Octyl Hydroxamic Acid Research Articles

Transport of Zn (Ⅱ) through matrix enhanced polymer inclusion membrane containing OHA and D2EHPA

Recovery of heavy metal ions from waste water has benefits both in terms of resources reuse and environmental protection. Polymer inclusion membrane (PIM) has received increasing attention as a gentle and simple method compared to other separation techniques for the removal and recovery of heavy metal ions. The extractant and matrix are the most important components of the PIM. In this paper, a novel matrix enhanced polymer inclusion membrane (ME-PIM) system containing both octyl hydroxamic acid (OHA) and di (2-ethylhexyl) phosphoric acid (D2EHPA) as the carriers as well as poly(vinyl) chloride (PVC) and poly (vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) as the matrix was reported. The SEM results indicate that the PVC has excellent compatibility with OHA and D2EHPA, resulting in dense ME-PIM compared to PVDF-CTFE. The effects of OHA and D2EHPA with different carrier ratios on the transport and the stability of the membrane were examined using Zn (Ⅱ) as a representative of heavy metal ions. The optimal results of this work showed that the initial mass transfer flux value of Zn (Ⅱ) was as high as 4.73 μmol/(m2·s), corresponding to a permeability of 2.21 × 10−2 m/h, using the ME-PIM composed of 61 wt.% PVC and 22 wt.% OHA + 17 wt.% D2EHPA. All these results suggest that the ME-PIM has a much higher initial mass transfer flux than those of PIMs in literatures. The addition of OHA to PIM introduced extractive functional groups into the polymer chain, forming an efficient and progressive mass transfer path with the extractant D2EHPA. Utilizing two extractants with synergistic effects, this novel ME-PIM system provides a potential advantage in promoting the mass transfer of metal ions in a PIM.

Revealing the role of dithiocarbamate ester group in hydroxamic acid flotation of cassiterite with in situ AFM, DFT and XPS

To explore the role of dithiocarbamate ester group in hydroxamic acid flotation of cassiterite, a special surfactant S-[(3-hydroxyamino)-propoxy]-N-octyl dithiocarbamate (DTCHA) was designed. With carbon disulfide, octylamine, methyl acrylate and hydroxylamine as raw materials, DTCHA was facilely synthesized by a “one-pot” approach. In situ AFM (atomic force microscopy) clearly captured DTCHA aggregates self-assembled on cassiterite, which significantly increased its surface hydrophobicity. DFT (density functional theory) calculation predicted that the dithiocarbamate ester group possessed the ability of electron-donating and electrostatic interaction, and might be the second reactive center of DTCHA. XPS (X-ray photoelectron spectroscopy) and FTIR (Fourier transform infrared spectra) allowed to infer a bonding interaction between DTCHA’s dithiocarbamate with Sn during DTCHA reaction with Sn(Ⅳ) ions in aqueous solutions, while that with surface Sn(Ⅳ) atoms of cassiterite wasn’t concluded. The attendance of the dithiocarbamate hardly weakened the flotation selectivity of DTCHA against calcite, while its hydrophobization towards cassiterite became much stronger. Thus, DTCHA possessed the stronger collecting power and better selectivity for flotation separation of cassiterite from calcite than octyl hydroxamic acid. Revealing the role of DTCHA’s dithiocarbamate as a hydrophobic group in cassiterite flotation offered a new strategy for designing oxide minerals collector. That was, besides alkyl groups, some sulfhydryl minerophilic groups for sulfide minerals could be designed as preferable hydrophobic groups for oxide minerals flotation.

Effect of lead ions on the selective flotation of ilmenite against titanaugite using octyl hydroxamic acid as collector

Froth flotation, the main process for separating ilmenite, depends heavily on the performance of flotation reagents. Herein octyl hydroxamic acid (OHA) and lead nitrate served as collector and activator were introduced into the ilmenite-titanaugite flotation system. The adsorption of Pb2+ on ilmenite and titanaugite surfaces and the subsequent influence on their flotation behaviors were systematically investigated by AFM, FTIR and XPS. Microflotation results showed that Pb2+ could selectively enhance the floatability of ilmenite rather than titanaugite. Contact angle and AFM measurements verified that OHA selectively adsorbed onto the surface of Pb2+-modified ilmenite and increased its hydrophobicity. As characterized by zeta-potential and XPS analyses, lead ions adsorbed onto ilmenite surfaces via chemisorption and physisorption, forming lead-containing complexes, while only Pb2+ physisorption occurred on titanaugite surfaces. Consequently, the active sites on ilmenite surfaces were dramatically increased and leading to the denser adsorption of OHA collector which contributed to the flotation of ilmenite.

