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[Display omitted] • TTCBT/BO/BI S atoms react with pyrite Fe atoms to form covalent bonding. (74/85) • Heterocyclic collectors adsorbed stronger under acidic condition. (66/85) • Thione form was the most stable adsorption form under acidic condition. (73/85) • MBTH, TTCBTH and TTCBIH gave stronger adsorption and high recoveries. (71/85) • Linear correlation between the recoveries and hydrated adsorption energies. (77/85) This study adopted both computational and experimental approaches to design by modification of 2-mercaptobenzothiazole (MBT), 2-mercaptobenzoxazole (MBO) and 2-mercaptobenzimidazole (MBI) heterocyclic collectors by introducing a carbon sulphide (–CS 2) group and forming 2-trithiocarbonatebenzothiazole (TTCBT), 2-trithiocarbonatebenzoxazole (TTCBO) and 2-trithiocarbonatebenzomidazole (TTCBI) derivatives collectors. The adsorption behaviour of the heterocyclic collectors (and derivatives) on pyrite and subsequent hydrophobicity at different pH conditions were characterised using molecular modelling and microflotation approaches, respectively. The computational adsorptions were performed on dry and hydrated surfaces in their neutral thiolate and thione (acidic) form on the pyrite (1 0 0) surface. It was found that under dry and neutral conditions the TTCBONa and TTCBTNa were more exothermic, while under dry and acidic conditions the TTCBIH was more exothermic followed by MBIH and MBTH. Under hydrated and neutral conditions MBONa was predicted as the most exothermic, while for hydrated and acidic conditions MBTH, TTCBTH and TTCBIH were more exothermic. It was found that under acidic conditions, the heterocyclic collectors were more exothermic than for neutral condition on the hydrated surface. The microflotation at pH = 8 showed that MBO achieved higher recoveries, while at pH = 6 MBT, TTCBT and TTCBI achieved higher recoveries that could reach 90 %. The derivatives under acidic conditions were found to have good recovery performance, which showed that the introduction of a –CS 2 group on the exocyclic sulphur atom improved the affinity and therefore hydrophobicity of the mercapto-heterocyclic collectors on the pyrite surface, and thus these derivatives can enhance the flotation of pyrite minerals. In addition, the computational predictions complimented by experimental recoveries are essential to a meaningful development of modelling as a tool in mineral processing reagent design. [ABSTRACT FROM AUTHOR]

• PAMDTC showed a strong depressing performance on molybdenite when using DEDTC collector. • PAMDTC could prevent the DEDTC attachment on molybdenite surface by competitive adsorption. • DS of the dithiocarbamate group in PAMDTC would greatly influence its depression power to minerals. • PAMDTC adsorbed on molybdenite surface mainly by physical adsorption based on DFT simulations. In this research, a co-poly(acrylamide-allyldithiocarbamate) (PAMDTC) depressant was prepared by modifying polyacrylamide (PAM) and firstly utilized to depress molybdenite in Cu/Mo flotation separation. PAMDTC exhibited superior depression efficacy on molybdenite to unmodified polyacrylamide (PAM) based on micro-flotation tests results when using diethyldithiocarbamate (DEDTC) as the collector. In addition, it was found that the degree of substitution (DS) of allyldithiocarbamate group in PAMDTC would greatly influence its depression power and selectivity to minerals as an important factor. Finally, a competitive adsorption between PAMDTC and DEDTC on molybdenite surface was discovered and detected by adsorption tests, contact angle measurements, FTIR, XPS analysis and DFT simulations. The findings from adsorption tests and contact angle measurements implied that PAMDTC could prevent DEDTC collector adsorbing on molybdenite surface, but had few influences on the adsorption of DEDTC on chalcopyrite surface, providing adequate evidence of a competitive adsorption. Moreover, FTIR, XPS and DFT simulation analysis results further confirmed that PAMDTC physically adsorbed on molybdenite surface, simultaneously, it showed a stronger adsorption than DEDTC collector judging from these results of bond length, adsorption energy and electron density in DFT simulations. [ABSTRACT FROM AUTHOR]

The article presents a study which examined the potential of the isolated Bacillus siamensis strain as a lipopeptide antibiotics and biocontrol agent against Fusarium head blight (FHB). FHB is a destructive fungal disease caused by Fusarium graminearum. Also cited are the use of scanning electron microscopy to monitor the effects of the isolated strain against the mycelia of F. graminearum, and the effectiveness of the lipopeptide biosurfactant as antifungal agent.

