Nonylphenol Polyethylene Glycol Research Articles

Removal of Nonylphenol Polyethylene Glycol (NPEG) with Au-TiO2 Catalysts: Kinetic and Initial Transformation Path

The purpose of this study was to evaluate the efficiency of the Au-TiO2 catalyst in the degradation of nonylphenol polyethylene glycol (NPEG). In the first part of the study, the catalyst was synthesized and characterized. Initially, the catalyst (TiO2 Degussa P-25) was doped with gold precursor salts (HAuCl4) at different concentrations (5, 10, and 15%) and the photodeposition method with UV light. It was determined by diffuse reflectance (DF) and scanning electron microscopy (SEM) that the photodeposition method was effective for the inclusion of gold particles on the surface. The catalyst band gap showed a reduction to 2.9 e.v (compared to TiO2 Degussa P-25), and it was observed that the gold-doped catalyst showed absorption in the visible light range 500 to 600 nm. The percentage of deposited gold was determined by energy dispersive spectroscopy (EDS). In the second part of the study, various NPEG degradation experiments were performed; with the catalyst that showed the best conversion percentages of NPEG, the experimental data were analyzed using UV-Vis spectrophotometry and TOC (total organic carbon). With these results, a carbon-based mass balance and reaction kinetics were generated using the Langmuir–Hinshelwood (L–H) heterogeneous catalysis model. For the estimation of the kinetic constants, the non-linear regression of the Levenger–Marquardt algorithm was used. With these results, kinetic models of the degradation of the molecule and the generation and consumption of organic intermediate products (OIPs) were generated.

Removal of an Ethoxylated Alkylphenol by Adsorption on Zeolites and Photocatalysis with TiO2/Ag

Two advanced removal methods (adsorption and photocatalysis) were compared for the elimination of an ethoxylated alkylphenol (nonylphenol polyethylene glycol, NPEG). For the adsorption process, zeolites were used in their natural state, and the process was characterized by DRX (X-ray diffraction) and SEM–EDS (Scanning electron microscopy). The analysis of the results of the adsorption kinetics was carried out using different isotherms to interpret the removal capacity of zeolites. The Temkin kinetic model better predicted the experimental data and was satisfactorily adjusted to models of pseudo-second order (PSO). On the other hand, for photocatalysis, nano-particles of Ag (silver) were deposited on titanium oxide (TiO2) Degussa-P25 by photo-deposition, and the catalyst was characterized by diffuse reflectance and SEM–EDS. The data obtained using the two removal techniques were analyzed by UV–Vis (ultraviolet-visible spectrophotometry) and total organic carbon (TOC). The kinetic data were compared. The photocatalytic process showed the highest efficiency in the removal of NPEG, corresponding to >80%, while the efficiency of the adsorption process was <60%. This was attributed to the recalcitrant and surfactant nature of NPEG.

Effects of the side chain density of polycarboxylate dispersants on dye dispersion properties

Comb‐like polycarboxylates were synthesised by copolymerisation of methacrylic acid and nonylphenol polyethylene glycol methacrylate ester, and can be used as dye dispersants. In order to achieve good dispersive ability, three polycarboxylates were synthesised, each having a different side chain density. The side chain density of polymers was controlled by different ratios of monomers in the copolymerisation process. Acidic polymers were neutralised using sodium hydroxide. These polymers exhibit good dispersing performance, such that carboxylate groups are adsorbed onto the dye particle surface and the side chains enable the formation of a thick layer, thus providing the steric hindrance effect. Improvement of dye dissolution in the presence of polycarboxylates was studied. Polymers with a lower side chain density demonstrated a higher dye dissolution in water, which could be as a result of more effective adsorption of dispersant on the dye surface (CI Disperse Blue 79). The dyeing performance of the prepared dye dispersions on polyester was investigated. Spectrophotometric analysis of dyed fabrics using synthesised polycarboxylates demonstrates that there should be an optimum side chain density of polymer in order to control both dye solubility and dispersive ability. The result of turbidimetry and particle size analysis have proven this phenomenon. A comb‐like polycarboxylate with optimum side chain density was a better dye dispersant compared with a commercial sodium naphthalene sulphonate compound, as a result of its better heat stability.

