Sorbent For Heavy Metals Research Articles

Lead Removal by Hydrochar from Hydrothermal Carbonization of Food Waste

Food waste recently emerged as a resource with a potential to be converted to hydrochar which could be utilized in various applications. In this study, we focused on investigation of the lead removal of hydrochar obtained from hydrothermal carbonization of food waste. Hydrochar was collected after hydrothermal liquefaction of food waste at 180°C for 2 h. The adsorption of hydrochar towards Pb 2+ in aqueous solution was conducted in batch mode to investigate the sorption kinetics, isotherm and pH edge. The results showed that hydrochar derived from food waste exhibits high performance in adsorption of lead from aqueous solution, achieving 160.21 mg g −1 removal capacity within the first 2 h of reaction. This indicated promising application as heavy metal sorbents of hydrochar from hydrothermal conversion of food waste.

Magnetite nanoparticles incorporated porous kaolin as a superior heavy metal sorbent for water purification

Water pollution has become one of the key global environmental problems. Heavy metal ions are major pollutants of water. Therefore, this research is focused on fabrication of high-efficient heavy metal adsorbing filter for water purification using low cost materials. The filtering material has been fabricated by incorporating co-precipitated magnetite nanoparticles into the micro-porous kaolin granules. The porosity of the magnetite nanoparticles incorporated kaolin granules (NPIKG) is obtained by burning well ground rice husk at 6500○C for 3 h. The synthesized NPIKG adsorbent efficiently adsorb heavy metal cations of lead and cadmium. The adsorption for Pb2+ and Cd2+ ions are evaluated according to a series of initial metal ion concentrations from 10.00 ppm to 100.00 ppm and contact time ranges from 2 h to 24 h for bare kaolin granules (KG) and NPIKG. Characterization of samples involved FTIR, XRD, AAS, SEM and TEM analytical techniques. Both types of adsorbents fitted well with Freundlich adsorption isotherm model than Langmuir isotherm. Adsorption capacity ranges of Pb2+ and Cd2+ for NPIKG according to Langmuir isotherm are 294–909 and 1111–3333 mg/kg respectively. Similarly, adsorption capacity ranges of Pb2+ and Cd2+ for KG are 256–555, 909–2500 mg/kg respectively. Iron leaching of the fresh NPIKG is zero and already used NPIKG is less than 2 mg/kg. Desorption of Pb2+ and Cd2+ ions is very low in NPIKG compared to KG adsorbent. Therefore, both types of kaolin adsorbents are suitable for heavy metal adsorption from polluted water for the purification of water.

Sorption of Heavy Metal Ions by Composite Materials Based on Polycarboxylic Acids and Bentonite Clay

The paper shows the study results of sorption capacities of composite gels based on polyacrylic and polymethacrylic acids with bentonite clay as the mineral filler concerning heavy metal ions (Pb+2, Cu+2, Ni+2, Zn+2, Fe+2, Cd+2). The binding of metal ions to gels occurs through the formation of electrostatic bonds between the charged surface of bentonite clay and ionogenic functional groups of polymers in the composition, as well as the coordination bonds between metal ions and unshared pairs of oxygen electrons in the functional groups of polymers. The gel swelling degree decreases in metal solutions with increasing metals concentration and the content of BC in the composite. The sorption and desorption of heavy metal ions from the polymer-clay composites from model solutions and samples of industrial wastewater from the Kazakhstani metallurgical plants were evaluated. The adjustment of the pH, the temperature of the medium and the clay content in the composite leads to increasing the degree of sorption and achieving regeneration of the used composite gels in certain media. The data obtained testify to the prospects of using these composites as effective sorbents of heavy metals from industrial wastewaters expanding the range of composite materials for wastewater treatment.

