Search

Dynamic adsorption and desorption kinetics of 137Cs, 85Sr, 60Co radionuclides on granulated phosphate adsorbent based of phosphatized dolomite were studied. The influence of the model solutions composition (distilled water, 0.1 M NaCl, 0.05 M CaCl2) on the efficiency of dynamic adsorption was established. Experimental data on the distribution of 137Cs, 85Sr, 60Co radionuclides over the depth of the adsorbent layer were obtained. The mechanism of radionuclides adsorption was proposed. The regularities of desorption kinetics depending on pH (4.0, 7.0, 10.0) and the composition of leaching solutions (distilled water and model sea solution) were studied.

With increasing attention to the environment and health, the demand for environmentally friendly plasticizers, which were applied to produce phthalate-free flexible poly(vinyl chloride) (PVC), is becoming more and more urgent. In this work, a novel high efficiency plasticizer, an ester-capped oligomeric lactic acid mixture (EOL), was successfully synthesized by a two-step esterification reaction, with L-lactic acid as the main raw material. The structure of EOL was characterized by using FT-IR, 1H NMR and time of flight mass spectrometry (TOF-MS). The plasticizing performance of EOLs in PVC was tested and compared with those of commercial environmental plasticizers acetyl tributyl citrate (ATBC) and di-2-ethylhexyl terephthalate (DOTP). According to the results of tensile tests, the elongation at break of PVC plasticized by 50 phr EOLs reached 725.5%, indicating its superior mechanical properties. The result of TGA showed that the thermal stability of PVC plasticized by EOLs was as comparable as that of PVC plasticized by DOTP or ATBC. Furthermore, compared with ATBC and DOTP, EOLs showed better migration resistance in the leaching test. All test results showed that the comprehensive performance of EOLs was better than those of commercial green plasticizers ATBC and DOTP, which provided a new method for the development of novel green plasticizers.

In entrapment an active species, which is often a catalyst, is trapped within a material by a solid or gel forming event; thus, it becomes dispersed within the solid or semi-solid matrix. Entrapment methods can be used to immobilize isolated enzymes and render them more stable, and easier to separate and recycle. Entrapment immobilization methods are well established for whole cell biocatalysis. Despite this the applications of entrapment towards isolated enzyme immobilization have lagged the use of covalent attachment and crosslinking methods. In this review entrapment methods are contrasted with other methods of enzyme immobilization and literature methods of enzyme entrapment are reviewed. A key advantage of this approach is that no formal interaction with the protein is required, but this must be balanced against the threat of enzyme leaching, or introduction of mass transfer limitations. The main methods of entrapment are characterized, and some recent innovations are highlighted.

Controlling the product selectivity of a ring-opening hydrolysis reaction remains a great challenge with mineral acids and to an extent with homogeneous catalysts. In addition, even trace amounts of metal impurities in a bioactive product hinder the reaction progress. This has necessitated the development of robust and metal-free catalysts to offer an alternative sustainable route. We report a nitrogen-rich sulfonated carbon as a catalyst derived from an inexpensive precursor for the synthesis of bioactive vicinal diols of spiro-oxindole derivatives. The well-characterized catalyst shows wide generality with different electronic and steric substituents in the substrates under mild reaction conditions. Hot filtration test confirms no leaching of the acid moiety and the catalyst could be reused for four cycles with retention of activities.

Lithium-ion batteries are used for energy storage and as an energy source in a wide range of applications from small handheld to powering consumer-driven vehicles. With the global change from fuel-based vehicles to electric vehicles and the rise in use of batteries for other functions, it is imperative to start considering industrial-scale recycling of spent batteries to recover the critical components and reduce the ecological footprint generated by untreated disposal of the batteries. The present work was carried with the objective to check the environmental impact of leaching with mild phosphoric acid by using the material and energy flow data obtained from laboratory experiments. Lithium and cobalt were recovered from dead cell phone batteries that were composed of Lithium Cobalt Oxide (LiCoO2) on aluminum foils as cathodes and graphite on copper foils as anodes. The mass and energy flow data from the experiments performed were tabulated and used for the estimation of the environmental impact by executing a Life Cycle Impact Assessment (LCIA) using Umberto NXT universal software with ReCiPe (endpoint) method of analysis.

We report a method of glycosylated enzymes' surface immobilisation and stabilisation. The enzyme is immobilised at the surface of silica nanoparticles through the reversible covalent binding of vicinal diols of the enzyme glycans with a surface-attached boronate derivative. A soft organosilica layer of controlled thickness is grown at the silica surface, entrapping the enzyme and thus avoiding enzyme leaching. We demonstrate that this approach results not only in high and durable activity retention but also enzyme stabilisation.

