Adsorption of crude oil on anhydrous and hydrophobized vermiculite

This publication reports the adsorption of crude oil on vermiculite samples, expanded and hydrophobized with carnauba (Copernícia Cerífera) wax. The adsorption studies were performed by using columns filled with the vermiculite matrices and by dispersion of the vermiculite samples in an oil-water (50 ppm of oil) emulsion. The hydrate vermiculite exhibits a very low adsorption capacity against crude oil. On the other hand, anhydrous (expanded) and hydrophobized matrices show a high adsorption capacity. The 10% hydrophobized matrix show a 50% increased adsorption capacity, in comparison with the expanded one. For adsorption performed in the water-oil emulsion, saturation of the solid hydrophobized matrix is achieved after 60 min. The hydrophobized samples exhibit adsorption factors in the 0.7-1.0 range.     

Optimization of preparation conditions for activated carbon from palm oil fronds using response surface methodology on removal of pesticides from aqueous solution

Palm oil fronds were used to prepare activated carbon using the physiochemical activation method, which consisted of potassium hydroxide (KOH) treatment and carbon dioxide (CO₂) gasification. The effects of variable parameters activation temperature, activation time and chemical impregnation ratios (KOH: char by weight) on the preparation of the activated carbon and for the removal of pesticides: bentazon, carbofuran and 2,4-Dichlorophenoxyacetic acid (2,4-D) were investigated. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were respectively employed to correlate the effect of variable parameters on the preparation of activated carbon used for the removal of pesticides with carbon yield. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing the activated carbon from oil palm fronds were found as follows: activation temperature of 750 °C, activation time of 2 h and chemical impregnation ratio of 2.38. The percentage error between predicted and experimental results for the removal of bentazon, carbofuran and 2,4-D were 8.2, 1.3 and 9.2%, respectively and for the yield of the palm oil frond activated carbon was 5.6.     

Isotherm modelling and optimization of oil layer removal from surface water by organic acid activated plantain peels fiber

This research aimed to optimize and model the adsorption process of oil layer removal using activated plantain peels fiber (PPF), a biomass-based material. The adsorbent was activated by thermal and esterification methods using human and environmentally friendly organic acid. Effects of process parameters were examined by one factor at a time (OFAT) batch adsorption studies, revealing optimal conditions for oil removal. Also, RSM, ANN and ANFIS were used to adequately predict the oil removal with correlation coefficient > 0.98. RSM modelling revealed the best conditions as 90 °C, 0.2 mg/l, 1.5 g, 6 and 75 mins, for temperature, oil–water ratio, adsorbent dosage, pH and contact time respectively. Under these simulated conditions, the predicted oil removal was 96.88 %, which was experimentally validated as 97.44 %. Thermodynamic studies revealed the activation energy, change in enthalpy and change in entropy for irreversible pseudo-first order and pseudo-second order model as (15.82, 24.17, ?0.614 KJ/mols) and (33.21,40.31, ?0.106 KJ/mols) respectively, indicating non-spontaneous process; while modeling studies revealed that the adsorption process was highly matched to Langmuir’s isotherm, with maximum adsorption capacity of 50.34 mg/g. At the end of the overall statistical modelling, ANFIS performed marginally better than the ANN and RSM. It can be concluded from these results that our biomass-based material is an efficient, economically viable and sustainable adsorbent for oil removal, and has potentials for commercialization since the process of adsorption highly matched with standard models, and its capacity or percentage oil removal also compares favorably to that of commercially available adsorbents.     

Application of the response surface methodology for modeling demulsification of crude oil emulsion using a demulsifier

The main objective of this research is to determine the capability of four surface-active compounds namely poly(ethylene glycol) distearate, N,N-dimethyldodecylamine N–oxide solution, polyoxyethylene (10) tridecyl ether, and polyethylene glycol sorbitan monooleate as demulsifier agents in breaking water-in-crude oil emulsion through the bottle test method. The influence of temperature, concentration, water content, and pH on demulsification efficiency of the studied demulsifiers was investigated via the response surface methodology (RSM) and the central composite design method (CCD) was applied to design the experiments. The optimum values of input variables to obtain the maximum water separation efficiency were determined based on the developed model by analyze of variance (ANOVA). The R-squared values demonstrate that the developed models could appropriately predict the experimental results of all demulsifier agents.     