Crown Ethers: Selective Sorbents of Radioactive and Heavy Metals

Crown Ethers: Selective Sorbents of Radioactive and Heavy Metals

THE SORPTION CAPACITY OF MOSSES AND LICHENS OF ZAURALIE IN RELATION TO LEAD IONS

The purpose of the study is mosses and lichens of the Kurgan region for use as sorbents of heavy metals.
 The sorption of lead ions (II) is studied on the native and mechanochemically activated samples of true moss (Pleurozium schreberi), white moss (Sphagnum fuscum), lichen genus cladonia: cladoniaforest (Cladonia sylvatica) and cladonia horned (Cladonia cornuta), growing in the ecologically clean districts of Zauralie.
 The concentration of lead ions in model solutions has been measured ionometrically (ion-selective electrode – XC-Pb-001). The specific surface area of natural sorbents has been determined using the classical dynamic method of low-temperature adsorption of inert gases (Sorbi®-MS device).
 Sorption isotherms have been obtained. The sorption kinetics has been studied. Equilibration time varies from 30 to 45 min. It is shown that the maximum sorption of lead ions (is) on white moss (a=0.25 mmol/g). The mathematical treatment of sorption isotherms has been fulfilled, actual values of empirical constants of Freundlich’s and Langmuir’s equations and correlation coefficients have been calculated. Langmuir’s model is most suitable to describe the sorption processes.
 All the used sorbents are macroporous. The mechanochemical activation of moss and lichen with solid sodium hydrogen carbonate leads to an increase in the sorption of lead ions (II) by 2–3 times, which is an indirect confirmation of the ion-exchange mechanism of sorption.

Magnetoactive Compound Based on Humic Acid and Magnetite as a Sorbent for Heavy Metals

In the process of in situ synthesis using ultrasound, a magnetoactive sorbent based on humic acid and magnetite was produced for the extraction of heavy metals from industrial wastewater by magnetic solid-phase extraction. When exposed to ultrasound, substances are dispersed, which results in an increase in the specific surface area of the studied sorbent and the opening of inaccessible pores on its surface. Humic acid, which is part of the magnetoactive sorbent, is a stabilizer of the size of magnetite nanoparticles. The composition and sorption properties of a magnetoactive compound with respect to heavy metal ions Pb(II), Cu(II), Zn(II), Sr(II), Fe(III), and Al(III) were investigated. The dependence of the sorption value of the studied metal ions on the temperature and pH of the waste water was examined, the sorption capacity of the magnetoactive compound and the degree of waste water purification were determined. It was found that the maximum extraction of metal ions Pb(II), Cu(II), Al(III), Zn(II), Sr(II), Fe(III) from wastewater occurs at 25°C and pH 6.5, after additional sorption post-treatment, the content of Pb(II), Cu(II) and Zn(II) ions decreases by more than 15 times, and of Al(III), Pb(II), and Fe(III) ions, more than 12 times. The maximum degree of water purification from metal ions Pb(II), Cu(II), Al(III), Zn(II), Sr(II), and Fe(III) is 98.8, 83.1, 81.5, 78.1, 69.5, and 42.5%, respectively.

Studying glauconite of the bakchar deposit (Western Siberia) as a prospective sorbent for heavy metals

Glauconite is one of natural clay minerals that are low-cost and readily available. Its specific characters, including potassium cations activity, layered structure and absorption capacity, explain the comprehensive interest to this mineral. It is especially prospective in regard of water treatment. Glauconite composition depends on the formation conditions, which lead to different sorption properties. Here we studied the sorption parameters and physical characteristic of unique glauconite of the Bakchar deposit by mean of granulometric analysis, electromagnetic separation, X-ray fluorescence analysis, inductively coupled plasma-mass spectroscopy, petrographic studies, scanning electron microscopy, X-ray diffraction analysis, nitrogen thermal desorption method, inversion voltammetry. Finally, we tested this mineral as a sorbent. The studied glauconitic concentrate has the best comparative sorption properties. Results show that glauconite of the Bakchar deposit is a cheap and prospective sorbent for heavy metals.