UiO-66 is a zirconium-based metal–organic framework (MOF) that has numerous applications. Our group recently determined that UiO-66 is not as inert in aqueous dispersions as previously reported in the literature. The present work therefore assessed the behaviour of UiO-66 in buffers: 2-amino-2-(hydroxymethyl)-1,3-propanediol (TRIS), 4-(2-hydroxyethyl)piperazine-1-ethane sulfonic acid (HEPES), N-ethylmorpholine (NEM) and phosphate buffer (PB), all of which are commonly used in many UiO-66 applications. High performance liquid chromatography and inductively coupled plasma mass spectrometry were used to monitor degradation of the MOF at 25 °C. In each buffer, the terephthalate linker was released to some extent. The chemical nature of the buffer media played a decisive role in the stability with a more pronounced leaching effect in the saline forms of these buffers. The HEPES buffer was found to be the most benign, whereas NEM and PB should be avoided at any concentration as they were shown to rapidly degrade the UiO-66 framework. Low concentration TRIS buffers are also recommended, although these offer minimal buffer capacity to adjust pH. Regardless of the buffer used, rapid terephthalate release was observed, indicating that the UiO-66 was attacked immediately after mixing with the buffer. This process was even more pronounced at 37 °C, i.e., at typical temperature in biological and medical applications. In addition, the dissolution of zirconium, observed in some cases, intensified the UiO-66 decomposition process. These results demonstrate that sensitive analytical techniques have to be used to monitor the release of MOF components so as to quantify the stabilities of these materials in liquid environments.

This study proposes a green process for selective and rapid extraction of lithium from the cathode materials of spent lithium iron phosphate (LiFePO4) batteries via mechanochemical solid-phase oxidation. The advantages of the designed process are: (1) acid/base free; (2) extremely short time (5.0 min); (3) wastewater-free discharge; (4) three new chemical products; (5) high economic profit. The results show that by using solid-phase oxidant sodium persulfate (Na2S2O8) as a mechanochemical co-grinding agent and by carrying out the mechanochemical reaction under optimal conditions (rotary speed of 600 rpm, reaction time of 5.0 min, and Na2S2O8 : LiFePO4 mass ratio of 2 : 1), 99.7 wt% of the lithium in LiFePO4 can be selectively released and converted to lithium sulphate (Li2SO4), while the iron phosphate maintains an olivine frame structure. Lithium can then be recovered as a lithium phosphate (Li3PO4) product by integrated water leaching and chemical precipitation. Mechanism analysis shows that mechanochemical-assisted solid-phase oxidation may be a new approach for the selective release of lithium from LiFePO4; lithium behaves differently in this process compared to liquid-phase oxidation. This study provides a new approach to the selective and green recovery of lithium in spent LiFePO4 batteries.

Extraction of metal ions into perfluorocarbon solvents using fluorinated ligands has shown promise in a number of applications ranging from catalysis to biomedical imaging. However, the speciation of the extracted metal complexes is poorly understood hindering the design and implementation of new fluorous extraction systems. The extraction of s-, p-, d-, and f-block metal ions from the aqueous phase to the fluorous phase (perfluoro-15-crown-5 ether) with a fluorinated acetylacetonate pro-ligand was investigated and the speciation of the extracted metal complexes characterized, including coordinatively saturated mononuclear and polynuclear species and coordinatively unsaturated mononuclear species. The leaching of these species back into aqueous media was studied along with the effects of synergistic extraction using a combination of fluorinated acac and nonfluorinated neutral ligands. Our findings indicate that formation of coordinatively saturated mononuclear metal complexes in the fluorous phase is essential for retaining extracted species and suggest an important role for synergistic extraction for metal ions that do not form these types of metal complexes with acac ligands alone.

Homogeneous molecular catalysts are valued for their reaction specificity but face challenges in manufacturing scale-up due to complexities in final product separation, catalyst recovery, and instability in the presence of water. Heterogenizing these molecular catalysts, by attachment to a solid support, could transform the practical utility of molecular catalysts, simplify catalyst separation and recovery, and prevent catalyst decomposition by impeding bimolecular catalyst interactions. Previous strategies to heterogenize molecular catalysts via ligand-first binding to supports have suffered from reduced catalytic activity and leaching (loss) of catalyst, especially in environmentally friendly solvents like water. Herein, we describe an approach in which molecular catalysts are first attached to a metal oxide support through acidic ligands and then “encapsulated” with a metal oxide layer via atomic layer deposition (ALD) to prevent molecular detachment from the surface. For this initial report, which is based upon the well-studied Suzuki carbon–carbon cross-coupling reaction, we demonstrate the ability to achieve catalytic performance using a non-noble metal molecular catalyst in high aqueous content solvents. The catalyst chosen exhibits limited catalytic reactivity under homogeneous conditions due to extremely short catalyst lifetimes, but when heterogenized and immobilized with an optimal ALD layer thickness product yields >90% can be obtained in primarily aqueous solutions. Catalyst characterization before and after ALD application and catalytic reaction is achieved with infrared, electron paramagnetic resonance, and X-ray spectroscopies.