Rapid removal of anionic organic dye from contaminated water using a poly(3-aminobenzoic acid/graphene oxide/cobalt ferrite) nanocomposite low-cost adsorbent via adsorption techniques

This research study aims to remove hazardous anionic azo dyes (Congo red (CR)) from aqueous solutions via a simple adsorption method using a poly(3-aminobenzoic acid/graphene oxide/cobalt ferrite) nanocomposite (P3ABA/GO/CoFe₂O₄) as a novel and low-cost nanoadsorbent, as synthesized by a simple and straightforward polymerization method. Typically, 3-aminobenzoic acid (3ABA), as monomer, was chemically polymerized with graphene oxide (GO) and cobalt ferrite (CoFe₂O₄) in an aqueous acidic medium containing an ammonium persulfate initiator. The adsorbent P3ABA/GO/CoFe₂O₄ nanocomposite was characterized using various techniques such as Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, energy-dispersive analysis by X-ray and Brunauer–Emmett–Teller, vibrating sample magnetometer, and zeta potential techniques. These techniques confirmed the interaction between the poly(3-aminobenzoic acid) with GO and CoFe₂O₄ due to the presence of π-π interactions, hydrogen bonding, and electrostatic forces. Herein, the removal efficiency of dye from aqueous solution by the adsorbent was studied according to several parameters such as the pH of the solution, dye concentration, dosage of adsorbent, contact time, and temperature. The adsorption of the dye was fitted using a Langmuir model (R² between 0.9980 and 0.9995) at different temperatures, and a kinetic model that was pseudo-second order (R² = between 0.9993 and 0.9929) at various initial concentrations of CR dye. In addition, the data revealed that the P3ABA/GO/CoFe₂O₄ nanocomposite exhibited a high adsorption capacity (153.92 mg/g) and removal for CR dye (98 %) at pH 5. Thermodynamic results showed the adsorption process was an endothermic and spontaneous reaction. It was found that, in terms of reusability, the P3ABA/GO/CoFe₂O₄ adsorbent can be used for up to six cycles. In this study, P3ABA/GO/CoFe₂O₄ nanocomposites were found to be low cost, and have an excellent removal capability and fast adsorption rate for CR from wastewater via a simple adsorption method. Moreover, this adsorbent nanocomposite could be simply separated from the resultant solution and recycled.     

Distribution of weight,density, and molecular weight in crude oil derived from computerized capillary GC analysis

Chromatographic separation of crude oil components has been performed on a 50 m Chrompack Sil 5 fused silica capillary column, temperature programmed from 10 to 300°C. Approximately 70 peaks eluting before n-nonane (n-C₉) and all normal paraffins to n-C₁₉ were identified by a retention time table. Peak areas were converted to weight % using 1-heptene as internal standard and relative response factors. Components were divided into boiling range groups from n-C₆ to n-C₁₉. Paraffinic, naphthenic, and aromatic distributions were obtained for the boiling point fractions up to n-C₉. Group average densities and molecular weights were calculated from pure component properties up to n-C₉. Knowing the density and molecular weight as functions of boiling range group to n-C₉, these functions can be extrapolated to n-C₁₉, based on data and correlations from more than 20 distillations of paraffinic North Sea oils adn condensates. The densities and molecular weights of the C₁₀+ and the C₂₀+ residues were calculated to satisfy a balance of weight, volume, and number of moles for the whole sample. Measurements on the residues were used to cross-evaluate the GC method against distillation. The difference in weight was estimated to be less than ± 0.5% in absolute terms for the C₁₀+ residue. The corresponding figure for C₂₀+ was ± 2%. Relatively, calculated densities are within ± 1%, molecular weights within ± 2% compared to direct measurements. Calculations were performed by a BASIC program in a GC interfaced computer.     