Circular economy in olive oil production – Olive mill solid waste to ethanol and heavy metal sorbent using microwave pretreatment

Olive mill solid waste (OMSW) is an abundant agricultural waste without viable solution. The effects of OMSW different pretreatments (microwave or autoclave), different additives (water, formic, or sulfuric acid), and utilization of different saccharification enzymes (Cellic® CTec2 or Accellerase® 1500) were tested on saccharification process and sugar release, and on fermentation inhibitors formation and ethanol production. Microwave treatment with formic acid resulted in highest saccharification rates (90% of cellulose fraction) and fermentation yields (15.9 g/L ethanol), although loss of sugars and fermentation inhibitors production was notable. Microwave with water treatment resulted in less saccharification and ethanol (9.6 g/L). To facilitate economical process and to extract maximum value, solid remnants after saccharification were tested as heavy metal sorbent. Microwave with water resulted in the best sorbent, followed by microwave with formic acid. Addition of sulfuric acid, to either microwave or autoclave, resulted in very poor saccharification and absorbance capacity. Therefore, combination of ethanol and sorbent production from OMSW are suggested.

Sorption properties of new fibrous chelate ion exchanger

The sorption properties of new iminodiacetate fibrous cation exchanger FIBAN XC-1 synthesized on a chemically resistant matrix of polypropylene fiber with a grafted copolymer of styrene and divinylbenzene, which can withstand elevated temperatures and aggressive environments, were studied. It was shown that the fibrous chelate ion exchanger FIBAN XC-1 is an effective sorbent of heavy and non-ferrous metals from multi-ionic aqueous solutions under static and dynamic conditions. It was found that the cation exchanger operates at high speeds up to 20 column volumes / min in water purification from copper and lead ions (purification from Cu2+ – 82 % and purification from Pb2+– 65 %). It was found that the fibrous chelate ion exchanger FIBAN XC-1 is easily regenerated and does not lose its sorption and mechanical properties in the sorption– regeneration cycles.

Formation of Fe(III)-phosphonate Coatings on Barium Hexaferrite Nanoplatelets for Porous Nanomagnets.

Amorphous coatings formed with mono-, di-, and tetra-phosphonic acids on barium hexaferrite (BHF) nanoplatelets using various synthesis conditions. The coatings, synthesized in water with di- or tetra-phosphonic acids, were thicker than that could be expected from the ligand size and the surface coverage, as determined by thermogravimetric analysis. Here, we propose a mechanism for coating formation based on direct evidence of the surface dissolution/precipitation of the BHF nanoplatelets. The partial dissolution of the nanoplatelets was observed with atomic-resolution scanning transmission electron microscopy, and the released Fe(III) ions were detected with energy-dispersive X-ray spectroscopy and electron energy loss spectroscopy in amorphous coating. The strong chemical interaction between the surface Fe(III) ions with phosphonic ligands induces the dissolution of BHF nanoplatelets and the consequent precipitation of the Fe(III)-phosphonates that assemble into a porous coating. The so-obtained porous nanomagnets are highly responsive to a very weak magnetic field (in the order of Earth’s magnetic field) at room temperature, which is a major advantage over the classic mesoporous nanomaterials and metal–organo-phosphonic frameworks with only a weak magnetic response at a few kelvins. The combination of porosity with the intrinsic magneto-crystalline anisotropy of BHF can be exploited, for example, as sorbents for heavy metals from contaminated water.

Disulfide polymer grafted polypropylene/polyethylene filter media for selective cadmium removal

