Adsorption Of Iron Research Articles

Improving the adsorption properties of low surface area hardwood biochar for the removal of Fe+ and PO₄3- from aqueous solution.

Biochar produced from wood residues may provide a new method and material for managing the environment, particularly in terms of carbon sequestration and contaminant remediation. Additionally, biochar produced from wood residues is free of chemical fertilizers, likewise in rice straw, wheat straw, corn straw, etc. This study investigated the removal of iron from aqueous solutions by a novel low-cost and eco-friendly biochar made from hardwood trees and modified by adding MgCl2 for effective phosphate removal. Optimal adsorption conditions were determined through studies of adsorption time, pH, and adsorbent dosage. Batch equilibrium isotherm and kinetic experiments and pre/post-adsorption characterizations using FESEM-EDS, XRD, and FTIR suggested that the presence of carboxyl group elements and colloidal and nano-sized MgO (periclase) particles on the biochar surface were the main adsorption sites for aqueous iron and phosphate respectively. In this study, the HW and MgO-HW biochar showed excellent Dubinin-Radushkevich isotherm (D-R) maximum adsorption capacities of 289.45 and 828.82mg/g for iron and phosphate. The kinetic study for iron and phosphate adsorption was described well by pseudo second-order model and pseudo second-order model respectively. The HW biochar and the prepared MgO-HW biochar exhibited commendable iron adsorption (98.25%) performance at 10 pH units and phosphate (96.22%) at pH 6 respectively. Thus, this research reveals a waste-to-wealth strategy by converting hardwood waste into mineral-biomass biochar with excellent Fe and P adsorption capabilities and environmental adaptability.

Effective removal of nitrate by palygorskite-supported nanoscale zero-valent iron from aqueous solution

Nitrate nitrogen (NO3--N) has become an important pollutant in industrial and agricultural production processes in China. In this study, Palygorskite-supported nanoscale zero-valent iron (nZVI/PG) adsorbent was prepared using the liquid-phase reduction method for the removal of NO3--N from water. Benefiting from the good dispersion uniformity of nZVI on the Palygorskite carrier, the prepared nZVI/PG exhibited a significantly increased specific surface area compared to nZVI, with a noticeable reduction in nZVI aggregation. The Fe/PG mass ratio of 2:1 was found to be the optimal loading ratio for the removal of NO3--N by nZVI/PG, with a removal capacity of 24.36 mg/g and a removal efficiency of 81.23 %, with a nitrogen gas conversion rate of 40.92 %. The removal process of NO3--N by nZVI/PG followed a pseudo-second-order kinetic model, with the removal rate inversely proportional to the initial concentration of NO3--N and directly proportional to the dosage. nZVI/PG exhibited high removal efficiency for NO3--N within the pH range of 2 to 9, with the highest selectivity for NO3--N conversion to N2 observed at pH 5. The main mechanism for the removal of NO3--N by nZVI/PG was found to be adsorption and reduction, with the main products being NH4+-N, NO2--N, and N2.

Adsorption of herbicide iron chelate EDDHA 6 % and fungicide copper oxychloride in drainage water on activated carbon derived from carob pods

The study addresses a significant environmental issue regarding the removal of harmful agricultural chemicals from wastewater. Specifically, it investigates the potential of activated carbon produced from carob pods (CAC) as an effective adsorbent for removing the fungicide copper oxychloride and the herbicide iron chelate EDDHA 6 % from drainage water. The research highlights the importance of finding sustainable and cost-effective methods for treating agricultural runoff, which often contains toxic substances detrimental to ecosystems and human health. CAC was obtained using a saline solution (0.9 % NaCl). The CAC had a surface area of 441.15 m2/g and a pore diameter of 1.18 nm. Adsorption equilibrium for each product was reached in 180 min. The results showed that the adsorption processes followed the pseudo-first-order model perfectly. Moreover, the adsorption of these products onto the CAC was affected by the initial pH of the drainage water. Furthermore, the adsorption isotherm data showed a closer fit to the Langmuir model, suggesting monolayer adsorption occurring on a uniform surface. The maximum Langmuir adsorption capacities obtained were 16.72 and 45.99 mg/g for copper oxychloride and iron chelate, respectively. The thermodynamic parameters showed that adsorption was spontaneous, favorable and exothermic. Considering its commendable adsorption capacity, the adsorbent formulated in this study demonstrates promising potential for the treatment of phytosanitary products wastewater within practical applications.

