Sorption Capacity For Ions Research Articles

INFLUENCE OF WASTEWATER TREATMENT TECHNOLOGY AND SLUDGE STABILIZATION ON THE SORPTION CAPACITY OF SEWAGE SLUDGE

This article investigates the influence of sewage sludge treatment processes and stabilizationmethods on metal-binding capacity and susceptibility to metal remobilization from sewagesludge. The materials (stabilized sewage sludge) were collected from two mechanical-biologicalsewage treatment plants located in an industrial area in southern Poland (Silesian Province):1) one with nutrient removal (nitrogen and phosphorus) and anaerobic sludge digestion (WWTPIII),and 2) a facility without nutrient removal and with aerobic sludge stabilization (WWTP-II).Concentrations of PTEs in sewage sludge samples were measured using the inductively coupledplasma optical emission spectrometry (ICP-OES). Sewage sludge from WWTP-III showeda significantly higher sorption capacity for Cu ions (20–50%) and Ni ions (50% to 2.5-fold) ascompared to sewage sludge from WWTP-II. However, sewage sludge from WWTP-II exhibiteda higher sorption capacity for Cd ions. The studied potentially toxic elements (PTEs), irrespectiveof anion type, formed unstable bonds with sewage sludge, which may lead to their desorption intothe environment. The high mobility of Cd, Cu, Ni and Zn ions in chloride and sulphate system, aswell as the low susceptibility to Cr ion release, should be considered in various applications of thetested sewage sludge.

3D Printing and Blue Sustainability: Taking Advantage of Process-Induced Defects for the Metallic Ion Removal from Water.

Additive manufacturing (AM), commonly known as 3D printing, allows for the manufacturing of complex systems that are not possible using traditional manufacturing methods. Nevertheless, some disadvantages are attributed to AM technologies. One of the most often referred to is the defects of the produced components, particularly the porosity. One approach to solving this problem is to consider it as a non-problem, i.e., taking advantage of the defects. Commercially, LAY-FOMM®60 polymer was successfully used in AM through a material extrusion process. This filament is a blend of two polymers, one of them soluble in water, allowing, after its removal from the printed components, the increase in porosity. The defects produced were exploited to evaluate the metallic ion removal capacity of manufactured components using non-potable tap water. Two experimental setups, continuous and ultrasound-assisted methods, were compared, concerning their water cleaning capacity. Results revealed that continuous setup presented the highest metallic ion removal capacity (>80%) for the following three studied metallic ions: iron, copper, and zinc. High water swelling capacity (~80%) and the increase in porosity of 3D-printed parts played a significant role in the ion sorption capacity. The developed strategy could be considered a custom and affordable alternative to designing complex filtration/separation systems for environmental and wastewater treatment applications.

Experimental and theoretical study for the sorption of Ni2+ and Cd2+ onto phosphoryl functionalized aluminum silicate composite

Phosphoryl functionalized Aluminum silicate (ASP) composite sorbent was synthesized using sol–gel technique and characterized with different techniques. The synthesized sorbent was tested for the sorption of Ni2+ and Cd2+ in aqueous solution at both single- and binary-solute systems under simulated conditions using batch technique. Batch experiments were executed as a function of pH, initial metal ion concentration and temperature. Structural and surface morphology of the synthesized sorbent were determined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The studied kinetic models suggested that the sorption of Ni2+ and Cd2+ onto ASP was found to follow the pseudo-second order and the Langmuir-Freundlich model was the best model to depict the sorption isotherms. The sorption equilibria of both ions were analyzed using two diverse statistical physics models (homogeneous and heterogeneous monolayer models). A Theoretical scrutiny of statistical physics calculations indicated that Ni2+ and Cd2+ sorption was multi-ionic where two sorption sites were involved but with a diverse contribution degree. The removal nature of Ni2+ and Cd2+ was endothermic and the calculated sorption amounts at saturation implied that Ni2+> Cd2+. Calculated interaction energies indicated the participation of physical forces in the sorption of both ions onto the synthesized sorbent surface and the variation of these sorption energies confirmed that both sorption sites participated in the removal of Ni2+ and Cd2+ but through different interactions type. Ions sorption capacity was increased with the temperature owing to increase in thermal agitation. This study reveals that phosphoryl functionalized aluminum silicate is an efficient sorbent that can be used for the sorption of Ni2+ and Cd2+ from aqueous solutions in both single- and binary -solute systems.

