Innovative Green Alginate-Cellulose Composite for Light Lanthanides: Experimental Design and Comprehensive Studies on Kinetics, Equilibrium, Thermodynamics, and Reusability

Nowadays, there is a great interest in efficient adsorbent development due to the recent demand for lanthanides, which are widely used in high-tech technology. Alginates, owing to their natural occurrence, gel formation capability, and safety, could be promising feasible adsorbents for lanthanide removal. This study proposes the alginate-cellulose composite as an ecological, sustainable adsorbent for light lanthanide sorption. The structure, morphology, qualitative and quantitative compositions, average diameter, and pHpzc of the composite were discussed in great detail. Using the batch approach, sorption trials were performed to evaluate the metal sorption performance. The maximum lanthanide accumulation was attained at pH 5.0 and a dosage of 0.05 g. The uptake kinetics are successfully explained by the Ho and McKay model, whereas the equilibrium data is best represented by the Langmuir equation. The presence of Cl-, NO3 -, SO4 2-, Ni(II), and Co(II) did not have any impact on the adsorption capacity. In turn, the presence of Fe(III) ions led to a 15 % reduction in the adsorption. The lanthanide ions were eluted from the adsorbent following the treatment with 0.1 M HNO3. The adsorbent retained over 95 % of its initial adsorption capacity after 6 series of sorption/desorption studies.

Improved Soil Amendment by Integrating Metal Complexes and Biodegradable Complexing Agents in Superabsorbents

The superabsorbents' application as materials for the preparation of modern mineral fertilizers of controlled activity is presented. Under the static conditions, the commercial acrylic-based Agro® Hydrogel was used as a sorbent for Cu(II), Fe(III), Mn(II), and Zn(II) ions in the presence of three biodegradable complexing agents of the new generation: (N-1,2-dicarboxyethyl)-D,L-aspartate acid (IDHA), N,N-ethylenediaminedisuccinic acid (EDDS) and N,N-bis(carboxymethyl) glutamic acid (GLDA). The ions and complexes concentrations were determined by the inductively coupled plasma optical emission spectrometer (ICP-OES). The characterization of hydrogel before and after the adsorption process was made using the Fourier transform infrared spectroscopy (FT-IR), surface area determination (ASAP), scanning electron microscopy (SEM-EDS) as well as the thermogravimetric (TGA) methods. The influence of the phase contact time, initial concentration, and pH on the adsorption capacities was investigated. The kinetic and adsorption parameters were determined. The Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin adsorption models were applied to describe the experimental data. The Langmuir isotherm model accurately characterized the equilibrium process. The adsorption process was fast, and it reached equilibrium after 60 min of the phase contact time. The research on the adsorption of Cu(II), Fe(III), Mn(II), and Zn(II) onto Agro® Hydrogel with IDHA, EDDS, and GLDA indicates that these complexing agents improve process efficiency.

Metagenomic Analysis of the Composition of Microbial Consortia Involved in Spruce Degradation over Time in Białowieża Natural Forest

Deadwood plays an important role in forest ecology; its degradation and, therefore, carbon assimilation is carried out by fungi and bacteria. To quantify the abundance and distribution of microbial taxa inhabiting dead spruce logs fallen over a span of 50 years and the soil beneath, we used taxonomic profiling with NGS sequencing of hypervariable DNA fragments of ITS1 and 16S V3-V4, respectively. The analysis of sequencing data revealed a high level of diversity in microbial communities participating in the degradation of spruce logs. Differences in the relative abundance of microbial taxa between the samples of the wood that died in 1974 and 2014, and of the soil in its immediate vicinity, were visible, especially at the genus level. Based on the Lefse analysis significantly higher numbers of classified bacterial taxa were observed in the wood and soil samples from 2014 (wood: 1974-18 and 2014-28 taxa; soil: 1974-8 and 2014-41 taxa) while the number of classified fungal taxa was significantly higher in the wood and soil samples from 1974 (wood: 1974-17 and 2014-9 taxa; soil: 1974-57 and 2014-28 taxa). Most of the bacterial and fungal amplicon sequence variants (ASVs) unique to wood were found in the samples from 1974, while those unique to soil were detected in the samples from 2014. The ATR-FTIR method supported by CHN analysis revealed physicochemical changes in deadwood induced by the activity of fungal and bacterial organisms.

Fixed-Bed Column Adsorption Studies: Comparison of Alginate-Based Adsorbents for La(III) Ions Recovery

The paper investigated the adsorption of the packed-bed column with the alginate-based adsorbents (ALG-based adsorbents) such as alginate-biochar, alginate-clinoptilolite, alginate-lignin, and alginate-cellulose for La(III) ions' removal. Fixed-bed adsorption studies with various alginate-based adsorbents were carried out and compared to the La(III) ions adsorption. The columns were filled with ALG-based adsorbent beads of approximately 1.1 ± 0.005 mm spherical shapes. The effects of the inlet concentrations on the breakthrough curves were studied in terms of the adsorption performance of the ALG-based adsorbents. The experimental data were correlated with the Adams-Bohart, Yoon-Nelson, Thomas, and Wolborska models to determine the best operational parameters. Based on the comparison of R² values, the Thomas and Yoon-Nelson models were found to be more suitable than the Adams-Bohart and Wolborska models. In the desorption study, the ALG-based adsorbents packed columns showed the maximum desorption of La(III) just after passing 100 cm³ of 1 mol/dm³ HCl. Overall, the results show that ALG-based adsorbents could be used for continuous recovery of La(III) ions from aqueous solutions and were not only cost-effective but also environmentally friendly.

