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AbstractThe Guar Gum Xanthate based hydrogel GGmX-g-poly(AA-co-HEMA) has been successfully synthesized by using the graft copolymerization of two monomers, acrylic acid (AA) and 2-hydroxyethyl methacrylate (HEMA) hydrogel. The synthesis follows the free-radical graft polymerization method. UV-visible spectroscopy (UV), Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), Point zero charge (PZC), and field emission scanning electron microscopy (FESEM) were employed for the characterization of the synthesized hydrogel. This hydrogel has shown a high swelling ratio of 430.2 g/g and retention of 75.82% in distilled water which is a notable result. By using GGmX-g-poly(AA-co-HEMA) hydrogel, the maximum percentage of heavy metal ions removal from wastewater was found to be 98.5(±1.5)% and 97.1(±1.5) at optimum pH 6 and 6.5 for Cu2+ and Ni2+ solutions respectively. The Langmuir adsorption isotherm fits best for the adsorption data indicating a monolayer adsorption with maximum adsorption capacity of 423.72 (±26.1) mg/g and 404.85 (±31.4) mg/g for Cu2+ and Ni2+ ions respectively. The pseudo-second-order kinetic model provides the most accurate depiction of adsorption kinetics with rate constant 9.1 × 10−4 (±1.37×10−4)g/(mg.min) for Cu2+ and 8.3 × 10−4 (±1.24×10−4)g/(mg.min) for Ni2+ ions, respectively. The negative ΔG value (-4.75 kJ/mol for Cu2+ and −3.26 kJ/mol for Ni2+ ions) and positive value of ΔH (57.55 (±5.41) kJ/mol for Cu2+ and 40.60(±5.37) kJ/mol for Ni2+ ions) suggested the process to be spontaneous, endothermic, and feasible. It has been found that the hydrogel has excellent regenerative capacity with the % adsorption has been found to be 84.8% for Cu2+ and 82.4% for Ni2+ ions for the fifth cycle. [ABSTRACT FROM AUTHOR]

Pyrite is the most widely distributed sulfide mineral with a wide range of uses, and pyrite is mainly recovered by means of flotation in practical production, and the commonly used flotation collectors are mainly xanthates with good flotation performance. The adsorption behavior of commonly used collectors ethyl xanthate and butyl xanthate on the surface of pyrite is investigated by using the density functional tight bounding theory (DFTB). The results show that when a single reagent acts on the pyrite surface, butyl xanthate has a stronger effect than ethyl xanthate, and the adsorbed mineral surface shows obvious hydrophobicity. The interaction between ethyl xanthate and butyl xanthate had a stronger effect than that of a single reagent, and the simulation of the flotation environment at ordinary temperature using molecular dynamics revealed that the synergistic adsorption of the two different reagents on the surface of pyrite was more hydrophobic, that is, the synergistic adsorption of the combined collector of ethyl xanthate and butyl xanthate on the surface of pyrite was stronger. The results of the study are of great significance for the synergistic effect between the combined collector and the mineral. [ABSTRACT FROM AUTHOR]

A highly efficient hydrogel derived from D-Mannitol xanthate has been successfully synthesized using a free-radical solution copolymerization technique. An equimolar mixture of acrylonitrile (AN) and acrylic acid (AA) has been reacted with D-Mannitol xanthate (DMX) under inert atmosphere. Three distinct grades of D-Mannitol xanthate-based hydrogels viz. DMXHGs-1, DMXHGs-2, and DMXHGs-3, were prepared. Extensive analyses were conducted on the hydrogels using various methods such as UV, FT-IR, SEM, XRD, GPC, TGA and ΔpHPZC. The maximum swelling ratio of DMXHGs-3 was found to be 52122%, 50434% and 48576% for 24 h with water retention ratio of 80.98%, 78.64% and 79.22% for 30 h in distilled, tap and gray water respectively. These findings indicate the DMXHGs-3 hydrogel has remarkable swelling and water retention capacity. Comprehensive investigations were carried out to evaluate the hydrogel's remarkable adsorption capacity to act as an adsorbent for effectively removing hazardous metal ions. The highest removal percentages of 95.5% and 94.4% and maximum adsorption capacities of 523.56 mg g-1 and 462.96 mg g-1 were observed with DMXHGs-3 hydrogel for Cu2+ and Co2+ ions, respectively. Metal ion removal experiments were conducted by varying several parameters including dosage, pH, temperature, concentration, and time. The quantification of Cu2+ and Co2+ was accomplished using UV–visible spectroscopy. Present studies demonstrate the suitability of D-mannitol xanthate-based hydrogels for the efficient removal of toxic metal ions from wastewater [ABSTRACT FROM AUTHOR]

Developing multifunctional nanomaterials with distinct photochemical properties, such as high quantum yield, improved photostability, and good biocompatibility is critical for a wide range of biomedical applications. Motivated by this, we designed and synthesized a dansyl‐tagged xanthate‐based capping agent (DX) for the synthesis of fluorescent silver nanoparticles (AgNPs). The capping agent DX was characterized by 1H and 13C‐NMR, LC–MS, and FT‐IR. The synthesized DX‐capped fluorescent AgNPs were thoroughly characterized by UV–visible spectroscopy, fluorescence spectroscopy, field emission scanning electron microscope (FE‐SEM), transmission electron microscope (TEM), dynamic light scattering (DLS), and zeta potential. The fluorescent AgNPs showed distinct surface plasmon resonance absorption at λmax = 414 nm, fluorescence at λmax = 498 nm, quantum yield = 0.24, zeta potential = +18.6 mV, average size = 18.2 nm. Furthermore, the biological activity of the fluorescent AgNPs was validated by its interaction with the most abundant protein in the blood, that is, BSA (Bovine serum albumin) and HSA (Human serum albumin) with binding constant of 2.34 × 104 M−1 and 2.14 × 104 M−1 respectively. Interestingly, fluorescence resonance energy transfer (FRET) was observed between the fluorescent AgNPs and BSA/HSA with a FRET efficiency of 77.23% and 56.36%, respectively, indicating strong interaction between fluorescent AgNPs and BSA/HSA. [ABSTRACT FROM AUTHOR]

Thioethers are critical in the fields of pharmaceuticals and organic synthesis, but most of the methods for synthesis alkyl thioethers employ foul-smelling thiols as starting materials or generate them as by-products. Additionally, most thiols are air-sensitive and are easily oxidized to produce disulfides under atmospheric conditions; thus, a novel method for synthesizing thioethers is necessary. This paper reports a simple, effective, green method for synthesizing dialkyl or alkyl aryl thioether derivatives using odorless, stable, low-cost ROCS2K as a thiol surrogate. This transformation offers a broad substrate scope and good functional group tolerance with excellent selectivity. The reaction likely proceeds via xanthate intermediates, which can be readily generated via the nucleophilic substitution of alkyl halides or aryl halides with ROCS2K under transition-metal-free and base-free conditions. [ABSTRACT FROM AUTHOR]