This paper aims to establish a mathematical model that can analyze the whole leaching kinetics process of ion-adsorption type rare earth ores. This leaching process is composed of three steps: (1) ammonium ions arrive at the ore particle surface through the diffusion layer; (2) ammonium ions exchange with rare earth ions; and (3) rare earth ions enter into the external solution through the diffusion layer. In the leaching process, it is hypothesized that the ore particle size remains constant. The process of ammonium ions and rare earth ions passing through the diffusion layer was described by the Fick law, and the reversible ion exchange process between ammonium ions and rare earth ions was described by the Kerr model. A leaching kinetics model of rare earth ions by ammonium ions was constructed. Accuracy of this kinetics model was verified with laboratory tests. It is found that the correlation coefficients of all data are greater than 0.9000. The proposed kinetics model is therefore feasible for kinetics analysis throughout the leaching process.

With rapid economic progress worldwide, the search for new resources for materials has become a priority due to mineral resource depletion. Enhanced requirements for manganese alloys and compounds for several commercial applications created a desperate demand for manganese recovery technologies from primary as well as secondary resources. The future demand for manganese alloys and compounds is expected to increase. The growing need of electrolytic manganese dioxide (EMD) for different battery usage in automobile and energy sectors could create a gap in the supply and demand of manganese. There is an urgent necessity for eco-friendly and efficient technologies to boost the production of manganese from low-grade ores as well as post-consumer products. The framework of effective leaching processes and proper solvent extraction techniques for the recovery of manganese could be a novel pathway to get a clean, green and healthy environment for a sustainable future in the automotive and energy segment where this metal has a significant contribution.

In this article, we analyze the leaching kinetics with phosphoric acid of LiCoO2 samples from spent Li-ion batteries and commercial LiCoO2. The purpose was to study the mechanism by which the extraction reaction of cobalt and lithium is produced from the solid samples. The experimental results showed that raising the temperature and the reaction time contributed to improving both the extraction of Li and Co from the structure. The leaching rate of the metals from both samples in the phosphoric acid solution could be expressed as: ln (1 − X) = −b1 [ln (1 + b2t) − 1+b2bt2t]. The morphology of the solid revealed that the dissolution reaction of the samples develops from preferential growth of active sites, points susceptible to chemical interaction, occurring in one direction, giving rise to the start and progress of the reaction. The generation of these sites in the LCO-H3PO4 reaction system is of the "sequential type". The apparent activation energy values for the leaching of Co and Li would indicate that the surface chemical reaction is the rate-controlling step during this dissolution process. Fil: Pinna, Eliana Guadalupe. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina Fil: Drajlin Gordón, Diego Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina Fil: Toro, Norman. Universidad Católica del Norte; Chile. Universidad Politécnica de Cartagena; España. Universidad Arturo Prat; Chile Fil: Rodriguez, Mario Humberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Interdisciplinario de Ciencias Básicas. - Universidad Nacional de Cuyo. Instituto Interdisciplinario de Ciencias Básicas; Argentina

The contamination of water bodies by pesticide residues through direct flow, leaching and other methods has motivated the development of analytical methods for the determination of these compounds in water. A vortex-assisted liquid-liquid microextraction method followed by gas chromatography coupled to mass spectrometry for the determination of anilazine, linuron, prothiofos, and tebuconazole residues in water samples from the culture and processing of potatoes (Solanum tuberosum L.) was optimized. The complete factorial design and the central rotational compound design combined with the desirability function were used to evaluate and optimize the parameters of the method. The optimized conditions for extracting the pesticides were as follows: 316 µL of toluene, no sodium chloride addition, and a stirring time of 187 s. The method presented an enrichment factor of 142.4 times and good linearity, precision and accuracy, with limits of detection (LOD) of 0.005 - 0.007 mg L-1 and limits of quantification (LOQ) of 0.016 - 0.022 mg L-1. The co-extractives of the wastewater samples caused the suppression of the chromatographic response of linuron and prothiofos by 7.82 and 27.63%, respectively. The analyte concentrations in the wastewater samples from the industrial shing process, manual potato washing, and dam water were either lower than the LODs of the method or were absent.