Investigation of the structure and morphology of modified materials based on polyvinyl chloride

The use of polyvinyl chloride in practice is associated with many difficulties due to the hydrophobic nature of the polymer surface. This can lead to great adverse consequences when used in technological processes of the chemical industry and hydrometallurgy. Due to its high hydrophobicity and low surface free energy, PVC has a low degree of wettability with water, resulting in low ion sorption capacity, as well as undesirable protein absorption and bacterial adhesion. The aim of the work was to increase the hydrophilicity of the surface of industrially produced powdered PVC by modifying it with various organic amines and, as a result, hydrophilic ion-exchange materials of various structures and morphology will be obtained on its basis. The course of the reactions was studied by potentiometric titration, IR spectroscopy, and diffractionometry. The correlation between the morphology and chemical properties of the products obtained in the studied reactions and the formation of new covalent bonds in the structure of the polymer matrix was investigated using IR spectroscopy and diffractionometry. The influence of the nature of the modifying reagent, solvent and temperature on the modification process has been established.

Influence of Natural Clinoptilolite Modification with Ions and Zero-Valent Silver on Its Sorption Capacity

Areas of use of natural clinoptilolite were analyzed. The emphasis was placed on its application in water technology and medical practice. The results of the study of the dehydration of clinoptilolite at different temperatures were presented. The influence of the activation temperature of clinoptilolite on its sorption capacity for silver ions was determined. The effect of modification with ions and highly dispersed silver particles on the sorption capacity of various zeolite fractions with respect to water was investigated.

Recovery of rhodium from glacial acetic acid manufacturing effluent using cellulose-based sorbent

Rhodium (Rh) is a rare and highly demanded metal in metallurgy, making its efficient recovery from waste streams essential. However, there is a lack of detailed studies on the recovery of Rh from acidic waste effluents using biosorbents. This study aims to extract RhIII from acidic effluents using dithiocarbamate-modified cellulose (DMC) as a biosorbent, and subsequently recover the extracted Rh in its elemental form (Rh0). The parameters affecting the RhIII extractability of DMC, such as solution pH, acid concentration, Cl− ion concentration, contact time, and sorption capacity at different temperatures, were optimized. The sorption kinetics of RhIII onto DMC was best fitted to the pseudo-second-order (PSO) model, the equilibrium sorption isotherm data fitted well with the Langmuir model. DMC had a maximum sorption capacity of 2.57 mmol g−1, which is substantially higher than that reported in previous studies. Waste effluent (Rh-containing glacial acetic acid) obtained from the acetic acid manufacturing industry was used to assess the applicability of DMC in capturing RhIII from a real sample. DMC was capable of sorbing approximately 90 % of RhIII from the real sample of Rh-containing glacial acidic acid. The sorbed RhIII was recovered in elemental form (Rh0) by incineration of RhIII-loaded DMC, yielding >99 %. The sorption of RhIII onto DMC followed a chemisorption mechanism that was confirmed by sorption experiments, Fourier-transform infrared spectroscopy (FTIR), and X-ray absorption spectroscopy (XAS) analyses. This study demonstrates the applicability of DMC in the efficient recovery of Rh from waste streams.