Green Extractants in Assisting Recovery of REEs: A Case Study

The recycling of REEs from the end of life (EoL) products, such as nickel metal hydride batteries (NiMH), offers great opportunities for their supply in Europe. In the presented paper, the application of 'green' extractants such as citric (CA), metatartaric (TA), and ethylenediaminedisuccinic acid (EDDS) (also with H₂O₂ addition) for the recovery of REEs was studied. The studies were conducted considering the effects of the phase contact time, the initial concentration of CA, TA, and EDDS, as well as H₂O₂, pH, and temperature. It was found that the addition of TA to the CA solution meant that higher rates of metal ion binding and, thus, leaching was observed. The optimal conditions were obtained in the system: CA-TA and H₂O₂ for the concentration 0.6M-0.3 M-2%.

Quality of Phosphate Rocks from Various Deposits Used in Wet Phosphoric Acid and P-Fertilizer Production

Phosphate rocks (PRs) play a crucial role in ensuring the availability of phosphorous for the world's food needs. PRs are used to manufacture phosphoric acid in the wet process as well as P-fertilizers. The chemical and mineralogical compositions of PRs from Djebel Onk (Algeria), Khneifiss (Syria), Negev (Israel), Bou Craa (Morocco), and Khouribga (Morocco) are discussed in this study. PRs were characterized by inductively coupled plasma optical emission spectrometry (ICP-OES), cold vapor atomic absorption spectrometry (CVAAS), ion chromatography (IC), and X-ray diffraction (XRD), as well as gravimetric and potentiometric methods. All PRs were mainly composed of CaO, P₂O₅, SiO₂, F, SO₃, Na₂O, MgO, Al₂O₃, Fe₂O₃, SrO, and K₂O at the level of wt.%. The P₂O₅ content accounted for 28.7-31.2%, which indicates that these are beneficial rocks to a marketable product. The degree of PR purity expressed by the minor elements ratio index (MER index) varied from 2.46% to 10.4%, and the CaO/P₂O₅ weight ratio from 1.6 to 1.9. In addition, the occurrence of trace elements such as As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Ti, V, U, and Zn, as well as Cr(VI) and Cl ions at the level of mg∙kg^-1 was found. Since PRs will be used to produce P-fertilizers, their composition was compared with the regulatory parameters set up by EU Regulation 2019/1009 related to the heavy metals (As, Cd, Pb, Ni, Hg, Cu, Zn) and Cr(VI) contents in inorganic fertilizers. The heavy metals and Cr(VI) content in all PRs did not exceed the limit values. XRD analysis revealed that fluorapatite, hydroxyapatite, carbonate fluorapatite, and carbonate hydroxyapatite were the dominant minerals. The accuracy and precision of the used methods were evaluated by analysis of standard reference materials (SRM) for Western Phosphate Rock (NIST 694). The recovery was 85.3% for U and 109% for K₂O, and the RSD ranged from 0.67% to 12.8%.

Determination of the Ni(II) Ions Sorption Mechanism on Dowex PSR2 and Dowex PSR3 Ion Exchangers Based on Spectroscopic Studies

This paper estimates the suitability of the strongly basic anion exchangers, Dowex PSR2 and Dowex PSR3, as sorbents of nickel ions in aqueous solutions. These actions are aimed at searching for new solutions due to the growing discharge of nickel into wastewaters, primarily due to its addition to steel. The nickel sorption experiments were conducted under static conditions and resulted in the optimization of pH, phase contact time, initial solution concentration, and temperature. The next step was to calculate the kinetic, isothermal, and thermodynamic parameters. Moreover, the ion exchangers were characterized by means of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and CHN elemental analysis. It was found that the sorption process was most effective at pH 6 after 240 min and at the temperature of 293 K. The values of the thermodynamic parameters revealed that the adsorption was exothermic and spontaneous. The physicochemical analyses combined with the experimental research enabled determination of the sorption mechanism of Ni(II) ions.

Insight into the removal of vanadium ions from model and real wastewaters using surface grafted zirconia-based adsorbents: Batch experiments, equilibrium and mechanism study

This study concerns the fabrication of CTAB- and N,N-dimethyltetradecylamine-grafted zirconia and evaluation of their ability to adsorb vanadium ions. The effectiveness of ZrO₂ functionalization and the different nature of the modifiers used were confirmed by differences in the porosity (ZrO₂: S_BET = 347 m²/g; ZrO₂-CTAB: S_BET = 375 m²/g, ZrO₂-NH⁺: S_BET = 155 m²/g), types of functional groups, and isoelectric points (the ZrO₂ and CTAB-modified samples have IEPs = 3.8 and 3.9, ZrO₂-NH⁺ has IEP = 7.1) of the prepared adsorbents. The designed materials were tested in batch adsorption experiments involving the removal of vanadium ions from model wastewaters at various process parameters, among which pH proved to be the most important. Based on equilibrium and kinetic evaluations, it was proved that the sorption of V(V) ions followed pseudo-second-order and intraparticle diffusion models, and the data were better fitted to the Langmuir model, suggesting the following order of the sorbents in terms of favorability for V(V) ion adsorption: ZrO₂-NH⁺ > ZrO₂ > ZrO₂-CTAB. The estimated maximum monolayer capacity of ZrO₂-NH⁺ for V(V) (87.72 mg/g) was the highest among the tested materials. Additionally, it was confirmed that adsorption of V(V) ions onto synthesized materials is a heterogeneous, exothermic, and spontaneous reaction, as evidenced by the calculated values of thermodynamic parameters. The key goals included the transfer of experimental findings obtained using model solutions to the adsorption of V(V) ions from solutions arising from the leaching process of spent catalysts. The highest adsorption efficiencies of 70.8% and 47.5% were recorded for the ZrO₂-NH⁺ material in acidic solution; this may be related to the protonization of -NH⁺ groups, which favors the sorption of V(V) ions. Based on desorption tests as well as the results of infrared and X-ray photoelectron spectroscopy, irrespective of the process conditions, the physical nature of the adsorbent/adsorbate interaction was confirmed.

