Adsorption Of Carboxymethyl Cellulose Research Articles

Effect of NaCl concentration on the dispersion, stability and rheological properties of MWNTs by CMC

A detailed study of the dispersion, rheological and adsorption behaviors between multi-walled carbon nanotubes (MWNTs) and sodium carboxymethylcellulose (CMC) at different NaCl concentration were presented. The experimental results suggested that NaCl concentration governed the dispersion and stability of MWNTs. A small amount of NaCl was contributed to the dispersion and stability of MWNTs, while as the NaCl concentration increased, the MWNTs formed aggregates and the MWNTs suspension became unstable. Adsorption amount, Raman spectroscopy, zeta potential, and adsorption conformation were investigated systematically to elucidate the mechanism of this interesting phenomenon. Surprisingly, results from thermogravimetric analysis (TGA) shown that adsorption amount of CMC on MWNTs didn’t change under any circumstances. The value of zeta potential increased slightly at first and then dropped sharply as the increasing of NaCl concentration. The microstructures were measured by TEM. It was found that uniform CMC adsorption layers were formed on the surface of MWNTs at low NaCl concentrations. However, for the high-salt solution, the MWNTs were wrapped by CMC agglomerates, resulting in poor dispersion stability.

Effect of carboxymethyl cellulose on the flow behavior of lithium-ion battery anode slurries and the electrical as well as mechanical properties of corresponding dry layers

We present a holistic view on the role of polymeric binders in waterborne LiB anodes, including preparation and processing of wet slurries as well as microstructure, electrical conductivity and mechanical integrity of dry electrode layers. We focus on carboxymethyl cellulose (CMC), with respect to technical application the influence of soft, nano-particulate styrene–butadiene rubber (SBR) as secondary binder is also addressed. We discuss the influence of CMC concentration, molecular weight (Mw) and degree of substitution (DS) on flow behavior of anode slurries. Rheological data are not only relevant for processing, here we use them to characterize the adsorption of CMC on active material particles and dispersion of these particles in the slurry at technically relevant concentrations. The fraction of CMC adsorbed onto graphite particles increases with increasing Mw and decreasing DS. Electrical conductivity increases with Mw, i.e. with decreasing free polymer deteriorating conductive carbon black pathways. CMC does not contribute to the adhesion of electrode layers, irrespective of Mw or DS, technically feasible adhesion is inferred by SBR. Cohesive strength of anode layers, determined here for the first time under well-defined mechanical load, increases with increasing Mw and decreasing DS, i.e. with increasing fraction of adsorbed CMC and corresponding improved particle dispersion. Strong cohesion and high electrical conductivity are correlated to an alignment of graphite particles as revealed by electron microscopy, presumably enabled by higher particle mobility in well-dispersed slurries. Accordingly, targeted choice of CMC is a valuable means to control processing, electrical conductivity and mechanical strength of LiB electrodes.

Binding aspects of carboxymethyl cellulose onto polymeric surface from its aqueous solutions

Carboxymethyl cellulose (CMC) is a most versatile cellulose derivative having several industrial applications such as mineral processing, pelletisation process, oil drilling, surface modifications, functionalization of materials, and other promising utilizations. However, due to less explore insight the binding aspect of the CMC onto the polymeric surface in its aqueous medium hinders its applications. Therefore, this research work has been made to explore the binding aspects of CMC onto the polymeric surface (modified polypropylene powder (MPP)) derived from polypropylene (PP). The porosity nature of the MPP and specific surface area (S BET) =22.842 m2 g−1 was confirmed by the BET analysis. The pH and ionic strength suggest that electrostatic interaction is responsible for adsorption and confirmed by depth cauterization techniques. Furthermore, to clear the binding aspect urea test was carried out during the adsorption which added assurance that adsorption in the present case is also attributed to the presence of hydrogen bonding. The adsorption free energy of CMC was found as –22.561 kJ/mol which is a close agreement with H-bonding. All of the above results coupled with reported facts strongly support that the adsorption of CMC onto MPP surface is associated with electrostatic interaction and hydrogen bonding. Thus, an apparent overview of the binding aspect of CMC onto polymeric surfaces can endorse CMC as a potential adsorbate for various industrial applications.