Green synthesis and characterization of iron oxide nanoparticles for the removal of heavy metals (Cd2+ and Ni2+) from aqueous solutions with Antimicrobial Investigation

Clove and green Coffee (g-Coffee) extracts were used to synthesize green iron oxide nanoparticles, which were then used to sorb Cd2+ and Ni2+ ions out of an aqueous solution. Investigations with x-ray diffraction, Fourier-transform infrared spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption and desorption (BET), Zeta potential, and scanning electron microscopy were performed to know and understand more about the chemical structure and surface morphology of the produced iron oxide nanoparticles. The characterization revealed that the main component of iron nanoparticles was magnetite when the Clove extract was used as a reducing agent for Fe3+, but both magnetite and hematite were included when the g-Coffee extract was used. Sorption capacity for metal ions was studied as a function of sorbent dosage, metal ion concentration, and sorption period. The maximum Cd2+ adsorption capacity was 78 and 74 mg/g, while that of Ni2+ was 64.8 and 80 mg/g for iron nanoparticles prepared using Clove and g-Coffee, respectively. Different isotherm and kinetic adsorption models were used to fit experimental adsorption data. Adsorption of Cd2+ and Ni2+ on the iron oxide surface was found to be heterogeneous, and the mechanism of chemisorption is involved in the stage of determining the rate. The correlation coefficient R2 and error functions like RMSE, MES and MAE were used to evaluate the best fit models to the experimental adsorption data. The adsorption mechanism was explored using FTIR analysis. Antimicrobial study showed broad spectrum antibacterial activity of the tested nanomaterials against both Gram positive (S. aureus) (25923) and Gram negative (E. coli) (25913) bacteria with increased activity against Gram positive bacteria than Gram negative one and more activity for Green iron oxide nanoparticles prepared from Clove than g-Coffee one.

Optimization of Lead and Diclofenac Removal from Aqueous Media Using a Composite Sorbent of Silica Core and Polyelectrolyte Coacervate Shell.

The modification of inorganic surfaces with weak cationic polyelectrolytes by direct deposition through precipitation is a fast approach to generating composites with high numbers of functional groups. The core/shell composites present very good sorption capacity for heavy metal ions and negatively charged organic molecules from aqueous media. The sorbed amount of lead ions, used as a model for priority pollutants such as heavy metals, and diclofenac sodium salt, as an organic contaminant model for emerging pollutants, depended strongly on the organic content of the composite and less on the nature of contaminants, due to the different retention mechanisms (complexation vs. electrostatics/hydrophobics). Two experimental approaches were considered: (i) simultaneous adsorption of the two pollutants from a binary mixture and (ii) the sequential retention of each pollutant from monocomponent solutions. The simultaneous adsorption also considered process optimization by using the central composite design methodology to study the univariate effects of contact time and initial solution acidity with the purpose of enabling further practical applications in water/wastewater treatment. Sorbent regeneration after multiple sorption-desorption cycles was also investigated to assess its feasibility. Based on different non-linear regressions, the fitting of four isotherms (Langmuir, Freundlich, Hill, and Redlich-Peterson models) and three kinetics models (pseudo-first order (PFO), pseudo-second order (PSO), and two-compartment first order (TC)) has been carried out. The best agreement with experiments was found for the Langmuir isotherm and the PFO kinetic model. Silica/polyelectrolytes with a high number of functional groups may be considered efficient and versatile sorbents that can be used in wastewater treatment processes.

Selective Recovery of Gold from Electronic Waste by New Efficient Type of Sorbent.

Modular connectors are applied by computer users, and they can be metallic secondary sources containing metals such as gold and copper. Because gold is a micro-component, the solution obtained after the pin digestion contains a low concentration of gold(III) ions, and efficient and selective sorbent should be used for gold(III) ion recovery. The selective removal of small amounts of gold(III) from 0.001-6 M hydrochloric acid solutions using pure and solvent-impregnated macroporous polystyrene crosslinked with divinylbenzene sorbents (Purolite MN 202 and Cyanex 272) is presented. Gold(III) ions were recovered effectively from the chloride solution after the digestion of the modular connector RJ 45 (8P8C) using Purolite MN 202 after the impregnation process. The dependence of the recovery percentage (R%) of gold(III) on the contact time was determined. The highest value of gold(III) ion sorption capacity (259.45 mg·g-1) was obtained in 0.001 M HCl for Purolite MN202 after the Cyanex 272 impregnation. The results can be applied to gold recovery from e-waste. The presented method of gold recovery does not generate nitrogen oxides and does not require the use of cyanides.