Context: Xanthates are organic compounds of great interest in coordination chemistry due to their different basic sites, which allow them to form complexes with different coordination modes and geometries. These compounds are relevant in the environment and act as heavy metal collectors in aqueous environments. In this theoretical–experimental work, electronic spectroscopy studies of n-propyl xanthate complexes with group 12 metals were performed. This study verified structural differences in these systems, depending on the environment in which they are inserted. In addition, structural differences were observed when the solid was changed to an n-hexane solution. Thus, it was observed that the complexes assume a mononuclear structure in solution, while they present a polymeric form in the solid phase. The electronic spectra obtained through TD-DFT calculations were compared to those of the previously synthesized complexes. In the final theoretical analysis, the main orbitals involved in these transitions were assigned using population analysis calculations. The synthesis of the complexes was confirmed through infrared (MID and FAR), UV‒Vis, Raman, and NMR-1H spectroscopic analyses. Methods: The structures of the mononuclear and polymeric complexes were optimized in vacuum and n-hexane. Under vacuum, DFT levels M06L/6–311 + + G** + LANL2TZ and M06L/def2-TZVP were used for the mononuclear complexes, and M06L/LANL2DZ + LANL2 were used for the polymer complexes. For the calculations of the mononuclear complexes in n-hexane, the same level of theory was used for the solid state. TD-DFT calculations for 300 excited states were performed with the same levels of theory and used the optimized structures of the complexes. Furthermore, population analysis was carried out on all the systems studied. Gaussian 09 software was used for the structure optimization, TD-DFT, and population analysis calculations. GaussSum software was used to evaluate the molecular orbitals and electronic spectra. [ABSTRACT FROM AUTHOR]

Large amounts of xanthate wastewater generated from mineral beneficiation significantly threaten the ecological environment. MOF photocatalysis is considered as a promising method for the removal of xanthate that is environmentally friendly and has high efficiency. However, the defects in MOFs limit their large-scale application due to poor visible light absorption efficiency and stability in water. In this study, a novel composite material composed of g-C 3 N 4 /AgCl/Ti-MOFs was prepared, and the catalytic degradation effect of butyl xanthate solution under different catalyst ratios and reaction conditions was investigated. The results showed that the composite could still maintain excellent catalytic performance (degradation rate of 99.5% within 90 min) under xenon light and low dosage. The characterization results showed that this excellent photocatalytic performance could be attributed to the following three points: 1) The material could absorb up to 670 nm visible light absorption capacity; 2) excellent stability was achieved (86% degradation efficiency after six cycles); and 3) the Schottky junctions formed by Ag0 and other materials in the composite increased the transfer rate of e−/h+. The possible photodegradation mechanism was proposed according to UV–vis DRS and trapping experiments. [ABSTRACT FROM AUTHOR]

Xanthates have long been described as poor RAFT/MADIX agents for styrene polymerization. Through the determination of chain transfer constants to xanthates, this work demonstrated beneficial capto-dative substituent effects for the leaving group of a new series of α-amido trifluoromethyl xanthates, with the best effect observed with trifluoroacetyl group. The previously observed Z-group activation with a O-trifluoroethyl group compared to the O-ethyl counterpart was quantitatively established with Cex = 2.7 (3–4 fold increase) using the SEC peak resolution method. This study further confirmed the advantageous incorporation of trifluoromethyl substituents to activate xanthates in radical chain transfer processes and contributed to identify the most reactive xanthate reported to date for RAFT/MADIX polymerization of styrene. [ABSTRACT FROM AUTHOR]

The main task facing modern enrichment scientists is to maintain the quality of final concentrates (FCC) at the proper level. One of the main methods is the use of local reagents during flotation enrichment, the cost of which is many times lower than that of imported reagents. Research on the use of polymers as collecting reagents in the flotation process is the main topic of these studies and of this article. [ABSTRACT FROM AUTHOR]

Mercury is the heavy metal that is most difficult to remove from cyanide solution. This situation brings with it many environmental, health and economic problems. This study aims to effectively utilize xanthate by presenting a new strategy for purifying mercury in the cyanidation process of amalgamation residues. In the study, the removal of mercury by precipitation using PAX from cyanidation leach solutions of a well-characterized amalgamation residue was investigated. The dosage of the precipitation reagent is the most important parameter in the removal of mercury. The mercury removal efficiency increases with the increase in the PAX/Hg ratio, and when the removal ratio is 60, the precipitation efficiency reaches a value of 66.7%. Applying coagulation and flocculation procedures after the precipitation process increases the mercury removal efficiency. It is seen that with this application, mercury can be removed with an efficiency of 95.6% at the same reagent rate. With this application, the particle sizes of the precipitates are enlarged and their filtration properties are improved. It has also been determined that the precipitates formed are in the form of HgS, a stable mercury compound. These results indicate that mercury can be effectively removed in its steady state. It was found that the concentration of Au and Cu did not change significantly, while the concentration of Ag decreased during the precipitation processes. [ABSTRACT FROM AUTHOR]

The adsorption of some flotation reagents on galena is affected by the chemical composition of the process water used. This study evaluated the effects of water quality on the adsorption of the collector xanthate and the depressant dextrin. For this purpose, the effect on the adsorption of ions typically present in process water of a copper-lead flotation operation was studied. The evaluation was made using solutions prepared with individual salts resembling the concentrations found in process water. The superficial modifications suffered by galena exposed to these solutions were evaluated by means of open circuit potential, electrochemical impedance spectroscopy (EIS), and contact angle measurements. These results showed that the effects on the flotation reagents could be grouped depending on the salts used. Hence, group 1 involves the salts (NaCl, Na2SO4, and MgSO4) that improve the performance of xanthate, which was inferred by the highest adsorption of xanthate measured and the lowest capacitance values registered, while group 2 includes the salts (CaCl2, Ca(OH)2, CaSO4, MgCl2, and NaNO3) that negatively affected the adsorption of xanthate. On the other hand, it was found that divalent ions, such as Ca2+ and Mg2+, generally favor the adsorption of dextrin and inhibit the adsorption of xanthate. From EIS measurements, an equivalent circuit (EC) was adjusted and validated, and it was found that it correlates well with contact angle, adsorption and microflotation test results. Hence, the kinetics parameters obtained from EC are useful for the evaluation of water quality effects on either the flotation or depression of galena. [ABSTRACT FROM AUTHOR]

Three grades of pectin xanthates (PX1, PX2, and PX3) have been prepared by the reaction of pectin with carbon disulfide (CS2) in an alkaline medium using NaOH, via the xanthation process. The percentage yield of prepared pectin xanthates has been found to be 87.06%, 90.38%, and 93.80% for PX1, PX2, and PX3, respectively. Prepared pectin xanthates and raw pectin were utilized for heavy metals (Cu(II) and Ni(II)) and lignin enriched paper industry wastewater (LEPIW) treatment. The removal percentage of pectin, PX1, P X2, and PX3 for Cu removal at optimum condition (adsorbent dose: 5.14 g/L, pH: 5 for Cu and 7 for Ni, optimum temperature: 50°C and time: 80 min for Cu(II) and 100 min for Ni(II)) has been found as 85%, 92.33%, 93.5%, and 94.66% and 76.66%, 89.44%, 91.66%, and 93.33%, respectively, for Ni removal. The LEPIW treatment efficacy for pectin, PX1, PX2, and PX3 has been found to be 54%, 77%, 83%, and 86% for the initial COD: 2000 mg/L, pH: 7, optimum temperature: 40°C in 105 min operation time. Adsorption isotherm studies suggest that Langmuir isotherm is most appropriate which indicates adsorption follows chemisorption. The adsorption capacities of PX1, PX2, and PX3 are found as 309.59, 352.11, and 380.22 mg/g for Cu(II) and 299.40, 315.45, and 328.94 mg/g and for Ni(II), respectively, which is very high in comparison with many other recent literature studies. [ABSTRACT FROM AUTHOR]