Photocatalytic degradation of acetaminophen, tergitol and nonylphenol with catalysts TiO2/Ag under UV and Vis light

Nanoparticles of silver deposited on TiO2 have been tested as catalysts for the removal of three organic molecules with photocatalysis treatments. The catalysts were prepared by the photodeposit method and characterized by ray techniques (R-X) and scanning electronic microscopy and EDS, as well as by diffuse reflectance. The values of the surface area were determined by N2-physisorption. The photocatalysis is an efficient treatment for the removal of numerous organic compounds; however, when the catalyst is modified by the addition of metal particles as silver, its efficiency can be increased and even be activated in visible light. To establish the kinetic parameters, it was used high-performance liquid chromatography and UV spectroscopy; the results show that the amount of the dopant does not have influence in the value of the catalyst band gap. But if it has influence on the surface area of the catalyst. The removal of organic material is increased when the concentration of the dopant decreases for acetaminophen and nonylphenol polyethylene glycol (NPG). Doped catalyst removal capacity also depends on the characteristics of the molecule to be treated as it was verified with the use of visible light where the removal percentages for the NPG were higher in comparison with the use of UV radiation.

Micellar interaction of binary mixtures of alpha olefin sulfonate and nonylphenol polyethylene glycol ethers: Length effects of ethylene oxide

The micellization behavior of binary surfactant mixtures constituted by an anionic surfactant, alpha olefin sulfonate (AOS), and a nonionic surfactant nonylphenol polyethylene glycol ether (NPE) with different numbers of ethylene oxide (EO), namely, NP10EO, NP20EO, NP30EO, and NP40EO was comprehensively investigated by surface tensiometer, conductometer, cloud point measurement, and dynamic light scattering. Theoretical treatments were carried out to explain molecular interaction in the mixed micelles based on regular solution theory of Rubingh, micellization thermodynamics of Molyneux et al. and Maeda, and molecular thermodynamic theory of Pavvada and Blankschtein. Results indicate non-ideal mixing behavior in all AOS-NPE mixtures, where nonionic surfactant EO chain length was found to play critical roles. In the absence of additional electrolytes, NPEs exhibited substantially higher activity in micelles than bulk solution; with growth of EO groups, shrinkage on the scale of synergistic interaction was evidenced. In contrary, with swamping amount of electrolytes, synergistic interactions enlarged with the rise of EO groups, and AOS activity in mixed micelles was found depending on both EO length and bulk mole fraction (αA). These findings are of great significance in mixed surfactant formulation design/optimization to maximize the synergistic efficiency of the system thus to minimize the chemical consumption and cost.

EFFECT OF CERTAIN SURFACTANTS ON THE LEACHING AND PRECIPITATION PROCESSES IN ZINC FERRITE RESIDUE TREATMENT

The effect of a surfactant mixture of nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2), and polyethylene glycol with molecular weight 400 (D3) on the dissolution of zinc and metal impurities present in zinc ferrite residue in dilute sulfuric acid (160 g L−1 H2SO4) as well as on both jarosite and goethite precipitation was studied at 90°C. The following influences of the surfactant mixture (D1 + D2 + D3), determined by comparing the results obtained in the presence and absence of surfactants, were found. Adsorption of surfactants on zinc ferrite residue surface decreases the dissolution of zinc and metal impurities (Fe, Cu, Cd, As, Sb, and Co). Their extraction efficiencies at the end of the super hot leaching process carried out with surfactants are 4.85–6.29% lower than without them. The formation of a sulfur “sponge” layer on the surface of liquor during the dissolution of ZnS present in zinc ferrite residue is hindered by the surfactants due to their effect as wetting agents and sulfur dispersants. The presence of surfactants reduces the amount of zinc and metal impurities (Fe, Cu, Cd, and As) remaining in the solution after jarosite or goethite precipitation by 5.33–5.86% or 8.03–9.93%, respectively. The volume of jarosite and goethite precipitates increases in the presence of surfactants due to their effect as wetting and flocculation agents. On the other hand, D1 and D3 act as complexing agents. The abovementioned effects of surfactants improve the sorption capacity of both jarosite and goethite, thus ensuring better purification of zinc sulphate solutions, but hindering zinc leaching.