Inhibited mechanism of carboxymethyl cellulose as a galena depressant in chalcopyrite and galena separation flotation

Carboxymethyl cellulose (CMC) is a highly efficient, nontoxic, and biodegradable depressant in Cu-Pb separation. However, poor understanding of the interaction mechanism has hindered the application of CMC in this separation process. Herein, galena was entirely inhibited by 250 mg·L−1 CMC at pH above 10, with minor effects on chalcopyrite flotation. As confirmed in zeta potential tests, CMC adsorbed much more easily to galena than chalcopyrite. The adsorption kinetics of CMC on galena was best described using a pseudo-second-order model dominated by chemisorption. In the presence of CMC, 74.4% of the electrochemical reaction sites on galena were inhibited and the resistance of the galena electrode surface film dramatically increased from 3838.7 to 17547.5 Ω·cm2. The likely mechanism of CMC adsorption on galena is competitive adsorption between CMC and sulfate to Pb2+.

Sulfidation enhances stability and mobility of carboxymethyl cellulose stabilized nanoscale zero-valent iron in saturated porous media

Sulfidation can enhance the reactivity and longevity of nanoscale zero-valent iron (nZVI), but little is known about its effect on the fate and transport of nZVI in saturated porous media. This work compared the stability and mobility of carboxymethyl cellulose (CMC) stabilized nZVI (CMC-nZVI) and sulfidated nZVI (CMC-S-nZVI) particles in saturated porous media. After sulfidation, the hydrodynamic size of CMC-S-nZVI was 100–150 nm larger than CMC-nZVI due to enhanced adsorption of CMC onto the S-nZVI surface, which was facilitated by the bidentate bridging interaction between CMC and the FeSx phase on S-nZVI. Of note is that they had a similar core size and zeta potential. In comparison to CMC-nZVI, CMC-S-nZVI exhibited less physical settling (0–5% vs. 5–73%) and chemical dissolution (2–10% vs. 3–27%) within 55 min under the same ionic conditions (Na+, K+ < 200 mM; Al3+ < 0.75 mM). Column breakthrough experiments showed that both CMC-S-nZVI and CMC-nZVI had relatively high mobility in saturated porous media. However, CMC-S-nZVI exhibited greater breakthrough (C/C0 = 0.57–1.0) and corresponding greater mass recovery rates than the corresponding CMC-nZVI (C/C0 = 0.44–1.0) under most of the experimental conditions (e.g., different ion type and concentration, flow rate, and input concentration). The fitted colloid filtration theory model was in good agreement with experiments. This work suggests that in addition to the significant reactivity and longevity improvements demonstrated in other studies, CMC-S-nZVI is also more mobile than CMC-nZVI suggesting that CMC-S-nZVI has many of the characteristics favorable for field application.

Changes in the CMC/ZrO2 system properties in the presence of hydrocarbon, fluorocarbon and silicone surfactants

The influence of cationic surfactants: hydrocarbon - myristyltrimethylammonium bromide (MTAB), silicone - Silquat J2 (C-Si) and fluorine one (S-106A) on the stabilizing properties of the carboxymethyl cellulose (CMC)/zirconia (ZrO2) system was studied using the spectrophotometric measurements. The obtained results prove that all used polysaccharide/surfactant mixtures can be used as stabilizers of zirconia suspensions, however, the CMC/S-106A mixture is the most effective. The reason for that is formation of the CMC/S-106A complexes with 1:2 stoichiometry and their adsorption on the metal oxide surface. In order to find possible mechanisms of stabilization the CMC adsorption on the ZrO2 was studied. To obtain some information on the structure of the polysaccharide/surfactant/oxide adsorption layer, the surface charge density measurements were conducted. The obtained results can be applied in the fields of ceramics and catalysis.