Biosorption of heavy metal ions by the cell walls of yeast Saccharomyces cerevisiae in their combined presence

By the stationary method ions biosorption Pb(II), Cd(II) and Cu(II) in di-and tri- ionic systems is studied. It is shown that the presence of extraneous ion in solution leads to a reduction (inhibition) of biosorbent sorption capacity. It is set that ion Pb (II) has the best adsorption capacity as in the case of individual ions, and in di- and tri-ionic systems. The explanation of this phenomenon from the point of the Lewis-Pearson theory of the nature of the specific binding of “hard” and “soft” ion-complex with the appropriate ligands - unctionally active groups of biopolymers budding fungi cell walls is given. It is offered that the relative electronegativity of the element on the Pauling scale can be an indicator of the relative sorption capacity of heavy metal ions.

Lead Ion Sorption Capacity and the Structural Properties of the Humic Acid Extracts from Evergreen Forests of Different Agro-ecological Zones of Kerala Western Ghats

Forest soils are enriched with soil carbon content. The vegetation and precipitation influences it’s chemical structure. The chemical structure directly contributed to its entire properties. Physico-chemical properties play vital role in its soil functioning. The sorption capacity of the humic acid can be applied in the nutrient uptake enhancement and waste water treatment. The study was conducted in the humic acid extract of evergreen forest of different agro-ecological zones of Kerala. Extraction was done by the acidic precipitation method recommended by International Humic Substance Society (IHSS). Determine the chemical structural variations and properties of the humic acid extracts followed by determining the sorption capacity of the material with lead ion. The study revealed the higher percentage of adsorption of lead ion with humic acid extract from evergreen forest of northern high hills –charnockite zone of western ghats of Kerala. This was the combined effect of enhanced cation exchange capacity and –COOH acidity of the material. These chemical structure and the functional properties to the sorption capacity of the humic acid extract to chelate the lead ion was evaluated .The higher cation exchange capacity and the –COOH acidity favoured the lead ion adsorption. Adsorption isotherm modeling was revealed the multilayer and monolayer adsorption of lead ion on humic acid depends with the heterogeneity of the HA surfaces. Maximum amount of lead ion molecule adsorbed on the HA surface was observed for humic acid from SHH-K agro-ecological zone. This method can be considered as economically viable green method for looking forward technology for waste water treatment.

Фиторемедиация почв, загрязненных ионами тяжелых металлов, с помощью древесных и кустарниковых растений

The use of woody and shrubby plants with a developed root system and a large biomass in the technology of phytoremediation of soils contaminated with heavy metals is analyzed. Woody plants can be used in the process of phyto-recovery of urban systems as long-term absorbers of heavy metal ions from the soil. The main mechanisms of phytoremediation of contaminated urban areas with the help of trees and shrubs are considered. The sorption capacity of cobalt, manganese and chromium ions by some species of woody and shrubby plants has been studied. The accumulation of heavy metals by seedlings under conditions of soil contamination with cobalt, manganese and chromium ions was studied. The transfer factor of cobalt, manganese and chromium ions was determined for the studied plant species. Species-hyperaccumulators of heavy metals, Gleditsia triacanthos L., Caragána arboréscens L., have been identified, which can be used for phytorestoration of soils of the technogenic region contaminated with cobalt, manganese and chromium ions. Low concentrations of cobalt, manganese and chromium were noted in the seedlings of Quercus robur L. and Robinia pseudoacacia L. in the aerial part, which indicates their ability to exclude heavy metal ions from their aerial parts. It has been established that seedlings of Gleditsia triacanthos L., Caragána arboréscens L., resistant to soil pollution, due to their excellent adaptability, even on degraded and contaminated with heavy metals soil of the experimental plot, have a high level of biomass accumulation without reliable facts of inhibition of growth processes. During the controlled process of phytoremediation carried out in the field, their high sorption capacity was noted, which makes it possible to recommend these species for use in technologies for the restoration of soils contaminated with heavy metal ions.