EFFECT OF CERTAIN SURFACTANTS ON Co CEMENTATION USING Zn DUST IN THE PRESENCE OF BOTH Cu AND Sb

The effect of surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′- disulphonic acid (D2) and polyethylene glycol with a molecular weight 400 (D3) added separately or as a mixture (D1+D2+D3) on Co-Zn dust cementation kinetics and morphology of obtained deposits was investigated in the presence of both Cu and Sb. The rate constant obtained in the presence of Cu and Sb was 3 to 5 times lower than that found in the presence of Cu and up to 3 times higher than that in the presence of Sb. This indicates a high inhibition effect of Sb on Co cementation. D1, D3 and D1+D2+D3 inhibit Co and Sb cementation. The highest effect was obtained in presence of D1. A decrease in the Sb concentration from 200 to 35 mg dm-3 at a constant Cu concentration increased Co cementation rate by up to 3 times despite the presence of D1+D2+D3. An increase of Sb concentration substantially decreased the crystallite size and deposit porosity.On a investigué l’effet des agents surfactants nonylphénolpolyéthylène de glycol (D1), acide bisulfonique binaphthylméthane-4,4′ (D2) et glycol polyéthylénique avec poids moléculaire de 400 (D3), ajoutés séparément ou en un mélange (D1+D2+D3), sur la cinétique de cémentation de la poussière de Co-Zn et sur la morphologie des dépôts obtenus, tant en présence de Cu que de Sb. La constante cinétique obtenue en présence de Cu et de Sb était 3 à 5 fois plus basse que celle trouvée en présence de Cu et jusqu’à 3 fois plus élevée que celle en présence de Sb. Ceci indique un effet important d’inhibition du Sb sur la cémentation du Co. D1, D3 et D1+D2+D3 inhibent la cémentation du Co et du Sb. On a obtenu l’effet le plus important en présence de D1. Une diminution de la concentration de Sb de 200 à 35 mg dm-3 à une concentration constante de Cu augmentait le taux de cémentation du Co jusqu’à 3 fois en dépit de la présence de D1+D2+D3. Une augmentation de la concentration de Sb diminuait substantiellement la taille de cristallite et la porosité du dépôt.

Ceramic membrane ultrafiltration of anionic and nonionic surfactant solutions

The ultrafiltration of two types of surfactants, sodium dodecyl sulfate (SDS, anionic) and Tergitol NP-9 (nonylphenol polyethylene glycol ether, nonionic), using a 20 nm ZrO 2 tubular membrane was investigated. The influence of crossflow velocity, temperature, pressure, and surfactant concentration on the permeate flux, close to and above the critical micelle concentration (CMC), is reported. Permeate flux and surfactant retention were measured in order to evaluate concentration polarization and fouling phenomena, and also the variation of these parameters due to surfactant/membrane interactions. High surfactant retentions (60–70%) were achieved depending on the feed concentration.

Kinetics of emulsification of dodecane in the absence and presence of nonionic surfactants

The effect of a nonylphenol polyethylene glycol ether (Tergitol NP-4) and a PEO/PPO/PEO type triblock copolymer (Pluronic L-61) surfactants on the emulsification of dodecane oil was investigated. The oil was emulsified in a standard mixing tank at different stirrer speeds. Kinetics of emulsification of dodecane with nonionic surfactants was measured by droplet size distribution of dodecane as a function of time. A phenomenological model was used to analyze the kinetics of emulsification. The results showed that the breakage of oil droplet in the mixing tank was accelerated in the presence of nonionic surfactants acting as emulsifiers. The mechanism of the breakage was explained in terms of reduction of interfacial tension by the adsorption of surfactants the liquid/oil interface.

