Search Results (29)

Hydroxamic acid extractants, such as LIX984, demonstrate high efficiency in extracting nickel from electron-free nickel waste solutions; however, they suffer from a slow extraction rate. This study investigated the effect of adding 2–5 vol.% of three organophosphate extractants (P507, P204, and Cyanex272) to LIX984. The results show that incorporating 2–5 vol.% of P507 or Cyanex272 significantly improves both extraction efficiency and kinetics. The addition of organophosphate extractants increased the extraction rate by 1.5–10 times, indicating a direct correlation between the extractant content and the acceleration of the extraction process, with higher concentrations yielding faster extraction. Compared to the use of LIX984 alone, where nickel extraction efficiency was only 46%, the addition of 5 vol.% P507 increased efficiency to over 99%, with a substantial improvement in extraction rate. Similarly, 2 vol.% P204 achieved a nickel removal efficiency of 99.8%. In non-electroplating waste solutions (pH 4–6), selective removal of iron and zinc impurities was achieved by first adding 2–5 vol.% P204 or P507, followed by adjusting the pH to 6–7 and using a mixture of organophosphate extractants. The spent electroless nickel plating baths were then treated with LIX984 combined with organophosphoric acid extractants, yielding nickel salt solutions of higher purity. Thus, P507, P204, and Cyanex272 serve as effective promoters for the hydroxamic acid extractant LIX984, resulting in both enhanced nickel extraction efficiency and faster extraction kinetics. Full article

Adsorption is a popular method for the recovery of low-grade lithium. It is a low-cost and highly efficient way to treat solutions with low lithium concentrations. The impurity content determines the industrial application. This study investigated a novel strategy to remove divalent cations from a desorption solution containing Mg²⁺, Ca²⁺, and Mn²⁺, generated by a manganese absorbent using an organophosphoric acid, followed by precipitation of lithium carbonate from the concentrated raffinate by evaporation. Di(2-ethylhexyl)phosphoric acid (P204) was selected as the preferred extractant. The saponification method and degree of saponification were determined, and the extraction parameters (pH, extractant concentration, and phase ratio) were investigated. A three-stage countercurrent extraction process was tested. Removal efficiencies of Mg²⁺, Ca²⁺, and Mn²⁺ from the manganese-containing desorption solution exceeded 99%, leaving <1.0 mg/L divalent cations in the raffinate. The raffinate was evaporated and concentrated to >23 g/L lithium. The total concentration of divalent cations in the lithium-rich solution was approximately 10.0 mg/L. Further conversion with sodium carbonate was carried out to prepare a battery-grade lithium carbonate product with a purity of 99.83%. The present work may provide a novel means of lithium recovery from a manganese-containing desorption solution. Full article

Pesticides, essential for controlling pests and weeds, significantly boost agricultural productivity. However, their excessive use leads to substantial contamination of environmental matrices, including soil and water. Organophosphorus compounds, which constitute more than 30% of the global use of insecticides and herbicides, are particularly concerning, and their widespread application raises alarms among environmentalists and regulatory agencies due to their high toxicity to aquatic organisms. Therefore, to avoid the spread of these compounds within the environment, the contaminated sites may be treated with various methods. This study explored a soil detoxification procedure utilizing gaseous ozone. As a representative of organophosphorus pesticides, chlorfenvinphos was utilized as soil contaminant. This compound is still reported to occur in a number of environmental matrixes. The method used in this study involved the exposure of the soil matrix in a fluidized state to an ozone-enriched atmosphere. The ozonation procedure enabled the removal of the pesticide from the soil matrix. During its oxidation, some degradation products were detected; in particular, they included 2,4-dichlorobenzoic acid and 2-chloro-1-(2,4-dichloro-phenyl)-ethanone, whose presence was confirmed by a GC-MS system and the NIST database. However, they also underwent degradation. Moreover, on the basis of stereoselective reaction of Z and E isomers, the pesticide degradation pathway was proposed. Additionally, the efficacy of this detoxication method was evaluated using a combination of chronic and acute toxicity tests, employing Eisenia foetida earthworms as bioindicators. On the basis of the obtained results, it can be concluded that organophosphorus herbicides containing unsaturated bonds in their structure, including glyphosate, can be removed using this method. Full article