Chitosan-Modified Biochars to Advance Research on Heavy Metal Ion Removal: Roles, Mechanism and Perspectives

The chitosan-modified biochars BC-CS 1-1, BC-CS 2-1 and BC-CS 4-1 were subjected to the synthetic application of biochar from agriculture waste and chitosan for the adsorption of Cu(II), Cd(II), Zn(II), Co(II) and Pb(II) ions from aqueous media. The results displayed a heterogeneous, well-developed surface. Additionally, the surface functional groups carboxyl, hydroxyl and phenol, determining the sorption mechanism and confirming the thermal stability of the materials, were present. The sorption evaluation was carried out as a function of the sorbent dose, pH, phase contact time, initial concentration of the solution and temperature. The maximum value of q_t for Pb(II)-BC-CS 4-1, 32.23 mg/g (C₀ 200 mg/L, mass 0.1 g, pH 5, 360 min), was identified. Nitric acid was applied for the sorbent regeneration with a yield of 99.13% for Pb(II)-BC-CS 2-1. The produced sorbents can be used for the decontamination of water by means of the cost-effective and high-performance method.

Adsorption of vanadium (V) ions from the aqueous solutions on different biomass-derived biochars

The paper presents the results of the studies on the vanadium (V) ions removal from the aqueous solutions in the adsorption process on biochars from different biomass types (cow manure BC1, wet distiller grains BC2, spent mushroom substrates BC3). The adsorbents were characterized by means of the SEM-EDS, FTIR, XRD and XPS techniques. The influence of adsorbent type and basic process parameters, such as pH and metal ion concentration in aqueous phase, adsorbent dose and time of contact of phases on the efficiency of V(V) was determined. Based on the obtained results, the mechanism and kinetics of the adsorption processes occurring on the biochar originating from the wet distiller grains as adsorbents with the greatest affinity for the V(V) ions were characterized, using isotherm models of Langmuir, Freundlich, Temkin and Dubinin-Radushkevich and pseudo-first-order, pseudo-second-order as well as intraparticle diffusion kinetic models. Under the constant process conditions (pH = 3.0; m = 0.5 g; c₀ = 50 mg/L) the order of V(V) ions removal from aqueous solutions was as follows: BC2 > BC1 = BC3. The biochar BC2 exhibited the maximum sorption capacity of 1.61 mg V(V)/g. The experimental kinetic data show the adsorption course according to the pseudo-second order model.

Arsenate removal on the iron oxide ion exchanger modified with Neodymium(III) ions

In this study the iron oxide ion exchanger with the quaternary ammonium groups, Ferrix A33E was modified with neodymium (III) ions in order to obtain the new material Ferrix A33E-Nd(III) characterized by greater sorption efficiency of arsenate(V) ions. A33E-Nd(III) was described by various techniques including scanning electron microscopy SEM, nitrogen adsorption/desorption isotherms, Fourier transform infrared spectroscopy FTIR and X-ray photoelectron spectroscopy XPS. The point of zero charge, pH_PZC was also determined. The kinetic and thermodynamic parameters of the arsenate(V) sorption were calculated. The experimental data was fitted to the four isotherm models - Langmuir, Freundlich, Dubinin-Radushkevich and Halsey. Kinetic and equilibrium studies allowed to get to know the behaviour of arsenate(V) ions during the sorption on A33E-Nd(III). The obtained material A33E-Nd(III)- was found to possess a larger maximum sorption capacity than A33E, great stability and the possibility of regeneration at least 3 times without a significant decrease in efficiency. This allows for the complete removal of As(V) ions from a solution with a concentration of 50 mg/dm³ in just 30 min. The Nd(III)-modification improved the sorption properties of the tested ion exchanger.

Fabrication, Characterization and Evaluation of an Alginate-Lignin Composite for Rare-Earth Elements Recovery

The recent increase in interest in rare earth elements is due to their increasing use in many areas of life. However, along with their increasing popularity, the problem of their natural resources availability arises. In this study, an alginate–lignin composite (ALG-L) was fabricated and tested for adsorptive abilities of the rare earth elements (La(III), Ce(III), Pr(III), and Nd(III)) from aqueous solutions. The characterization of the newly synthetized calcium alginate–lignin composite was performed using ATR/FT-IR, SEM, EDX, OM, AFM, XRD, BET, sieve analysis and pH_pzc measurements. The adsorption mechanism of the ALG₅L₁ composite for REEs was analyzed through a series of kinetic, equilibrium and thermodynamic adsorption experiments. Under the optimum sorption conditions, i.e., sorbent mass 0.1 g, pH 5.0, temperature 333 K, the maximum adsorption capacities of the ALG₅L₁ composite for La(III), Ce(III), Pr(III), and Nd(III) reached 109.56, 97.97, 97.98, and 98.68 mg/g, respectively. The desorption studies indicate that the new calcium alginate–lignin composite is characterized by good recycling properties and can be also reused. To sum up the advantages of low cost, easy synthesis, high adsorption efficiencies and reusability indicate that the ALG₅L₁ composite has great application perspectives for REEs recovery.