THE EFFECT OF CERTAIN SURFACTANTS ON ZINC DISSOLUTION IN SULPHURIC ACID SOLUTIONS CONTAINING METAL IMPURITIES

The effect of surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmetane-4,4′- disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) added alone or as a mixture (D1+D2+D3) on zinc dissolution rate in suphuric acid solutions containing metal impurities more positive than zinc (Cd2+, Cu2+, Ni2+, as well as Cd2++ Cu2+ and Cu2+ + Ni2+) was investigated at 50 °C and a high content of impurities (30 mg .dm−3 for each). Zinc dissolution carried out with and without surfactants indicated a different effect of D1, D2 and D3. In all experiments surfactants D1 and D3 decrease zinc dissolution rate, but the effect of D1 is substantially higher compared to D3. When only Cd2+ or Ni2+ are present surfactant D2 inhibits zinc dissolution but in the presence of Cu2+, Cd2++ Cu2+ or Cu2+ + Ni2+ its effect becomes opposite. In all experiments surfactant mixture D1+D2+D3 decreases zinc dissolution rate but its effect is lower compared to D1.The effect of metal impurities on zinc dissolution was determined by comparing the results with and without impurities. Metal impurities increase zinc dissolution rate, the lowest and the highest effect being obtained in the presence of Cd2+ and Ni2+ respectively. The effect of Cd2++ Cu2+ is slightly stronger compared to the effect of Cu2+. The influence of Cu2+ + Ni2+ is substantially stronger than the effect of Cu2+ only or Ni2+ only which indicates that the presence of Cu2+ in zinc sulphate solutions increases deposition of Ni2+ on zinc surface.The inhibition effect of D1+D2+D3 on zinc dissolution causes both a decrease of the negative effect of metal impurities on zinc current efficiency during zinc electrowinning stage and corrosion protection of cathodic zinc till the melting stage of zinc hydrometallurgy.On a étudié l’effet des agents de surface nonylphénolpolyéthylène glycol (D1), acide dinaphtylmétane-4,4′-bisulfonique (D2) et polyéthylène glycol avec poids moléculaire de 400 (D3), ajoutés seuls ou en un mélange (D1+D2+D3), sur la vitesse de dissolution du zinc dans des solutions d’acide sulfurique contenant des impuretés métalliques plus positives que le zinc (Cd2+, Cu2+, Ni2+, ainsi que Cd2+ + Cu2+ et Cu2+ + Ni2+), à 50 ????????C et avec un contenu élevé en impuretés (30 mg·dm−3 pour chacun). La dissolution du zinc, effectuée avec et sans agents de surface, indiquait un effet différent du D1, du D2 et du D3. Dans toutes les expériences, les agents de surface D1 et D3 diminuent la vitesse de dissolution du zinc, mais l’effet du D1 est substantiellement plus élevé que l’effet du D3. Quand seulement Cd2+ ou Ni2+ sont présents, l’agent de surface D2 inhibe la dissolution du zinc, mais en présence de Cu2+, de Cd2+ + Cu2+ ou de Cu2+ + Ni2+, il a un effet opposé. Dans toutes les expériences, le mélange des agents de surface D1+D2+D3 diminue la vitesse de dissolution du zinc, mais son effet est plus faible en comparaison avec le D1.Les impuretés métalliques augmentent la vitesse de dissolution du zinc, l’effet le plus faible et le plus élevé étant obtenus en présence de Cd2+ et de Ni2+ respectivement. L’effet de Cd2+ + Cu2+ est légèrement plus fort en comparaison avec l’effet de Cu2+. L’influence de Cu2+ + Ni2+ est substantiellement plus forte que l’effet du Cu2+ seul ou du Ni2+ seul, ce qui indique que la présence du Cu2+ dans les solutions de sulfate de zinc augmente la déposition du Ni2+ sur la surface du zinc.L’effet d’inhibition du D1+D2+D3 sur la dissolution du zinc cause à la fois une diminution de l’effet négatif des impuretés métalliques sur la performance du courant de zinc lors de l’étape d’extraction électrolytique et un effet de protection contre la corrosion du zinc cathodique jusqu’à l’étape de fonte d’hydrométallurgie du zinc.