Uncovering the flotation performance and adsorption mechanism of a multifunctional thiocarbamate collector on malachite

In this paper, a novel collector N-octanoyl-S-carboxyethyl thiocarbamate (OCETC) containing CO, CS and -COOH groups was synthesized and applied to recover malachite. The flotation performance and adsorption mechanism of OCETC on malachite surface were systematically investigated by DFT calculation, zeta potential, FTIR, XPS, contact angle measurements and flotation experiments. It was found that CO, CS and -COOH groups were the functional sites which could react with Cu(II) ions on malachite surface and formed COCu(I) and CSCu(I) bonds. The adsorption of OCETC on malachite surface significantly improved its surface hydrophobicity since the contact angle of water on malachite changed from 46.5° to 78.0°. The flotation experiments demonstrated that 6 × 10−5 mol/L OCETC enabled the recovery of up to 98.24% malachite at pH 8.0. Under the same flotation conditions, OCETC exhibited comparable flotation recovery for malachite compared to octyl hydroxamic acid (98.43%), but much better than that by benzoyl hydroxamic acid (54.13%).

Experimental and Computational Studies on Octyl Hydroxamic Acid as an Environmentally Friendly Inhibitor of Cobalt Chemical Mechanical Polishing.

Octyl hydroxamic acid (OHA) was investigated as an inhibitor in H2O2-based alkaline silica dispersions for the polishing of cobalt (Co) films for interconnect applications. A combination of experiments and density functional theory (DFT) was used to investigate the inhibition effect and the mechanism of OHA on the Co surface. On the basis of the experiments, it can be proven that OHA has an inhibition effect on Co, which came from the inhibition of the cathodic reaction. The X-ray photoelectron spectroscopy (XPS) experiments show that the adsorption of OHA weakened the oxidation of the Co surface and protected the Co surface from corrosion. On the basis of the calculations, it can be proven that the OHAketone (ion) is most likely to react with the Co surface, and it can adsorb on the Co surface by Co-O bonds. This study provides important microscopic insights for understanding the corrosion protection of Co interconnect metals and helps to explain the corrosion inhibition mechanism of the organic-metal interface during the CMP process.

Investigations on the effect of Fe2+ and Mn2+ in the flotation of fine wolframite with octyl hydroxamic acid

The effect of Fe2+ and Mn2+ in the flotation of fine wolframite with octyl hydroxamic acid (OHA) as a collector was studied through a series of experiments. The XPS analysis indicates that Fe2+ and Mn2+ species on the wolframite surface are the active sites to interact with OHA collector. However, microflotation and contact angle tests show that the excess Fe2+ and Mn2+ ions in pulps decrease the flotation recovery and surface hydrophobicity of wolframite, playing inhibition roles on the flotation performance. The zeta potentials of wolframite shift toward positive values in the presence of Fe2+ and Mn2+. Fe(OH)2(s) and Mn(OH)2(s) precipitates being dominated species preferentially coat onto wolframite surfaces and then hinder the OHA adsorption. The adsorption results further give evidences that the excess Mn2+ and Fe2+ ions in the aqoeous solution also will consume OHA collector. These two processes decrease the adsorption of OHA and the flotation recovery of wolframite.

Flotation separation of bastnaesite from fluorite with an eco-friendly depressant polyepoxysuccinic acid and its depression mechanism

In this work, an eco-friendly depressant polyepoxysuccinic acid (PESA) was introduced for the flotation separation of bastnaesite from fluorite using octyl hydroxamic acid (OHA) as the collector. The depression effect and mechanism of PESA on the fluorite and bastnaesite were investigated by micro-flotation tests, contact angle, adsorption experiments, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). The flotation results showed that the recovery of fluorite decreased by 89.71% when 4 mg/L PESA was added to the flotation system, while the bastnaesite recovery only exhibited a slight reduction of 2.88% under these conditions. Wettability results suggested that the PESA in the presence of OHA could make the fluorite surface hydrophilic, whereas it had a negligible impact on the hydrophobicity of the bastnaesite surface. The addition of PESA could impede the OHA adsorption on fluorite surface, which was revealed by adsorption tests and FT-IR, and the XPS analysis confirmed that the chemisorption of PESA on the Ca sites of fluorite occurred. For bastnaesite, the adsorption of OHA still could be detected, making the bastnaesite well floatable. Therefore, the efficient separation of bastnaesite from fluorite could be achieved with the PESA as a selective depressant.