The work detailed here examined the presence and possibility of leaching of phthalic acid esters (PAEs) and polycyclic aromatic hydrocarbons (PAHs) from various products in everyday use. Due to the complicated matrix, which is plastic, extraction parameters should be selected separately each time. The properties of both the extractant and the material selected for testing should also be taken into account, which is very difficult in practice. In addition, when designing new methods, it is particularly important to take into account the principles of green chemistry so as not to burden the environment additionally. For this purpose, it is important to know the factors that affect the extraction of impurities. Therefore, the main objective was to assess the impact of selected environmental conditions on the process by which such pollutants in plastics like polyvinyl chloride (PVC), polystyrene (PS), polypropylene (PP) and rubber migrate. Analysis inter alia addressed the impacts of type of plastic, migration time, temperature and microplastic particle size. It proved possible to note the presence in PVC and rubber of both PAEs and PAHs—as substances posing a particular threat to the environment. One of the former is the commonly-used plasticiser di(2-ethylhexyl) phthalate (DEHP), a listed priority hazardous substance under the provisions of Directive 2013/39/EU as regards priority substances in the field of water policy. As monitoring of this substance in the environment indicates amounts that are increasing steadily, the design of effective removal methods needs to start with initial estimates of amounts appearing in the environment over time. Main sources need to be explored, albeit in the certain knowledge that the ubiquitous microplastics are among these, inter alia as influenced by elution mechanisms. An attempt was also made to identify and characterise other auxiliary substances added to plastics as they are being produced. Indeed, chromatograms and GC/MS spectra suggest leaching of many other plastic substances. Relationships between eluted pollutants were also sought.

Kinetics, as a fundamental requirement of nearly all industrial activities and engineering researches, plays a great role in leaching processes. Although there are many pieces of research on its application, there is not a clear pathway for investigating the kinetics of leaching and researchers usually follow different strategies in their studies. The conventional investigation techniques, which usually do not consider the mixed mechanisms and possibility of any change in the mechanism, normally include many calculations, plots, and inadequate capabilities to detect changes in the controlling mechanism of leaching. In this review, the main mathematical models of leaching and all possible scenarios are presented and discussed. The effect of various leaching parameters (including leaching agent, temperature, particle size, agitation, and solid to liquid ratio) on the rate of dissolution is summarized. Besides, two main approaches of rate determination step (single controlling mechanism and combined resistances method) are described and compared by reporting related equations and suitable examples. A technique to detect any changes in the leaching controlling mechanism is introduced and the alternatives to confirm the results are described. Additional models and equations were suggested for the cases that there is no agreement between data and the conventional models. Also, situations which are ignored in simple models (e.g., reversibility of the leaching reactions, adsorption and desorption of leached species, influence of charge and surface potential, existence of multiple reactants in the solid, galvanic effect, wide particle size distribution, etc.) to develop more legalistic models are discussed. Considering various possible mechanisms in the kinetics of leaching, equations are derived for industrial leaching reactors.

Considering the shortage and toxicity of raw materials, recycling cathode materials from spent lithium-ion batteries is currently the most promising measure to realize the green sustainability of c...

Acid methods for processing of bauxites and aluminosilicates with high silicon content become attractive in connection with the exhaustion of natural alumina-containing resources suitable for processing by standard procedures based on using alkalis. The main problems in using acid procedures are associated with organization of closed-loop processes with low consumption of chemicals and power. The acid–salt technologies suggested by now are based on using ammonium hydrosulfate in the whole cycle and are economically inferior to the classical Bayer alkaline procedure. This study demonstrates on the laboratory level good prospects for developing a new efficient technology for alumina production from low-grade raw materials in a closed-loop process with recuperation of the consumed salt reagent in each cycle. The process takes advantage of the relationships of the aluminum and iron distribution in the solid phases and equilibrium solutions, revealed by the authors. Another feature is the use of a special method of acid retardation in nanoporous media for separating the residual amounts of the acid and salt, which are returned to the head of the process, with substantial saving of the power and chemicals.

At elevated temperatures (130 and 180°C) in hydrothermal autoclave conditions, the possibility of deep extraction of noble metals from poor intermediate products of refining (or affinage) production was investigated. The conditions (temperature, processing conditions) of leaching of impurity elements into the solution are determined, under which the uncontrolled distribution of precious metals according to the technological scheme is prevented and their concentration in the solid phase is ensured. It was found that the processing of the poor intermediate product in two stages (alkaline and acidic) under autoclave conditions makes it possible to increase the total content of noble metals in the solid phase from 0.5 to 17.5 wt %, which allows returning this product to the refining cycle. In this case, more than 99 wt % tellurium passes into a solution that does not contain impurities of noble metals and is suitable for further processing.

Palm fatty acid distillate (PFAD) is a waste from refining crude palm oil, and it is a cheap low-quality feedstock due to its high free fatty acid (FFA) content. Esterification process is necessary to lower the level of FFA in PFAD. The physical and chemical properties of PFAD were studied and compared with previously reported studies and it was found that most of the PFAD parameters showed comparable values or were within the expected range. GC-MS analysis confirmed that the fatty acid in PFAD is 44.99% palmitic acid and 38.15% oleic acid. The optimized reaction conditions obtained for the esterification of PFAD by using ammonium ferric sulfate-calcium silicate (AFS-CS) as heterogeneous acid catalyst were 2-h reaction time, 12 wt% of AFS-CS catalyst amount and 15:1 methanol to PFAD molar ratio at 65 °C to produce maximum methyl esters conversion of 80%. The rate of leaching at active sites on the catalyst was very high; hence, the catalyst is not suitable to be reused.

