel is an exothermic process. The above experiments show that M. aeruginosa can be used as a biological adsorbent to remove heavy metals, which lays a theoretical foundation for the subsequent treatment of heavy metal pollution by algae.

Adsorption of cadmium ion on humic acid extracted from laterite soils of Kannur district, Kerala

Adsorption of cadmium ion on humic acid extracted from laterite soils of Kannur district, Kerala

ASSESSMENT OF THE EFFICIENCY OF SAWDUST FROM THREE HARDWOOD SPECIES AS LOW-COST ADSORBENT FOR THE REMOVAL OF CADMIUM FROM CONTAMINATED WATER

A lot of wastes are generated in the wood industries which constitute series of negative environmental effects. Nevertheless, sawdust has some organic compounds which can remove heavy metal ions from an aqueous solutions using the adsorption procedure. This investigated the potentials of three hardwood species for the removal of cadmium ion from contaminated water. The wood species utilized in this study include Triplochiton scleroxylon, Brachystegia eurycoma, and Blighia sapida sawdust. The sawdust samples were sieved before the pretreatment to remove both impurities and extractives. The experiments were conducted in batches for adsorption in order to determine the effect of pH solution, contact time, on adsorption of cadmium ions. The experiment was laid out in a 3 × 2 × 4 factorial experimental design. The results revealed that the adsorption capacity for (treated and untreated species, Triplochiton scleroxylon, Brachystegia eurycoma and Blighia sapida (treated and untreated) were 92.40±6.42% and 82.66±13.25%, 85.43±17.21%, and 78.00±24.15%, 78.00±20.08% and 80.75±17.07% respectively at the different pH levels (1-4). The results at the optimum pH (2) also revealed that the adsorption capacity for treated and untreated species of Triplochiton scleroxylon, Brachystegia eurycoma and Blighia sapida were 96.99±1.76% and 96.99±1.68%, 97.94±1.20% and 98.48±0.66%, 97.73±1.59% and 99.10±0.81% respectively at the different contact time (30, 60, 90 and 120). This research revealed that pre-treated sawdust adsorbed metal ions faster even at a low time interval compared to untreated samples. Also, it was observed that the highest adsorption capacity (%) of cadmium took place at pH 2 for all samples of sawdust both (treated and untreated). Hence, the selected wood species were found appropriate for the extraction of cadmium from contaminated water and therefore recommended for use.

Novel diaminoguanidine functionalized cellulose: synthesis, characterization, adsorption characteristics and application for ICP-AES determination of copper(II), mercury(II), lead(II) and cadmium(II) from aqueous solutions

In this study, the novel adsorbent diaminoguanidine-modified cellulose (DiGu.MC) was synthesized to extract mercury, copper, lead and cadmium ions from aqueous solutions and environmental water samples. The synthetic strategy involved oxidizing cellulose powder into dialdehyde cellulose (DAC) and reacting DAC with diaminoguanidine to create an imine linkage between the two reactants to form diaminoguanidine-modified cellulose (DiGu.MC). The structure and morphology of the adsorbent were studied using a variety of analytical techniques including Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) surface area measurements. Adsorption of mercury, copper, lead, and cadmium ions was optimized by examining the effects of pH, initial concentration, contact time, dose, temperature and competing ions. Under optimal adsorption conditions, the adsorption capacities of Cu2+, Hg2+, Pb2+, and Cd2+ were 66, 55, 70 and 41 mg g−1, respectively. The adsorption isotherm is in very good agreement with the Langmuir isotherm model, indicating that a monomolecular layer is formed on the surface of DiGu.MC. The kinetics of adsorption are in good agreement with the pseudo-second kinetics model that proposes the chemical adsorption of metal ions via the nitrogen functional groups of the adsorbent. Thermodynamic studies have confirmed that the adsorption of heavy metals by DiGu.MC is exothermic and spontaneous. Regeneration studies have shown that the adsorbent can be recycled multiple times by removing metal ions with 0.2 M nitric acid. The removal efficiency for regeneration was over 99%. DiGu.MC is introduced as a unique adsorbent in removing mercury, copper, lead and cadmium with a simple synthetic strategy, with cheap starting materials, a unique chemical structure and fast adsorption kinetics leading to excellent removal efficiency and excellent regeneration. The mechanism of adsorption of the investigated heavy metals, is probably based on the chelation between the metal ions and the N donors of DiCu.MC.