Selective flotation separation of bastnaesite from dolomite using β-naphthyl sulfonate formaldehyde condensate as depressant: Experimental and calculational studies

It is difficult to recover bastnaesite from dolomite when using octyl hydroxamic acid (OHA) as collector owing to the similar chemical properties between bastnaesite and dolomite. In this work, β-naphthyl sulfonate formaldehyde condensate (NSFC), as an effective depressant for dolomite has been employed. The flotation performance of NSFC in bastnaesite-dolomite system has been investigated with the help of single minerals flotation and artificially mixed minerals flotation. The depression mechanism has been first proposed from micro level by means of XPS analyses and molecular dynamic simulations. The flotation results demonstrate that NSFC showed a higher affinity towards dolomite instead of bastnaesite, and rare earth element can be effectively recovered using NSFC as depressant in bastnaesite-dolomite system. Mg active sites existing on dolomite surface are more prone to reacting with NSFC depressant through chemical bonding. The distance between Mg active sites on dolomite surface and oxygen components in sulfo groups became closer after interaction, which is opposite to that of Ca active sites, indicating that Mg active sites are the predominant place for NSFC attachment. The findings reveal that NSFC in conjunction with OHA could be used as an effective flotation reagent scheme for satisfactory recovery of bastnaesite when dolomite is the main associated gangue mineral.

Roles of the hydrophobic and hydrophilic groups of collectors in the flotation of different-sized mineral particles

A controlled study was carried out in this work to decouple the effects of the hydrocarbon chains and the type of hydrophilic groups of the collectors on their collecting ability for minerals with different particle sizes. A high purity niobium oxide (pyrochlore) sample, with two different sizes (medium size of 64 µm and 16 µm, respectively), were floated by four anionic collectors, whose hydrocarbon chain was either octyl or oleoyl and hydrophilic group was either carboxylate or hydroxamate. The four combinations were: octyl hydroxamic acid (OHA), sodium octanoate (C8OONa), oleoyl hydroxamic acid (C18HA) and sodium oleate (NaOl). Through small-scale flotation tests, it was observed that the carboxylate-based collectors were inferior to hydroxamate-based collectors. Sodium octanoate could not float either the coarse or the fine pyrochlore. Replacing the octyl group in octanoate with a longer hydrocarbon chain, sodium oleate could float the coarse pyrochlore well but its effectiveness dropped sharply when floating the fine pyrochlore. Interestingly, the two hydroxamate-based collectors, octyl hydroxamic acid and oleoyl hydroxamic acid, showed excellent collecting ability to both the coarse and the fine pyrochlore tested. While FTIR analysis showed that all tested collectors adsorbed through chemisorption, isothermal titration calorimetry (ITC) measurements showed a positive correlation between the adsorption affinity and fine pyrochlore flotation recoveries. It is concluded that while the longer hydrocarbon chain of the collector benefited flotation recovery of relatively coarse size particles, for effective fine particle flotation, collectors need to have a hydrophilic group that has a strong affinity to the mineral surface. This work provided useful insights into collector molecular structure design and selection for improved flotation performance of minerals with specific particles sizes.

Depression behavior and mechanism of sodium silicate on bastnaesite and parisite flotation

Parisite (CaCe2(CO3)3F2) and bastnaesite (CeCO3F), important rare earth minerals, have different elemental compositions and crystal structures. Their flotation behavioral differences under commonly used sodium silicate (SS) depressant and hydroxamate collector are important for rare earth ore beneficiation, which is still unknown. In this study, the effect of sodium silicate on bastnaesite and parisite flotation with octyl hydroxamic acid (OHA) as collector was comparatively investigated through microflotation, zeta potential measurements, X-ray photoelectron spectroscopy (XPS), and mineral crystal computational analysis. The results indicated that the inhibition effect of SS on parisite was significantly stronger than that on bastnaesite. SS had little effect on the adsorption of OHA on bastnaesite surface, rendering a slight inhibition on bastnaesite flotation. However, SS strongly hindered the adsorption of OHA on parisite surface, rendering the heavy inhibition on parisite flotation. The inhibition mechanism of SS on parisite was due to the reaction of the calcium species with silicate, thereby forming Ca-SiO3 hydrophilic complex on parisite surfaces. This hydrophilic complex hindered the adsorption of OHA and increased the hydrophilicity on parisite surface, thus, causing significant inhibition on parisite flotation.