In the present work, the extraction kinetics of copper using the resulting actual leach solution obtained from the leaching of malachite ore in perchloric acid solutions and the stripping kinetics of copper from the loaded organic phase were examined. The organic phase was prepared by using Acorga M5640 and kerosene. In the extraction process, the effects of the initial pH of aqueous solution, initial concentration of copper, extractant concentration, temperature, and stirring speed on the extraction rate were investigated. In the stripping process, the effects of the concentration of perchloric acid, temperature, stirring speed, and extractant concentration on the stripping rate were examined. It was determined that the extraction rate increased with increasing the initial pH of aqueous solution, stirring speed, extractant concentration and temperature, and with decreasing the initial concentration of copper ions. In the stripping process, it was observed that the stripping rate increased with increasing the concentration of perchloric acid, temperature and stirring speed, and with decreasing the extractant concentration. It was determined that both the solvent extraction and stripping processes could be described by the first order pseudo homogenous reaction model. The activation energy for the extraction and stripping processes was calculated to be 50.04 kJ/mol and 32.42 kJ/mol, respectively.

The limited lifespan, ever-growing demand, and significant lithium and cobalt content are responsible factors for the immediate recycling of discarded lithium-ion batteries. Discharged batteries were dismantled, segregated, and size reduced to recover cathode and anode material. The active cathode material comprises LiCoO2 (65.8%) and LiMn2O4 (34.2%) and was carbothermal reduced with recovered graphite in a microwave furnace followed by water leaching and magnetic separation. A Box Behnken statistical experimental design is used for process optimization. Both cobalt and manganese report to magnetic fraction, whereas graphite and lithium carbonate report to non-magnetic fraction and solution crystal respectively. The final product comprises of cobalt 73% and manganese of 14% with process yield of 36% and saturation magnetization of 76 emu/g.

The science of oil paint cleaning is an interdisciplinary and challenging field of study due to the complex nature of both paintings and cleaning materials. The topic requires an intimate and iterative collaboration between conservation scientists and paintings conservators. In such an interdisciplinary field, it can sometimes be difficult to interpret the practical applicability of the available literature. This review aims to bring both conservators and scientist up-to-date on the recent advances in the literature on oil paint cleaning and proposes a framework for experimental and theoretical investigations into solvent transport in oil paint. We define the physicochemical processes that occur simultaneously during cleaning as solvent action and investigate how these processes vary with the polymeric structure of the oil binding medium. The sections in this overview of the technical cleaning literature are divided into solubility, swelling and diffusion, leaching, solvent evaporation and retention and solvent-mediated chemical reactions. Models that have been used to predict varnish solubility or oil paint swelling, such as Teas chart, are critically reviewed from the perspective of the most recent developments in the various scientific disciplines involved. Technological developments in the field of modern materials for solvent- and water-based cleaning are also discussed. Finally, an outlook for the field of cleaning science is presented.

The recovery of valuable metals from the spent catalysts has become a part of exhaustive research not only due to reducing the inventory cost of catalysts but also for minimizing the spent catalyst generation to prevent environmental pollution. In the present investigation, the kinetic study of the hydrometallurgical based leaching of Zn and Cu from the spent low-temperature shift catalyst (CuO/ZnO/Al2O3) have been performed. Additionally, the process parameters affecting the leaching process have been optimized by Taguchi’s orthogonal array design. The results of the kinetic analysis indicated that the leaching process was mainly controlled by the diffusion through the porous product layer. The activation energy for the leaching of Zn and Cu were estimated as 18.63 kJ/mol and 18.14 kJ/mol respectively. Quantitative leaching of Zn (96.71%) and Cu (94.82%) was observed under the optimum levels such as HCl concentration − 3 M, leaching time − 3 h, stirring speed—600 rpm, S/L − 0.01, particle size − 90 µm and temperature – 80 C.

Oxidative-alkaline leaching of vanadium from vanadium-chromium-reducing residues with K2Cr2O7 was investigated in this paper. The effects of processing parameters including dosage of NaOH, dosage of K2Cr2O7, reaction time, and reaction temperature on the leaching efficiency of vanadium were studied. The results simulated by response surface methodology indicated that vanadium leaching was affected significantly by the dosage of K2Cr2O7 and NaOH, and the processing parameters that affected the leaching efficiency of vanadium followed the order m(NaOH)/m(residue) > m(K2Cr2O7)/sssssm(residue) > reaction temperature > reaction time. The leaching efficiency of vanadium was up to 99.92% under optimal conditions: reaction temperature of 90 °C, reaction time of 60 min, liquid-to-solid ratio of 5:1 mL g-1, m(K2Cr2O7)/m(residue) = 0.10, and m(NaOH)/m(residue) = 0.30. The kinetics analysis indicated that diffusion through the product layer was the controlling step and the apparent activation energy for vanadium leaching was calculated to be 58.275 kJ·mol-1.