The strain Staphylococcus PT-1 was isolated from soy sauce mash and whole genome sequencing revealed it didn’t contain drug resistance genes and virulence genes. Salt tolerance test showed that PT-1 could withstand 20% NaCl. It was inoculated into a pork broth medium. Through volatile component detection, the content of pyrazine in the fermentation broth was 0.83% pyrazine and 1.36% 2, 5-dimethylpyrazine. When the strain was applied to the brewing process of soy sauce, the contents of total nitrogen and amino acid nitrogen in the resulting product were higher than those in the control group; the contents of ammonium salt and NaCl were lower than those in the control group; the total acid content was similar. Solid phase microextraction–gas chromatography–mass spectrometry was used to detect the volatile components of two finished soy sauce products. Compared to soy sauce fermented by typical means, that added with PT-1 contained unique components, such as 2,5-dimethylpyrazine (1.8027%), 2-methylpyrazine (0.0158%), 3-ethyl-2,5-dimethylpyrazine (0.5809%), and 4-ethyl guaiacol (8.7477%). Sensory evaluation showed that the total score of PT-1-fermented soy sauce was higher than that of the control group and was characterized by full and rich flavor. These results provide new insights for improving the quality of soy sauce by using novel strains for fermentation. [ABSTRACT FROM AUTHOR]

In present research, a new chelating collector S -carboxymethyl- O , O ′-dibutyl dithiophosphate (CMDT) was used in the flotation separation of malachite from quartz. The flotation performances of CMDT on malachite (Cu 2 CO 3 (OH) 2 and quartz (SiO 2) were evaluated by micro-flotation tests. The flotation results demonstrated that CMDT exhibited a stronger adsorption and a better selectivity on malachite against quartz. A good separation efficiency for artificially mixed minerals was obtained at pH around 9.0 with Na 2 S as a regulator together. The CMDT adsorption mechanism was investigated and analysed by Fourier transform infrared spectroscopy (FT-IR), zeta potential and X-ray Photoelectron Spectroscopy (XPS) analysis. The FT-IR spectra showed that CMDT could react with Cu2+ ions and might adsorb on malachite surface by strong chemisorption. On the other hand, zeta potential and XPS analysis results provided enough evidences that CMDT possessed a stronger affinity on malachite than quartz. Unlabelled Image • CMDT is innovatively used as malachite collector. • CMDT shows excellent flotation performance for malachite against quartz. • Cu2+ ions released by malachite could promote the recovery of quartz with CMDT. • Adsorption mechanism of CMDT on malachite surface is revealed by FT-IR and XPS. [ABSTRACT FROM AUTHOR]

In this paper, a novel macromolecular depressant of hematite, polymaleic anhydride-triethylenetetramine (PMTA) with multiple carboxyl and amine groups, has been synthesized and used for cationic reverse flotation separation of quartz from hematite. The structure is characterized by Fourier transform infrared spectroscopy (FT-IR). The depression performance and adsorption mechanism of PMTA onto hematite and quartz surface are investigated by micro-flotation tests, FT-IR, zeta potential and X-ray photoelectron spectra (XPS). The micro-flotation results indicate that PMTA exhibits a good depression performance compared to starch. We find that 98.29% of hematite is depressed with a grade of 65.24% at pH 11 with 12 mg/L dosage. The FT-IR spectra, zeta potential and XPS analysis demonstrate that PMTA may mainly chemisorb on the hematite surface by Fe O bonds, and mainly adsorb on the quartz surface by hydrogen bond interaction. PMTA could be a good depressant of hematite in the separation from quartz. [ABSTRACT FROM AUTHOR]

In this paper, a novel macromolecular depressant polymaleamide-propyl dithiocarbamate (PMA-PDTC) was designed and synthesized according to density functional theory (DFT) calculations results, and its structure was characterized by infrared spectra (IR). The flotation experiments results demonstrated that PMA-PDTC was an effective depressant for galena in separating galena from chalcopyrite, and it exhibited a stronger depressing ability and a better selectivity for galena than for chalcopyrite. When the dosage of PMA-PDTC was 2.0 mg/L, a good separation result was obtained with O-isopropyl-N-ethyl thionocarbamate (IPETC) as collector at pH 8.5 for an artificial mixture of Cu-Pb minerals. The Cu concentrate could reach a grade of 28.89% containing 12.12% Pb, and the Pb concentrate could reach a grade of 80.65% containing 1.49% Cu. The experimental results agreed with the DFT calculations results well, which indicated that DFT method was useful for predicting the adsorption strength of some molecules on mineral surfaces and for guiding the design of the depressant for galena or other minerals. [ABSTRACT FROM AUTHOR]