This work investigated the effects of NaCl addition on galena flotation in the presence of xanthate. The micro-flotation experiments were performed using NaCl solutions which also included xanthate, at pH 9 (±0.1). Our results indicated that galena recovery improved for higher NaCl as well as higher xanthate concentrations.A pH-dependent chemisorption model for the galena surface, with the addition of xanthate adsorption was calibrated using measured zeta potential values. We propose that xanthate adsorption on galena can take place via two separate mechanisms. The first mechanism involves direct xanthate chemisorption to specific surface sites. The second mechanism involves lead/xanthate complexes formed in the bulk solution. These lead/xanthate complexes attach on the galena surface as hydrophobic lead xanthate salts.The galena-air bubble interactions are repulsive in 1 mM NaCl, with or without xanthate, consistent with the lower galena recovery measured experimentally. An increase to 100 mM NaCl, irrespective of the xanthate addition, resulted in attractive galena-air bubble total interaction energies. The agreement with the experimental results shows the effectiveness of the charge regulated model for estimating the galena and air bubble behaviours during flotation in NaCl solutions.

This research includes the synthesis and characterization of twelve new complexes of mono nuclear xanthate for a number of transition metal ions Mn(II) , Fe(II) , Co(II) and through the interaction with ligand (decyl xanthate potassium) and complexes of formula [M(DEXANT)2] were formed , as : M= Mn(II) , Fe(II) , Co(II) and then the interaction of these complexes with Lewis bivalve bases , to give complexes with the formula [M(DEXANT)2 . L], where : L= 1,10-phenanthroline , 8-hydroxyquinoline, 2,2-Pipyridine. The prepared complexes were characterized by melting point , atomic absorption, micro elemental analysis , infrared , nuclear magnetic resonance spectrum of the proton , molar electrical conductivity , electronic absorption spectra and susceptibility measurements. Magnetic moment and electronic spectra indicated that the complexes of type [M(DEXANT)2] had a tetrahedral geometry, while complexes of type [M(DEXANT)2.L] had an octahedral geometry,The conductivity measurements proved the non-electrolytic behavior of all compounds .

Thioethers are critical in the fields of pharmaceuticals and organic synthesis, but most of the methods for synthesis alkyl thioethers employ foul-smelling thiols as starting materials or generate them as by-products. Additionally, most thiols are air-sensitive and are easily oxidized to produce disulfides under atmospheric conditions; thus, a novel method for synthesizing thioethers is necessary. This paper reports a simple, effective, green method for synthesizing dialkyl or alkyl aryl thioether derivatives using odorless, stable, low-cost ROCS2K as a thiol surrogate. This transformation offers a broad substrate scope and good functional group tolerance with excellent selectivity. The reaction likely proceeds via xanthate intermediates, which can be readily generated via the nucleophilic substitution of alkyl halides or aryl halides with ROCS2K under transition-metal-free and base-free conditions.

Xanthates have long been described as poor RAFT/MADIX agents for styrene polymerization. Through the determination of chain transfer constants to xanthates, this work demonstrated beneficial capto-dative substituent effects for the leaving group of a new series of α-amido trifluoromethyl xanthates, with the best effect observed with trifluoroacetyl group. The previously observed Z-group activation with a O-trifluoroethyl group compared to the O-ethyl counterpart was quantitatively established with Cex = 2.7 (3–4 fold increase) using the SEC peak resolution method. This study further confirmed the advantageous incorporation of trifluoromethyl substituents to activate xanthates in radical chain transfer processes and contributed to identify the most reactive xanthate reported to date for RAFT/MADIX polymerization of styrene.

Four triazine mantic acid derivative additives were synthesized, and their tribological properties in rapeseed oil (RSO) were investigated with a four-ball tester. The results showed that the emulsions prepared with thiotriazine derivatives had excellent tribological properties. For the same S content, the antiwear performance was enhanced by increasing the carbon chain length at low load and deduced by increasing the carbon chain length at high load. The superior antiwear performance was attributed to forming the organic sulfide and nitrogen adhering layer, moreover, under low load, the thiotriazine xanthate derivatives containing a longer substituent chain would be hardly damaged during sliding, and the branch chain on the substituent group would be beneficial to enhance the tribological properties of triazine xanthine derivatives. Sulfur-containing triazine derivatives have a good corrosion inhibition effect for Q235 steel because they contain N, O, S, and other active sites. These heteroatoms have unshared lone pair electrons, which can coordinate with the unoccupied orbital of Fe atoms to form covalent bonds and prohibit the corrosive media from contacting the surface of the Q235 steel, thus inhibiting the corrosion processes. [ABSTRACT FROM AUTHOR]

The present study provides a novel, selective analysis method for the determination of low xanthate concentrations. The rising concern over the environmental effects of xanthates demands the development of analysis methods which this study answers. Complex formation in aqueous solution between xanthates and an excess of Co(II), Ni(II), Pb(II), Cd(II), Cu(II), and Zn(II) ions was utilized to selectively determine xanthates by high‐performance liquid chromatography–inductively coupled plasma tandem mass spectrometry for the first time. The complexes that were formed were extracted to ethyl acetate using liquid–liquid extraction and separated by high‐performance liquid chromatography technique before the quantitative determination of metal ions and sulfur in the xanthate complexes. Good separation and high measurement sensitivity were achieved using Cu(II) as the complex metal ion. The analysis method was optimized for the determination of sodium isopropyl xanthate and sodium isobutyl xanthate with detection limits of 24.7 and 13.3 μg/L, respectively. With a linear calibration range of 0.1–15 mg/L and a total analysis time of 4–5 min, the present method is a fast and sensitive option for selective xanthate determination. [ABSTRACT FROM AUTHOR]

Considering the prevalence of alcohols and carboxylic acids, their fragment cross‐coupling reactions could hold significant implications in organic synthesis. Herein, we report a versatile method for synthesizing a diverse range of ketones from alcohols and carboxylic acid derivatives via N‐heterocyclic carbene (NHC) catalysis. Mechanistic investigations revealed that photoexcited xanthates and acyl azoliums undergo single electron transfer (SET) under photocatalyst‐free conditions, generating NHC‐derived ketyl radicals and alkyl radicals. These open‐shell intermediates subsequently undergo the radical‐radical cross‐coupling reaction, yielding valuable ketones. Furthermore, this approach can be employed in three‐component reactions involving alkenes and enynes, resulting in structurally diverse cross‐coupled ketones. The unified strategy offers a unique opportunity for the fragment coupling of a diverse range of alcohols and carboxylic acid derivatives, accommodating diverse functional groups even in complex settings. [ABSTRACT FROM AUTHOR]

The main task facing modern enrichment scientists is to maintain the quality of final concentrates (FCC) at the proper level. One of the main methods is the use of local reagents during flotation enrichment, the cost of which is many times lower than that of imported reagents. Research on the use of polymers as collecting reagents in the flotation process is the main topic of these studies and of this article.