Mining of organophosphorous (OPs)-degrading bacterial enzymes in collections of known bacterial strains and in natural biotopes are important research fields that lead to the isolation of novel OP-degrading enzymes. Then, implementation of strategies and methods of protein engineering and nanobiotechnology allow large-scale production of enzymes, displaying improved catalytic properties for medical uses and protection of the environment. For medical applications, the enzyme formulations must be stable in the bloodstream and upon storage and not susceptible to induce iatrogenic effects. This, in particular, includes the nanoencapsulation of bioscavengers of bacterial origin. In the application field of bioremediation, these enzymes play a crucial role in environmental cleanup by initiating the degradation of OPs, such as pesticides, in contaminated environments. In microbial cell configuration, these enzymes can break down chemical bonds of OPs and usually convert them into less toxic metabolites through a biotransformation process or contribute to their complete mineralization. In their purified state, they exhibit higher pollutant degradation efficiencies and the ability to operate under different environmental conditions. Thus, this review provides a clear overview of the current knowledge about applications of OP-reacting enzymes. It presents research works focusing on the use of these enzymes in various bioremediation strategies to mitigate environmental pollution and in medicine as alternative therapeutic means against OP poisoning. Full article

Encapsulated phosphotriesterase nanoreactors show their efficacy in the prophylaxis and post-exposure treatment of poisoning by paraoxon. A new enzyme nanoreactor (E-nRs) containing an evolved multiple mutant (L72C/Y97F/Y99F/W263V/I280T) of Saccharolobus solfataricus phosphotriesterase (PTE) for in vivo detoxification of organophosphorous compounds (OP) was made. A comparison of nanoreactors made of three- and di-block copolymers was carried out. Two types of morphology nanoreactors made of di-block copolymers were prepared and characterized as spherical micelles and polymersomes with sizes of 40 nm and 100 nm, respectively. The polymer concentrations were varied from 0.1 to 0.5% (w/w) and enzyme concentrations were varied from 2.5 to 12.5 μM. In vivo experiments using E-nRs of diameter 106 nm, polydispersity 0.17, zeta-potential −8.3 mV, and loading capacity 15% showed that the detoxification efficacy against paraoxon was improved: the LD₅₀ shift was 23.7xLD₅₀ for prophylaxis and 8xLD₅₀ for post-exposure treatment without behavioral alteration or functional physiological changes up to one month after injection. The pharmacokinetic profiles of i.v.-injected E-nRs made of three- and di-block copolymers were similar to the profiles of the injected free enzyme, suggesting partial enzyme encapsulation. Indeed, ELISA and Western blot analyses showed that animals developed an immune response against the enzyme. However, animals that received several injections did not develop iatrogenic symptoms. Full article