[Display omitted] • ATT heterocyclic surfactant could adsorb on chalcopyrite interface and make it hydrophilic. • ATT can selectively and strongly depress chalcopyrite and has no obvious negative effect on molybdenite. • A four-coordination structure was formed through S-Cu and N -Cu bonds confirmed by XPS and DFT. • Water could strengthen the adsorption of ATT on chalcopyrite interface via DFTB+ method. Flotation is an interfacial chemical reaction in essence. The selective adsorption of flotation reagents on mineral surfaces leads to the transition of hydrophilicity/hydrophobicity of mineral particles, and then to regulate the floatability differences between various minerals. 5-amino-1,3,4-thiadiazole-2-thiol (ATT) is a heterocyclic ring compound, which can chelate copper ions easily and usually used as a copper corrosion inhibitor. Based on those good chelating properties with copper ions, this paper attempted to apply ATT as a chalcopyrite depressant in the flotation separation of Cu/Mo ores. The adsorption mechanism of ATT on chalcopyrite surface was explored by means of UV–vis, FTIR, contact angle and XPS analysis, and it revealed the possibility of ATT using as a selective chalcopyrite depressant in the flotation separation of Cu/Mo ores by micro-flotation tests. Finally, the adsorption morphology of ATT depressant on chalcopyrite surface was unveiled by DFT method from a microscopic level. Through these FTIR and XPS analysis, combined with DFT simulation results, it was inferred that ATT was mainly chemically adsorbed on chalcopyrite surface by S Cu and N Cu bonds. These studies confirmed that ATT was very likely to be an excellent chalcopyrite depressant in Cu/Mo flotation separation. [ABSTRACT FROM AUTHOR]

[Display omitted] We employed computational density functional theory (DFT) and microflotation tests complemented by analysis of electronic properties and X-ray photoelectron spectroscopy (XPS) data to investigate the adsorption mechanism of O-isopropyl-N-ethyl-thionocarbamate (IPETC), O-isopropyl-N-diethyl-thionocarbamate (IPDETC) and S-allyl-N-diethyl-dithiocarbamate (ADEDTC) on chalcopyrite reconstructed-(1 1 2) surface and pyrite (1 0 0) surface. The adsorption of the thiocarbamate collectors on chalcopyrite was observed to preferentially occur at Cu atoms instead of Fe atoms. The thiocarbamate collector adsorption on chalcopyrite Cu sites decreased in the order ADEDTC > IPDETC > IPETC, while on pyrite Fe sites, the adsorption strength decreased in the order ADEDTC > IPETC > IPDETC. This shows that the adsorption of ADEDTC was strong, although the adsorption on pyrite was weaker than the adsorption on chalcopyrite. In the associated microflotation tests, the chalcopyrite recoveries exceeded 90%, while the pyrite recoveries reached only 25%, with ADEDTC exhibiting the highest recoveries. XPS analysis of chalcopyrite treated and not with ADEDTC revealed that the adsorption of the ADEDTC S1 atom was stronger at Cu sites than at Fe sites. These findings provide a clear correlation between experiments and DFT predictions and therefore suggest that these thiocarbamate collectors may be useful in the floatation separation of chalcopyrite from pyrite minerals. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel polymer depressant DTC-PAA was synthesized and used as galena depressant. • DTC-PAA showed excellent depressing performance on galena at pH 8.5. • Chalcopyrite was separated effectively from galena in the presence of DTC-PAA. • DTC-PAA chemisorbed on galena surface via dithiocarbamate groups and Pb sites. In this research, to achieve green effective separation of chalcopyrite and galena, a novel synthetic depressant, dithiocarbamated poly(acrylamide-allyamine) (DTC-PAA), was prepared and innovatively employed as a galena depressant. The flotation behaviours of chalcopyrite and galena were investigated by micro-flotation experiments in the absence and presence of DTC-PAA depressant comparing with potassium dichromate with O-isopropyl-N-ethyl thiocarbamate (IPETC) as the collector. The micro-flotation results showed that DTC-PAA was an effective depressant for galena in the flotation separation from chalcopyrite when using IPETC collector. Their adsorption mechanisms were unravelled by FT-IR, zeta potential, adsorption capacity measurement, XPS and DFT calculations. The results of adsorption capacity tests showed that DTC-PAA prevented the adsorption of IPETC collector on galena surface. However, DTC-PAA could not prevent IPETC from adsorbing on chalcopyrite surface. It was found that DTC-PAA depressant could chemisorb onto Pb sites of galena surface through dithiocarbamate groups in DTC-PAA. These findings were also supported by FT-IR, zeta potential, XPS analysis and DFT calculations results. It implied that DTC-PAA might be a promising alternative of the potassium dichromate depressant in the flotation separation of Cu-Pb ores. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carbamates from known IBECTC, BBCTC IBBCTC to DFT predicted BECTC, IBIBCTC (84/85) • S1 carbamates atoms react with Cu chalcopyrite atoms to form covalent bonding. (82/85) • DFT and µ-flotation show similar ranking: BBCTC > IBIBCTC > BECTC > IBBCTC > IBECTC (84/85) • Straight carbon chains are better in performance than branched ones on chalcopyrite (85/85) • DFT predicts chalcopyrite recovery by thiocarbamates reliably (64/84) First-principle quantum mechanical density functional theory (DFT) was employed to explore the bonding behaviour, adsorption energies and electronic properties directly related to the reactivity's of O-butyl-N-ethoxycarbonyl-thiocarbamate (BECTC), O-isobutyl-N-ethoxycarbonyl-thiocarbamate (IBECTC), O-butyl-N-butoxycarbonyl-thiocarbamate (BBCTC), O-isobutyl-N-butoxycarbonyl-thiocarbamate (IBBCTC), and O-isobutyl-N-isobutoxycarbonyl-thiocarbamate (IBIBCTC) with the chalcopyrite (CuFeS 2) (1 1 2) surface and complimented by micro-flotation recoveries of the chalcopyrite. The partial density of states (PDOS) of the isolated oxycarbonyl-thiocarbamate collector showed that the sulphur atom (S1) was more active and will be more reactive during adsorption. Adsorption of the oxycarbonyl-thiocarbamate collectors preferred the Cu atom over Fe atoms. The adsorption energies and micro-flotation recoveries yielded similar trends and the order followed: BBCTC > IBIBCTC > BECTC > IBBCTC > IBECTC, which showed that BBCTC exhibited the strongest exothermic adsorption. This showed that the adsorption energies that determined how a collector binds to the mineral surface can predict the flotation recoveries. The PDOS and atomic population charges after adsorption showed that both Cu and S1 atoms lose charges (electron donor) forming σ-bonds, and simultaneously, dative π-bonds. The results also showed that BBCTC and BECTC are better collectors for the selective flotation of chalcopyrite minerals and indicated that a straight hydrocarbon chain gave stronger adsorption than a branched hydrocarbon chain. [ABSTRACT FROM AUTHOR]