Influence of Microbubble on Fine Wolframite Flotation

The recovery of fine wolframite is low when using traditional flotation that does not use a microbubble. In this study, a microbubble was introduced into the fine wolframite flotation system; −20 μm wolframite was used as an experiment sample and octyl hydroxamic acid as the collector. The recovery of microbubble flotation reached 84.07%, which is about 12.04% higher than that of traditional flotation. A single-factor flotation experiment, high-speed camera analysis, and SEM (Scanning Electron Microscopy) analysis were used to study the influence of microbubbles on the flotation of fine wolframite. The results show that fine wolframite will more easily agglomerate under the action of microbubbles. The octyl hydroxamic acid adsorbed on the surface of wolframite treated with microbubbles is denser and more abundant.

Flotation of rhodochrosite fines induced by octyl hydroxamic acid as hydrophobic agglomerates

In this study, the flotation of rhodochrosite fines induced by octyl hydroxamic acid (OHA) as hydrophobic agglomerates was investigated through the measurements of micro-flotation, laser diffraction, microscopy observations and zeta potential. The experimental results showed that the apparent particle size and morphology of rhodochrosite agglomerates were greatly affected by OHA concentration and stirring speed. Bigger agglomeration particle size and more regular agglomerates could be obtained at the OHA concentration of 60 mg/L, and appropriate stirring speed was required to form an optimum particle size of agglomerates for micro-flotation. The increased apparent particle size of rhodochrosite was favorable for micro-flotation recovery even though the particles were negatively charged in the presence of OHA. It's considered that OHA adsorbed on the surface of rhodochrosite through zeta potential results as well as the species distribution analysis of OHA and rhodochrosite.

Study on the role of a hydroxamic acid derivative in wolframite flotation: Selective separation and adsorption mechanism

Wolframite, as the main mineral for extracting tungsten, is usually separated and enriched by flotation in mineral processing, thus the construction of efficient flotation collector is of great concern to the effective utilization of tungsten resources. In this study, by introducing a phenyl group into octyl hydroxamic acid (OHA) structure, we design and synthesize a hydroxamic acid derivative N-substituted phenyl octyl hydroxamic acid (NPOHA), and report its first employment as a collector in wolframite flotation. Density functional theory (DFT) calculations and surface activity characterization revealed that compared to OHA and benzohydroxamic acid (BHA), NPOHA possessed not only superior electron-donating ability and chemical reactivity, but also stronger hydrophobicity, which contributed to its application in wolframite flotation. Micro-flotation tests proved that NPOHA possessed much stronger collecting ability to wolframite than BHA and OHA, with superb flotation selectivity against quartz and fluorite, which was regarded as an appropriate collector for wolframite flotation. Zeta potential, Fourier Transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) measurements indicated that NPOHA chemisorbed onto wolframite surfaces through the formation of N-O-Fe and C-O-Fe bonds, which was further verified and explained by binding ability evaluations.

A selective flotation of cassiterite with a dithiocarbamate-hydroxamate molecule and its adsorption mechanism

N-[(3-hydroxyamino)-propoxy]-N-octyl dithiocarbamate (OAHD) was designed as cassiterite flotation collector. AFM clearly showed that OAHD assembled on cassiterite surfaces to generate innumerable nano-aggregates. The FTIR and XPS recommended that the adsorption of OAHD was related to forming the ▪ and ▪ configurations in the surface OAHD-Sn(IV) complexes, which improved the hydrophobicity, decreased the surface energy and hydrophilicity index, and realized an effective flotation enrichment of cassiterite particles. In addition, the dithiocarbamate group might act as a hydrophilic group for calcite flotation, while as a chelating group for cassiterite flotation, which rendered OAHD to return the lower flotation recovery of calcite than octyl hydroxamic acid, and the excellent collecting properties towards cassiterite.

Flotation separation performance of malachite from calcite with new chelating collector and its adsorption mechanism

In this study, the flotation separation performances of malachite from calcite were investigated using a new chelating collector S-carboxymethyl-O, O’-dibutyl dithiophosphate (CMDTP) by micro-flotation tests, which showed that CMDTP exhibited a stronger collecting power and a better selectivity on malachite than octyl hydroxamic acid (OHA), 8-hydroxyquinoline (HQ) and sodium isobutyl xanthate (SIBX). In the flotation separation of artificially mixed minerals, malachite could be separated successfully from calcite at pH around 9.0 when using Na2S as a regulator. Its adsorption mechanism was also studied by FT-IR, zeta potential and XPS measurements, all of which confirmed that CMDTP showed a better affinity to malachite surface than to calcite surface. Furthermore, XPS provided obvious evidence that CMDTP could easily react with Cu2+ sites on malachite surface, and only a tiny adsorption occurred on calcite surface without Cu2+ ions.