Extractive metallurgy has recently turned its attention to waste treatment for the recovery of precious metals through innovative metallurgical processes, such as ion flotation. This work studied the influence of several chemical and physical factors, such as the concentration of xanthate [x], frother agent [e], dithiophosphate [xl], pH, superficial gas velocity Jg, percentage of gas holdup Eg, bubble diameter (Db) calculated with the drift flux model, and the type of sparger, in the efficiency of silver(I) recovery by the ion flotation technique in sub-aerated cells. The results obtained indicate a 90.7% v/v recovery of silver(I) under conditions of 3.77 × 10−4 M [x], 1.25 × 10−4 M [e], Jg 0.5 cm/s, Jl 0.19 cm/s, Eg of 4.1% v/v, and Optimal Db of 0.11 cm, with a rigid bubble generator, achieving an apparent flotation kinetics of 4.16 1/min. The use of combinations [x]–[xl] achieve a silver(I) recovery of 86.9% with a Jg of 1.0 cm/s. The best recovery efficiencies achieved 93% w/w silver(I) are with pH 8.0, [e] of 1.25 × 10−4, Jl of 0.19 (cm/s) and a rigid sparger compared to a flexible one. [ABSTRACT FROM AUTHOR]

It is infrequent to have a single metal in the wastewater. For this reason, the elimination of Pb2+ and Cd2+ in one and two-component system was examined by xanthate-modified Phaseolus vulgaris in a batch mode. Through grafting, sulphur-bearing groupings with the help of magnesium xanthate were added onto P. vulgaris and xanthate-modified innovative P. vulgaris biosorbent has been produced for the removal of metal ions, that is, lead and cadmium. These innovative sulphur sites were attained successfully and confirmed with the help of Fourier-transform infrared spectroscopy, elemental analysis, and change in surface morphology by scanning electron microscopy. The point of zero charges pHpzc of xanthate-modified P. vulgaris was observed to be 7.20 which makes it appropriate for the sorption of cations. The batch sorption implementation of xanthate-modified P. vulgaris includes sorbent amount, pH, linear and non-linear regression analysis, and kinetic curves. The xanthate-modified P. vulgaris adsorbed 95.65% cadmium (at pH 4.0) and 90.36% of lead (at pH 5.0) from a single aqueous system. The sorption of Pb2+ and Cd2+ by xanthate-modified P. vulgaris follow the linear regression of Langmuir isotherm with qmax of 160.97 and 150.50 mg/L, respectively which is substantially greater than that of many other reported ones. The xanthate-modified P. vulgaris demonstrated rapid uptake capacity of Pb2+ and Cd2+ following the high value of correlation coefficient with pseudo-second-order kinetics. This sorption process for Pb2+ and Cd2+ was found to be endothermic and spontaneous. The binding capacities however reduced in the binary system. This, therefore revealed that the xanthate-modified P. vulgaris can be an encouraging biosorbent for the remediation of Pb2+ and Cd2+ from contaminated water. [ABSTRACT FROM AUTHOR]

Photo‐iniferter reversible addition‐fragmentation chain transfer (PI‐RAFT) polymerization of N‐vinylformamide (NVF) is demonstrated by using purple light. PNVFs with predetermined molar masses and narrow molar mass distributions are obtained. High RAFT chain‐end fidelity is confirmed by matrix‐assisted laser desorption ionization time‐of‐flight (MALDI‐TOF) and electrospray‐ionization time‐of‐flight mass spectrometry (ESI‐TOF‐MS), and chain extension experiment. To demonstrate the potential of this approach, an original poly(N‐vinylpyrrolidone)‐b‐poly(N‐vinylformamide) (PVP‐b‐PNVF) diblock copolymer is synthesized and characterized by aqueous size‐exclusion chromatography (SEC), asymmetric flow field‐flow fractionation (A4F), and 1H diffusion‐ordered spectroscopy nuclear magnetic resonance (1H DOSY NMR). Finally, selective hydrolysis of PNVF block to corresponding pH‐responsive poly(N‐vinylpyrrolidone)‐b‐poly(N‐vinylformamide) (PVP‐b‐PVAm) is performed. [ABSTRACT FROM AUTHOR]

In this study, the desulphurization of iron ore concentrate using reverse flotation was investigated. In this paper first, behavior of the flotation of both pure – pyrite and iron oxides-pyrite with xanthate has been examined based on micro-flotation results and zeta-potential measurements. Then, an effort has been made to investigate the effect of pH, chemical reagent dosages, impeller speed, pulp density, flotation time and conditioning time parameters on desulphurization of actual iron ore concentrate using lab-scale mechanical flotation cell. Results of zeta-potential measurements displayed that iso-electric points (IEP) for pure and iron oxides-pyrite were around pH 7 and 8, respectively. Based on the micro-flotation results, the recoveries were highly dependent on pH. Both pyrite types showed high recoveries at pH 4.75 to 8, but in the flotation of iron oxides-pyrite, partial depression was found in the pH range of 6–7. The presence of iron ions in solution considerably depressed iron oxide-pyrite flotation in the pH range of 2.5–3. Recovery of both pyrites decreased dramatically when going from pH 10, due to the formation of iron hydroxides and the instability of dixanthogen. According to the data obtained from batch flotation tests, the maximum recovery of total sulfur was achieved when the operational parameters were set to the PAX dosage 200 gr/t, MIBC dosage 150 gr/t, CuSo4 75 gr/t, impeller speed 1500 rpm, pH 7.5, flotation time 7 min and pulp density 30%. With these optimum parameters, final concentrate with the grade of 69.48% Fe and 0.1% S was obtained. [ABSTRACT FROM AUTHOR]

The reaction of dry and pulverized rice husk with alkaline CS2 followed by treatment of the resulting xanthate derivative with zirconyloxychloride at room temperature led to functionalization of the xanthated biomass with sodium zirconate grouping. The as-prepared sodium salt of the rice-husk xanthatozirconate was characterized physicochemically and found to be an efficient, robust, and recyclable catalyst for the three-component synthesis of some spiro[4H-pyran-4,3′-indoline]s in water. [ABSTRACT FROM AUTHOR]