The demand for non-ferrous copper metals has increased dramatically with the development of the global economy; accordingly, some refractory copper sulfide ores with low grade and their associated minerals are beginning to be utilized, making the flotation separation of copper concentrates exceptionally difficult, especially the separation of chalcopyrite and pyrite. In this paper, S-allyl-O, O′-dibutyl phosphorodithioate (ADTP) was synthesized by a one-pot method and used as a chalcopyrite collector in the flotation separation of chalcopyrite and pyrite. Flotation experiments results have shown that ADTP exhibits better selectivity and greater collecting power for chalcopyrite under neutral or weak base conditions. The 95% recovery of chalcopyrite can be achieved at pH 8.0 and 8.0 mg/L ADTP. From the analysis results of the contact angle, the SEM-EDS spectrogram, and elemental mapping, it was found that ADTP adsorbed uniformly on a chalcopyrite surface and made a significant contribution to the hydrophobicity of the surface. Confirmed by FTIR and XPS analysis, ADTP was able to form P–S–Cu bonds on a chalcopyrite surface, proving that it was adsorbed on the chalcopyrite surface in the form of chemisorption. [ABSTRACT FROM AUTHOR]

• A macromolecule PAM-ATU was employed as a galena depressant. • PAM-ATU could realize the separation of molybdenite from galena at pH around 10.5. • PAM-ATU could adsorb on galena surface via chemisorption by FT-IR and XPS analysis. In the present research, a macromolecular depressant poly(acrylamide-allylthiourea) (PAM-ATU) was explored to depress galena in the flotation separation from molybdenite. Its flotation behavior was evaluated by micro-flotation tests. The micro-flotation results revealed that PAM-ATU could depress galena strongly at 4.0 mg/L within pH 6.0–12.0, while molybdenite was found sensitive to the pH. At pH around 10.5, molybdenite showed a relatively good floatability with a nearly 80.0% recovery in the presence of 4.0 mg/L PAM-ATU. The flotation separation results for artificially mixed minerals proved that 1.0 mg/L PAM-ATU could selectively depress galena well. FT-IR and XPS analysis results demonstrated that PAM-ATU was likely to adsorb on galena surface by chemisorption. This study indicated that the synthesized PAM-ATU with low molecular weight might be a promising galena depressant in the flotation separation of Mo/Pb ores. [ABSTRACT FROM AUTHOR]