Recycling of discarded integrated circuits is an important issue related to waste management, resource conservation, and metal recovery aspects. In this study, physical processing comprising water fluidization, magnetic separation, and density separation of discarded units was followed to recover Cu, Fe, Ni, and Si values. The fluidization technique provided an enriched metal concentrate comprising 53.05% Cu, 16.2% Fe, and 10.5% Ni in the underflow fraction, and the overflow fraction comprised 63.1% Si with 17.8% C. High metallic dissolution was attained for the processed samples compared with the feed leaching because of effective separation of the non-metallic fraction during physical processing. Overall, 1 kg of discarded ICs yielded ~ 120 g ferrous metal with ~ 57.4% Fe and ~ 26% Ni purity and ~ 390 g metallic values with 85% Cu and ~ 490 g non-metallic values with ~ 84% Si.

Due to the increasing criticality of rare earth elements (REEs), it has become essential to recover REEs from alternative resources. In this study, systematic REEs leaching tests were performed on the calcination product of a coal coarse refuse using hydrochloric acid and different types of organic acid as lixiviants. Experimental results show that the recovery of REEs, especially heavy REEs (HREEs) and scandium (Sc), is improved by using selected organic acids. Citric acid and dl -malic acid afford the best leaching performances; whereas, malonic acid, oxalic acid, and dl -tartaric acid are inferior to hydrochloric acid. Results of zeta potential measurements and solution chemical equilibrium calculations show that malonic acid is more likely adsorbed on the surface of the calcined material compared with citric acid and dl -malic acid. The adsorption may reduce the effective concentration of malonic species in solution and/or increase the amount of REEs adsorbed on the surface, thereby impairing the leaching recovery. Compared with light REEs (LREEs), a stronger adsorption of the HREEs on the surface is observed from electro-kinetic test results. This finding explains why organic acids impose a more positive impact on the leaching recovery of HREEs. By complexing with the HREEs, organic acids can keep the metal ions in solution and improve the leaching recovery. The adsorption of Sc3+ on the surface is the lowest compared with other REEs. Therefore, rather than complexing, the organic anionic species likely play a function of solubilizing Sc from the solid, which is similar to that of hydrogen ions.

© 2021 Elsevier B.V.Fouling and contamination of surfaces are prevailing challenges humanities facing today in fields such as healthcare, hospitality, and food manufacturing. These challenges strongly motivate the development of multifunctional surfaces with antifouling and antimicrobial properties that are coupled with sensing capabilities. To address this challenge, we prepared a multifunctional superhydrophobic surface using eco-friendly materials: polydimethylsiloxane (PDMS) and carnauba wax. After deposition of a thin film of Ag, the surface gained surface-enhanced Raman scattering (SERS) activity and bactericidal property. The multifunctional superhydrophobic surface showed extreme liquid repellency towards water and common liquid food. The strong SERS activity enabled the detection of adulterant rhodamine B in a sausage down to a nanomolar level. Notably, the surface showed excellent bactericidal activity towards two common bacteria, E. coli, and S. aureus, significantly reducing their adhesion and killing. Additionally, the surface showed anti-fouling behavior against common liquid food, and even towards sticky foods such as yogurt, honey, and pomegranate sauce, reducing residual food by >97 %. Furthermore, the superhydrophobic surface showed excellent chemical stability in dynamic and static flow conditions and leaching of Ag in neutral and basic solutions was minimal.

Objectives Only little is known about degradation of methacrylate monomers. Therefore, using in vitro chemical and saliva degradation this study aimed to identify the degradation products of organic compounds present in resin-based dental materials. Methods Ten dental monomers and nine polymerized dental resin-based materials were immersed for 24 h in chemical media (0.1 M HCl, 0.1 M NaOH) and human pooled saliva in order to identify leached monomers and degradation products from chemical and saliva degradation. Samples were analyzed using liquid chromatography coupled to high-resolution mass spectrometry to identify previously unknown degradation products. Results During in vitro chemical degradation, uncured monomers were rapidly hydrolyzed into mono- and demethacrylated degradation products. During chemical degradation in alkaline conditions of polymerized materials, considered the worst-case scenario, only degradation products could be detected. In acidic conditions, monomers and their degradation products were detected. In addition, different additives such as EDMAB, DMPA and HMBP were present in acidic degradation samples. Degradation in human pooled saliva for 24 h to mimic the in vivo situation, resulted in the identification of both monomers and their degradation products. Clinical Significance Using state-of-the-art high-resolution mass spectrometry previously unknown degradation products of commonly used monomers were identified for the first time. Results show that patients may be exposed to monomers and their degradation products in the first 24 h after restorative procedures. The results provide a base for further research on the degradation of resin-based dental composites in order to assess their safety using elution and toxicity studies.