Functionalization of Zeolite NaP1 for Simultaneous Acid Red 18 and Cu(II) Removal

The efficiency of azo dye Acid Red 18 (AR18) and Cu(II) ions simultaneous removal from an aqueous solution on NaP1CS and NaP1H was investigated, taking into account the effect of the phase contact time, pH, initial concentration, temperature, and interfering ions presence. Zeolite denoted as NaP1CS was modified by chitosan (CS) and zeolite denoted as NaP1H was modified by hexadecyltrimethylammonium bromide (HDTMA). In order to characterize sorption properties of NaP1CS, the obtained sorbent was characterized using Fourier transform infrared spectroscopy (FTIR) and nitrogen adsorption/desorption (ASAP). The kinetic parameters were determined by means of the pseudo first order (PFO), pseudo second order (PSO), and intraparticle diffusion (IPD) kinetic models. To present the adsorption data, three different isotherm models (Langmuir, Freundlich and Dubinin-Radushkevich) were used. The desorption process was also examined. It was found that for sorbent NaP1CS the pseudo second order (PSO) kinetic model and the Langmuir isotherm fitted best the experimental data. Moreover, it was noted that the acidic pH is appropriate to achieve the best sorption properties of NaP1CS for Cu(II) and NaP1H for AR18 and Cu(II). The thermodynamic parameters indicate an endothermic process. The most effective solution for the desorption process was found to be 1 M HCl. The results indicate that simultaneous removal of dye AR18 and Cu(II) on modified zeolite NaP1CS or NaP1H is possible and proceeds with a very good efficiency. The obtained zeolites could effectively adsorb AR18 an Cu(II) simultaneously, but their adsorption abilities were rather different.

Superabsorbents and Their Application for Heavy Metal Ion Removal in the Presence of EDDS

Three acrylic-based superabsorbents—TerraHydrogel^®Aqua (THA), Zeba^®Hydrogel (ZH) and Agro^®Hydrogel (AH) were used to investigate the influence of chemical conditions on kinetic and adsorption behavior towards metal ions in the presence of a chelating agent of a new generation called ethylenediamine-N,N′-disuccinic acid (EDDS). The effects of relevant parameters—mainly including those of sorbent dose, pH of the solution and initial concentration of Cu(II), Zn(II), Mn(II) and Fe(III) complexes with EDDS as well as phase contact time and temperature—on the adsorption efficiency were studied in detail by the static method. The experimental data were also characterized by kinetic and adsorption parameters obtained based on the Langmuir and Freundlich models of sorption as well as the Lagergren, Ho and McKay and Weber–Morris models.

Impacts of heavy metals and medicinal crops on ecological systems, environmental pollution, cultivation, and production processes in China

Heavy metals are widely distributed in the environment due to the natural processes and anthropogenic human activities. Their migration into no contaminated areas contributing towards pollution of the ecosystems e.g. soils, plants, water and air. It is recognized that heavy metals due to their toxicity, long persistence in nature can accumulate in the trophic chain and cause organism dysfunction. Although the popularity of herbal medicine is rapidly increasing all over the world heavy metal toxicity has a great impact and importance on herbal plants and consequently affects the quality of herbal raw materials, herbal extracts, the safety and marketability of drugs. Effective control of heavy metal content in herbal plants using in pharmaceutical and food industries has become indispensable. Therefore, this review describes various important factors such as ecological and environmental pollution, cultivation and harvest of herbal plants and manufacturing processes which effects on the quality of herbal plants and then on Chinese herbal medicines which influence human health. This review also proposes possible management strategies to recover environmental sustainability and medication safety. About 276 published studies (1988-2021) are reviewed in this paper.

Development of functional lignin-based spherical particles for the removal of vanadium(V) from an aqueous system

A new type of functional lignin-based spherical particles (L-CTAB) prepared with the use of hexadecyltrimethylammonium bromide (CTAB) was applied as an effective biosorbent for removing vanadium(V) ions. The porous structure, characteristic functional groups, electrokinetic stability, morphology and size of the L-CTAB particles were examined. The conditions of removal were also investigated, including pH (2-12), sorbent mass (0.1-0.5 g), concentration (10-100 mg/dm3), phase contact time (1-240 min) and temperature (293-333 K). At pH 5.0 the maximum sorption percentage (%S) of V(V) was 45%, while at pH 2.0 it was 32%. The maximum sorption capacity of V(V) for L-CTAB was found to be 10.79 mg/g. The kinetic data indicate that the sorption followed the pseudo-second-order and film diffusion models. Sorption equilibrium for V(V) ions removal by L-CTAB was reached after 60 min at the initial concentrations 10 and 50 mg/dm³. It has been shown that the adsorption of V(V) ions on the surface of L-CTAB is a heterogeneous, endothermic and spontaneous reaction, as evidenced by the calculated values of thermodynamic parameters - free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) - for the tested systems at different temperatures. HCl solutions, used as an L-CTAB regeneration agent, quantitatively eluted V(V) ions.