Use of lupine flour and cavbuz puree in bread technology

Introduction. The influence of vegetable additives: сavbuz (a hybrid of watermelon and pumpkin) puree and flour of non–alkaloid lupine on the nutritional and biological value of wheat bread, its sorption capacity in relation to toxic lead ions was studied. Materials and methods. Content of following substances was determined: proteint by Bradford method; starch by polarimetric method; fat by exhaustive extraction with chemically pure hexane; vitamins E, P (rutin), β–carotene colorimetrically; vitamin C titrimetrically; В1, В2 fluorometrically; fiber by acid hydrolysis; pectin by the calcium–pectate method; te amount of lead absorbed by “wet burning” method. Results and discussion. Cavbuz puree is a rich source of substances with antioxidant activity: β-carotene, 13.4 mg, Р (rutin), 45.4 mg, phenolic compounds, 283.23 mg, as well as natural food sorbents such as fiber 1.7% and pectin, 1.5% per 100 g of product with moisture content 83.1%. According to sensory and physico-chemical characteristics, cavbuz puree may be used as a component in the manufacturing of health products. Lupine flour contains 3.9 times more protein, 40 times more fiber, 10.5 pectin substances compared to wheat flour; a significant amount of tocopherols, 12.8 mg, β-carotene, 0.52 mg, vitamin C, 35.84 mg per 100 g of product with moisture content 9.5%. The inclusion of 4-7% of lupine flour and 3–5% of cavbus puree in the recipe of wheat bread, makes it possible to obtain bread for health purposes, in which the protein content is 22–32%, fiber content is two to three times higher, tocopherols are 9 times higher than in control, provided that the physico-chemical and organoleptic parameters of the product are acceptable. 100 g of developed bread provides 23% of the minimum rate of pectin consumption, 6% of the daily need for vitamin E; 13.8% in В1, 14% in β–carotene; 6.6% in flavonoids, which are absent in wheat bread. Enriched bread has a 25–30 times higher sorption capacity for toxic divalent lead ions than wheat bread. Conclusions. It is recommended to use of cavbuz puree and flour of non–alkaloid lupine varieties for the production of wheat bread with increased nutritional value.

Coagulation removal of nickel (II) ions by ferric chloride: Efficiency and mechanism.

Removal of heavy metal ions, in particular, divalent nickel ions from natural and wastewater, is of great importance for the environment. Nickel (II) ions are very toxic and provoke many diseases. The purpose of this work was to study the possibility of removing toxic nickel (II) ions from polluted water using an iron (III) chloride (FeCl3) coagulant. It is shown that the removal of nickel ions from aqueous solution by iron (III) hydroxide precipitate formed during the coagulation process at pH7 and 8 is described with satisfactory accuracy by the classical adsorption isotherms of Freundlich, Langmuir, and Dubinin-Radushkevich. The studies performed with the use of X-ray powder diffraction and thermal analyses, IR, Raman, and Mössbauer spectroscopy have shown that the uptake of nickel ions by iron (III) hydroxide precipitate is due to simple physical adsorption and is not accompanied by the formation of mixed iron and nickel compounds. No alloying of the formed iron (III) hydroxide precipitate with nickel ions takes place either. The formed iron (III) hydroxide precipitate is a two-line ferrihydrite having the gross formula Fe2 O3 × 3H2 O. Its sorption capacity for nickel ions is almost an order of magnitude higher than that of some mineral and carbon sorbents, and at pH7 and 8, it is 60.5 and 141.9mg/g, respectively. PRACTITIONER POINTS: Coagulant FeCl3 cleans contaminated solutions from Ni(II) ions. Iron (III) hydroxide precipitated at pH 7 and 8 is a two-line ferrihydrite Fe2 O3 × 3H2 O. Removing of Ni(II) ions is described by classical adsorption isotherms. The most complete removal of Ni(II) ions occurs at pH = 8.