Heavy metal pollution caused by stormwater runoff has triggered a demand for effective heavy metal sorbents. Effective heavy metal removal using conventional stormwater runoff treatment processes that employ filtration mechanisms as primary removal mechanisms is difficult. Therefore, we attempt to improve cadmium removal performance by attaching disulfide polymer (DiS−COP) containing soft bases, thiols, onto the surface of polypropylene/polyethylene (PP/PE) fiber media, which is widely used for stormwater runoff treatment. Material characterization demonstrated that DiS−COP was successfully grafted and grown on the surface of PP/PE (Dis-PP/PE). The batch and continuous flow adsorption capacities of Dis-PP/PE were 81.1 mg/g and 2.33 mg/g, respectively, which is 40 times higher than those of pristine PP/PE. Applicability of DiS-PP/PE at pH 6–8 was demonstrated, and effects of calcium and humic acid on cadmium adsorption were investigated. Calcium marginally affected cadmium adsorption, which can be explained using the Hard and soft (Lewis) acids and bases theory (HSAB), but cadmium removal efficiency decreased owing to humic acid (HA)-Cd complex formation and agglomeration in the presence of organic material. In a breakthrough test, the adsorption column exhibited complete cadmium uptake over 24 h until it reached the breakthrough point. Therefore, heavy metal adsorption performance of PP/PE was successfully enhanced by grafting DiS−COP on its surface.

Апробация технологии выявления и коррекции элементозов молочных коров по элементному составу шерсти

Abstract. The study is aimed at assessing the effectiveness of a new technology for the diagnosis and correction of dairy cattle elementoses according to the chemical composition of hair, using elementoses of various etiologies. Methodology and methods. The experimental design included two studies: the first is a micropopulation of the Simmental cows with a deficiency of calcium, zinc, selenium and manganese in hair; the second is Black Spotted cows with a significant excess in the established standards for lead and cadmium against the background of a deficiency of calcium, zinc, selenium and copper. Based on a comparison of data after initial analysis of hair according to 25 parameters with physiological norm intervals a mineral premix consisting of organic forms of limited chemical elements was included in the diet for animals in the first and second experiments. In order to optimize lead and cadmium pools, sorbent of heavy metals was additionally included in the diets of experimental animals in the second experiment. Results and practical relevance. Feeding with corrective additives in the diets led to the normalization of elemental status for the vast majority of elements in both experiments. Moreover, cows in the first experiment had an increase in the yield of milk and milk fat by 7.2 % during the lactation period; in the second experiment, an increase in the number of fruitful inseminations was registered, it was accompanied by a decrease of calving interval and service periods by 4.5 and 17.7 %, with an increase in the calf yield. Scientific novelty. For the first time, the elemental profile of dairy cattle was described using distiller’s grain in feeding; the technology for identifying and correction of dairy cattle elementoses based on data of hair elemental composition has been developed in production conditions.

EXPRESS EVALUATION OF SORPTION MECHANISM ON PEAT CONTAINING MATERIALS

Peat is an effective sorbent of heavy metals, which is due to its high cation-exchange ability. The use of peat sorbents has many advantages. It is an inexpensive, affordable, and effective sorbent for a wide range of environmental pollutants. Also, it can be used either separately or as a combined sorbent and complex constituents; however, it also has several disadvantages, such as insufficient mechanical strength and low chemical stability of peat particles. To overcome these shortcomings, various methods of peat modification have been developed (e.g., peat modified with chitosan, which is used as a sorbent for heavy metals removal like peat). The ion-exchange sorption properties of sorbents on the base of peat and chitosan - modified peat were evaluated by the method of pH meter. An acid-activated peat sample was also investigated. The experiments were carried out in a static mode using natural peat samples taken from the Lake Sevan (near the city of Vardenis of the Gegharkunik region of the Republic of Armenia). Also, a similar study was conducted on KU-2-8 cation exchange resin. The purpose of this article was the express evaluation of the sorption mechanism of peat sorbents. Cation exchanger was transferred to the H+ form by treatment with HCl (1N). Changes in the pH profile as a function of the exposure time indicate their identity with the pattern of the pH change of the cation exchanger. It was found that acid activation of peat (exposure of a peat sample in HCl 1N for 10-16 hours) increases its adsorption capacity. In this case, the maximum decrease in pH is pH = 2.33, which is 1.44 points lower than for peat (pH = 3.77) and 0.95 points more than for KU-2-8 cationite. This indicates that sorbents based on peat can be regenerated. Chitosan-modified peat exhibits deterioration in sorption capacity. In this case, pHmin = 3.9, which shows that sorption on chitosan is not ion-exchange in nature.