Improving froth characteristics and flotation recovery of phosphate ores with nonionic surfactants

The beneficial effect of a series of nonylphenol polyethylene glycol ether surfactants were tested in the flotation of phosphate ores in which the mixtures of sodium oleate and dodecane were used as collectors. In order to elucidate the flotation results, equilibrium surface tension of single and binary surfactant solutions prepared with sodium oleate and nonionic surfactants were investigated. Synergism between surfactants was determined by observing the change in surface tension of solutions and by the calculation of interaction parameter from surface tension data. The lowering of surface tension of sodium oleate solutions was observed in the presence of nonionic surfactants. The interaction parameter between sodium oleate and a nonionic surfactant (i.e., NP-4) was calculated to be −0.21, showing attraction between the two surfactant molecules. The nonionic surfactant NP-4 was then tested in batch flotation of phosphate ores. The beneficial effect of nonionic surfactant was obtained at different collector dosages and surfactant combinations.

The effect of certain surfactants on the acid and neutral leaching of zinc calcine obtained by roasting of sphalerite concentrates

The effect of the mixture of surfactants nonylphenolpolyethylene glycol with molecular weight 900 (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on the processes taking place during the acid and neutral leaching of zinc calcine was investigated: dissolution of zinc and metal impurities from calcine; precipitation of Fe(OH) 3 and AL(OH) 3 and coagulation of colloidal silicic acid solutions. The influence of the surfactant mixture (D1+D2+D3) was determined by comparing the results obtained with and without surfactants. The following effects of surfactants were found: • The presence of surfactants causes a small decrease of zinc, copper and cadmium dissolution during the acid leaching of zinc calcine; • The surfactant mixture improves deposition of impurities during the neutral leaching stage; • The volume of Fe(OH) 3 or Al(OH) 3 precipitated in solutions increases in the presence of surfactants which improves the effect of both hydroxides as scavengers; • Surfactant mixture initiates silicic acid coagulation at lower pH values compared to experiments without surfactants providing higher purification of zinc sulphate solutions and better separation from the insoluble residue.

The Effect of Certain Surfactants on the Cementation of Cobalt From Zinc Sulphate Solutions By Suspended Zinc Particles in the Presence of Copper or Antimony

The effect of surfactants nonylphenolpolyethylene glycol with molecular weight 900 (D1), dinaphthylmethane-4,4'-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on both cobalt-zinc dust cementation kinetics and the structure of obtained deposits was investigated in the presence of copper or antimony. The reaction of cobalt cementation was found not to follow first-order kinetics due to the hydrogen evolution which takes place along with cementation reaction.Two rate regions were observed. Surfactants D1 and D3 inhibit but D2 has no effect on cobalt cementation rate. Copper increases but antimony decreases cobalt deposition. On the other hand, the presence of antimony substantially increases the inhibition effect of D1 and D3 on cobalt cementation. A higher temperature improves cobalt cementation.D1 and D3 inhibit antimony cementation.The effect of D1 is substantially higher and contributes to a large decrease of antimony deposition by zinc dust.The influence of copper and antimony on the structure of obtained deposits is strikingly different. The presence of copper causes the deposition of coarser products containing massive formations of lamellar crystallites. The addition of antimony contributes to the formation of compact uniform layers of deposits with a low porosity on the surface of zinc particles. Surfactants D1 and D3 decrease the crystallite size and deposit porosity and their effect is substantially larger in the presence of antimony. The lowest porosity is found in the presence of both D1 and antimony.According to the obtained results, the concentration of antimony during the cobalt cementation by zinc dust from the solutions containing surfactants D1 and D3 must be lower than that of copper.On a étudié l'effet d'agents de surface sur la cinétique de cémentation de la poussière de cobaltzinc et sur la structure des dépôts obtenus, en présence de cuivre ou d'antimoine. Les agents étudiés incluent le glycol nonylphénolpolyéthylénique, avec un poids moléculaire de 900 (D1), l'acide dinaphthylméthane-4,4'-disulfonique (D2) et le polyéthylène-glycol, avec un poids moléculaire de 400 (D3). On a trouvé que la réaction de cémentation du cobalt ne suivait pas une cinétique de premier ordre à cause du dégagement d'hydrogène qui se produit en même temps que la réaction de cémentation. On a observé deux régions avec différents taux. Les agents de surface D1 et D3 inhibent le taux de cémentation du cobalt, mais le D2 n'a aucun effet sur celui-ci. Le cuivre augmente la formation de cobalt mais l'antimoine la réduit. D'un autre côté, la présence d'antimoine augmente substantiellement l'effet d'inhibition du D1 et du D3 sur la cémentation du cobalt. Une température plus élevée améliore la cémentation du cobalt.Le D1 et le D3 inhibent la cémentation de l'antimoine. L'effet du D1 est substantiellement plus élevé, contribuant à une grande diminution de la formation d'antimoine par la poussière de zinc.L'influence du cuivre et de l'antimoine sur la structure des dépôts obtenus est remarquablement différente. La présence de cuivre entraîne la formation de produits plus grossiers contenant des structures massives de cristallites lamellaires. L'addition d'antimoine contribue à la formation de couches uniformes compactes de dépôts ayant une faible porosité à la surface des particules de zinc. Les agents de surface D1 et D3 diminuent la taille de cristallite et la porosité du dépôt et leur effet est substantiellement plus important en présence d'antimoine. La porosité la plus faible se trouve en présence simultanée du D1 et de l'antimoine.D'après les résultats obtenus, la concentration de l'antimoine, lors de la cémentation du cobalt par la poussière de zinc à partir de solutions contenant les agents de surface D1 et D3, doit être plus faible que celle de cuivre.