Selective Sorption of Silver Ions from Aqueous Solutions Using Poly(N-thiocarbamoyl‑ 3-aminopropylsilsesquioxane)

The accumulation of electronic waste (e-waste) on the ground leads to environmental pollution with toxic metal ions, which subsequently harms all living organisms. Many countries still use hydrometallurgical or manual methods to extract silver ions from e-waste. These methods are unsustainable and highly toxic; therefore, it becomes necessary to introduce new environmentally compatible methods for separating valuable components from objects of various compositions. This article proposes an environmentally compatible method for the extraction of silver ions from multicomponent systems using poly(N-thiocarbamoyl‑3-aminopropylsilsesquioxane). The sorbent surface was studied by Fourier-transform infrared spectroscopy using an attenuated total internal reflection accessory. The concentration of grafted thiourea groups is 1.39 mmol/g according to elemental analysis. It has been determined that this sorbent is capable of quantitatively extracting silver ions in the pH range from 0 to 6 at a concentration of silver ions in the initial solution of 1·10–4 mol/dm3; the static sorption capacity for silver ions under experimental conditions reaches 1.22 mmol/g. When sorption is carried out in dynamic mode, the value of the dynamic capacity before breakthrough is 0.046 mmol/g, and the value of the total dynamic capacity for silver ions is 0.132 mmol/g. The highest desorption (71–78 %) is achieved using sulfuric acid solutions with a thiourea concentration gradient.

Synthesis and spark plasma sintering of solid-state matrices based on calcium silicate for 60Co immobilization

An effective sorption material for the immobilization of cobalt radionuclides into highly safe and reliable solid-state matrices is proposed. The resulting silicate sorbent СaSiO 3 had an amorphous mesoporous structure (A BET 53 m 2 /g) and a sorption capacity Co ions of 3.32 mmol/g. The physico-chemical characteristics of the СaCoSi 2 O 6 sample obtained after Co 2+ ions sorption were studied using XRD, N 2 and Ar adsorption-desorption, SEM-EDX and TG/DTA methods. Solid-state silicate matrices characterized by high density values (2.86–3.16 g/cm 3 ), compressive strength (150–637 MPa) and Vickers microhardness (1.80–5.25 GPa) were obtained by spark plasma sintering (SPS). The sample obtained at 1000 °C had the lowest values of Co 2+ ions leaching (R Co ~10 −7 g/(cm 2 ×day)) and diffusion coefficient (De 1.73 ×10 −17 cm 2 /s) from silicate matrices. Thus, the obtained СaCoSi 2 O 6 silicate matrices saturated with Co ions comply with the regulatory requirements of GOST R 50926–96 and ANSI/ANS 16.1 for 60 Co immobilization. • Amorphous CaSiO 3 with 3.32 mmol/g Co ions sorption capacity was prepared. • SPS method allowed to obtain the CaCoSi 2 O 6 matrices at 1000 °C for 2 min. • CaCoSi 2 O 6 solid-state matrices exclude Co 60 ions leaching and diffusion. • The characteristics of CaCoSi 2 O 6 matrices exceeded the GOST and ANSI/ANS 16.1 requirements.

Competitive biosorption of rare-earth elements on bacterial biomass: equilibrium and kinetic studies

Previous studies showed that chemical modified Bacillus subtilis biomass possessed the high potential for recovery rare-earth elements, and, in this study, mathematical models were applied to explain the B. subtilis biomass La3+ and Sm3+ ions sorption capacity. The experimental isotherm data were analyzed using Langmuir, Freundlich, Temkin, and DRK equations. Both Langmuir and Freundlich isotherms models that fit the equilibrium data. Temkin model showed that it occurs physisorption. In more dilute solutions, the adsorption preference follows the order La3+ > Sm3+. With the increase in the concentration of rare-earth elements, there is an inversion in the preference for Sm3+ > La3+. The results demonstrate that the optimum model for describing the kinetics of the biosorption of both rare-earth elements is the pseudo-second-order model as well as the viability of recovering lanthanum using bacterial biomass sorbents, a practical technique.

Detection and Sorption of Heavy Metal Ions in Aqueous Media by a Fluorescent Zr(IV) Metal-Organic Framework Functionalized with 2-Picolylamine Receptor Groups.