Changing cellulose acetate deriving from cigarette filters to be used as catalyst in effluent treatment

Cigarette butts are a significant environmental issue, mainly when they are improperly discarded. However, this waste type is recyclable, since its structure is based on cellulose acetate, which is used in the industrial sector for absorbent and filtering purposes. The aim of the present study is to chemically change cellulose acetate deriving from cigarette filters by incorporating iron to it, in order to use it as catalyst in effluent treatment processes. Three different methods were used for iron immobilization purposes in basic, acidic and ferric media, for 7 days. The method showing the best iron adsorption, based on spectroscopic analyses, was the one wherein cigarette butts remained in contact with 0.1 mol/L ferric solution. Therefore, the group of cigarette butts resulting from this method was used in Fenton and photo-Fenton processes. Moreover, it recorded positive results for textile dye mix discoloration, as evidenced by spectral changes in the 350-700 nm range, which pointed out significant color change in the assessed sample. Although the current article results from a preliminary study, the herein collected data point towards the potential use of cigarette butts as alternative to treat effluents deriving from companies that use large amounts of dye.

Using Sugarcane Bagasse as an Adsorbent Material to Remove Iron from Water

This study evaluates the effectiveness of chemically treated sugarcane bagasse as an adsorbent for iron removal from water. The bagasse was modified using sodium hydroxide and citric acid, and its adsorption capabilities were characterized [1-3]. Batch adsorption experiments were conducted to determine the impact of initial iron concentration, contact time, pH, and adsorbent dosage. Results indicated that the treated sugarcane bagasse exhibited a significantly higher iron adsorption capacity compared to the raw material, with an enhancement factor of 1.7. Optimal conditions were identified as a contact time of 100 minutes, a pH of 3, and an adsorbent dosage of 1.5 grams. Adsorption isotherms were best described by the Langmuir model, yielding a maximum adsorption capacity (qmax) of 15.57 mg/g. Additionally, dynamic adsorption tests showed that the adsorbent could be reused effectively, with a desorption efficiency of 75.20%. These findings demonstrate that chemically treated sugarcane bagasse is a viable, cost-effective, and environmentally friendly option for iron removal in water treatment [4].

MnO2@Al‐BDC nanocomposite as adsorbent of remarkable high efficiency toward iron remediation from wastewaters

Global environmental problems, especially those related to water contamination brought on by rapid industrialization and economic growth, are among the most dangerous threats facing humanity today. In this research work, Al3+ based metal–organic framework with 1,4‐benzenedicarboxylic acid (H2BDC) linker has been synthesized by a simple and economic coprecipitation method. The obtained Al‐BDC MOF was utilized as an adsorbent for sequestering iron from wastewater, but only 54.0% of iron concentration was eliminated after 120 min. To boost the removal efficiency, modification of the Al‐BDC MOF was carried out. MnO2@Al‐BDC nanocomposite was prepared and applied as a nanoadsorbent for iron remediation from water. The adsorption capability of Al‐BDC MOF was greatly enhanced by facile modification. The adsorption efficiency reached 97.0% using 35.0 mg of the nanocomposite after 120 min compared to 54.0% iron removal using the un‐modified MOF. The effect of pH of the medium was then studied using MnO2@Al‐BDC nanocomposite. The best elimination efficacy of iron was accomplished at pH ~ 2.2. The adsorption of iron on the surface of MnO2@Al‐BDC nanocomposite attains 97.0% (120 min) using a 35.0 mg dose of adsorbent and reaches 98.7% utilizing a 50.0 mg dose of adsorbent. In contrast, at pH = 9.2, the removal efficiency drops to 90.0% (after 120 min, 35.0 mg adsorbent). The adsorption capability was examined also using a variety of iron concentrations, i.e., 2.5, 5.0, and 7.5 mg/L where the adsorption efficiency dropped notably upon increasing the concentration. It dropped from 96.3% to 87.0% using 35.0 mg of MnO2@Al‐BDC nanocomposite at 90 min. The newly developed adsorbent showed a pronounced efficiency for Fe3+ removal against real samples collected from different water sources. Ultimately, this research introduces a novel MnO2@Al‐BDC nanocomposite, synthesized through a simple and economical coprecipitation method, to address water contamination by iron. The innovation lies in the significant enhancement of iron elimination efficiency, from 54.0% with unmodified Al‐BDC MOF to 97.0% with the MnO2@Al‐BDC nanocomposite.