The effect of certain surfactants on the cementation of nickel from zinc sulphate solutions by suspended zinc particles in the presence of copper

The effect of surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on both nickel-zinc dust cementation kinetics and the structure of obtained deposits was investigated. Experiments were carried out in the presence of copper to increase the low cementation rate of nickel. The reaction of nickel cementation was found not to follow first-order kinetics due to hydrogen evolution which takes place along with the cementation reaction. Two rate regions were observed. Hydrogen evolution in the presence of D1 is lower than with D2, D3 and without surfactants. D1 and D3 decrease but D2 has no effect on nickel cementation. The influence of D1 and D3 is higher at the beginning of the process. Higher temperature improves nickel cementation only in the initial period. The structure of cementation products depends on the temperature. Uniform layers of lamellar crystallites on the surface of zinc particles were observed at 65°C with and without surfactants. At 85°C the morphology changes to massive spheroid formations of lamellar crystallites. The presence of D1 and D3 decreases both the crystallite size and deposit porosity. The lowest porosity was found in the presence of D3. The inhibition effect of D1 on the hydrogen evolution contributes to decrease in zinc consumption during the cementation of nickel.

The influence of copper on the effect of certain surfactants during the cementation of cadmium by suspended zinc particles

The influence of copper on the effect of nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) during cadmium–zinc dust cementation was investigated. The behaviour of D1, D2 and D3 was determined by comparing the results obtained with and without surfactant. It was found that in the presence of copper D1 improves, but D2 and D3 inhibit cadmium cementation. The presence of copper substantially changes the effect of D1 and D3 which becomes opposite to the effect of these surfactants in the absence of copper. The addition of copper has no effect on the influence of D2. SEM study of cementation products indicates a change of deposit structure in the presence of copper. The addition of copper causes the formation of coarser deposits. Morphology of cementation products changes from a completely compact layer in the presence of D1 to a porous layer in the presence of both copper and D1 which corresponds to the cementation kinetics results. The addition of copper enhances dendrite formation in the presence of D2 and contributes to the formation of clusters in the presence of D3. Dendrite formation in the presence of D2 probably increases hydrogen evolution which inhibits cadmium deposition. The addition of D1 to the zinc sulphate solution containing copper and cadmium increases co-deposition of these impurities during the cementation by suspended zinc particles.