Recent progress on adsorption of cadmium ions from water systems using metal-organic frameworks (MOFs) as an efficient class of porous materials

Various articles have been written about MOFs, which are organic-inorganic polymer structures that are unique in three-dimensional porosity, crystalline structure, and their ability to adsorb cadmium ion pollutants from aqueous solutions. These materials possess active metal sites, highly porous structures, high specific surfaces, high chemical functionality, and porous topologies. It is necessary to study adsorption kinetics, isotherms, and mechanisms in order to better understand the adsorption process. Adsorption kinetics can provide information about the adsorption rate and reaction pathway of adsorbents. Adsorption isotherms analyze the possibility of absorbances based on the Gibbs equation and thermodynamic theories. Moreover, in practical applications, knowledge of the adsorption mechanism is essential for predicting adsorption reactions and designing MOFs structures. In this review, the latest suggested adsorption mechanisms, kinetics, and isotherms of MOFs-based materials for removing cadmium ions are presented. A comparison is then conducted between different MOFs and the mechanisms of cadmium ion removal. We also discuss the future role of MOFs in removing environmental contaminants. Lastly, we discuss the gap in research and limitations of MOFs as adsorbents in actual applications, and probable technology development for the development of cost-efficient and sustainable MOFs for metal ion removal.

Isotherm study for adsorption of lead and cadmium ions using magnesium oxide nanoparticles

In our study, the green method was adopted using green tea leaf extract in the preparation of nano-magnesium oxide. This method was chosen in the preparation because it reduces toxicity and produces low-cost materials that do not require high energy and are environmentally friendly. The prepared magnesium oxide was diagnosed using UV-Vis, FTIR, XRD and FESEM techniques. After diagnosis, the prepared MgO NPs was used in the adsorption of heavy metal ions, lead and Cadmium, to determine the optimum conditions for the oxide adsorption process and study the experimental data through adsorption isotherms. (Langmuir, Freundlich and Temkin) in order to clarify how the correlation occurs between the adsorbate ions and the surface of the adsorbent material to understand the mechanism of adsorption.

Development of Eggshell-Based Orange Peel Activated Carbon Film for Synergetic Adsorption of Cadmium (II) Ion.

Heavy metal contamination has spread around the world, particularly in emerging countries. This study aimed to assess the effectiveness of starch/eggshell/orange peel-activated carbon-based composite films in removing cadmium (II) ions from water samples. X-ray diffraction and scanning electron microscopy were used to characterize the composite films. The effect of Cd2+ was studied using a UV-Vis spectrophotometer and atomic absorption spectroscopy. The morphology of the composite film reveals a highly porous and rough surface with more open channels and a non-uniform honeycomb, indicating that the film has a high potential to adsorb Cd2+. The diffraction peaks for this film were found to be at 13.74°, 17.45°, 18.4°, and 23.6°, indicating a typical crystalline A-type packing arrangement within the starch granules. The results indicate that crystalline structure was unaffected by the addition of eggshell powder and orange peel-activated carbon. In 0.5 mg L−1 and 1.0 mg L−1 Cd2+ ions, the composite film removed 100% and 99.7% of the Cd2+, respectively, while the maximum removal efficiency for methylene blue was 93.75%. Thus, the current study shows that starch/eggshell/orange peel activated carbon film has a high potential for commercial activated carbon as a low-cost adsorbent.

Clay honeycomb monoliths for the simultaneous retention of lead and cadmium in water

Natural illite–smectite and stevensite Moroccan clays were used for the simultaneous removal of lead and cadmium from aqueous medium. The clays were employed in raw state and extruded as honeycomb monoliths form without any additives, which confirms the novelty of this approach in water treatment. The experiments were done in batch conditions with continuous stirring and using a recirculated flow, respectively. In addition to a characterization of the clays by XRF, XRD, TGA, laser granulometry, N 2 physisorption, FTIR spectroscopy, SEM-EDS and evaluation of the cation exchange capacity, special attention was paid to the influence on the co-adsorption of variables such as adsorbent dosage, contact time and initial concentration of Cd 2+ and Pb 2 + . Pseudo-second order kinetics and good fitting to Redlich–Peterson model for both heavy metals were found. Our results also suggest that Pb 2 + and Cd 2 + uptake is controlled by chemisorption with predominance of Langmuir characteristics. No significant depletion of the metals retention attributable to competition was observed, particularly for the stevensite (maximum retention capacity of 1.2 mg Pb 2 + /g and 4.6 mg Cd 2 + /g) that showed higher specific surface area. For both clays, cadmium ions adsorption was relatively favoured in the bimetallic solution, and the honeycombs kept the powders performance. Honeycomb monoliths as a compact adsorbent offer a promising way of water treatment thanks to their stability and easy incorporation into dynamic processes avoiding the issues of pressure drop under wastewater circulation. • Natural illite–smectite and stevencite for lead and cadmium co-adsorption in water. • Metals competition does not reduce total response but relatively favours Cd 2+ ions. • Clays extruded without additives as honeycomb monoliths keep powders performance. • Structured design adds easy handling and prevents from sludge generation. • Great potential as low cost solution for water depollution in developing regions.