The extraction of metals from waste printed circuit boards (WPCBs) with ionic liquids (ILs), Deep Eutectic Solvents (DESs) and organophosphorous-based acid (Cyanex 272) has been presented. The study was undertaken to assess the effectiveness of the application of the new leaching liquids, and the new method of extraction of metals from the leachate and the solid phase with or without the leaching process. Solvent extraction from the liquid leachate phase has been studied in detail with popular ILs, such as tetraoctylphosphonium bromide, {[P_8,8,8,8][Br] and tributyltetradecylphosphonium chloride, [P_4,4,4,14][Cl] using Aqueous Biphasic Systems (ABS) method. Trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, [P_6,6,6,14][Cyanex272], ([P_6,6,6,14][BTMPP]), trihexyltetradecylphosphonium thiocyanate, [P_6,6,6,14][SCN], methyltrioctylammonium chloride (Aliquat 336), as well as bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) were also used in the extraction of metals from the leachate. Two DESs (1) {choline chloride + lactic acid, 1:2} and (2) {choline chloride + malonic acid, 1:1} were used in the extraction of metals from the solid phase. The extraction behavior of metals with DESs was compared with that performed with three new bi-functional ILs: didecyldimethylammonium salicylate, [N_10,10,1,1][Sal], didecyldimethylammonium bis(2-ethylhexyl) phosphate, [N_10,10,1,1][D2EHPA], and didecyldimethylammonium bis(2,4,4-trimethylpentyl) phosphinate, [N_10,10,1,1][Cyanex272]. The [P_6,6,6,14][Cyanex272]/toluene and (Cyanex 272 + diethyl phosphite ester) mixtures exhibited a high extraction efficiency of about 50–90% for different metal ions from the leachate. High extraction efficiency of about 90–100 wt% with the ABS method using the mixture {[P_8,8,8,8][Br], or [P_4,4,4,14][Cl] + NaCl + H₂O₂ + post-leaching liquid phase} was obtained. The DES 2 revealed the efficiency of copper extraction, E_Cu = 15.8 wt% and silver, E_Ag = 20.1 wt% at pH = 5 from the solid phase after the thermal pre-treatment and acid leaching. The solid phase extraction efficiency after thermal pre-treatment only was (E_Cu = 9.6 wt% and E_Ag = 14.2 wt%). The use of new bi-functional ILs did not improve the efficiency of the extraction of metal ions from the solid phase. Process factors such as solvent concentration, extraction additives, stripping and leaching methods, temperature, pH and liquid/solid as well as organic/water ratios were under control. For all the systems, the selectivity and distribution ratios were described. The proposed extraction processes can represent alternative paths in new technologies for recovering metals from electronic secondary waste. Full article

The DOPO-based flame-retardant additives DOPO-HQ, DOPO-AP and DOPO-Van were synthesized in varying numbers of phenolic hydroxyl groups and amine groups. Moreover, their influence on the polymerization of a bisphenol F-based benzoxazine, as well as the thermal properties of the resulting materials, were studied. All DOPO-based derivatives influenced the polymerization temperature onset with a reduction of up to 20 °C, while thermo-mechanical properties remained high. Surprisingly, phosphorous content below 0.4 wt% significantly improved the reaction against small flames yielding an increase in the limited oxygen index by 2% and a V-0 rating in the UL-94 test. DOPO-HQ proved to be the most effective additive regarding the reaction against small flames at an astonishingly low phosphorous concentration of below 0.1 wt%, whereas DOPO-AP and DOPO-Van simultaneously lowered the polymerization temperature. Full article

Median lethal concentration values are commonly used to express the relative risk related to the acute toxicity of chemicals. In this paper, we considered rat and mouse acute toxicity (LD₅₀) data of organophosphorous compounds (OPs) with diverse structures. Interspecies QSTTR (quantitative structure-toxicity–toxicity relationships) models were developed to predict the mouse oral acute toxicity using the multiple linear regression (MLR) approach. Descriptors were calculated from the OPs structures optimized by molecular mechanics calculations. Model validation was performed using several statistical parameters. The results suggest the suitability of the developed QSTTR models to reliably predict the acute toxicity of OPs. Full article

Coumaphos is an organophosphorus compound used as insecticide and frequently used by beekeepers for the management of parasitic mites. The most important metabolite, chlorferron (CFN), has been identified in biological samples and foodstuff. The need to quickly identify the presence of typical metabolites, as an indication of interaction with coumaphos has driven the need to produce a highly sensitive electrochemical method for chlorferron analysis, based on molecularly imprinting polymers (MIP) technology. It showed irreversible behaviour with mixed diffusion/adsorption-controlled reactions at the electrode surface. A monoelectronic mechanism of reaction for oxidation has also been suggested. The linear range observed was from 0.158 to 75 µM. Median precision in terms of %RSD around 3% was also observed. For DPV, the limit of detection (LOD) and the limit of quantitation (LOQ) for the CFN-MIP were 0.158 µM and 0.48 µM, respectively. The obtained median % recovery was around 98%. The results were also validated to reference values obtained using GC-MS. Urine and human synthetic plasma spiked with CFN were used to demonstrate the usability of the method in biological samples, showing the potential for biomonitoring. The developed imprinted sensor showed maximum signal change less than 16.8% when related metabolites or pesticide were added to the mix, suggesting high selectivity of the MIP sensor toward CFN molecules. The results from in vitro metabolism of CMP analysed also demonstrates the potential for detection and quantification of CFN in environmental samples. The newly developed CFN-MIP sensor offers similar LoDs than chromatographic methods with shorter analysis time. Full article