[Display omitted] • Froth reagent scheme for complex base-metal sulphide ore. • Recoveries of 84.0% and 83.8% for chalcopyrite and sphalerite. • Optimum recovery at 3 min grinding and pH 6. • SEM images show co-occurring copper and zinc. Generating a flotation reagent scheme for a complex base-metal sulphide ore using reagents that are commonly found in mineral processing can be a challenging, complex process. Ensuring that optimum operating conditions including particle size, pH, types of reagents, and dosages of reagents are found is critical in establishing a foundation for future research. A modified xanthate reagent scheme was chosen using potassium amyl xanthate (PAX) as the collector, methyl isobutyl carbinol (MIBC) as the frother, copper sulphate as activator, carboxy methyl cellulose (CMC) and zinc sulphate as depressants. The operating conditions that generated the highest recoveries and grades for copper and zinc were found using a grinding time of 3 min and a slightly acidic medium of pH 6 achieving maximum recoveries of 84.0% and 83.8% for chalcopyrite and sphalerite, and grades of 3.9 and 21.0, respectively. These results allow for comparisons to industrial results with ore of a similar composition while simultaneously providing a baseline in which to evaluate the results of future, innovative research. [ABSTRACT FROM AUTHOR]

• Developed nanophotocatalyst for efficient degradation of potassium ethyl xanthate. • Taguchi statistical approach is used for the optimization of parameters. • Kinetics and isotherm studies were done for better insight into the processes. Xanthate from mineral processing wastewater is a major threat to the ecosystem. Photocatalysis is emerging as the most effective process with the invention of new nanophotocatalytic materials. The present research focuses on developing the ternary nanocomposite Fe 2 O 3 /TiO 2 /Flyash by a facile hydrothermal method combined with a water bath precipitation method for the efficient degradation of potassium ethyl xanthate (KEX). Taguchi's experimentation (L 16) orthogonal array is used for the optimization of process parameters to get maximum KEX degradation efficiency. The optimized parameters are found to be calcination temperature 400 OC, photocatalyst dosage 0.7 g/L, pH 5, pollutant concentration 10 mg/L, and light intensity 100 W. The percentage contribution of each parameter is obtained through the ANOVA statistical approach as calcination temperature > pH>pollutant concentration > photocatalyst dosage > light intensity. The adsorption mechanism follows the Freundlich isotherm and fits well with pseudo-first-order and second-order kinetics. Material characterization is also done to analyze the crystal structure and morphology of the newly developed nanocomposite to gain a better understanding of the mechanism. This study indicates that the newly developed nanocomposite photocatalyst can effectively degrade potassium ethyl xanthate under light irradiation for 60 min. [ABSTRACT FROM AUTHOR]

Xanthates, common mining flotation reagents, strongly bind thiophilic metals such as copper (Cu), lead (Pb), cadmium (Cd), and zinc (Zn) and consequentially change their bioavailability and mobility upon their discharge into the environment. However, accurate quantification of the metal-xanthate complexes has remained elusive. This study develops a novel and robust method that realizes the accurate quantification of the metal-xanthate complexes resulted from single and multiple reactions of three typical xanthates (ethyl, isopropyl, and butyl xanthates) and four thiophilic metals (Cu, Pb, Cd, and Zn) in water samples. This method uses sulfur (S2-) dissociation, followed by tandem solid phase extraction of C 18 + PWAX and subsequent LC-MS/MS analysis. It has a wide linearity range (1–1000 μg/L, R 2 ≥ 0.995), low method detection limits (0.002–0.036 μg/L), and good recoveries (70.6–107.0 %) at 0.01–10 mg/L of xanthates. Applications of this method showed ubiquitous occurrence of the metal-xanthate complexes as the primary species in flotation wastewaters, which the concentrations were 4.6–28.9-fold higher than those previously determined. It is the first quantitative method established for the analysis of metal-xanthate complexes in water samples, which is of great importance to comprehensively understand the fate and risks of xanthates in the environment. [Display omitted] • A method for accurate quantification of the metal-xanthate complexes is developed. • The method is developed based on S2- dissociation and tandem SPE of C 18 + PWAX. • The method shows satisfactory accuracy and sensitivity. • Metal-xanthate complexes are prevalent in flotation wastewater as primary species. • Metal-xanthate complexes shows higher toxicity than single metal or xanthate. [ABSTRACT FROM AUTHOR]

[Display omitted] • HAP with piezoelectric property was synthesized using MSWI-FA as raw material. • HAP could stabilize heavy metals in the MSWI-FA with high efficiency. • The piezoelectric coefficient of HAP could be improved by modifying of Ca/P molar ratio of synthesized HAP. • HAP was capable of degrading 92.0 % of potassium butyl xanthate in 60 min under piezocatalysis. • The synthesized HAP has potential broad applications in organic wastewater treatment. Municipal solid waste incineration fly ash (MSWI-FA) is a typical hazardous waste and contains various harmful heavy metals. MSWI-FA can be transformed into mineral-containing materials (MCMs) by hydrothermal treatment, which stabilize the heavy metals in MSWI-FA synchronously. However, whether MCMs are capable of catalyzing the degradation of organic pollutants remains elusive. In this study, the hydroxyapatite (HAP; sample numbers were HAP-1, HAP-2, and HAP-3) with piezoelectric property was successfully synthesized from MSWI-FA using hydrothermal approach, and simultaneous stabilization of heavy metals in MSWI-FA was achieved. The piezoelectric coefficient (d 33) and piezocatalytic performance of HAP could be improved by regulating Ca/P molar ratio of the synthesized HAP to the theoretical value of 1.67. The d 33 of HAP-2 (Ca/P molar ratio = 1.49) was 4.39 pm V−1 which was 3.4 times that of HAP-1 (Ca/P molar ratio = 2.48), while HAP-3 (Ca/P molar ratio = 0.74) had no significant piezoelectric signal. Meanwhile, HAP-2 showed that the best piezocatalytic degradation efficiency of 92.0 % of potassium butyl xanthate (PBX, 10 mg/L) within 60 min, and it was almost 1.37 and 1.92 times that of HAP-1 and HAP-3, respectively. Free radical scavenging and reactive species quantitative experiments showed that O 2 − and OH were the dominant reactive oxygen species in the piezocatalytic degradation of PBX by HAP. The generation rates of O 2 − and OH in piezocatalysis of HAP-2 were 3.28 and 12.60 μmol g−1h−1, respectively, implying that the degradation of PBX was mainly determined by O 2 − and OH. This work provides a useful reference for converting MSWI-FA into the promising mineral materials with highly efficient catalytic performance for the treatment of organic pollutants from domestic and industrial wastewater. [ABSTRACT FROM AUTHOR]

The title four-coordinate mononuclear complex, [Hg(C3H5OS2)2(C6H16N2)] or [Hg(C3H5OS2)2(tmeda)] (tmeda: N,N,N′,N′-tetramethylethane-1,2-diamine), has a distorted tetrahedral geometry. The HgII ion is coordinated to two N atoms of the N,N,N′,N′-tetramethylethylenediamine ligand and two S atoms from two ethylxanthate xanthate ligands. In the crystal, molecules are linked by weak C—H...S hydrogen bonds, forming a two-dimensional supramolecular architecture in the ab plane. The most important contributions for the crystal packing are from H...H (59.3%), S...H (27.4%) and O...H (7.5%) interactions.