Studies on the Mechanism of Cu(II) Ion Sorption on Purolite S 940 and Purolite S 950

The aim of the presented research was to investigate the mechanism of sorption of Cu(II) ions on the commercially available Purolite S 940 and Purolite S 950 chelating ion exchangers with the aminophosphonic functional groups. In order to understand better the sorption mechanism, the beads were cut with an ultramicrotome before and after the Cu(II) ion sorption process. The cut beads were examined by scanning electron microscopy (SEM) with an EDX detector. The performed linear profiles of the elemental composition allowed us to examine the depth with which the sorbed metal penetrates into. For further investigations concerning the mechanism of the sorption process, the Fourier transform infrared spectroscopy (FTIR) analysis using the attenuated total reflectance (ATR) technique and the X-ray photoelectron spectroscopy (XPS) methods have been used. The comparison of FTIR and XPS spectra before and after the sorption of Cu(II) ions showed that free electron pairs from nitrogen and oxygen in the aminophosphonic functional groups participate in the process of copper ion sorption. In addition, the microscopic studies suggested that the process of ion exchange between Na(I) ions and sorbed Cu(II) ions takes place on the Purolite S 940 and Purolite S 950. This study concerning the in-depth understanding the of Cu(II) sorption mechanism, using modern analytical tools and research methods could be very useful for its further modifications leading to the improvement of the process efficiency.

Static and dynamic studies of lanthanum(III) ion adsorption/desorption from acidic solutions using chelating ion exchangers with different functionalities

Increasing the number of applications of rare earth elements (REEs) has led to increased release of these metals into the environment. Removal of REEs from e-wastes is very important considering the increasing demand for these elements, the limited resource availability of them as well as the significant environmental issues. In this present study, optimization of the La(III) ions sorption from acidic solutions on chelating ion exchangers containing different functional groups, i.e. Amberlite IRC748, Purolite S930, Lewatit® Monoplus TP208, Amberlite IRC747, Purolite S940, and Purolite S950, was carried out. The sorption data was analyzed using the Lagergren pseudo-first order, Ho and McKay pseudo-second order, Weber-Morris intraparticle diffusion, Boyd kinetic models, pore and film diffusion coefficients as well as the Langmuir, Freundlich, and Temkin isotherm models. Additionally, thermodynamic parameters and regeneration abilities of chelating ion exchangers were evaluated. The maximum recovery of La(III) ions was found for HNO₃ concentration equal to 0.2 mol/dm³. The La(III) ions sorption was fast and sorption equilibrium was achieved after about 60 min. The best fitting for the lanthanum(III) ions sorption was obtained using the pseudo-second order kinetic and Langmuir isotherm models. Moreover, breakthrough curves were obtained from dynamic studies. The physicochemical characterization places special emphasis on determination of chemical composition of ion exchangers using ATR/FT-IR and XPS spectroscopy. Furthermore, characterization parameters of ion exchangers such as surface area and porosity (pore size), point of zero charge, and thermal stability were estimated. Chelating ion exchangers with aminophosphonic functional groups are characterized by the best adsorption properties towards La(III) ions so they could be used for the recovery of rare earth elements from spent battery solutions.

Recovery of Lanthanum(III) and Nickel(II) Ions from Acidic Solutions by the Highly Effective Ion Exchanger

The recovery of La(III) and Ni(II) ions by a macroporous cation exchanger in sodium form (Lewatit Monoplus SP112) has been studied in batch experiments under varying HNO₃ concentrations (0.2-2.0 mol/dm³), La(III) and Ni(II) concentrations (25-200 mg/dm³), phase contact time (1-360 min), temperature (293-333 K), and resin mass (0.1-0.5 g). The experimental data revealed that the sorption process was dependent on all parameters used. The maximum sorption capacities were found at CHNO₃ = 0.2 mol/dm³, m = 0.1 g, and T = 333 K. The kinetic data indicate that the sorption followed the pseudo-second order and film diffusion models. The sorption equilibrium time was reached at approximately 30 and 60 min for La(III) and Ni(II) ions, respectively. The equilibrium isotherm data were best fitted with the Langmuir model. The maximum monolayer capacities of Lewatit Monoplus SP112 were equal to 95.34 and 60.81 mg/g for La(III) and Ni(II) ions, respectively. The thermodynamic parameters showed that the sorption process was endothermic and spontaneous. Moreover, dynamic experiments were performed using the columns set. The resin regeneration was made using HCl and HNO₃ solutions, and the desorption results exhibited effective regeneration. The ATR/FT-IR and XPS spectroscopy results indicated that the La(III) and Ni(II) ions were coordinated with the sulfonate groups.