Highly efficient adsorption of Pb(II) by cubic nanocrystals in aqueous solution: Behavior and mechanism

As one of the most toxic heavy metal ions, lead pollution has become an urgent problem. Here, a cubic crystal nanoparticle (Prussian blue analogue, PBA), referred to as potassium manganese ferrocyanide (KMFC) was synthesized and used as a highly-effective sorbent for removing Pb(II) from aqueous solution. KMFC is a mesoporous material that has excellent ion exchange properties, which was confirmed by a series of characterizations. This paper investigated the adsorptive attributes of KMFC for lead ions in aqueous solution. The influences of temperature, contact time and pH on adsorption were studied in batch experiments. The KMFC possessed a robust adsorption capacity for resident lead ions in aqueous solution, which attained 1075.27 mg g−1 at room temperature (25 °C), based on the Langmuir model, which was far higher than any previously reported values. The adsorption process was well fitted to a pseudo-second-order kinetic model, as well as Langmuir and Temkin isotherm models, and was endothermic and spontaneous on the basis of thermodynamic analysis. The adsorption of Pb(II) on the surface of KMFC started with electrostatic attraction, due to the electronegativity of KMFC. Further, ion exchange was the dominant mechanism in this adsorption process, which was confirmed by FTIR, XPS, and other supplementary experiments. The good chemisorption (K+ exchange) properties of KMFC suggested that it likely has excellent prospects in applications for heavy metal ions adsorption. This study not only provided a new perspective for the design and development of heavy metal sorbents but provided a deep insight into the mechanism of adsorption of heavy metal ions by PBA.

The Effect of Thermomechanical Pretreatment on the Structure and Properties of Lignin-Rich Plant Biomass.

The cooperative thermomechanical properties of plant-derived polymers have been studied insufficiently, although this feedstock has a very high potential. In the present paper, we analyzed the changes in the structure and physicochemical properties of lignin-rich biomass induced by thermomechanical pretreatment. Low-temperature treatment allows one to retain the original supramolecular structure of the cell walls, while an appreciably high disintegration degree is reached. This increases the reactivity of the material in the subsequent heterogeneous reactions. Mechanical pretreatment at medium temperatures (10 °C), when almost all cell wall polymers except for low-molecular-weight lignin are in the glassy state, enhances the mobility of cell wall polymers and causes sufficient cellulose disordering, while the specific surface area is not significantly increased. High-temperature pretreatment of reed biomass is accompanied by pore formation and lignin release from the cell wall structure, which opens up new prospects for using this biomass as a matrix to produce core–shell-structured sorbents of heavy metals. The energy consumed by mechanochemical equipment for the activation of reed biomass was determined.

Scaling up the Mechanochemical Technology for Producing Materials Enriched in Humic Acids

Mechanochemical treatment is widely used in industry as it allows one to reduce the number of processing stages, either reduce or completely eliminate the use of solvents, automate the technology and ensure its mobility. Energy input is an important parameter of mechanochemical treatment. In this study, the technology of mechanochemical oxidation of brown coal was scaled up using the planetary mills of AGO-2 and APF types, as well as K-7 and CEM-20 flow-type vibrocentrifugal mills. The technology of mechanochemical oxidation of brown coal makes it possible to increase the availability of humic acids in brown coal and the content of oxygen-bearing groups capable of complexation, as well as to improve sorption characteristics of the resulting product. Materials enriched in humic acids can be used as heavy metal sorbents in water bodies and as agents for soil amelioration. The rotor speed of 1400 rpm and the feed rates of 15 kg/h and 1.8 kg/h for CEM-20 and for K-7 vibrocentrifugal mills, respectively, are the optimal modes from the point of view of chemical and economic efficiency. These modes increase the yields of alkali-soluble and water-soluble humic acids from 23 to 59 % and from <1 to 7%, respectively, which corresponds to the values reached using the laboratory-scale equipment.