In this study, two novel photoactive xanthates, which bear a photoinitiator (PI) group in the middle and an S-alkyl dithiocarbonate group (–O–C(S)–S–R) at each of the two ends of the molecule, were synthesized as chain transfer agents (CTA) to be used in reversible addition-fragmentation chain transfer/macromolecular design via the interchange of xanthate (RAFT/MADIX) polymerization. Having the same central photoinitiator group, two chain transfer agents (CTA-PI-CTA 1 and CTA-PI-CTA 2) differ from each other in their R leaving groups; C6H5–CH2– and C6H5–CH(COOEt)–, respectively. The structures of CTA-PI-CTAs were elucidated via elemental analysis and spectroscopic techniques, such as 13C NMR, 1H-NMR, and FT-IR. Styrene (St) was used as the model monomer in MADIX polymerization. Its RAFT/MADIX polymerization with these chain transfer agents successfully produced mid-chain functional polystyrene macrophotoinitiators (PSt-PI-PSt 1 and PSt-PI-PSt 2) with well-defined structures. The GPC, FT-IR, 1H-NMR, UV, and fluorescence spectroscopic studies revealed that low-dispersity polystyrenes with desired photoinitiator functionality in the middle of the chain were obtained. Finally, these macrophotoinitiators were used as prepolymers in photoinitiated free radical polymerization of methyl methacrylate (MMA) to obtain polystyrene-poly(methyl methacrylate) (PSt-PMMA) block copolymers. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) has been applied to study the adsorption morphology of various collectors, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX) and Cytec Aerofloat 238 (sodium dibutyl dithiophosphate), on chalcocite in situ in aqueous solutions. The AFM images show that all these collectors adsorb strongly on chalcocite. Xanthate adsorbs mainly in the form of insoluble cuprous xanthate (CuX), which binds strongly with the mineral surface without being removed by flushing with ethanol alcohol. This xanthate/chalcocite adsorption mechanism is very similar to the one obtained with the xanthate/bornite system; while it is different from the one of the xanthate/chalcopyrite systems, for which oily dixanthogen is the main adsorption product on chalcopyrite surface. On the other hand, dibutyl dithiophosphate adsorbs on chalcocite in the form of hydrophobic patches, which can be removed by rinsing with ethanol alcohol. AFM images show that the adsorption of collectors increases with increasing adsorption time and collectors' concentration. In addition, increasing the solution pH to 10 does not prevent the adsorption of xanthate and Aerofloat 238 on chalcocite and the result is in line with the fact that chalcocite floats well in a wide pH range up to 12 with xanthate and dialkyl dithiophosphate being used as collectors. The blending collectors study shows that xanthate and dialkyl dithiophosphate can co-adsorb with both insoluble cuprous xanthate and oily Cu(DTP)2 (Cu dibutyl dithiophosphate) on a chalcocite surface. The present study helps to clarify the flotation mechanism of chalcocite in industry practice using xanthate and dialkyl dithiophosphate as collectors. [ABSTRACT FROM AUTHOR]

Xanthates are commonly used collectors in flotation processes but are highly toxic to the aquatic environment. However, there are few methods for reliable determination of low xanthate concentrations in water samples. In this work, a sensitive, selective, and fast method is presented for the determination of potassium ethyl xanthate (KEX). KEX was determined by high-performance liquid chromatography–inductively coupled plasma–mass spectrometry (HPLC-ICP-MS/MS) directly and as diethyl dixanthogen [(EX)2] after oxidation with triiodide. The HPLC method was optimized for (EX)2 and the separated compounds were detected by ICP-MS/MS. The ICP-MS/MS was used in mass-shift mode using O2 as the cell gas and S+ was measured as SO+ to reduce spectral interferences. Detection limits of 88 µg L−1 for KEX and 20 µg L−1 for (EX)2 calculated from the peak area were obtained using mass-shift 32S+ → 32S16O+. No significant matrix effects were present when spiking experiments of (EX)2 were done to a sample collected from the tailings of a flotation process. The developed method demonstrates the potential of the HPLC-ICP-MS/MS for the determination of ethyl xanthate. This method may be extended to analyzing other xanthates and similarly structured sulfur containing collectors. [ABSTRACT FROM AUTHOR]

The mineral industry consumes a large amount of xanthate as collector, especially for the sulfide mineral's flotation. Nonetheless, the significant amount of xanthate also discharged from the processing plants, in proportion to the amount of used xanthate. In this work, the hazardous aqueous xanthate was aimed to be removed from water using electrocoagulation with three different electrodes: aluminum, iron and copper. Three separate experimental setups and designs were formed. The response surface methodology was implemented for the estimation of mathematical models for each electrode used in the electrocoagulation. All models were found statistically significant with p-values < 0.0015 and adjusted R2-values > 0.95. According to the formed linear and quadratic models, the commonly used aluminum electrodes in the literature proved to be useless for the elimination of xanthate. The dissolved aluminum could not react with xanthate, and no precipitation was observed during the treatment. Iron electrode yielded better results than aluminum when the system parameters were statistically optimized at pH 6.54 and electrical current of 0.6 A. The most effective formation of hydroxyl ferric xanthates was actualized at these specific levels of parameters, and the maximum removal% of xanthate was obtained as 82.34%. On the other hand, the last electrode made from copper remarkably decreased the concentration of xanthate with a removal% of 100%. The copper ions released from the electrodes with the help of electricity had a great affinity for xanthate. Following the electrocoagulation process, Cu(I) ethyl xanthate/Cu(II) ethyl xanthate efficiently precipitated, forming a yellow solid sediment at the bottom of the reactor. Consequently, the maximum desirability values for the removal of xanthate were found as 0.0037, 0.7700 and 1.000 respectively for aluminum, iron and copper electrodes. Based on this statistical optimization, the copper electrodes enabled the accomplished separation of hazardous xanthate from water using electrocoagulation at pH 9 and electrical current of 0.6 A. [ABSTRACT FROM AUTHOR]

Thiazole and carbonyl often act as core functional or regulative moieties in biological molecules as well as optical materials. Designing and synthesis of carbonyl‐containing thiazoles are of great importance for related fields, hence, a simple and practical method was developed using commercially xanthates, benzylamine, and readily available alkynones as substrates. The reaction was achieved using one‐pot Michael addition and cascade iodine mediated C−H thiolation under mild conditions. This method features a broad substrate scope with high yield. Remarkably, the obtained carbonyl substituted thiazoles bearing electronic‐donating substituents exhibit promising performance for aggregation‐induced emission (AIE) and have been successfully used in biological imaging. [ABSTRACT FROM AUTHOR]