Novel multifunctional ion exchangers for metal ions removal in the presence of citric acid

The present study deals with the potential application of Purolite S957 and Diphonix Resin® for the removal of rare earth elements from aqueous liquors as a result of the extraction of spent Ni-MH batteries in the presence of citric acid. The effects of the metal ion and the citric acid ratio, pH, ion exchanger dose, contact time, initial concentration and temperature were studied using the batch technique. The Langmuir and Freundlich adsorption isotherm models were used for the description of the adsorption process. The equilibrium adsorption data were fitted using the pseudo first order, pseudo second order, intraparticle diffusion, Boyd, film diffusion and Dumwald-Wagner models. The maximum adsorption capacity q₀ obtained from the Langmuir isotherm was found to be 46.63 mg/g for Ni(II) and 60.75 mg/g for La(III) on Purolite S957 as well as 46.55 mg/g for Ni(II) and 60.12 mg/g for La(III) on Diphonix Resin®. The kinetics followed the pseudo second order reaction. Based on the Weber-Morris model the adsorption process proved to proceed in two stages. Based on the Boyd model the rate controlling steps were film and intraparticle diffusions. The adsorption process was spontaneous and endothermic in nature. Reusability of ion exchangers in the desorption studies was also evaluated as a sustainable approach. The physicochemical properties of Purolite S957 and Diphonix Resin® were studied using the ASAP analysis, optical and scanning electron microscopy, potentiometric titration, pH_PZC and FT-IR as well as XPS analysis.

Enhanced Arsenic(V) Removal on an Iron-Based Sorbent Modified by Lanthanum(III)

Modification of a commercial iron oxide ion exchanger (Arsen X^np) was carried out to enhance the removal of arsenic(V) ions. The modification consisted of the adsorption of lanthanum(III) ions on the Arsen X^np surface. After adsorption, the material was dried at 313 K to obtain the modified ion exchanger Arsen X^np-La(III). The modification process itself was tested for optimal pH, kinetics, and equilibrium adsorption isotherm study. Accurate sorbent characteristics were made using, among others, SEM, FTIR, and nitrogen adsorption/desorption isotherms. Then, various tests were carried out to compare the adsorption properties of the modified and unmodified material. It turned out that the tested material was able to completely remove arsenic from an aqueous solution with an initial concentration of up to 50 mg/dm³. Without modification, it was not possible to reach the WHO recommended 10 μg/dm³ arsenic limit even at an initial concentration of 25 mg/dm³. Moreover, the maximum sorption capacity increased from 22.37 to 61.97 mg/g after modification (3 times greater than before modification). It is worth noting that the process of removing arsenic on Arsen X^np-La(III) is fast—equilibrium is reached after about 120 min. Under almost neutral conditions, precipitation and adsorption can be the main mechanisms of As(V) removal. After modification, the removal capacity was enhanced by the co-precipitation and adsorption by exchange of the OH– group with arsenic ions. Such La(III) based adsorbent can be successfully applied in wastewater purification and displays superior performance for removing arsenic.

Hypertensive Rats Treated Chronically With Nω-Nitro-L-Arginine Methyl Ester (L-NAME) Induced Disorder of Hepatic Fatty Acid Metabolism and Intestinal Pathophysiology

N^ω-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide (NO) biosynthesis, results in hypertension and liver injury. This study aimed at investigating the changes of liver lipometabonomics and exploring the underlying mechanisms of liver injury in the L-NAME-treated rats. The male Sprague-Dawley (SD) rats were treated with L-NAME (40 mg/kg, p.o.) for 8 weeks. After that, the liver, aorta, fecal, and serum were collected for analysis. The results showed that L-NAME induced hypertension and disordered the endothelial nitric oxide synthase (eNOS)-NO pathway in the treated rats. L-NAME could also increase the levels of serum total cholesterol (TC), triglyceride (TG), alanine transaminase (ALT), and aspartate transaminase (AST). The multidimensional mass spectrometry-based shotgun lipidomics (MDMS-SL) analysis showed that L-NAME could induce significant changes of the total hepatic lipids and most hepatic triglycerides, as well as fatty acid (FA). A positive correlation was found between the blood pressure and TAG. Immunofluorescence and Western-Blot experiments indicated that the L-NAME treatment significantly influenced some FA β-oxidation, desaturation, and synthesis-related proteins. The increase of intestinal inflammation, decrease of microcirculation and tight junction proteins, as well as alterations of microbial communities were observed in the L-NAME induced hypertensive rats, as well as alterations of microbial communities were notable correlation to TAG and FA species. This study demonstrated that the L-NAME-induced hypertensive rats exhibiting liver injury were the joint action of hepatic abnormal fatty acid metabolism and microcirculation disorder. Furthermore, the gut microflora, as well as the changes of FA β-oxidation (ACOX, CPT1α), desaturation (SCD-1), and synthesis (FAS) may be the potential mechanisms for abnormal fatty acid metabolism.

Zeolites in Phenol Removal in the Presence of Cu(II) Ions-Comparison of Sorption Properties after Chitosan Modification

Nowadays, the contamination of water with phenol is a serious environmental problem. This compound occurs very often with heavy metal ions which makes purification of water even more difficult. This article presents the problem of the removal of phenol from aqueous solutions in the presence of Cu(II) ions on synthetic zeolite NaP1 and zeolite NaP1 modified with chitosan. The adsorbents were determined with the use of Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption/desorption isotherm, and scanning electron microscopy (SEM). The studies on isotherms and batch kinetics under diversified experimental conditions with respect to initial concentration, contact time, and pH were discussed. Both Cu(II) and phenol adsorption increases with the initial concentration. Different isotherm models correspond well with the data acquired through experiments. The kinetics of adsorption follows the pseudo-second order rate equation. The studies indicate that the obtained sorbents can be employed for efficient removal of phenol from wastewater in the presence of Cu(II) ions.