CMC as a stabiliser of metal oxide suspensions

Stabilizating properties of carboxymethyl cellulose (CMC) towards nano-zirconia (n-ZrO2) and alumina (Al2O3) were studied using spectrophotometric, turbidimetric and zeta potential measurements. The obtained results prove that CMC might be successfully used as a stabilizer of nano-zirconia, however, its stabilizing properties are much lower in the case of the alumina + containing systems. Due to the fact that CMC is an anionic polymer the influence of not only the polymer concentration but also of pH on stability of the metal oxide suspensions was studied. It turned out that the CMC concentration has larger influence on stability of the metal oxide suspensions than pH. In order to estimate the stabilization mechanism in the studied systems the adsorption of CMC on both oxides was conducted using the spectrophotometric method confirmed by FTIR. The obtained results could find practical applications particularly in the fields of ceramics and catalysis.

Adsorption mechanism of carboxymethyl cellulose onto mesoporous mustard carbon: Experimental and theoretical aspects

Carboxymethyl cellulose (CMC) is a versatile polymer for several industrial applications such as oil drilling, detergents, food and beverage, papers, ceramics, coatings, and other promising utilization. However, the deficiency for exploring the binding mechanism of the CMC onto the solid surfaces in aqueous system retards its applications. Herein, the binding aspect of CMC onto mesoporous mustard carbon (MMC) was illuminated where the BET analysis reveals that MMC had a surface area (SBET) = 16.576 m2 g−1, which was primarily contributed by mesopores (average pore diameter and total pore volume of MMC were found to be 12.432 nm and 0.051 cm3 g−1, respectively). The electrokinetic analysis demonstrated that the surface of the MMC is negatively charged with point of zero charge value 9.8 which favor the adsorption of CMC at particular pH value (pH = 3.0). The adsorption free energy of CMC was found as -22.561 kJ mol−1 which was in close agreement with H-bond energy suggesting hydrogen bonding as a governing parameter for CMC L2 type adsorption (also confirmed by high-resolution X-ray photoelectron spectrophotometer, attenuated total reflection Fourier transformation infra-red and urea test). A theoretical model of adsorbent-adsorbate complex (MMC-CMC) was considered in order to probe the interaction between the both. The structural, stability, electronic, and charge transfer features have been explained on the basis of binding energy, HOMO-LUMO gap, natural population analyses, Bader’s QTAIM analysis using DFT approach. The molecular electrostatic potential surface is calculated in probing the reactive sites of the system. Different forms of CMC aggregates stabilized by the HB(s)/π…π stacking, demonstrate varied structural and electronic properties. Such variations could have a significant assessment on the performance of food and pharmaceutical industries. Thus, an apparent overview of the binding aspects of CMC onto the MMC can endorse CMC as a potential adsorbate for various industrial applications.

Adsorption of Carboxymethyl Cellulose onto Titania Particle Films Studied with in Situ IR Spectroscopic Analysis.

Adsorption of carboxymethyl cellulose (CMC) in aqueous solution onto a titania nanoparticle film has been studied using in situ attenuated total reflectance infrared spectroscopy (ATR-IR). CMC was adsorbed onto the positively charged titania surface in neutral, partially charged, and fully charged state. The response of the adsorbed polyelectrolyte layer was monitored upon changing the electrolyte pH and ionic strength. The degree of dissociation of the CMC increased upon adsorption onto the titania surface and changed with the surface coverage. Ionic strength change was observed to influence the degree of dissociation of the adsorbed CMC similar as when in solution. No significant peak shifts were observed in the spectrum of the adsorbed CMC during adsorption or in response to changing solution conditions; therefore, inner-sphere complexation between the carboxyl groups and the titania could not be confirmed. The effect of ion identity on the adsorption process was studied using soft and hard cations and mono- and divalent cations. The presence of a divalent counterion was observed to cause changes in the carboxymethyl vibrations, which can be related to formation of intra- or interchain linkages.