• A PAM-ATU polymer was introduced as the chalcopyrite depressant. • PAM-ATU showed a stronger depressing power to chalcopyrite than TGA. • A good separation efficiency was achieved when using diesel collector. • PAM-ATU chemisorbed on chalcopyrite surface via Cu sites and thiourea groups. In the present study, the poly(acrylamide-allyl thiourea) (PAM-ATU) with an average molecular weight of approximately 1.66 × 104 g/mol was introduced as the chalcopyrite depressant in the flotation separation of molybdenite and chalcopyrite. The effects of PAM-ATU on their flotation performances were evaluated by micro-flotation and bench-scale experiments, and its adsorption mechanism to chalcopyrite was investigated by Fourier transform infrared spectroscopy (FT-IR), zeta potential tests and X-ray Photoelectron Spectroscopy (XPS) measurements. The flotation experiments results demonstrated that PAM-ATU had a stronger depressing ability than the conventional depressant thioglycolic acid (TGA) for chalcopyrite. At pH around 10.5, a good separation efficiency for artificially mixed minerals could be achieved with a 78.2% Mo recovery and a 58.9% Mo grade in the froth products, in which, the Cu grade was only 1.68%. It was also found that nearly 80.0% of Cu was depressed effectively with 150 g/t PAM-ATU after one rougher flotation in bench-scale experiments with a Mo recovery of almost 80.0%. FT-IR, zeta potential tests and XPS analysis results provided strong evidence that PAM-ATU could adsorb on chalcopyrite surface. Further, FT-IR and XPS analysis suggested that PAM-ATU might mainly chemisorb on chalcopyrite via Cu sites on surface through S and N atoms in PAM-ATU polymer. This study indicated that the synthesized PAM-ATU polymer with low molecular weight could be a promising depressant for chalcopyrite in the flotation separation of Cu-Mo ores. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-Triazine S and N1 atoms react with cooperite Pt atoms to form covalent bonding. (82/85) • SDTBAT adsorbs stronger than xanthate and dithiocarbamate: SDTBAT > SNBDTC > SNBX. (83/85) • DOS and atomic charges depicted charge gain on Pt and loss on S atoms. (71/85) • SDTBAT exhibited strong adsorption on cooperite. (52/85) • Adsorption energies are stronger on dry surface compared to hydrated surface. (78/85) The high demand of platinum has drawn much attention on the recovery of the platinum group minerals (PGMs). Cooperite (PtS) is one of the major sources of platinum which is found in high concentration as sulphide minerals in the Platreef. This current study used the density functional theory with dispersion correction method and applying the U-parameters (DFT-D + U) to understand the interaction of the well-known collectors, sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC) which are utilised in industry in comparison with the green novel sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) collectors on dry and hydrated cooperite (1 0 1) surface. In the adsorptions, different adsorption sites were initially tested on dry surface, to identify the most preferred active and exothermic site of the colletors on the surface. The SNBX and SNBDTC collectors preferred to form a binuclear-bidentate, while the SDTBAT formed trinuclear-tridentate bonding on the 3-coordinated Pt atoms of the PtS (1 0 1) surface. The adsorption energies on dry surface were in the order as: SDTBAT > SNBDTC > SNBX. The adsorption energies of collectors on hydrated PtS (1 0 1) surface also followed similar adsorption trend (SDTBAT > SNBDTC > SNBX). This suggested that SDTBAT had strong affinity with the surface. Most importantly it was found that the hydrated condition adsorption energies were significantly reduced compared to the dry condition adsorption energies. It was apparent that the SDTBAT collector displayed an ability to improve the recovery of the cooperite mineral and therefore a potential replacement of the well-known dithiocarbamate and xanthate collectors for use in PGMs. [ABSTRACT FROM AUTHOR]

[Display omitted] • S-Triazine S and N1 atoms react with cooperite Pt atoms to form covalent bonding. (82/85) • SDTBAT adsorbs stronger than xanthate and dithiocarbamate: SDTBAT > SNBDTC > SNBX. (83/85) • DOS and atomic charges depicted charge gain on Pt and loss on S atoms. (71/85) • SDTBAT exhibited strong adsorption on cooperite. (52/85) • Adsorption energies are stronger on dry surface compared to hydrated surface. (78/85) The high demand of platinum has drawn much attention on the recovery of the platinum group minerals (PGMs). Cooperite (PtS) is one of the major sources of platinum which is found in high concentration as sulphide minerals in the Platreef. This current study used the density functional theory with dispersion correction method and applying the U-parameters (DFT-D + U) to understand the interaction of the well-known collectors, sodium normal butyl xanthate (SNBX) and sodium normal butyl dithiocarbamate (SNBDTC) which are utilised in industry in comparison with the green novel sodium 2,6-dithio-4-butylamino-1,3,5-triazine (SDTBAT) collectors on dry and hydrated cooperite (1 0 1) surface. In the adsorptions, different adsorption sites were initially tested on dry surface, to identify the most preferred active and exothermic site of the colletors on the surface. The SNBX and SNBDTC collectors preferred to form a binuclear-bidentate, while the SDTBAT formed trinuclear-tridentate bonding on the 3-coordinated Pt atoms of the PtS (1 0 1) surface. The adsorption energies on dry surface were in the order as: SDTBAT > SNBDTC > SNBX. The adsorption energies of collectors on hydrated PtS (1 0 1) surface also followed similar adsorption trend (SDTBAT > SNBDTC > SNBX). This suggested that SDTBAT had strong affinity with the surface. Most importantly it was found that the hydrated condition adsorption energies were significantly reduced compared to the dry condition adsorption energies. It was apparent that the SDTBAT collector displayed an ability to improve the recovery of the cooperite mineral and therefore a potential replacement of the well-known dithiocarbamate and xanthate collectors for use in PGMs. [ABSTRACT FROM AUTHOR]