International audience; Anaerobic digestion allows renewable energy to be produced through the degradation of bio-waste. The process, which is of economic and ecological interest, is implemented industrially in concrete digesters. Bio-waste is a complex medium with a composition that can vary in time and space. It contains several chemical compounds, including volatile fatty acids, ammonium, and CO2, which are aggressive towards concrete and compromise its durability. The individual effects of the different compounds on concrete are significantly different. To move toward a better design of concrete intended for the building of biogas digesters, this paper aims to understand the mechanisms and intensity of alteration associated with the different components of biowaste and their contribution to the total deterioration. Ordinary Portland cement pastes were immersed for 16 weeks in six synthetic solutions made of the three metabolites, taken alone or in mixes. The mass variations of the specimens, the pH, and the concentration of the chemical elements in solution were monitored over time. The microstructural, chemical and mineralogical changes of the samples were analysed by scanning electron microscopy, electron probe micro-analysis and X-Ray diffraction analyses and showed phenomena of dissolution, leaching and carbonation. The results show that the acetic acid solution was the most aggressive, in accordance with its pH value, and had a predominant effect in mixed solutions, whereas sodium bicarbonate solution induced carbonation and showed a protective effect. Interestingly, despite its reputed high aggressiveness, ammonium nitrate did not have a major impact in mixed solutions.

Surface antimicrobial materials are of interest as they can combat the critical threat of microbial contamination without contributing to issues of environmental contamination and the development drug resistance. Most nanostructured surfaces are prepared by post fabrication modifications and actively release antimicrobial agents. These properties limit the potential applications of nanostructured materials on flexible surfaces. Here, we report on an easily synthesized plastic material with inherent antimicrobial activity, demonstrating excellent microbicidal properties against common bacteria and fungus. The plastic material did not release antimicrobial components as they were anchored to the polymer chains via strong covalent bonds. Time-kill kinetics studies have shown that bactericidal effects take place when bacteria come into contact with a material for a prolonged period, resulting in the deformation and rupture of bacteria cells. A scanning probe microscopy analysis revealed soft nanostructures on the submicron scale, for which the formation is thought to occur via surface phase separation. These soft nanostructures allow for polyionic antimicrobial components to be present on the surface, where they freely interact with and kill microbes. Overall, the new green and sustainable plastic is easily synthesized and demonstrates inherent and long-lasting activity without toxic chemical leaching.

Solvent extraction (SX) is one of the most widely applied hydrometallurgical processes in copper production from oxide ore. As the high-grade ore deposits have been developed and depleted, now only low-grade ore deposits are being developed and are therefore facing obstacles of extreme processing conditions. This results in leaching gangue minerals and requires a more complicated solvent extraction system. Recently, synergistic solvent extraction has been introduced to separate copper from the leached solution with high impurities. However, operational obstacles arise due to the complicated solvent extraction process, including multi-stages of extraction, and using more than one extractant in a single solvent extraction system. The phase separation in solvent extraction is one of the major issues in field operation. A poor phase separation could affect the entire process and eventually cause production loss. Therefore, in this study, the phase separation behaviours were studied in consideration of the field operation. Major parameters considered in the study were the type of diluent, temperature, mixing speed, solution pH and Oxidation Reduction Potential (ORP), and addition of impurities (flocculant and colloidal silica). The phase separation behaviours in the continuous counter-current SX system using a pilot-scale mixer-settler in the above conditions was investigated.

The Bayer process holds an exclusive status for alumina extraction, but a massive amount of caustic “red mud” waste is generated. In this work, three oxalate reagents: potassium hydrogen oxalate (KHC2O4), potassium tetraoxalate (KHC2O4·H2C2O4), and oxalic acid (H2C2O4) were investigated for the Al and Fe extraction process from NIST SRM 600 – Australian Darling range bauxite ore. More than 90% of Al and Fe was extracted into the aqueous phase in less than 2 h with 0.50 M C2O42- for all three reagents. The Fe and Al can be selectively precipitated by hydrolyzing the aqueous phase. By acidifying the Al and Fe free filtrate, 80% of the C2O42- can be precipitated as KHC2O4·H2C2O4. Greater than 90% of the aqueous acid can also be recycled using a cation exchange resin. The proposed closed-loop process is an energy-efficient, cost-effective, environmentally-friendly route for extracting Al and Fe from bauxite ore.