Выбор сорбента для элиминации ионов железа из сточных и природных вод

Natural waters and wastewaters often contain heavy metals, e.g., iron. Iron ore mining contaminates groundwater with iron up to 30 maximal permissible concentrations (MPC) as this element gets washed out from rock and soil. Adsorption is the most effective and economically feasible method of additional purification of natural and wastewater from iron. Its efficiency depends on the type of adsorbent. The research objective was to select the most efficient sorption material to eliminate water from iron, as well as to establish the adsorption patterns for different sorbents, thus creating sustainable and effective purification. The study featured carbonaceous sorbent of the SKD-515 grade, mineral sorption materials with aluminosilicate of the AC grade, and silicate-based sorbent of the ODM-2F grade. The porous structure was studied by porometry methods while the surface image was obtained using scanning electron microscopy. Other indicators included equilibrium, kinetics, and dynamics of iron adsorption by various sorbents. The Freundlich and Langmuir equations made it possible to calculate the key adsorption parameters. The Gibbs energy values were obtained from the Langmuir equation and equaled 11.93–20.66 kJ/mol, which indicated the physical nature of the adsorption process. Under static conditions, the sorbents demonstrated a high adsorption capacity with respect to iron, depending on the structure, and could be arranged as AC > SKD-515 > ODM-2F. In SKD-515, iron adsorption occurred in micropores; in AC and ODM-2F, it took place in mesopores. The kinetics of iron extraction showed that the adsorption process was limited by external mass transfer. The research provided a new understanding of iron adsorption by materials of various structures. The conclusions were supported by scanning electron microscopy images. Initial concentration, flow velocity, and loading layer height were studied in dynamics, i.e., during continuous operation of the adsorption column. The system proved extremely effective and reached 99.0% Fe3+ extraction under the following conditions: flow rate = 1 L/min, loading column height = 0.15 m, column diameter = 0.05 m, initial concentration = 0.5 mg/L (5 MPC). The column performance was tested at an initial concentration of iron ions of 50 MPC, which simulated the wastewater treatment at industrial enterprises. This comprehensive study of iron adsorption from wastewater proved the efficiency of the mineral sorption materials with aluminosilicate of AC grade.

Lightweight pH-responsive chitosan hydrogel iron fertilizer: Efficient performance, controlled-release, and tomato application

Ensuring efficient iron absorption by crops is crucial in terms of high crop yields and food security. Bio-based materials effectively transport nutrients with minimal environmental impacts. Here, highly efficient lightweight iron fertilizers, CSG@Fe was prepared using chitosan hydrogels (CSG) as the adsorption carrier. Iron release from the various CSG@Fe preparations was slow under neutral conditions but rapid under acidic conditions. The effects of various cross-linking agents were investigated; 1.0 wt% genipin chitosan hydrogels iron fertilizer (GE-CSG@Fe) evidenced an excellent iron adsorption rate and a higher iron loading (326.15 mg/g) than the other two iron fertilizers. Iron release from CSG@Fe materials followed the Korsmeyer-Peppas model. Notably, wheat seed germination and tomato pot experiments revealed that GE-CSG@Fe significantly enhanced germination and growth. GE-CSG@Fe appropriately reduced the soil pH, protected ferrous ions from soil oxidation and rapid fixation, activated the soil microenvironment, and improved nutrient absorption by the roots of crops growing. This work provides a simple and effective strategy for overcoming constraints in the development and application of iron fertilizers and provides insights into the development of green and efficient iron fertilizers with intelligent response properties.