Understanding the Role of Polymeric Binders in Water Based Lithium Ion Electrodes

Polymers find application in Lithium ion Batteries (LiB) as binders, providing cohesion in the dry electrode layer as well as adhesion to the current collector. They may also be added as a thickener to control the flow and hence the processing behavior of the paste. Furthermore, polymeric binders can act as dispersing agents for active material or carbon black particles, thus strongly determining the component distribution in dry electrodes. Despite the vast amount of research activities in the field of LiB, the contribution of the binder to the cell performance still remains elusive. Therefore, the adsorption of carboxymethylcellulose (CMC) on LiFePO4 and graphite particles as active material was investigated. The flow behavior of the electrode pastes as well as the electrical conductivity, mechanical properties and microstructure of corresponding dry electrodes were thoroughly characterized. Rheological measurements were carried out to study paste flow behavior as a function of CMC and solid particle concentration. The electrical conductivity of thin electrode layers was measured using the four point resistivity test. The adhesion force between electrode layer and current collector was determined via 90°-peel test. Thick electrode layers were prepared to investigate the cohesion in the electrode employing compression, bending and shear tests. Finally, the microstructure of the dry electrodes was characterize by means of scanning electron microscopy (SEM). Yield stress and viscosity exhibit a pronounced minimum with increasing CMC concentration for both the cathode and anode pastes, indicating that CMC acts as dispersing agent at low concentrations and as a thickener at higher concentration when the equilibrium adsorption concentration is exceeded. Furthermore, the degree of substitution of CMC have no significant influence on the slurry viscosity, whereas higher molecular weights and CMC concentrations lead to significantly higher viscosities. Electrical conductivity of thin electrode layers increases with increasing CMC concentration and yields a pronounced maximum when the equilibrium adsorption concentration is covered, suggesting a critical polymer concentration at which electrode components ideally distribute. In addition, mechanical tests show no clear dependence of the adhesion strength on CMC concentration, irrespective of the degree of substitution or molecular weight, i.e. it does not contribute to the adhesive strength. In contrast, the cohesive strength of the electrode layers increases with higher polymer concentration and molecular weight, but decreases with increasing degree of substitution. Micrographs of the electrode layers show an alignment of the particles for electrodes based on high molecular weight CMC. Preliminary measurements exhibit higher adhesion strength when adding styrene butadiene rubber (SBR), whereas cohesion strength and electrical conductivity significantly decreases. This demonstrates that the optimum CMC concentration has to be chosen according to the required specifications with respect to cohesion and electrical performance.

Magnetically responsive Janus nanoparticles synthesized using cellulosic materials for enhanced phase separation in oily wastewaters and water-in-crude oil emulsions

A new class of magnetically responsive and interfacially active Janus (M−Janus) nanoparticles was designed and synthesized by sequential adsorption of cellulosic materials: hydrophobic ethyl cellulose (EC) and hydrophilic carboxymethyl cellulose (CMC) on the opposite sides of magnetite (Fe3O4) nanoparticles. The adsorption study using quartz crystal microbalance with dissipation (QCM-D) proved the concept of proposed synthesis of M−Janus nanoparticles. The adsorption of EC and CMC on magnetite nanoparticles was confirmed by zeta-potential measurements, thermogravimetric analysis (TGA), characterization using Fourier transform infrared spectroscopy (FTIR) and TEM. The surface wettabilities of the opposite sides on the M−Janus nanoparticles were investigated by measuring contact angles of nanoparticle surfaces deposited from the oil-water interfaces using the Langmuir-Blodgett method. SEM images revealed an excellent dispersion of M−Janus nanoparticles in both aqueous and organic phases. The results from the coalescence time and crumpling ratio measurement of particles-stabilized oil droplets along with the interfacial pressure-area isotherms demonstrated stronger interfacial activities of M−Janus nanoparticles and a stiffer interface with adsorbed M−Janus nanoparticles as compared with the interfaces stabilized by conventional interfacially-active nanoparticles. The microscopy images confirmed the deposition of M−Janus nanoparticles at the emulsion droplet surface during the phase separation process. The M−Janus nanoparticles not only exhibited excellent capability and high efficiency in separating emulsified water from water-in-crude oil emulsions and the oil from oily wastewaters under an external magnetic field, but also retained high interfacial activity and hence desirable separation efficiency after five-cycle applications. Because of the environmentally friendly and biodegradable cellulosic materials used in the synthesis, the M−Janus nanoparticle can achieve effective oil/water phase separation without causing further pollution to the continuous phase.