Increasing global environmental pollution due to heavy metal ions raises the importance of research on new multifunctional materials for simultaneous detection and removal of these contaminants from water resources. In this study, we report a microporous 8-connected Zr4+ metal-organic framework (MOF) based on a terephthalate ligand decorated with a chelating 2-picolylamine side group (dMOR-2), which shows highly efficient fluorescence sensing and sorption of heavy metal cations. We demonstrate by detailed fluorescence studies the ability of a water-dispersible composite of dMOR-2 with polyvinylpyrrolidone for real-time detection of Cu2+, Pb2+, and Hg2+ in aqueous media. The limits of detection were found to be below 2 ppb for these species, while the system's performance is not affected by the presence of other potentially competitive ions. In addition, sorption studies showed that a composite of dMOR-2 with calcium alginate (dMOR-2@CaA) is an excellent sorbent for Pb2+ and Cu2+ ions with capacities of 376 ± 15 and 117 ± 4 mg per gram of dMOR-2@CaA, respectively, while displaying the capability for simultaneous removal of various heavy metal ions in low initial concentrations and in the presence of large excesses of other cationic species. Structural and spectroscopic studies with model ligands analogous to our material's receptor unit showed chelation to the 2-picolylamine moiety to be the main binding mode of metal ions to dMOR-2. Overall, dMOR-2 is shown to represent a rare example of a MOF, which combines sensitive fluorescence detection and high sorption capacity for heavy metal ions.

Amidoximated graphene/konjac glucomannan composite gel for uranium extraction from saline lake brine

To overcome the separation defect of amidoximated graphene oxide (rGO-PAO) in uranium sorption from water solutions, the renewable natural polymer material konjac glucomannan (KGM) is selected as the immobilization reagent, since KGM can easily form gel structure and very cheap. A rationally designed strategy is developed to synthesize the new composite gel sorbent denoted as rGO-PAO/KGM. The acquired sorbents are characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and BET specific surface area analyses. All the results prove that rGO-PAO is successfully immobilized by KGM and composite gels with three dimensional (3D) sponge-like architectures are obtained. Batch uranium sorption experiments are conducted and the effects of initial solution pH, ion strength, time, uranium concentration and coexisting ions on uranium sorption are investigated. Blank KGM is found to have low uranium sorption capacity and most of uranium ions are sorbed by rGO-PAO. The maximum experimental sorption capacities are determined to be 52.6 ± 0.5 mg/g for 20-rGO-PAO/KGM. Furthermore, the sorption mechanism of uranium by rGO-PAO/KGM are revealed by using different analytical methods. Amidoxime groups are found to play the major role in uranium sorption. Uranium extraction from natural saline lake brine sample by rGO-PAO/KGM is conducted. Although the sorption capacity is not very high, rGO-PAO/KGM can be regarded as potential sorbents for uranium extraction from natural complicated waters, considering some of their superior properties.

Performance of Treated and Untreated Spent Coffee Ground on the Removal of Cu (II) in Aqueous Solution: A Comparative Study

The performance of two types of spent coffee ground (SCG), (i) untreated spent coffee ground (USCG) and (ii) acid-treated spent coffee ground (TSCG) on the Cu (II) removal from aqueous solution was investigated and compared in this study. The effects of operating parameters such as pH, contact time and initial Cu (II) concentration on the adsorption rate were studied in batch adsorption mode. The USCG showed better results than the TSCG. The highest removal efficiency of Cu (II) (50 mg/L) by USCG was 91.03% with an adsorption capacity of 45.52 mg/g, which was achieved at pH 6 and 90 min of contact time. The TSCG showed lower performance with a removal efficiency of 44.18% and adsorption capacity of 37.06 mg/g. This may be due to the flushed off in the functional groups of SCG that used for metal binding in the adsorption during acid treatment and the existence of Cl- ions on the TSCG surface, interfering the Cu (II) adsorption and reduces its adsorption capacity. Freundlich fitted well with the equilibrium data for copper (II) removal, as indicated by the R2 coefficient, for USCG and TSCG were 0.9912 and 0.9622, respectively. These data indicate that both USCG and TSCG have high sorption capacity and affinity for metal ions. The USCG showed a better Cu (II) removal than the TSCG, indicating a promising function as a low-cost natural adsorbent for Cu (II) and also other heavy metals removals.