To address the issue of mediocre separation efficiency of depressants in the copper-lead separation process, this article synthesized a macromolecular organic depressant, polymaleic anhydride-ethylenediaminetetraacetic acid (PMA–EDTC), using a polycarboxylic macromolecule as the backbone and also introducing –N–(C=S)–S– as the solidophilic group and employed as a galena depressant. The structure of PMA–EDTC was characterized using Fourier transform infrared (FT-IR). The effect of PMA–EDTC on the floatability of galena and chalcopyrite was investigated through micro-flotation and Contact angle measurements. The experimental results demonstrated that PMA–EDTC exhibited selectivity inhibition towards galena rather than chalcopyrite across a wide pH range. At a dose of 8 mg/L, there was effective separation between galena and chalcopyrite with a separation coefficient of 24.17, effectively altering the floatability of galena while having little impact on the floatability of chalcopyrite. The selective inhibition behavior and adsorption mechanism of PMA–EDTC on galena and chalcopyrite were investigated using FT-IR, Zeta potential, and X-ray photoelectron spectroscopy (XPS). FT-IR and Zeta potential studies indicated that PMA–EDTC formed chemical adsorption on the surface of galena. XPS confirmed the model of chemical adsorption of PMA–EDTC on lead atoms in the galena surface. The results indicate that PMA–EDTC adsorbs on the surface of galena via its –(C=S)–S–group, forming a hydrophilic complex and achieving selective depression of lead and the cleaning flotation of copper. [ABSTRACT FROM AUTHOR]

Sphalerite is a common sulfide mineral, and xanthate is usually used as the collector of sphalerite flotation. In order to realize the simultaneous flotation of sphalerite- and zinc-containing oxide ores, in this paper, dodecylamine was used as the collector and sodium sulfide as the regulator to explore the flotation behavior of sphalerite in a sulfuration–amine system through single mineral flotation tests, and several analytical methods, including contact angle measurement, adsorption capacity test, FT-IR, and XPS, were employed to discuss the interaction mechanism of dodecylamine on the surface of sphalerite. The results confirm that dodecylamine had a strong collecting effect on sphalerite throughout almost the entire pH range, and the flotation recovery increased with the increase in pH, reaching 86.81% at pH 12. It was found that the effect of sodium sulfide on the floatability of sphalerite was relatively weak, and a weak activation effect, of about 2% improved recovery, was achieved. The results of the mechanism analysis further show that dodecylamine underwent both physical adsorption and chemical adsorption on the surface of sphalerite, and the physical adsorption was enhanced with the increase in pH. The above findings provide evidence for the simultaneous flotation of zinc-containing sulfide-oxide mixed minerals. [ABSTRACT FROM AUTHOR]

[Display omitted] • BDTP was synthesized via a simple one-pot reaction. • BDTP was innovatively used for Pb-Zn flotation separation under low alkali conditions. • BDTP could adsorb on galena surface by chemisorption confirmed by FTIR, SEM-EDS and XPS. • A six-membered ring and a "bullet" shape complex were formed by P-S-Pb and C-O-Pb bonds. In this paper, a novel selective galena collector, called S-benzoyl-O, O'-dibutyl dithiophosphate (BDTP), was synthesized via an one-pot reaction with ammonium dibutyl dithiophosphate (DTP) and benzoyl chloride as initial raw materials, and was innovatively used in Pb-Zn flotation separation. Its flotation performances and adsorption mechanism on galena surface were detailly studied. The micro-flotation results illustrated that BDTP exhibited superior selectivity and collecting power over the conventional collectors (sodium isobutyl xanthate (SIBX) and sodium diethyldithiocarbamate (DTC)), realizing the effective flotation separation of galena and sphalerite at pH around 9.0 with ZnSO 4 and Na 2 SO 3 as modifiers. The contact angle (CA) results demonstrated that the treated galena surface by BDTP was more hydrophobic than that of sphalerite. Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDS) results also told us BDTP had been adsorbed on galena surface successfully. In addition, FTIR and X-ray Photoelectron Spectroscopy (XPS) analysis results suggested that the interaction of BDTP with galena may be dominated by the chemisorption. The BDTP may act as a bidentate ligand, bonding with Pb atoms on galena surface via S atoms in the P=S group or O atoms in the C=O group to form two different adsorption geometries, which are a six-membered ring structure with one Pb atom and a "bullet"-shape complex with two different Pb atoms. [ABSTRACT FROM AUTHOR]

[Display omitted] • TMA was first explored as a chalcopyrite depressant in Cu-Mo flotation separation. • TMA could realize the effective separation of Cu-Mo artificially mixed minerals. • TMA could effectively reduce the contact angle of chalcopyrite. • TMA was likely to chemisorb on chalcopyrite by FT-IR and XPS analysis. In this study, N-thiourea-maleamic acid (TMA) was first introduced as a chalcopyrite depressant in flotation separation of Cu-Mo sulfide ores. The effects of TMA on the separation of Cu-Mo were investigated by micro-flotation tests. The results indicated that TMA was beneficial to separate chalcopyrite and molybdenite in the flotation separation of artificially mixed minerals at pH around 9.0 with a Mo recovery of 95.56% and depressing 94.64% of Cu. Its adsorption mechanism was revealed by contact angle, UV–Vis spectra, FT-IR and XPS measurements, in which, the contact angle and UV–Vis spectra measurements further proved that TMA did adsorb on chalcopyrite surface. Moreover, FT-IR and XPS measurements demonstrated that S atoms in the thiourea group of TMA interacted with Cu sites on chalcopyrite surface. All these findings confirmed that TMA would be a highly effective chalcopyrite depressant. TMA could adsorb onto chalcopyrite surface thereby increase its hydrophilicity without significant influence on molybdenite. [ABSTRACT FROM AUTHOR]