Detoxification of municipal solid waste incinerator (MSWI) fly ash by single-mode microwave (MW) irradiation: Addition of urea on the degradation of Dioxin and mechanism

The detoxification of municipal solid waste incinerator (MSWI) fly ash dioxins urgently requires an effective treatment technology. In this study, we adopted a single-mode microwave (MW)-based pyrolysis to treat MSWI fly ash under N₂ atmosphere and further elucidated the main influencing factors, including the chemical inhibitor, for dioxin control. The results show that (1) the detoxification process was optimized with a mass ratio of fly ash to SiC of 1:9, 23.1% (wt%) urea addition and pyrolysis temperature of ˜ 480 °C; (2) the total polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) destruction efficiency and the bioassay-derived 2,3,7,8-TCDD toxic equivalent (Bio-TEQ) removal efficiency reached 98.5% and 97.9%, respectively, accompanied with ˜ 1.3% of the total amount of dioxin being submitted to exhaust gas; (3) the MW-based pyrolysis of urea (133˜300 °C) was favourable for the generation of hot spots as well as the PCDD/F rapid destruction in fly ash. In addition, the leaching toxicity of heavy metals was also partially reduced after MW pyrolysis reactions. To the best of our knowledge, this is the first report adopting a MW-based pyrolysis to eliminate dioxin in MSWI fly ash with the addition of urea, which is a promising alternative to current methods.

Dielectric functions, chemical and atomic compositions of the near surface layers of implanted GaAs by In+ ions

The surfaces of (100) GaAs were irradiated with In⁺ ions. The implanted samples were isobaric annealed at 800°C and then of dielectric function, the surface atomic concentrations of atoms and also the chemical composition of the near surface layers in these implanted semiconductor samples were obtained. The following investigation methods were used: spectroscopic ellipsometry (SE), Rutherford backscattering spectrometry analyses (RBSA) and X-ray photoelectron spectroscopy (XPS) in the study of the above mentioned quantities, respectively. The change of the shape spectra of the dielectric functions at about 3.0eV phonon energy, diffusion of In⁺ ions as well as chemical composition changes were observed after ion implantation and the thermal treatment. Due to displacement of Ga ions from GaAs by the In⁺ ions the new chemical compound InAs was formed. The relative amounts Ga₂O₃ and As₂O₃ ratio increase in the native oxide layers with the fluences increase after the thermal treatment of the samples. Additionally, it was noticed that the quantities of InO₂ increase with the increasing values of the irradiated ions before thermal treatment.

Titania-Coated Silica Alone and Modified by Sodium Alginate as Sorbents for Heavy Metal Ions

The novel organic-inorganic biohybrid composite adsorbent was synthesized based on nanosized silica-titania modified with alginate within the development of effective adsorbent for heavy metal ions. Effects of metal species Cu(II), Zn(II), Cd(II), and Pb(II); concentrations; pH; temperature; and adsorption onto titania-coated silica (ST20) initial or modified by sodium alginate (ST20-ALG) were studied. The equilibrium and kinetic data of metal ions adsorption were analyzed using Langmuir and Freundlich adsorption models and kinetic models: pseudo first order, pseudo second order, intraparticle kinetic model, and Elovich. The maximum sorption capacities observed were higher for the ST20-ALG composite compared to the initial ST20 oxide for all studied metal ions, namely their values for ST20-ALG were 22.44 mg g^- 1 for Cu(II) adsorption, 19.95 mg g^- 1 for Zn(II), 18.85 mg g^- 1 for Cd(II), and 32.49 mg g^- 1 for Pb(II). Structure and properties of initial silica-titania ST20 and modified by sodium alginate ST20-ALG adsorbents were analyzed using nitrogen adsorption/desorption isotherms, ATR-FTIR, SEM-EDS, and pHpzc techniques.

Investigations of Heavy Metal Ion Sorption Using Nanocomposites of Iron-Modified Biochar

Magnetic biochar nanocomposites were obtained by modification of biochar by zero-valent iron. The article provides information on the impact of contact time, initial Cd(II), Co(II), Zn(II), and Pb(II) ion concentrations, dose of the sorbents, solution pH and temperature on the adsorption capacity. On the basis of experiments, it was found that the optimum parameters for the sorption process are phase contact time 360 min (after this time, the equilibrium of all concentrations is reached), the dose of sorbent equal to 5 g/dm³, pH 5 and the temperature 295 K. The values of parameters calculated from the kinetic models and isotherms present the best match to the pseudo second order and Langmuir isotherm models. The calculated thermodynamic parameters ∆H ⁰, ∆S ⁰ and ∆G ⁰ indicate that the sorption of heavy metal ions is an exothermic and spontaneous process as well as favoured at lower temperatures, suggesting the physical character of sorption. The solution of nitric acid(V) at the concentration 0.1 mol/dm³ was the best acidic desorbing agent used for regeneration of metal-loaded magnetic sorbents. The physicochemical properties of synthesized composites were characterized by FTIR, SEM, XRD, XPS and TG analyses. The point characteristics of the double layer for biochar pH_PZC and pH_IEP were designated.