The effect of certain surfactants on the cementation of cadmium by suspended zinc particles

The effect of the surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on cadmium-zinc dust cementation kinetics as well as on cadmium deposit structure was investigated. The behaviour of each surfactant was determined by comparing the results obtained with and without surfactant. The reaction of cadmium cementation follows first-order kinetics in the presence of and without surfactants. Additions D1 and D2 decrease but D3 increases the rate of cadmium deposition. Highest inhibition effect on the cementation rate was found in the presence of D1. The increase of cadmium deposition in the presence of D3 probably corresponds to the inhibition of hydrogen evolution due to the addition of this surfactant. SEM study of cadmium deposits showed the formation of a uniform layer of cadmium on the zinc particles surface in the presence of D1 and D3 as well as the formation of many dendrites in the presence of D2. The lowest deposit porosity is observed in the presence of D1 which correlates with the high inhibition effect of this surfactant on cadmium cementation rate. Dendrite formation in the presence of D2 probably increases hydrogen evolution which is in accordance with the obtained inhibition effect of D2 on cadmium cementation. Cadmium deposited in the presence of D3 forms a layer with a high porosity.

The effect of certain surfactants on the cementation of copper by suspended zinc particles

The effect of the surfactants nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on copper-zinc dust cementation kinetics, as well as on the structure of the copper deposits was investigated, varying the temperature and the concentration of the surfactants. In the presence of surfactants D1, D2 and D3 the reaction of copper cementation did not follow first-order kinetics. It was found that D1 improves but D2 and D3 inhibit the cementation of copper. A SEM study of copper deposits obtained in the presence of D1, D2 and D3 revealed the formation of a uniform layer of copper on the surface of zinc particles. The lowest deposit porosity was observed in the presence of D3, which corresponded to the highest decrease in the rate of copper cementation obtained in the presence of this surfactant. The results show that the addition of D1 to the solution during the zinc dust cementation stage increases the amount of copper deposition.

Effect of boric acid on the severity of vapor explosions in pure water and surfactant solutions

Four different dilute aqueous solutions of boric acid and surfactant/boric acid were tested to determine the impact of these coolant additives on the severity of vapor explosions in small-scale experiments with molten tin. Twelve grams of molten tin at 800°C were dropped into 6 l of coolant solution at room temperature; for each solution, the experiment was repeated 20 times. The coolants examined were pure water, 500 wppm boric acid solution, 2000 wppm boric acid solution, 5 wppm of a non-ionic surfactant (nonylphenol polyethylene glycol ether) in a 500 wppm boric acid solution, and 5 wppm of an ionic surfactant (dodecylbenzene sulfonate sodium salt) in a 500 wppm boric acid solution. Pressure and impulse data suggest that the presence of boric acid up to 2000 wppm concentration did not significantly affect the severity of the interactions. Particle size analysis, however, indicates that enhanced fragmentation took place at the higher concentration (2000 wppm). The data indicate that the presence of boric acid negates the potentially mitigating effects of the surfactant additives previously reported in experiments where the surfactants were added to pure water.

The electrodeposition of metal impurities during the zinc electrowinning at high current density in the presence of some surfactants

Co-deposition of metal impurities (Cu, Ni and Sb) with zinc from industrial acid sulphate solutions with a high concentration of impurities was studied at a current density of 1000 A m −2, without, and in the presence of, specific combinations of the following surfactants: nonylphenolpolyethylene glycol (D1), dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3). The effect of the combination D1+D2+D3 on the current efficiency, as well as on the inclusion and distribution of metal impurities throughout the cross-section of zinc deposits were determined.

The effect of some surfactants on the cathodic and anodic polarization of zinc and on the cathodic polarization of nickel electrodes in sulphate electrolytes

The cathodic and anodic polarization of zinc, together with the cathodic polarization of nickel, were used to determine the effect of the surfactants, nonylphenolpolyethylene glycol (D1) dinaphthylmethane-4,4′-disulphonic acid (D2) and polyethylene glycol with molecular weight 400 (D3) on zinc electrowinning, as well as on the influence of nickel impurity during the electrolysis of zinc sulphate solutions.