[Display omitted] • A PADEMA polymer depressant was first designed, synthesized and characterized. • Its interfacial adsorption mechanism on galena was further revealed by AFM, XPS and ToF-SIMS. • PADEMA could chemisorb on galena surface via the dithiocarbamate groups and Pb sites. • PADEMA could selectively depress galena and achieve the flotation separation from chalcopyrite. In mineral processing, a chemical with hydrophilic groups and mineral-avid groups together might be used as a depressant to depress target minerals. In the present study, a novel polymer depressant poly(acrylamide-2-(dithiocarbamate) ethyl maleamidic acid) (PADEMA) containing amide groups as hydrophilic groups and dithiocarbamate groups as mineral-avid groups, was first designed, synthesized and used to depress galena in the flotation separation from chalcopyrite. Its selective interfacial adsorption mechanism on galena surface was comprehensively investigated by Fourier transform infrared spectroscopy (FT-IR), adsorption capacity tests, contact angle, Atomic Force Microscope (AFM), X-ray photoelectron spectroscopy (XPS) measurements and time-of-flight secondary ion mass spectrometry (ToF-SIMS). These analysis results demonstrated that PADEMA was likely to chemisorb on galena surface by forming a polymer complex via Pb sites on galena surface and the dithiocarbamate groups in PADEMA structure. The micro-flotation separation results indicated that the PADEMA polymer depressant could adsorb on galena surface and render it hydrophilic, thus to improve the separation index during the flotation separation of chalcopyrite and galena. [ABSTRACT FROM AUTHOR]

• The flotation capture collector 5-NSA is made by our laboratory. • 5-NSA showed good selectivity (greater than 98 %) for malachite when using less dosage (12 mg/L). • The adsorption model between 5-NSA and malachite was deduced and proposed. • DFTB+ simulation was used to simulate the adsorption configurations of 5-NSA, TBSA and salicylaldoxime. In this study, 5-nonyl salicylaldoxime (5-NSA) was synthesized and used as a malachite collector. Its flotation performances and adsorption mechanism were systematically investigated by micro-flotation experiments, contact angle measurements, SEM-EDS, FT-IR, XPS and DFTB+ simulations. The micro-flotation test results showed that 5-NSA produced high recovery of malachite at pH 9.0–10.0, while showing lower collecting power to calcite or quartz. The contact angle analysis results indicated that the hydrophobicity of malachite surface was promoted after the adsorption of 5-NSA. SEM confirmed the adsorption of 5-NSA on malachite surface. FT-IR and XPS analysis results confirmed that O and N atoms in the oxime group were immobilized on malachite surface with Cu through O Cu O and N Cu O bonding. Their adsorption performances on malachite surface were simulated by DFTB+ method, including 5-NSA, tert -butylsalicylaldehyde oxime (TBSA) and salicylaldoxime agents, which analyzed the bond lengths of their covalent bond formation with Cu and speculated their adsorption properties. In general, according to the experimental test and simulation results, 5-NSA showed a stronger power to malachite than TBSA and salicylaldoxime, and only a small dosage can produce a high malachite recovery. The findings of this research will be helpful to improve the comprehensive utilization efficiency of malachite and promote the metallurgy of copper oxide ores. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To investigate the effect of recombinant human tumor necrosis factor (rhTNF) on telomerase activity and promoter expression of catalytic protein subunit–human telomerase reverse transcriptase (hTERT) in hepatoma cell lines HepG2 cells and HepG1-6. METHODS: The tartrate-resistant acid phosphatase– enzyme-linked immunosorbent assay method (TRAP-ELISA) was used to determine telomerase activity in HepG2 and HepG1-6 cells that had been treated with different concentrations of rhTNF. The plasmid TERTluc(800), which contained 800 bp of the hTERT promoter, was transiently transfected into HepG2 cells by using Lipofect, and different concentrations of rhTNF were added into the culture media 2 h later. The activity of the hTERT promoter was tested 48 h after transfection. RESULTS: The telomerase activity of hepatoma cells was suppressed by rhTNF in a dose-dependent manner. Furthermore, the transient transfection of HepG2 cells with the TERTluc(800) plasmid revealed that hTERT promoter activity is not affected by 10 IU/mL rhTNF, whereas the expression of the hTERT promoter is inhibited by rhTNF at concentrations ranging from 10 to 1000 IU/mL; the extent of inhibition is linearly related to the rhTNF concentration. The activity of the hTERT promoter in cells treated with 1000 IU/mL of rhTNF decreased to 60.3% of that of the control. No extra suppressive effect was observed when a concentration of 10 000 IU/mL was used. CONCLUSIONS: These results suggest that the antitumor activity of rhTNF may be attributed to its inhibitory effect on hTERT promoter expression. Together with other studies, it may indicate that telomerase is not only involved in carcinogenesis, but is also one of the main targets of anticancer cytokines. Further analysis of the molecular mechanism underlying the regulation of telomerase by TNF and isolation of the related transcription factor may provide new means for cancer gene therapy. [ABSTRACT FROM AUTHOR]