Diatom Chaetoceros Sp. as an Efficient Biological Antidote in Iron Toxicity: In‐Vitro and In‐Vivo Experiments

AbstractAll living organisms require mineral iron, but excess iron can lead to the production of free radicals and organ damage, such as liver damage in humans. This study investigated the diatom Chaetoceros sp. as an iron adsorbent in iron overload. First, the morphology and chemical composition of the diatom was characterized by spectroscopic and microscopic techniques. It was defined that diatoms have spherical particles with an average size of less than 2.0 μm. The affinity of diatoms for ionic Fe (II) uptake was evaluated. Fe (II) adsorption capacity was determined in vitro in two simulated intestinal and gastric aqueous media with pH values of 7.2 and 1.2. In both media, the diatom acted as a super‐adsorbent of Fe (II), while the highest adsorption occurred in a medium with a pH of 1.2. The correlation of the adsorption isotherm data was well studied with three well‐known equations, Langmuir, Fruindlich, and Redlich‐Peterson. The Langmuir model fitted the adsorption data best. The pseudo‐first‐order reaction model also provided a good fit for the adsorption kinetic data. In the in vivo study, the diatom was administered to iron‐overloaded rats. Biochemical parameters of organ damage and plasma Fe levels were determined at 2 h and 24 h intervals after diatom administration. The results show that diatoms can prevent acute iron poisoning by reducing plasma levels. Diatoms proved to be potent antidote agents in iron overdose conditions.

Chronoamperometric investigations on electrochemical synthesis of iron nitrides in molten salt system

A systematic investigation of the electrochemical iron nitride synthesis in a LiCl/KCl salt melt at 723 K shows an optimum of ϵ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon$$\\end{document}-Fe3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_3$$\\end{document}N1+x\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{1+x}$$\\end{document} formation in the range of 2.2 to 2.3 V and for γ′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\gamma '$$\\end{document}-Fe4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_4$$\\end{document}N between 2.4 and 2.5 V enabling the control of the desired iron nitride phase by setting the supplied terminal voltage. The product formation of iron nitrides starts when the electrochemical window is reached, which could be verified by linear sweep voltammetry. Hence, a maximum of nitrogen content in the formed iron nitride phases is observed for 2.27 V. During elongated synthesis periods, convection emerges as the predominant transport mechanism hindering an accelerated reaction rate with higher overpotential applied. Real-time analysis of the background current allows conclusions about the remaining nitride concentration. Additionally, there is concurrent iron nitride formation at the electrode surface through nitride adsorption and autonucleation-induced precipitation of iron and nitride ions. The analysis of the amount of sediment in comparison to the layer thickness of the nitrided working electrode suggests that the autonucleation mechanism dominates over the adsorption mechanism with increasing overpotential and can be further enhanced by this feature.Graphical abstract

Effects of low-molecular-weight organic acids on the transformation and phosphate retention of iron (hydr)oxides

The retention and mobilization of phosphate in soils are closely associated with the adsorption of iron (hydr)oxides and root exudation of low-molecular-weight organic acids (LMWOAs). This study investigated the role of LMWOAs in phosphate mobilization under incubation and field conditions. LMWOAs-mediated iron (hydr)oxide transformation and phosphate adsorption experiments revealed that the presence of LMWOAs decreased the phosphate adsorption capacity of iron (hydr)oxides by up to ~74 % due to the competition effect, while LMWOAs-induced iron mineral transformation resulted in an approximately six-fold increase in phosphate retention by decreasing the crystallinity and increasing the surface reactivity. Root simulation in rhizobox experiments demonstrated that LMWOAs can alter the contents of different extractable phosphate species and iron components, leading to 10 % ~ 30 % decreases in available phosphate in the near root region of two tested soils. Field experiments showed that crop covering between mango tree rows promoted the exudation of LMWOAs from mango roots. In addition, crop covering increased the contents of total phosphate and available phosphate by 9.08 % ~ 61.20 % and 34.33 % ~ 147.33 % in the rhizosphere soils of mango trees, respectively. These findings bridge the microscale and field scale to understand the delicate LMWOAs-mediated balance between the retention and mobilization of phosphate on iron (hydr)oxide surface, thereby providing important implications for mitigating the low utilization efficiency of phosphate in iron-rich soils.