Designing Cor–Shell Materials Using Humic Acids

Due to the high content of complexing moieties, humic acids are promising compounds for designing heavy metal sorbents that can be used in natural environment objects. Experiments focused on designing sorbent particles containing a humic shell and a core (that is supposed to impart the desired performance characteristics to the particle) and applying humic acids onto various materials were conducted. It is demonstrated that the sorbent with a “lignocellulosic core–humic shell” structure can be produced mechanochemically. The efficiency of humic acid binding to lignocellulosic materials directly correlates with lignin content within lignocellulosic materials. A method for passing lignin from the surface of lignocellulosic biomass into the solution using humic acids is found. Unmodified highly lignified biomass is the optimal material for applying humic acids onto lignocellulosic materials.

Reuse potential of residues of artichoke (Cynara scolymus L.) from industrial canning processing as sorbent of heavy metals in multimetallic effluents

The suitability of reusing artichoke agrowaste biomass from industrial canning processing as a low-cost and ecofriendly sorbent for the bioremoval of Pb(II), Cd(II) and Cu(II) in multi-metallic aqueous solutions is reported. Understanding the dynamic of heavy metals in the sorption process is critical to assess the removal of these contaminants in aquatic systems. The Taguchi approach was used to design a series of experiments to find the optimum conditions for maximum total sorption capacity, analysing the signal-to-noise (S/N) ratio to assess the experimental responses. Ranks of five controllable factors (the initial concentrations of Pb(II), Cd(II) and Cu(II), sorbent dosage and pH), at three levels each one, in a L27 array were conducted in batch sorption tests. The highest sorption capacity (241 μmol·g−1) was shown with initial concentrations of 315 μmol L−1 Cu(II), 445 μmol L−1 Cd(II) and 241 μmol L−1 Pb(II), pH 5 and 0.5 g L−1 of sorbent dosage. The metal ion predominantly adsorbed was Pb(II). Adsorption kinetics followed a pseudo-second order model. The study of the shares of each metal ion on the total sorption capacity revealed that Cd(II) is actually prone to be adsorbed but the presence of Pb(II) and Cu(II) hinders its adsorption. The valorization of artichoke agrowaste biomass as metal sorbent is considered a way to assist in the promotion of a circular economy.

Sorption of Molybdates and Tungstates on Functionalized Montmorillonites: Structural and Textural Features.

Montmorillonite—the most popular mineral of the smectite group—has been recognized as a low-cost, easily available mineral sorbent of heavy metals and other organic and inorganic compounds that pollute water. The aim of this work was to determine the sorption mechanism and to identify the reaction products formed on the surface of montmorillonite and organo-montmorillonite after sorption of molybdates (Mo(VI)) and tungstates (W(VI)). Montmorillonites are often modified to generate a negative charge on the surface. The main objective of the study was to investigate and compare the features of Na-montmorillonite (Na-M), montmorillonite modified with dodecyl trimethyl ammonium bromide (DDTMA-M), and montmorillonite modified with didodecyl dimethyl ammonium bromide (DDDDMA-M) before and after sorption experiments. The material obtained after sorption was studied by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The XRD pattern showed the presence of a new crystallic phase in the sample that was observed under an SEM as an accumulation of crystals. The FTIR spectra showed bands related to Mo–O and W–O vibration (840 and 940 cm−1, respectively). The obtained results suggest that molybdenum(VI) and tungsten(VI) ions sorb onto the organo-montmorillonite in the form of alkylammonium molybdates and tungstates.

Synthesis and investigation of properties of new chelate sorbent for water purification

Polymer analogous transformations of a “nitron” fiber were established and a new amino carboxylic fibrous cation exchanger FIBAN X-2 was obtained. It is shown that FIBAN X-2 is an effective sorbent of heavy and non-ferrous metals from multi-ionic aqueous solutions, regardless of the method of fiber amination. The cation exchanger obtained by amination of a “nitron” fiber in the vapor phase absorbs Mn+2 twice as much as the ion exchanger obtained by amination in the aqueous solution.