Aim. To develop a convenient synthetic approach for the preparation of multigram amounts of 4-(trifluoromethoxy)-piperidine and 4-(trifluoromethoxymethyl)piperidine – promising building blocks for medicinal chemistry. Results and discussion. 4-(Trifluoromethoxy)piperidine (8.4 g) and 4-(trifluoromethoxymethyl)piperidine (12.9 g) were synthesized in 5 stages starting from 4-hydroxypiperidine (the overall yield 40 %) and 4-(hydroxymethyl)piperidine (the overall yield 13.5 %), respectively. Experimental part. The first stage of the synthetic strategy was acylation of 4-hydroxypiperidine with benzoyl chloride. N-benzoyl-4-hydroxypiperidine obtained was transformed to N-benzoyl-4-(trifluoromethoxy)piperidine in two stages using the Hiyama method (the synthesis of the corresponding S-methyl xanthate with the subsequent desulfurization/fluorination using N-bromosuccinimide and Olah’s reagent). Then the N-benzoyl group was reduced to benzyl one, which was removed using 1-chloroethyl chloroformate. The similar approach was applied to the synthesis of 4-(trifluoromethoxymethyl)piperidine starting from 4-(hydroxymethyl)piperidine. The structure and composition of the compounds synthesized were confrmed by 1Н, 13C and 19F NMR spectroscopy, mass-spectrometry and elemental analysis. Conclusions. The synthetic approach developed is a convenient method for the multigram preparation of 4-(trifluoromethoxy)piperidine and 4-(trifluoromethoxymethyl)piperidine and can be used for the synthesis of other secondary amines containing the CF3O-group.

[Display omitted] • The influence of mineral supports on photocatalyst was studied. • Introducing attapulgite brings good dispersion and more active sites. • The photocatalytic degradation of xanthate under visible light was studied. • Possible degradation pathways and mechanisms were provided. Modulating the activity of semiconducting photocatalysts by altering their support properties is an appealing strategy for strengthening the photocatalytic reactions. In this study, BiOBr-TiO 2 (BT) semiconducting composites were synthesized and loaded on the pretreated attapulgite, montmorillonite, and diatomite supports, which were then optimized and labeled as BTA-300, BTM-400, and BTD-300, respectively. Xanthates were utilized as the target contaminants to assess the catalyst performance of the composite photocatalysts due to their high toxicity and extensive application in the mineral processing industry. It was revealed that the clay mineral supports had a great regulatory effect on the activity of BT photocatalysts in the xanthates photodegradation process under visible light. The reaction rate constant for the BTA-300 photocatalysts in the degradation of 20 mg/L sodium ethyl xanthate (SEX) was 0.108 min−1, exhibiting 1.55 and 1.41 times higher than that of BTM-400 and BTD-300, correspondingly. The inherent properties of the support clay minerals enhanced the activity of photo-excited carriers by influencing their migration and recombination, and thereby affected the photocatalytic activity. This study deduced potential molecular degradation pathways for SEX and analyzed the developmental toxicity and mutagenicity of the intermediates, which provides a valuable reference for future industrial applications. [ABSTRACT FROM AUTHOR]

Extractive metallurgy has recently turned its attention to waste treatment for the recovery of precious metals through innovative metallurgical processes, such as ion flotation. This work studied the influence of several chemical and physical factors, such as the concentration of xanthate [x], frother agent [e], dithiophosphate [xl], pH, superficial gas velocity Jg, percentage of gas holdup Eg, bubble diameter (Db) calculated with the drift flux model, and the type of sparger, in the efficiency of silver(I) recovery by the ion flotation technique in sub-aerated cells. The results obtained indicate a 90.7% v/v recovery of silver(I) under conditions of 3.77 × 10−4 M [x], 1.25 × 10−4 M [e], Jg 0.5 cm/s, Jl 0.19 cm/s, Eg of 4.1% v/v, and Optimal Db of 0.11 cm, with a rigid bubble generator, achieving an apparent flotation kinetics of 4.16 1/min. The use of combinations [x]–[xl] achieve a silver(I) recovery of 86.9% with a Jg of 1.0 cm/s. The best recovery efficiencies achieved 93% w/w silver(I) are with pH 8.0, [e] of 1.25 × 10−4, Jl of 0.19 (cm/s) and a rigid sparger compared to a flexible one.

Polymers derived from vinyl acetate, N-vinyl carbazole, N-vinyl pyrrolidone, and N-vinyl imidazole possess very interesting properties hence finding applications in pharmaceutical, cosmetics, textile, painting, paper, electric/electronic industries etc. However, these monomers are considered as less activated monomers (LAMs), which fall under the category of non-stabilized monomers. The higher reactivity as well as instability of the propagating radicals of these LAMs pose a challenge toward their controlled polymerization. Reversible addition-fragmentation chain transfer (RAFT) polymerization facilitated the polymerization of LAMs in a controlled fashion affording polymers with narrow dispersity. This review article deals with the study of different xanthate, dithiocarbonate, trithiocarbonate and dithioester based RAFT agents with varying activating and leaving groups for the polymerization of vinyl acetate, N-vinyl carbazole, N-vinyl pyrrolidone, and N-vinyl imidazole. [ABSTRACT FROM AUTHOR]

The title four-coordinate mononuclear complex, [Hg(C3H5OS2)2(C6H16N2)] or [Hg(C3H5OS2)2(tmeda)] (tmeda: N,N,N0,N0-tetramethylethane-1,2-diamine), has a distorted tetrahedral geometry. The HgII ion is coordinated to two N atoms of the N,N,N0,N0-tetramethylethylenediamine ligand and two S atoms from two ethylxanthate xanthate ligands. In the crystal, molecules are linked by weak C--H...S hydrogen bonds, forming a two-dimensional supramolecular architecture in the ab plane. The most important contributions for the crystal packing are from H···H (59.3%), S...H (27.4%) and O...H (7.5%) interactions. [ABSTRACT FROM AUTHOR]

In the title compound, (2,2′-bipyridine-κ2N,N′)bis(2-methoxyethyl xanthato-κS)zinc(II), [Zn(C4H7O2S2)2(C10H8N2)], the ZnII ion is coordinated to two N atoms of the 2,2′-bipyridine ligand and two S atoms from two 2-methoxyethyl xanthate ligands. The ZnII ion lies on a crystallographic twofold rotation axis and has distorted tetrahedral coordination geometry. In the crystal, molecules are linked by weak C—H...O hydrogen bonds, forming supramolecular chains propagating along the a-axis direction. Weak intramolecular C—H...S hydrogen bonds are also observed. The intermolecular contacts in the crystal were further analysed using Hirshfield surface analysis, which indicates that the most significant contacts are H...H (36.3%), followed by S...H/H...S (24.7%), C...H/H...C (15.1%), O...H/H...O (14.4%), N...H/H...N (4.1%) and C...C (2.9%).

In the title compound, bis(2-methoxyethyl xanthato-κS)(N,N,N′,N′-tetramethylethylenediamine-κ2N,N′)zinc(II) acetone hemisolvate, [Zn(C4H7O2S2)2(C6H16N2)]·0.5C3H6O, the ZnII ion is coordinated by two N atoms of the N,N,N′,N′-tetramethylethylenediamine ligand and two S atoms from two 2-methoxyethyl xanthate ligands. The amine ligand is disordered over two orientations and was modelled with refined occupancies of 0.538 (6) and 0.462 (6). The molecular structure features two C—H...O and two C—H...S intramolecular interactions. In the crystal, molecules are linked by weak C—H...O and C—H...S hydrogen bonds, forming a three-dimensional supramolecular architecture. The molecular structure was optimized using density functional theory (DFT) at the B3LYP/6–311 G(d,p) level. The smallest HOMO–LUMO energy gap (3.19 eV) indicates the suitability of this crystal for optoelectronic applications. The molecular electrostatic potential (MEP) further identifies the positive, negative and neutral electrostatic potential regions of the molecules. Half a molecule of disordered acetone was removed with the solvent-mask procedure in OLEX2 [Dolomanov et al. (2009). J. Appl. Cryst. 42, 339–341] and this contribition is included in the formula.