Adsorption of iron and manganese from acid mine drainage by zalacca (Salacca zalacca) peel- activated carbon

The low pH and high metal concentration in acid mine drainage cause environmental problems and affect human health. Adsorption not only removes the pollutants but also increases pH levels. Natural adsorbents have gained attention because of their widespread availability, low cost, and effectiveness. Zalacca peel waste is among the biomass materials showing promise as activated carbon for removing contaminants from acid mine drainage. This study aims to investigate the adsorption capacity of activated carbon from zalacca peel for removing iron and manganese from acid mine drainage. Adsorption studies were conducted in batch experiments using various dosages and contact times. Optimal results were achieved with a dosage of 0.8 grams per 100 mL and contact time of 60 minutes, resulting in 80% removal efficiency for iron and 24% for manganese. The neutralization process occurred post-adsorption, bringing the final pH close to neutral levels, suitable for environmentally safe discharge. Experiment data were fitted to the Freundlich isotherm and pseudo-second order kinetics. FTIR analysis revealed functional groups including C-H, C-O, and C=C was found in the adsorbent. Furthermore, surface area and pore volume experienced slight increases following activation with KOH.

Enhancement of Mn2+, Fe2+ and NH4+-N removal by biochar synergistic strains combined with activated sludge in real wastewater treatment

Acinetobacter sp. AL-6 combining with biochar was adapted in activated sludge (AS & co-system) to decontaminate Mn2+, Fe2+ and NH4+-N, and treat activated sludge (AS) for its activity and settling performance improvement. Specifically, the co-system promoted the growth of bacteria in the activated sludge, thus increasing its ability to nitrify and adsorb Mn2+ and Fe2+, resulting in the removal of high concentrations of NH4+-N, Mn2+, Fe2+ and COD in the reactor by 100%, 100%, 100%, and 96.8%, respectively. And the pH of wastewater was increased from 4 to 8.5 by co-system also facilitated the precipitation of Mn2+ and Fe2+. The MLVSS/MLSS ratio increased from 0.64 to 0.95 and SVI30 decreased from 92.54 to 1.54 after the addition of co-system, which indicated that biochar helped to improve the activity and settling performance of activated sludge and prevented it from being damaged by the compound Mn2+ and Fe2+. In addition, biochar promoted the increase of the tyrosine-like protein substance and humic acid-like organic matter in the sludge EPS, thus enhanced the ability of sludge to adsorb Mn2+ and Fe2+. Concretely, compared with AS group, the proteins content and polysaccharides content of the AS & co-system group were increased by 13.14 times and 6.30 times respectively. Further, microbial diversity analysis showed that more resistant bacteria and dominant bacteria Acinetobacter sp. AL-6 in sludge enhanced the nitrification and adsorption of manganese and iron under the promotion of biochar. Pre-eminently, the more effective AS & co-system were applied to the removal of actual electrolytic manganese slag leachate taken from the contaminated site, and the removal of NH4+-N, Mn2+, Fe2+ and COD remained high at 100%, 100%, 71.82% and 94.72%, respectively, revealing advanced value for high engineering applications of AS & co-system.

Influence of Cations on Direct CO2 Capture and Mineral Film Formation: The Role of KCl and MgCl2 at the Air/Electrolyte/Iron Interface.

Uncovering the mechanisms associated with CO2 capture through mineralization is vital for addressing rising CO2 levels. Iron in planetary soils, the mineral cycle, and atmospheric dust react with CO2 through complex surface chemistry. Here, the effect of cations on the growth of carbonate films on iron surfaces was investigated. In situ polarized modulated infrared reflection absorption spectroscopy was used to measure CO2 adsorption and oxidation of iron in MgCl2(aq) and KCl(aq), compared to FeCl2(aq) at the air/electrolyte/iron interface. The cation was found to influence the film composition and growth rates, as corroborated by infrared and photoelectron spectroscopy. In MgCl2(aq), a mixture of hydromagnesite, magnesite, and a Mg hydroxy carbonate film was grown on iron, while in KCl(aq), a potassium-rich bicarbonate film was grown. The cations were found to affect the rates of hydroxylation and carbonation, confirming a specific cation effect on carbonate film growth. In the submerged region, a heterogeneous mixture of lepidocrocite and iron hydroxy carbonate was produced, suggesting that Fe2+ dominates the surface products. Surface roughness measurements from in situ atomic force microscopy indicate iron initially corrodes faster in MgCl2(aq) than KCl(aq), due to the Cl- ions that initiate pitting and corrosion. In this region, cations were not found to affect the morphologies. This study shows surface corrosion is necessary to provide nucleation sites for film growth and that the cations influence the carbonate film, relevant for CO2 capture and planetary processes.