Insights into the interaction between octyl hydroxamic acid and the rutile surface activated by lead ion

Insights into the interaction between octyl hydroxamic acid and the rutile surface activated by lead ion

Hydrophobic intensification flotation: Comparison of collector containing two minerophilic groups with conventional collectors

The surface hydrophobization and flotation of a xanthate−hydroxamate collector toward copper oxide mineral were compared with the combined collectors of xanthate and hydroxamate through water contact angle (WCA) and micro-flotation experiments. The results showed that S-[(2-hydroxyamino)-2-oxoethyl]-O-octyl-dithiocarbonate ester (HAOODE) exhibited stronger hydrophobization and better flotation performance to malachite (Cu2(OH)2CO3) than octyl-hydroxamic acid (OHA) and its combination with S-allyl-O-ethyl xanthate ester (AEXE). To understand the hydrophobic intensification mechanism of HAOODE to malachite, zeta potential, atomic force microscopy (AFM) and XPS measurements were carried out. The results recommended that malachite chemisorbed HAOODE to form Cu—HAOODE complexes in which the hydroxamate—(O,O)—Cu and —O—C(—S—Cu)—S— configurations co-existed. The co-adsorption of HAOODE's hetero-difunctional groups was more stable than the single-functional- group adsorption of OHA and AEXE, which produced the “loop” structure and intensified the self-assembly alignment of HAOODE on malachite surfaces. In addition, the “h” shape steric orientation of the double hydrophobic groups in HAOODE facilitated stronger hydrophobization toward malachite than the “line” or “V” hydrophobic carbon chains of OHA or AEXE. Thus, HAOODE achieved the preferable flotation recovery of malachite particles in comparison with OHA and AEXE.

A novel decanedioic hydroxamic acid collector for the flotation separation of bastnäsite from calcite

In this work, decanedioic hydroxamic acid (DDHA) was introduced as a novel collector for the flotation separation of bastnӓsite and calcite, and the results were compared with those obtained for the conventional hydroxamic acid collectors benzohydroxamic acid (BHA) and octyl hydroxamic acid (OHA). The microflotation results showed that DDHA had better selectivity than BHA and OHA for the flotation of bastnӓsite from calcite. The flotation of artificially mixed minerals confirmed that the effective separation of bastnӓsite from calcite could be realized in the presence of DDHA. The zeta potentials of mineral surfaces with or without these collectors were measured, and the results indicated that DDHA strongly interacted with the bastnӓsite surface but was not adsorbed on the calcite surface.

Beneficial effects and mechanism of lead ions for bastnaesite flotation with octyl hydroxamic acid collector

The beneficial effects and mechanism of Pb ions (Pb2+) for bastnaesite flotation were systematically investigated. The results of micro-flotation tests indicated that the Pb2+ effectively enhanced the floatability of bastnaesite with octyl hydroxamic acid (OHA) collector. Maximum recovery of 67% was obtained at pH 8–9. Adsorption of the hydrolyzing species of Pb occurred at this pH, which provided more active sites on the bastnaesite surface for OHA absorption. Furthermore, lead species interacted with active Ce sites to form lead-containing complexes (Ce-O-Pb) on the bastnaesite surface, and the hydrophobic Pb-OHA chelates were formed via chemical adsorption between Pb2+-activated bastnaesite and OHA. These findings were confirmed by adsorption measurements, zeta-potential measurements, Fourier transform infrared analysis (FT-IR), and X-ray photoelectron spectroscopy (XPS).

Modulation of the morphology, surface energy and wettability of malachite through a S,O,O-ligand surfactant: Mechanism and hydrophobization

The modulation of solid surface properties via surfactants has a wide application in surface engineering. In this study, a novel S,O,O-ligand surfactant N-[(4-hydroxyamino)-4-butoxyl]-S-hexyl-dithiocarbamate (HABHTC) was first introduced to hydrophobize malachite surface. AFM morphology image clearly displayed that the dense HABHTC aggregates adsorbed on the whole surface of malachite, which increased its contact angle, decreased its surface energy, hydrophilicity index and interaction free energy with bubble. HABHTC exhibited stronger hydrophobization to malachite than calcite and quartz. FTIR and XPS recommended that HABHTC acted as a S,O,O-ligand to bond surface Cu atoms of malachite via building CuS and CuO bonds. The S,O,O-coordination enhanced the stability of Cu-HABHTC surface species on malachite and rendered HABHTC to possess better flotation specificity toward malachite versus calcite than octyl-hydroxamic acid (OHA). The C6H13SCNC3H6 configuration of HABHTC dramatically strengthened its hydrophobization toward malachite surface, resulted in a preferable hydrophobic flotation of malachite particles by using HABHTC as a collector.