Simple Summary Nanoscience and nanotechnology offer a new life for conventional pesticides with superior qualities by virtue of the physicochemical properties of the nanosized materials. These properties will improve bioavailability through different kinetics, mechanisms and pathways on their target organisms; enabling them to properly bypass biological and other unwanted resistances and therefore increase plant disease control efficacy. Inorganic two-dimensional (2D) layered hydroxides and layered double hydroxides were used as hosts, to act as functional nanocarriers for the delivery of various pesticides in combating various pests and diseases, in order to aid plant protection. This leads toward a new generation of more effective agrochemicals which are safe to life, humans and the environment. Abstract The rapid growth in the human population has triggered increased demand for food supply, and in turn has prompted a higher amount of agrochemical usage to meet the gaps between food production and consumption. The problem with conventional agro-nanochemicals is the reduced effectiveness of the active ingredient in reaching the target, along with leaching, evaporation, etc., which ultimately affect the environment and life, including humans. Fortunately, nanotechnology platforms offer a new life for conventional pesticides, which improves bioavailability through different kinetics, mechanisms and pathways on their target organisms, thus enabling them to suitably bypass biological and other unwanted resistances and therefore increase their efficacy. This review is intended to serve the scientific community for research, development and innovation (RDI) purposes, by providing an overview on the current status of the host–guest supramolecular chemistry of nanopesticides, focusing on only the two-dimensional (2D), brucite-like inorganic layered hydroxides, layered hydroxide salts and layered double hydroxides as the functional nanocarriers or as the hosts in smart nanodelivery systems of pesticides for plant protection. Zinc layered hydroxides and zinc/aluminum-layered double hydroxides were found to be the most popular choices of hosts, presumably due to their relative ease to prepare and cheap cost. Other hosts including Mg/Al-, Co/Cr-, Mg/Fe-, Mg/Al/Fe-, Zn/Cr- and Zn/Cu-LDHs were also used. This review also covers various pesticides which were used as the guest active agents using supramolecular host–guest chemistry to combat various pests for plant protection. This looks towards a new generation of agrochemicals, “agro-nanochemicals”, which are more effective, and friendly to life, humans and the environment.

The main objective of the article is to develop the concept of flock fragmentation and the averaging method for the application of electrocoagulation in the process of treating wastewater from coke ovens. The designed solution was part of an innovative system for the coke oven wastewater treatment process. The system is dedicated to removing the hazardous elements and compounds from wastewater from leaching ashes in municipal waste incineration plants. The design of the process and its automatization was based on a quantitative simulation method. The balance equations of mass, energy, and momentum of transport, complemented by the kinetics of the related reaction, are used during the calculation of the process. The main result achieved is a practical solution—the reactor’s scheme, classified due to a patent procedure in the Polish Patent Office.

Recent advances in the synthesis of polymer-immobilized clusters and metal nanoparticles and their use in catalysis of many organic reactions were presented. The main types of polymer-immobilized catalysts were considered, including cluster-containing polymers, polymer-protected metal nanoparticles fixed on inorganic supports, and gel-immobilized catalysts. Special attention was paid to the role of the polymer matrix. It functions not only as a stabilizing agent that prevents the aggregation of nanoparticles and their leaching into the reaction medium, but also as a ligand in the coordination sphere of the metal site, which allows the advantages of homogeneous and heterogeneous catalysts to be combined in one catalyst.

A disposal technology for lithium batteries with minimal environmental impact is proposed. Ground battery components are processed in five stages, to produce mechanically activated powder. Attention focuses on two stages: leaching; and purification and concentration of the lithium hydroxide and carbonate in a high-pressure membrane unit. Theoretical principles are outlined for mechanical–chemical destruction of the ground battery components with high product yield. Analysis of ball and product motion in a ball mill shows that waterfall motion of the balls is optimal. Formulas are given for the equivalent diameter of the particles and their specific surface.

An investigation was made of the production of boric acid from microwave-dehydrated ulexite waste by leaching with oxalic acid solution. An ulexite waste sample was dehydrated in a domestic microwave oven, and then dissolved in oxalic solution at temperatures of between 25 and 70°C. The experimental data from this dissolution process were analyzed using homogeneous and heterogeneous kinetic models, and the leaching kinetics of the microwave-dehydrated ulexite waste were defined. The activation energy of the oxalic acid solution of the microwave-dehydrated ulexite waste was also calculated. Öz Mikrodalga ile dehirate edilmiş uleksit atığından borik asidin oksalik asit çözeltisi liç yoluyla üretilmesi incelenmiştir. Üleksit atık numunesi, ev tipi bir mikrodalga fırında dehidrate edilmiştir. Mikrodalga ile dehirate edilmiş uleksit atığı, oksalik çözeltilerde 25 ila 70 °C arasındaki bir sıcaklıkta çözülmüştür. Bu çözünme işleminin deneysel verileri homojen ve heterojen kinetik modeller kullanılarak analiz edilmiş ve mikrodalga-dehidre edilmiş uleksit atığının çözünme kinetiği belirlenmiştir. Mikrodalga-dehidre edilmiş uleksit atığının oksalik asit çözeltisinin aktivasyon enerjisi de hesaplanmıştır.