Impact of design aspects on iron removal efficiencies from coal mine drainage in full-scale lagoons

In response to the potential ecological problems caused by coal mine drainage, passive Mine Water Treatment Schemes (MWTS), consisting of settlement lagoons and aerobic wetlands, are developed to remove iron and other contaminants prior to discharge into the environment. Existing research has examined individual design aspects separately, addressing the effect of lagoons' design on treatment performance. However, long-term research lacks data on the design aspects of full-scale mine drainage lagoons, to ensure consistent iron removal and optimal treatment of the mine drainage. This study analysed and assessed the design aspects of five full-scale lagoons, alongside monthly iron concentrations spanning over a period of twelve years, aiming to evaluate lagoon treatment performance based on different design aspects. Correlation and regression analyses were conducted to offer a better understanding of the potential relationships between iron removal efficiencies and the various design aspects of lagoons.Results indicated that the mean iron removal efficiencies of the lagoons studied, ranged from 25.12% to 92.85%, being impacted by the different design features. The correlation and multiple regression analysis results suggest that operational Water Levels, Surface Area, Aspect Ratio, layout and number of inlets and outlets, as well as shape of the lagoons affected iron removal (R2 0.78, p-value <0.05). Lagoons with larger aspect ratio were observed to have performed better in removing iron. In addition, a reduction in operational water level was observed to lead to increased iron removal. Furthermore, the result of the regression analysis demonstrated that the age of the lagoon significantly affects its treatment performance. Overall, lagoons with mid-mid configuration, multiple inlets and outlets and aspect ratio of 4 are found to allow for better flow and contaminant spread within the system, ensuring better adsorption and optimal removal of iron, although subject to regular ochre removal. This study offers valuable insights to lagoons design engineers, research scientists, policy makers and MWTS operators to optimize treatment performance.

Preparation and Modification of Biochar Derived from Agricultural Waste for Metal Adsorption from Urban Wastewater

This work evaluates the efficiency of three biochar samples toward the adsorption of manganese, iron, and selenium present in a sample of urban wastewater. The biochar was produced from the pyrolysis of rice husks at 350 °C for 6 h (RHB) and subsequently modified using HCl (RHBHCl) or NaOH (RHBNaOH) to increase its surface area. The RHBNaOH sample exhibited the highest removal efficiency for the three metals. The metals’ adsorption removal efficiency for RHBNaOH was in the order Mn (76%), Se (66%), and Fe (66%), while for RHBHCl, it was Fe (59%), Mn (30%), and Se (26%). The results show that the as-prepared RHB can remove the metals, even if in low amounts (Fe (48%), Mn (3%), and Se (39%)). The adsorption removal for the three types of adsorbents follows the Langmuir isotherm model. Pseudo-first-order and pseudo-second-order models were used to determine the adsorption mechanism for each of the three adsorbents. Both models showed a good fit with R2 (&gt;0.9) for the RHBNaOH and RHB sorption of Fe, Mn, and Se. Overall, this work demonstrates the potential of biochar for the removal of metals from real wastewater.

ADSORPTION OF IRON(III) IONS FROM SULFURIC ACID SOLUTIONS BY DOWEX G-26 RESIN (Н)

The adsorption of iron (III) from sulfuric acid solutions on a strongly acidic cation-exchange resin Dowex G-26 (H) has been studied. The factors influencing the adsorption of iron (III) have been investigated: solution pH, contact duration, adsorbent dose, initial concentration of iron (III) in solution. The obtained results show that Dowex G-26 (H) resin has a high exchange capacity for iron (III) ions from sulfuric acid solutions. Complete adsorption of iron (III) was achieved at pH2 (99%). Based on the experimental results, Langmuir and Freindlich adsorption isotherms have been constructed. Both isotherms fully describe the adsorption of iron(III) by the Dowex G-26 adsorbent. However, a comparison of the Langmuir correlation coefficient (R2=0.9098) with respect to Freundlich (R2=0.9915) shows that the Freundlich isotherm provides a better fit than the Langmuir isotherm. Quantitative and quantitative sorption properties of Dowex G-26 (H) relative to iron (III) have been investigated using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS). The maximum adsorption capacity (qm) for iron (III) was 166 mg/g at 250C. It has been shown that Dowex G-26(H) can be recommended as an adsorbent for sorption of Fe(III) from acidic solutions