Dual immobilization of magnetite nanoparticles and biosilica within alginate matrix for the adsorption of Cd(II) from aquatic phase

The adsorption of cadmium ions by magnetite (Fe3O4)@biosilica/alginate (MBA nano-hybrid) was the main aim of the present investigation. Herein, MBA nano-hybrid was synthesized via chemical precipitation technique. As-synthesized MBA nano-hybrid was characterized using FT-IR, FESEM and XRD analyzes. Based on the results, the maximum adsorption capacity of the adsorbent for the removal of Cd(II) was obtained at the initial pH of 7.0. At the initial Cd(II) concentration of 40 mg/L, increasing the reaction time to 180 min led to the Cd adsorption of 35.36 mg/g. Since the removal of Cd(II) after the reaction time of 60 min was insignificant, the reaction time of 60 min was considered as optimum reaction time for performing the experimental runs. According to the results, Langmuir isotherm and pseudo-second order kinetic models were the best fitted models with high correlation coefficients (R2 > 0.99). The results of thermodynamic study indicated exothermic (positive ΔH°) and spontaneous nature (negative ΔG°) of the adsorption of Cd(II) on the surface of MBA nano-hybrid. Negligible reduction in the adsorption capacity of the nano-hybrid was observed (16.57%) after fifth experimental runs, indicating high reusability potential of the as-synthesized nano-hybrid adsorbent.

Removal and kinetics of cadmium and copper ion adsorption in aqueous solution by zeolite NaX synthesized from coal gangue.

Zeolite can remove the heavy metals in wastewater, but the removal efficiency was determined by the types of zeolites and the treatment conditions. In this study, a kind of zeolite NaX synthesized from the coal gangue, a by-product of coal production, was used and the removal efficiency of Cd2+ and Cu2+and the kinetic models were studied. The effects of its dosage, initial pH value of wastewater, and adsorption temperature on its adsorption of heavy metals Cd2+ and Cu2+ in the simulated wastewater were studied through the indoor experiments in laboratory, and the adsorption mechanism was analyzed by the adsorption kinetic model based on its adsorption efficiency and its structures. The results show that the zeolite NaX synthesized from coal gangue has a good adsorption effect on Cd2+ and Cu2+. The adsorption reaches the best effect when the dosage of zeolite is 2g/L, the initial pH of simulated wastewater is 5, the adsorption temperature is room temperature (25 ℃), and the removal efficiency of Cd2+ and Cu2+ (100mg/L) is more than 90%. Additionally, the Langmuir, Freundlich, and Temkin isothermal adsorption models were used to compare and analyze the adsorption effects. The equilibrium data was better fitted by the Langmuir model with the maximum adsorption capacities of 100.11mg/g (Cd2+) and 95.29mg/g (Cu2+), and both separation coefficients were 0-1, which shows that the process was the favorable adsorption. Weber Morris diffusion model shows that the adsorption process at 120min was more consistent with the pseudo-second-order kinetics model, and the adsorption efficiency was simultaneously controlled by the liquid diffusion step and intraparticle diffusion step. Moreover, the removal mechanism of Cd2+ and Cu2+ mainly includes physical adsorption and ion exchange. Therefore, the adsorption effect of zeolite synthesized from coal gangue is remarkable, which will provide a feasible and potential alternative for its resource application.

Study of adsorption of cadmium ions from solutions on natural and modified diatomites

In this work, the use of the sorption method is proposed for the purification of wastewater from ions of heavy metals. The aim was to study the sorption activity of diatomite in relation to cadmium ions. The studies were carried out under static conditions. The processes of physicochemical modification of diatomite for the extraction of cadmium ions from aqueous solutions were investigated. The influence of time and pH on the value of sorption was studied. The optimal conditions for sorption extraction have been determined. Adsorption isotherms have been constructed, and quantitative characteristics of the values of adsorption of cadmium ions on the surface of modified sorbents have been obtained. The fundamental possibility of using diatomites for the purification of cadmium-containing wastewater has been assessed. Based on the data obtained, it can be concluded that acid activation does not promote adsorption (even negative adsorption is observed), which confirms the mobility of cadmium in the low pH region, it can be assumed that only an increase in alkalinity to the possibility of formation of hydroxocadmium (CdOH)+. Thermal, shows stable adsorption in relation to Cd+2, which suggests the possibility of using such activation of cadmium diatomite and other metals, that is, with complex pollution.

Assessment of alkalinity on the adsorption of cadmium ion using KOH-activated carbon from Sesame stem

The increase alkalinity on the adsorption of cd2+ using KOH-activated carbon from Sesame stem was studied. Determination of metal ion in solution shows adsorption capacities of 86.68 % for KOH-AC at saturated state. Effect of metal ion concentration shows that, Removal efficiency of Cd2+ by KOH-AC increases with increasing presence of the adsorbate due to the availability of adsorption sites on the activated carbon. Increase acidity general favors the adsorption. The effect of pH shows that the adsorption of cadmium ions increases with increasing acidity between the pH of 7.5 to 6. However, as the Cd2+ concentration becomes exceedingly high, the removal efficiency decreases. A general observation was that before equilibrium, there is rise in the removal efficiency of Cd2+ by KOH-AC with increasing contact time which is universally true for good adsorbents. Effect of metal ionic strength shows that activated carbon adsorption decrease with increase in ionic strength in any acidic medium.