The Effect of the Ionic Strength of Process Water on the Interaction of Talc and CMC: Implications of Recirculated Water on Floatable Gangue Depression

Previous studies speculate that hydroxo species present in flotation pulps at pH &gt; 9, particularly those of polyvalent cations, selectively adsorb onto gangue minerals. Such species supposedly enhance the depressive action of carboxymethyl cellulose (CMC) onto gangue via an acid-base interaction between the positively charged mineral surface and the negatively charged CMC molecule. Thus, the hydrophilicity of gangue minerals is enhanced, preventing the dilution of the concentrate. However, as there is little evidence to support these claims for complex process waters of increasing ionic strength, it is important to investigate. Adsorption data and mineral surface charge analyses provide a fundamental understanding of how electrolytes and their ionic strengths affect gangue mineral-depressant adsorption. It is strongly anticipated that decoupling these effects will allow process operators to tailor their process water quality needs towards best flotation operating regimes and, in the long run, effect closed water circuits. Thus, using talc as a proxy for naturally floatable gangue common in sulfidic Cu–Ni–PGM ores, this work investigates the influence of the ionic strength of process water on the adsorption of CMC onto talc for a perspective on how saline water in sulfidic ores would affect the behavior and therefore management of floatable gangue. In the presence of CMC, the microflotation results showed that the rate of talc recovery decreased with increasing ionic strength of process water. Increases in ionic strength resulted in an increase in the adsorption of CMC onto talc. Talc particles proved to have been more coagulated at higher ionic strength since the settling time decreased with increasing ionic strength. Furthermore, the zeta potential of talc particles became less negative at higher ionic strengths of process water. It is thus proposed that increases in the ionic strength of process water increased the zeta potential of talc particles, enhancing the adsorption of CMC onto talc. This in turn created a more coagulated nature on talc particles, increasing their hydrophilicity and thereby retarding floatability.

An Alternative Depressant of Chalcopyrite in Cu–Mo Differential Flotation and Its Interaction Mechanism

Carboxymethylcellulose (CMC) is a nontoxic and biodegradable polysaccharide, which can potentially replace the frequently used hazardous depressants in Cu–Mo separation. However, a lack of understanding of the interaction mechanism between the CMC and the minerals has hindered its application. In the present study, it is found that 50 mg·L−1 CMC can inhibit chalcopyrite entirely in the pH range 4–6, while having little effect on molybdenite. The results also showed that the inhibition effect of the depressant for chalcopyrite enhanced with the increase of the degree of substitution (DS) and molecular weight (Mw) of CMC. The low DS and high Mw of CMC were detrimental to the Cu–Mo separation flotation. Furthermore, CMC adsorption was found to be favored by a positive zeta potential but hindered by the protonation of the carboxyl groups. An electrochemical study showed that CMC inhibited 92.9% of the electrochemical reaction sites of chalcopyrite and greatly reduced the production of hydrophobic substances. The XPS and FTIR measurements displayed that the chemisorption was mainly caused by Fe3+ on the chalcopyrite surface and the carboxyl groups in the CMC molecular structure.

A novel method to improve carboxymethyl cellulose performance in the flotation of talc

A novel method to improve carboxymethyl cellulose (CMC) performance in talc flotation is described in this paper. Micro-flotation results showed that using CMC as the depressant, strong depression on talc floatability was observed when the pulp pH was adjusted from low (4.0) to high (8.5), which improved the separation performance between chalcopyrite and talc. Zeta potential measurements illustrated that talc surface charge was less negative when the pH was regulated from acid to base than the situation that the pulp pH was altered from base to acid. ICP test and XPS results indicated that more magnesium ions were dissolved from the talc lattices at pH 4 and the hydrolyzed species of magnesium cations were adsorbed onto the talc surfaces when the pulp pH was adjusted to 8.5, and thus promoting the CMC adsorption on the talc surfaces, which further decreased its floatability.