Egg Shells as an Adsorbent for the Adsorption of Lead (Pb) and Iron (Fe) Metals

An eggshell is estimated to have around 10,000–20,000 pores; this condition created a chance for the eggshells to be used as an adsorbent. This research aims to activate egg shells used as an adsorbent. Egg shells were applied as an adsorbent in solutions of lead (Pb) and iron (Fe). Test parameters for adsorption capacity were carried out on the optimum mass and absorption contact time with lead (Pb) and iron (Fe) while using the eggshell waste as an adsorbent. The adsorbent quality of egg shells was tested using parameters such as ash content, water content, and adsorption capacity towards methyl blue. This research aims to utilize egg shells as an adsorbent to absorb lead (Pb) and iron (Fe) content using an adsorption process. There are 3 stages of a method for this research to establish: adsorbent preparation, adsorbent activation, and the adsorption process. The adsorption process was carried out with variations of the mass sample, which are 0.75 grams, 1 gram, 1.25 grams, 1.50 grams, and 2 grams and time variations when contact occurred in 20, 30, 40, 50, and 60 minutes. The outcome of this research showed that the highest adsorption capacity at the optimum mass of Pb metal was 1.5 grams at 98.914% and for Fe metal at 96.386%. The highest adsorption capacity results were influenced by Pb metal contact time in 40 minutes, which was 99.30%, and the best capacity for adsorption of Fe metal was at a contact time in 50 minutes, which was 99.82%.&#x0D;

Adsorption of Iron (II) ions from Simulated Industrial Wastewater utilizing Activated Carbon from Cogon Grass (Imperata Cylindrica)

Adsorption of Iron (II) ions from Simulated Industrial Wastewater utilizing Activated Carbon from Cogon Grass (Imperata Cylindrica)

Contrasted redox-dependent structural control on Fe isotope fractionation during its adsorption onto and assimilation by heterotrophic soil bacteria.

Despite the importance of structural control on metal stable isotope fractionation in inorganic and abiotic systems, the link between metal structural changes and related isotopic fractionation during reactions with organic surfaces and live cells remains poorly established. We conducted reversible adsorption of Fe(II) and Fe(III) on the surface of exopolysaccharide (EPS)-rich and EPS-poor Pseudomonas aureofaciens, and we allowed Fe intracellular uptake by growing cells. We analyzed the Fe isotopic composition of the remaining fluid and cell biomass, and compared the isotopic fractionation during adsorption and assimilation reaction with relative changes in Fe structural status between aqueous solution and bacterial cells, based on available and newly collected X-ray absorption spectroscopy (XAS) observations. Iron(III) adsorption onto P. aureofaciens at 2.8 ≤ pH ≤ 6.0 produced an enrichment of the cell surface in heavier isotopes with Δ57Fecell-solution ranging from +0.7 to +2.1‰, without a link to pH in EPS-rich cultures. In contrast, the magnitude of isotopic fractionation increased with pH in EPS-poor cultures. Iron(II) adsorption produced an even larger enrichment of the cell surface in heavier isotopes, by up to 3.2‰, tentatively linked to Fe(III) hydroxide precipitation. Intracellular assimilation of Fe(II) favored heavier isotopes and led to Δ57Fecell-solution of +0.8‰. In addition, Fe(III) cellular uptake produced an enrichment of the bacterial biomass in lighter isotopes with Δ57Fecell-solution of -1‰. The XAS analyses demonstrated the dominance of Fe(III)-phosphate complexes both at the cell surface and in the cell interior. We suggest that heavier isotope enrichment of the cell surface relative to the aqueous solution is due to strong Fe(III)-phosphoryl surface complexes and Fe complexation to ligands responsible for metal transfer from the surface to the inner cell. In case of Fe(II) adsorption or assimilation, its partial oxidation within the cell compartments may lead to cell enrichment in heavier isotopes. In contrast, loss of symmetry of assimilated Fe(III) relative to the aqueous Fe3+ ion and longer bonds of intracellular ions relative to aqueous Fe(III)-citrate or hydroxo-complexes could produce an enrichment of cells in lighter isotopes. The versatile nature of Fe(II) and Fe(III) fractionation without a distinct effect of pH and surface exopolysaccharide coverage suggests that, in natural soil and sedimentary environments, Fe isotope fractionation during interaction with heterotrophic bacteria will be primarily governed by Fe complexation with DOM and Fe redox status in the soil pore water.