The aim of this study was to investigate the seasonal and spatial variations in the concentrations of a widely used organophosphorous pesticide (OPP), diazinon, and the associated risk posed by this OPP in the surface water from the three largest rivers located in the northern province of Iran: the Haraz, the Talar and the Babolrood rivers. These rivers are located in the agriculture province of Mazandaran, and are exposed to high doses of organophosphorus pesticides, especially diazinon. The concentration of diazinon was determined using gas chromatography, while the potential risk posed by diazinon was elucidated using a Risk Quotient (RQ) calculated for general (RQm) and worst-case (RQex) scenarios. The obtained results demonstrated that the average diazinon concentrations ranged from 41 ± 76 ng/L in the Talar River and 57 ± 116 ng/L in the Haraz River, to 76.5 ± 145 ng/L in the Babolrood River, with a significant difference noted between summer and autumn seasons for all three rivers. For some stations, the concentration of diazinon is higher than the standard guidelines of Australian/New Zealand Guidelines for Fresh and Marine Water Quality (FMWQ) and the United States Criteria Maximum Concentration (CMC). The calculated RQs indicated a medium risk of diazinon, RQm = 0.73 and RQex = 2.27, in the Talar River; RQm = 1.02 and RQex = 2.49 in the Haraz River; and RQm = 1.35 and RQex = 4.54 in the Babolrood River. The overall exposure of diazinon was defined to have a high risk (RQm and RQex > 1); however, the summer sampling revealed a high risk (RQm and RQex > 1), while the autumn had a medium risk (RQm and RQex < 1). The obtained results revealed not only elevated concentrations of diazinon in the studied rivers but most importantly the high risk posed by this OPP for the aquatic organisms and the wellbeing of the whole river ecosystem. The current study showed that development and implementation of appropriate standards and regulations toward diazinon in countries such as Iran are required to reduce the pollution levels and risks related to elevated concentrations of the studied pesticide. Full article

Organophosphorous nerve agents (OPNA) pose an actual and major threat for both military and civilians alike, as an upsurge in their use has been observed in the recent years. Currently available treatments mitigate the effect of the nerve agents, and could be vastly improved by means of scavengers of the nerve agents. Consequently, efforts have been made over the years into investigating enzymes, also known as bioscavengers, which have the potential either to trap or hydrolyze these toxic compounds. We investigated the previously described esterase 2 from Thermogutta terrifontis (TtEst2) as a potential bioscavenger of nerve agents. As such, we assessed its potential against G-agents (tabun, sarin, and cyclosarin), VX, as well as the pesticide paraoxon. We report that TtEst2 is a good bioscavenger of paraoxon and G-agents, but is rather slow at scavenging VX. X-ray crystallography studies showed that TtEst2 forms an irreversible complex with the aforementioned agents, and allowed the identification of amino-acids, whose mutagenesis could lead to better scavenging properties for VX. In conjunction with its cheap production and purification processes, as well as a robust structural backbone, further engineering of TtEst2 could lead to a stopgap bioscavenger useful for in corpo scavenging or skin decontamination. Full article