New insights into the carboxymethyl cellulose adsorption on scheelite and calcite: adsorption mechanism, AFM imaging and adsorption model

In this paper, the effect of depressant carboxymethyl cellulose (CMC) on the separation of scheelite from calcite was studied. Micro-flotation experiments results indicated that CMC could significantly depress the floatability of calcite, but its adverse effect on the floatability of scheelite was very small. The flotation recovery of calcite decreased from 90% to 17% and the flotation separation of scheelite from calcite can be achieved at pH 9.5 when the concentration of CMC reached 2.0 mg/L. Zeta potential tests results revealed that the adsorption of RCOO− species of CMC on the opposite positively charged calcite surface was more intense than scheelite. The FTIR results showed that CMC was chemisorbed on both scheelite and calcite surfaces, but the adsorption on calcite surface was more intensive. The XPS results depth revealed that the relative content of carbon was increased by 3.4% on calcite surface, which was greater than that of scheelite by 0.62%. And the shifts of binding energy on calcite surface were more obvious than scheelite. Atomic force microscopy (AFM) imaging intuitively showed the adsorption density and coverage of CMC on calcite surface was higher than that of scheelite. Finally, an adsorption model of regents on mineral surfaces could be obtained.

Anisotropic Polymer Adsorption on Molybdenite Basal and Edge Surfaces and Interaction Mechanism With Air Bubbles.

The anisotropic surface characteristics and interaction mechanisms of molybdenite (MoS2) basal and edge planes have attracted much research interest in many interfacial processes such as froth flotation. In this work, the adsorption of a polymer depressant [i.e., carboxymethyl cellulose (CMC)] on both MoS2 basal and edge surfaces as well as their interaction mechanisms with air bubbles have been characterized by atomic force microscope (AFM) imaging and quantitative force measurements. AFM imaging showed that the polymer coverage on the basal plane increased with elevating polymer concentration, with the formation of a compact polymer layer at 100 ppm CMC; however, the polymer adsorption was much weaker on the edge plane. The anisotropy in polymer adsorption on MoS2 basal and edge surfaces coincided with water contact angle results. Direct force measurements using CMC functionalized AFM tips revealed that the adhesion on the basal plane was about an order of magnitude higher than that on the edge plane, supporting the anisotropic CMC adsorption behaviors. Such adhesion difference could be attributed to their difference in surface hydrophobicity and surface charge, with weakened hydrophobic attraction and strengthened electrostatic repulsion between the polymers and edge plane. Force measurements using a bubble probe AFM showed that air bubble could attach to the basal plane during approach, which could be effectively inhibited after polymer adsorption. The edge surface, due to the negligible polymer adsorption, showed similar interaction behaviors with air bubbles before and after polymer treatment. This work provides useful information on the adsorption of polymers on MoS2 basal/edge surfaces as well as their interaction mechanism with air bubbles at the nanoscale, with implications for the design and development of effective polymer additives to mediate the bubble attachment on solid particles with anisotropic surface properties in mineral flotation and other engineering processes.

Inhibitive Performance of Carboxymethyl Cellulose and Additives on Corrosion of Carbon Steel in Acidic and Alkaline Environments

The potential of the mixture of carboxymethyl cellulose (CMC) and additives (PVP, PAA and PVAc, respectively) as an eco-friendly corrosion inhibitor for carbon steel in 1 M HCl and 1 M KOH solutions, respectively, was studied using gravimetric and potentiodynamic polarization measurements and quantum chemical calculations. Gravimetric results revealed that CMC inhibited the corrosion of carbon steel in both environments even at low concentration, and the efficiency of inhibition slightly increased with an increase in concentration. Also, the mixture of CMC with additives (PVP, PAA and PVAc, respectively) increased the inhibition efficiency significantly. Temperature studies indicated that efficiency decreased with an increase in temperature. The calculated corrosion activation energies and heat of adsorption parameters supported the physical adsorption mechanism proposed. Freundlich and Langmuir isotherm models were used to approximate the adsorption characteristics of CMC at KOH and HCl, respectively. Polarization curves revealed that CMC adsorption affected both anodic and cathodic partial reactions and acted as a mixed-type inhibitor. Quantum chemical calculations were used to confirm the ability of CMC to adsorb on a carbon steel surface.