Metal Ions Removal Using Nano Oxide Pyrolox™ Material

The paper presents the use of Pyrolox™ containing manganese nano oxides used for the removal of Cu(II), Zn(II), Cd(II), and Pb(II) as well as U(VI) ions. Their concentrations were analyzed using the atomic absorption spectrometer SpectrAA 240 FS (Varian) as well as UV-vis method. For this purpose the static kinetic and equilibrium studies were carried out using the batch technique. The effect of solution pH, shaking time, initial metal ion concentrations, sorbent dosage, and temperature was investigated. The equilibrium data were analyzed using the sorption isotherm models proposed by Freundlich, Langmuir-Freundlich, Temkin, and Dubinin-Radushkevich. The kinetic results showed that the pseudo second order kinetic model was found to correlate the experimental data well. The results indicate that adsorption of Cu(II), Zn(II), Cd(II), and Pb(II) as well as U(VI) ions is strongly dependent on pH. The value of pH 4-7 was optimal adsorption. The time to reach the equilibrium was found to be 24 h, and after this time, the sorption percentage reached about 70%. Kinetics of Cu(II), Zn(II), Cd(II), Pb(II), and U(VI) adsorption on the adsorbent can be described by the pseudo second order rate equation. Nitrogen adsorption/desorption, infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) measurements for adsorbent characterization were performed. Characteristic points of the double layer determined for the studied Pyrolox™ sample in 0.001 mol/dm³ NaCl solution are pH_PZC = 4 and pH_IEP < 2.

Gd-DTPA Adsorption on Chitosan/Magnetite Nanocomposites

The synthesis of the chitosan/magnetite nanocomposites is presented. Composites were prepared by co-precipitation of iron(II) and iron(III) salts by aqueous ammonia in the 0.1 % chitosan solution. It was shown that magnetite synthesis in the chitosan medium does not affect the magnetite crystal structure. The thermal analysis data showed 4.6 % of mass concentration of chitosan in the hybrid chitosan/magnetite composite. In the concentration range of initial Gd-DTPA solution up to 0.4 mmol/L, addition of chitosan to magnetite increases the adsorption capacity and affinity to Gd-DTPA complex. The Langmuir and Freundlich adsorption models were applied to describe adsorption processes. Nanocomposites were characterized by scanning electron microscopy (SEM), differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and specific surface area determination (ASAP) methods.

Development of New Effective Sorbents Based on Nanomagnetite

Magnetic hybrid nanocomposite material based on the kraft lignin was prepared by the co-precipitating method. Kraft lignin was modified by iron nanooxide in order to enhance its sorption properties towards heavy metal ions. The composite material was characterized by physicochemical methods such as BET N2, ATR-FTIR, TGA, DSC, pHpzc, XRD and SEM. Its adsorption behaviour was studied using the batch mode by varying different parameters like pH, initial concentration of metal ions and shaking time as well as the presence of interfering ions. Adsorption of Cu(II), Cd(II) and Pb(II) ions from the aqueous solutions was studied in comparison with the commercial kraft lignin. The adsorption capacity and kinetic sorption characteristics of the composite material were determined.

Silica with immobilized phosphinic acid-derivative for uranium extraction

A novel adsorbent benzoimidazol-2-yl-phenylphosphinic acid/aminosilica adsorbent (BImPhP(O)(OH)/SiO2NH2) was prepared by carbonyldiimidazole-mediated coupling of aminosilica with 1-carboxymethylbenzoimidazol-2-yl-phenylphosphinic acid. It was obtained through direct phosphorylation of 1-cyanomethylbenzoimidazole by phenylphosphonic dichloride followed by basic hydrolysis of the nitrile. The obtained sorbent was well characterized by physicochemical methods, such as differential scanning calorimetry-mass spectrometry (DSC-MS), surface area and pore distribution analysis (ASAP), scanning electron microscopy (SEM), X-ray photoelectron (XPS) and Fourier transform infrared (FTIR) spectroscopies. The adsorption behavior of the sorbent and initial silica gel as well as aminosilica gel with respect to uranium(VI) from the aqueous media has been studied under varying operating conditions of pH, concentration of uranium(VI), contact time, and desorption in different media. The synthesized material was found to show an increase in adsorption activity with respect to uranyl ions in comparison with the initial compounds. In particular, the highest adsorption capacity for the obtained modified silica was found at the neutral pH, where one gram of the adsorbent can extract 176mg of uranium. Under the same conditions the aminosilica extracts 166mg/g, and the silica - 144mg/g of uranium. In the acidic medium, which is common for uranium nuclear wastes, the synthesized adsorbent extracts 27mg/g, the aminosilica - 16mg/g, and the silica - 14mg/g of uranium. It was found that 15% of uranium ions leached from the prepared material in acidic solutions, while 4% of uranium can be removed in a phosphate solution.

Application of a new generation of complexing agents in removal of heavy metal ions from different wastes

Complexing agents are extensively applied in many fields of industry. They are used to provide effective controlling trace metal ions in cleaning industries, textile, pulp and paper production, water treatment, agriculture, food industries, etc. Recently, the low biodegradability of these ligands and their accumulation in the environment has become a cause for concern. Therefore, replacement of ethylenediaminetetraacetic acid and diethylenetriaminepentaacetic acid by more environmentally friendly chelating agents is highly desirable. So far, these acids and their salts have been applied as components of household chemistry, cosmetics, modern microelement fertilizers and agrochemicals. This paper reviews the sorption of heavy metal ions such as Cu(II), Zn(II), Cd(II) and Pb(II) in the presence of the above-mentioned complexing agents on commercially available anion exchangers of different matrix. The obtained sorption results were fitted using the Langmuir and Freundlich sorption isotherm models. The kinetic data were also analysed using the Lagergren, Ho and McKay sorption kinetic equations. The studies were carried out considering the effects of such important parameters as phase contact time, initial concentration, pH and temperature.