The present work introduces both synthesis of silica nanoparticles doped with Co^II ions by means of differently modified microemulsion water-in-oil (w/o) and Stöber techniques and characterization of the hybrid nanoparticles (Co^II@SiO₂) by TEM, DLS, XRD, ICP-EOS, SAXS, UV-Vis, and UV-Vis/DR spectroscopy and electrochemical methods. The results reveal the lack of nanocrystalline dopants inside the hybrid nanoparticles, as well as no ligands, when Co^II ions are added to the synthetic mixtures as Co^II(bpy)₃ complexes, thus pointing to coordination of Co^II ions with Si-O^- groups as main driving force of the doping. The UV-Vis/DR spectra of Co^II@SiO₂ in the range of d-d transitions indicate that Stöber synthesis in greater extent than the w/o one stabilizes tetrahedral Co^II ions versus the octahedral ions. Both cobalt content and homogeneity of the Co^II distribution within Co^II@SiO₂ are greatly influenced by the synthetic technique. The electrochemical behavior of Co^II@SiO₂ is manifested by one oxidation and two reduction steps, which provide the basis for electrochemical response on glyphosate and HP(O)(OEt)₂ with the LOD = 0.1 μM and the linearity within 0.1–80 μM. The Stöber Co^II@SiO₂ are able to discriminate glyphosate from HP(O)(OEt)₂, while the w/o nanoparticles are more efficient but nonselective sensors on the toxicants. Full article

Tricresyl phosphate (TCP) is an organophosphorous neurotoxin that has been detected in water, soil and air. Exposure to TCP in cockpit and cabin air poses a severe threat to flight safety and the health of the aircraft cabin occupants. Conventional methods for the detection of TCP in various samples are gas or liquid chromatography coupled to mass spectrometry, which are complex and expensive. To develop a simple low-cost methodology for the real-time monitoring of TCP in the environment, an effective catalyst is demanded for the hydrolysis of TCP under neutral condition. In this study, Ruthenium (III) hydroxide and Iron (III) hydroxide are found to facilitate the production of the alcoholysis and hydrolysis products of TCP, suggesting their role as a catalyst. With this finding, these metal hydroxides provide new potential to realize not only simple colorimetric or electrochemical detection of TCP, but also a simple detoxication strategy for TCP in environment. In addition, the catalytic capability of Ru (III) or Fe (III) hydroxide for TCP gives a hint that they can potentially serve as catalysts for the hydrolysis of alcolyolysis of many other organophosphate compounds. Full article

Between 25% and 30% of the nearly one million military personnel who participated in the 1991 Persian Gulf War became ill with chronic symptoms ranging from gastrointestinal to nervous system dysfunction. This disorder is now referred to as Gulf War Illness (GWI) and the underlying pathophysiology has been linked to exposure-based neuroinflammation caused by organophosphorous (OP) compounds coupled with high circulating glucocorticoids. In a mouse model of GWI we developed, corticosterone was shown to act synergistically with an OP (diisopropylflurophosphate) to dramatically increase proinflammatory cytokine gene expression in the brain. Because not all Gulf War participants became sick, the question arises as to whether differential genetic constitution might underlie individual differences in susceptibility. To address this question of genetic liability, we tested the impact of OP and glucocorticoid exposure in a genetic reference population of 30 inbred mouse strains. We also studied both sexes. The results showed wide differences among strains and overall that females were less sensitive to the combined treatment than males. Furthermore, we identified one OP-glucocorticoid locus and nominated a candidate gene—Spon1—that may underlie the marked differences in response. Full article

Microcantilevers are really promising sensitive sensors despite their small surface. In order to increase this surface and consequently their sensitivity, we nanostructured them with copper oxide (CuO) nanorods. The synthesis of the nanostructure consists of the oxidation of a copper layer deposited beforehand on the surface of the sample. The oxidation is performed in an alkaline solution containing a mixture of Na(OH) and (NH₄)₂S₂O₈. The synthesis procedure was first optimized on a silicon wafer, then transferred to optical cantilever-based sensors. This transfer requires specific synthesis modifications in order to cover all the cantilever with nanorods. A masking procedure was specially developed and the copper layer deposition was also optimized. These nanostructured cantilevers were engineered in order to detect vapors of organophosphorous chemical warfare agents (CWA). The nanostructured microcantilevers were exposed to various concentration of dimethyl methylphosphonate (DMMP) which is a well-known simulant of sarin (GB). The detection measurements showed that copper oxide is able to detect DMMP via hydrogen interactions. The results showed also that the increase of the microcantilever surface with the nanostructures improves the sensors efficiency. The evolution of the detection performances of the CuO nanostructured cantilevers with the DMMP concentration was also evaluated. Full article