Effect of calcium ionic concentrations on the adsorption of carboxymethyl cellulose onto talc surface: Flotation, adsorption and AFM imaging study

The effect of various calcium ionic concentration on the adsorption of carboxymethyl cellulose (CMC) onto talc surface has been investigated using flotation tests, adsorption measurements and tapping mode atomic force microscopy (AFM) imaging. Microflotation tests indicated that the depression of talc depressed by CMC was increasingly enhanced with the increase of Ca2+ at pH 8.5. And within the pH range of 2–11.5, in the presence of Ca2+, the depression of talc by CMC could be facilitated by Ca2+ stably. Adsorption experiments confirmed that with the increase of Ca2+, the adsorbed CMC on talc increased at pH 8.5. AFM imaging revealed the morphology of adsorbed CMC were different in the absence and presence of various Ca2+ ions concentration. In the absence of Ca2+ ions, the morphology of adsorbed CMC consisted of randomly distributed salient point domains with a lower area fraction of surface coverage; in the presence of 10−4 mol/L Ca2+ ions the morphology mingled with salient point and reticulate adsorption; in the presence of 10−3 and 10−2 mol/L Ca2+ ions the morphology is a reticulate multilayer adsorption with a higher area fraction of surface coverage.

The role of calcium and carbonate ions in the separation of pyrite and talc

Carboxymethyl cellulose (CMC), a negatively charged polymer, is commonly used as a depressant of talc. However, the separation of pyrite and talc can be deteriorated by the presence of calcium ions, which can facilitate the absorption of CMC onto both talc surfaces and pyrite. In this work, carbonate ions were introduced to solve this problem, and the effects of calcium and carbonate ions on the adsorption of CMC were also studied. Micro-flotation results revealed that CO32-. not only eliminated the inhibition of pyrite by Ca2+ and CMC, but also had no influence on the depression of talc at pH 6–10. The surface-specific study confirmed that the adsorption of Ca2+ onto talc basal planes at pH 8.5 was negligible and could be improved by the presence of CO32-. . The atomic force microscopy analysis showed the correlation between the coverage of CMC onto talc surfaces in the presence and absence of CO32-.. A mechanism for the adsorption of CMC onto talc surfaces was proposed based on the morphological differences in the presence and absence of CO32-.

Carboxymethylcellulose (CMC) as PbS depressant in the processing of Pb-Cu bulk concentrates. Adsorption and floatability studies

Adsorption of CMC on galena (PbS) was investigated through electrokinetic, adsorption and ATR-FTIR spectroscopic studies. In addition, CMC adsorption on chalcopyrite (CuFeS2) was carried out to compare it to that on PbS. The effect of CMC on the floatability of PbS and CuFeS2 was assessed by microflotation using PbS and CuFeS2 crystals and ethyl xanthate as collector. Furthermore, the effect of oxidation of the minerals on the floatability and CMC adsorption was studied. CMC adsorption on PbS took place within a pH range of significant concentration of the hydroxo-complex species PbOH+ wherein the COOH group of the CMC is as COO−. It is proposed that CMC adsorbs through intramolecular electrostatic and acid/base interactions between the COO− and PbOH+ at the PbS/aqueous solution interface. Adsorption of ethyl xanthate on PbS is more stable than that of CMC. Oxidation creates SO4 species on the PbS surface promoting co-adsorption of CMC, through which the PbS surface becomes hydrophilic on top of the hydrophobicity due to adsorbed ethyl xanthate. Upon oxidation, the high PbS floatability was largely hindered by CMC while that of CuFeS2 was not affected. Flotation strategies are presented for the application of the non-toxic polysaccharide CMC as a depressant of PbS in the separation of Pb-Cu bulk concentrates while floating CuFeS2.