In this study, flotation tests were conducted with purified pyrite and ore samples. The collectors employed were anionic and cationic type such as potassium ethlyl-amyl xanthate, Tomamine M73 and Resanol Bal. According to the flotation tests, it was found that pyrite floated at low pH and depressed at high pH values with xanthates. On the other hand, in the case of cationic collectors which are Tomamine M73 (alkyl ether amine, an amphoteric surfactant) and Resanol Bal (N-3-tridecyloxy propyl 1-3 diamine, branched acetate) pyrite floated at high pH values. It was shown that amine type collectors could be efficient to selectively float pyrite from chalcopyrite at alkali pH ranges in the case of ore samples. [ABSTRACT FROM AUTHOR]

Atomic force microscopy (AFM) has been applied to study the adsorption morphology of various collectors, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX) and Cytec Aerofloat 238 (sodium dibutyl dithiophosphate), on chalcocite in situ in aqueous solutions. The AFM images show that all these collectors adsorb strongly on chalcocite. Xanthate adsorbs mainly in the form of insoluble cuprous xanthate (CuX), which binds strongly with the mineral surface without being removed by flushing with ethanol alcohol. This xanthate/chalcocite adsorption mechanism is very similar to the one obtained with the xanthate/bornite system; while it is different from the one of the xanthate/chalcopyrite systems, for which oily dixanthogen is the main adsorption product on chalcopyrite surface. On the other hand, dibutyl dithiophosphate adsorbs on chalcocite in the form of hydrophobic patches, which can be removed by rinsing with ethanol alcohol. AFM images show that the adsorption of collectors increases with increasing adsorption time and collectors’ concentration. In addition, increasing the solution pH to 10 does not prevent the adsorption of xanthate and Aerofloat 238 on chalcocite and the result is in line with the fact that chalcocite floats well in a wide pH range up to 12 with xanthate and dialkyl dithiophosphate being used as collectors. The blending collectors study shows that xanthate and dialkyl dithiophosphate can co-adsorb with both insoluble cuprous xanthate and oily Cu(DTP)2 (Cu dibutyl dithiophosphate) on a chalcocite surface. The present study helps to clarify the flotation mechanism of chalcocite in industry practice using xanthate and dialkyl dithiophosphate as collectors.

Removal of toxic metal ions using adsorbents is a well‐known strategy for water treatment. While chitosan and cellulose can adsorb weakly some types of metals, incorporating thiols as metal chelating agents can improve their sorption behaviors significantly. Presented in this review are the various chemical modification strategies applicable for thiolation of chitosan and cellulose in the forms of mercaptans, xanthates and dithiocarbamates. Moreover, much attention has been paid to the specific strategies for controlling the thiolation degree and characterization approaches for establishing the structure‐property relationship. Also, the kinetics and isotherm models that elucidate the adsorption processes and mechanisms induced by the thiomers have been explained. These thiomers have found great potentials in the applications associated with metal removal, metal recovery and metal detection. [ABSTRACT FROM AUTHOR]

Copper-cobalt oxide ores contain several minerals that are economically treatable by concentration techniques. The most used technique is froth flotation in which selective reagents are used to recover more valuables. It is, therefore, important to examine the optimal doses of those reagents while investigating the behaviors of minerals at the same time. This study explored the influence of lead nitrate Pb(NO3)2 on the froth flotation of oxide ore to increase valuable metals recoveries. Four factors were investigated including Pb(NO3)2 dosage, its conditioning, its addition dose in the 2nd fraction, and sulfidiser dosage. Other parameters were kept constant. The optimum was found at 25 g/t of Pb(NO3)2, conditioning together with sodium silicate (Na2SiO3) for 5 min, the addition of 5 g/t of Pb(NO3)2 in the 2nd fraction, and 3,000 g/t of sulfidiser. Recoveries in concentrates were 79.51 % Copper (Cu) and 60.27 % Cobalt (Co), with grades of 9.49 and 0.67 %, respectively. The conclusion was that the use of Pb(NO3)2 can considerably improve copper and cobalt recoveries. [ABSTRACT FROM AUTHOR]

• TiO 2 nanoparticles are effective for the preparation of xanthate sensors. • Optimization of modified carbon paste electrodes improves xanthate detection. • Background current subtraction is effective in improving xanthate detection. • Xanthate quantification is possible over a wide linear range in flotation samples. • Xanthate quantification is possible without collector interference. A voltammetric method for xanthate quantification was developed by fabricating a new electrode based on TiO 2 nanoparticles (TiO 2 NPs). The nanomaterial in the anatase phase was synthesized by a simple sol-gel method followed by a thermal treatment (9 h at 500 °C). The nanoparticles have a spheroidal morphology with an average size of 20.61 ± 6.01 nm. The band gap energy (3.7 eV) was determined by means of UV–visible spectroscopy from the absorption band at 335 nm. The TiO 2 based sensor was employed as working electrode (electroactive area: 0.02248 cm2) in a cyclic voltammetry study, and a greater peak current was observed for the electrooxidation of isopropyl xanthate at pH 10 as compared to the unmodified electrode. The electrode optimization showed that the percentage of TiO 2 and the amount of mineral oil in the electrode have a significant influence on the electrochemical response, with 18.4 % of TiO 2 NPs, 0.74 mL of mineral oil, and 18 h of electrode rest before the first use as optimal conditions. In the polarization studies, the charge transfer reaction occurred through a lower overpotential with respect to the open circuit potential. The exchange current density was three times higher for the modified electrode. Electrochemical impedance spectroscopy indicated the detection of xanthate with lower charge transfer resistance than when the unmodified electrode was used. The electrochemical sensor allows the quantification of xanthate from 5 μmol/L to 10 mmol/L by cyclic voltammetry and the square wave technique. For the cyclic voltammetry calibration, the limits of detection and quantification were 40.6 μmol/L and 135 μmol/L, respectively. The limit of detection by square wave voltammetry was 2.4 μmol/L, and the limit of quantification was 7.9 μmol/L. The repeatability of the method showed a relative dispersion of 3.1 % at 0.51 mmol/L. The electroanalytical response of the sensor was reproducible up to 30 days. The recoveries of xanthate in real flotation samples were 91.9 % and 94.6 % for concentrations of 0.55 and 1.1 mmol/L, respectively. No statistically significant differences were found between the quantification using the sensor and the UV spectrophotometric method. Dicresyl dithiophosphate showed statistically significant interference with the xanthate oxidation signal. [Display omitted] [ABSTRACT FROM AUTHOR]