In this paper, a melamine formaldehyde resin modified with tris(2-hydroxyethyl) isocyanurate (THEIC), named MF-THEIC, was synthesized via a solid-phase reaction between hexahydroxymethyl melamine (HMM) and THEIC. MF-THEIC was firstly used as a charring agent in an intumescent flame-retardant system together with APP as well as 4A-zeolite in flame-retarding PP. APP/MF-THEIC (3/1) can effectively reinforce the flame retardancy of PP at a total 24.0 % additive amount, moreover, 1.5 % 4A-zeolite is sufficient to achieve an optimum synergistic effect. The corresponding composites (Sample-17) had passed UL-94 V-0 classification well. The synergistic flame-retarding mechanism was systematically investigated by SEM, 31P NMR, TGA, FTIR spectra, and TG-MS. 4A-zeolite can react with APP to generate highly-active phosphates with good catalytic efficacy on polyphosphate esterification, and then to promote the formation of the char layer, simultaneously, 4A-zeolite is helpful to enhance the char graphitization degree and the strength of the intumescing char layer, thereby reinforcing its flame retardancy via a synergistic effect. • A novel charring agent MF-THEIC was synthesized via a solid phase reaction between HMM and THEIC. • APP/MF-THEIC promoted the charring due to the chemical reactions. • 1.5 % 4A-zeolite synergistically improved the flame retardancy with APP/MF-THEIC in PP. • 4A-zeolite increased the graphitization degree and the strength of the intumescing char layer. [ABSTRACT FROM AUTHOR]

N-Dodecylethylenediamine (ND), which could be obtained by introducing secondary amino group into dodecylamine (DDA), has been testified to exhibit better flotation recovery for quartz than dodecylamine. In order to clarify the adsorption mechanism of ND on quartz surface, especially the effect of additional function group (-NH-) in the adsorption process, the states of absorbed ND on quartz surface as a function of pH were discussed by molecular dynamics simulation method. The results indicated that both of the primary amino group (-NH 2) and secondary amino group (-NH-) participated in the adsorption process. Moreover, the participation of secondary amino group adsorption on quartz surface increased the collectability of ND for quartz by adding extra active site. Flotation results indicated that neutral and weak base environment was favorable for quartz flotation. Computational results revealed that the protonated group with positive charge could adsorbed on quartz surface via electrostatic attraction, and hydrogen bond formed between hydrogen of protonated polar group and oxygen of quartz surface. Unlabelled Image • N-Dodecylethylenediamine (ND) exhibited better flotation recovery for quartz than dodecylamine (DDA) • The insertion of secondary amino group added another active site for ND adsorbed on quartz surface • The flotation recovery for quartz under different pH value were explained by molecular dynamics simulation • Electrostatic attraction and hydrogen bond affinity were the main forces between ND and quartz surface [ABSTRACT FROM AUTHOR]

In this study, a novel organic depressant maleyl 5-amino-1,3,4-thiadiazole-2-thiol (MATT) was synthesized and utilized as a galena depressant in the flotation separation of molybdenite and galena. The results of the flotation test indicated that MATT exhibited an excellent depression ability on galena but barely influenced the flotation of molybdenite in the pH range of 6.0–11.0. Zeta potential results suggested that MATT preferentially adsorbed on galena surface. UV-visible spectroscopy analysis indicated that the stoichiometric ratio of lead ion and reagent in the complex compound. XPS analysis demonstrated that the S (-SH) atom and N (1,3,4-thiadiazole group) atom of MATT coordinated with the Pb atom on galena surface. [ABSTRACT FROM AUTHOR]

• Galena and sphalerite floated well using diethyldithiocarbamate (DTC) as collector. • Cationic guar gum (CGG) exhibited selective depressant effect on sphalerite. • Only adding CGG after DTC could realize the separation of galena from sphalerite. • Addition order of CGG and DTC could lead to remarkable adsorption difference. In this study, the effect of cationic guar gum in the flotation separation of galena from sphalerite when diethyldithiocarbamate acted as galena collector was investigated, mainly through flotation tests and ToF-SIMS analysis. The flotation results showed that the cationic guar gum could selectively depress the sphalerite flotation and enhance the preferential flotation of galena only when it was added after collector diethyldithiocarbamate. The ToF-SIMS analysis found that addition of cationic guar gum after diethyldithiocarbamate exhibited no effect on the collector adsorption on galena surface but could selectively inhibit the collector coverage on sphalerite surface, and further result in the floatability difference. [ABSTRACT FROM AUTHOR]