Direct and simultaneous determination of Cr and Fe in crude oil using high-resolution continuum source graphite furnace atomic absorption spectrometry

A simple, fast and sensitive direct method for the simultaneous determination of Cr and Fe in crude oil samples is proposed using high-resolution continuum source graphite furnace atomic absorption spectrometry. No sample preparation is used except for a 10-minute homogenization in an ultrasonic bath. Aliquots of 0.1–4 mg of the samples are weighed onto solid sampling platforms and analyzed directly using aqueous standards for calibration. The simultaneous determination was possible because there is a secondary Fe line at 358.120 nm in the vicinity of the most sensitive Cr line at 357.868 nm, and both absorption lines were within the wavelength interval covered by the linear charge-coupled device array detector. It has also been of advantage that the sensitivity ratio between the two analytical lines corresponded roughly to the concentration ratio of the two elements found in crude oil, and that both analytes have very similar volatility, so that no compromises had to be made regarding pyrolysis and atomization temperatures. Two oil reference materials have been analyzed and the results were in agreement with the certified or reported values. Characteristic masses of 3.6 pg and 0.5 ng were obtained for Cr and Fe, respectively. The limits of detection (3σ, n = 10) were 1 µg kg^− 1 for Cr and 0.6 mg kg^− 1 for Fe, and the precision, expressed as the relative standard deviation, ranged from 4 to 20%, which is often acceptable for a rapid direct analytical procedure. Five crude oils samples were analyzed.     

Determination of volatile and non-volatile nickel and vanadium compounds in crude oil using electrothermal atomic absorption spectrometry after oil fractionation into saturates, aromatics, resins and asphaltenes

In recent work, it has been shown that electrothermal atomic absorption spectrometry (ET AAS) can be used to differentiate between volatile and non-volatile nickel and vanadium compounds in crude oil. In the present work, the distribution of these two groups of compounds over different fractions of crude oil was investigated. For this purpose two crude oil samples were separated in two steps: firstly, the asphaltenes were precipitated with n-heptane, and secondly, the maltenes were loaded on a silica column and eluted with solvents of increasing polarity. The four fractions of maltenes eluted from silica column were: F1, saturated and light aromatics; F2, polyaromatics; F3, resins; and F4, polar compounds. Fractions F1 and F2 were further investigated using gas chromatography, and all fractions were characterized by CHN analysis, confirming the increase of aromatics in the fractions 2, 3, 4 and asphaltenes. For the determination of Ni and V by ET AAS, oil-in-water emulsions were prepared. The speciation analysis was carried out measuring without chemical modifier (stable compounds) and with 20 μg palladium (total Ni and V) and the volatile fraction was calculated by difference. The limits of detection were 0.02 μg g⁻¹ and 0.06 μg g⁻¹, for Ni and V, respectively, based on an emulsion of 2 g of oil in 10 mL. The volatile species of Ni and V were associated with fractions F3 and F4, while only thermally stable Ni and V was precipitated in part together with the asphaltenes.     

固体碱对油品中有机硫化物的脱除性能及分析

预碱洗（电精制）是轻质油品精制中的重要环节,通过氢氧化钠水溶液预碱洗可除去油品中的硫化氢、低分子硫醇等酸性物质,但大量含硫废碱液的排放给环保造成很大压力。以固体碱代替液体碱预碱洗,是减少甚至消除废碱液产生和排放的最有效措施。近十几年来,许多学者致力于固体碱对轻质油品中硫醇、硫化氢的脱除研究。     

Comparison of direct sampling and emulsion analysis using a filter furnace for the determination of lead in crude oil by graphite furnace atomic absorption spectrometry

The determination of trace elements in crude oil is difficult due to the complex nature of the sample and the various different chemical forms in which the metals can occur. The advantage of graphite furnace atomic absorption spectrometry is that only a minimum of sample pretreatment is required. In this work two techniques have been compared to establish a fast and reliable method for lead determination in crude oil. In the first one the crude oil samples were weighed directly onto solid sampling (SS) platforms and introduced into the graphite tube for analysis. In the second one the samples were prepared as oil-in-water emulsions and analyzed in a filter furnace (FF). Twenty μL of a mixture of 0.5 mg L^− 1 Pd + 0.3 mg L^− 1 Mg + Triton X-100 has been used as the modifier, and calibration against aqueous solutions has been used for both methods. The sensitivity obtained with the FF was more than a factor of two better than that with SS; however, as a larger sample mass could be introduced in the latter case, so that the limits of detection for both techniques were 0.004 mg kg^− 1. Seven crude oil samples were analyzed using the two procedures, and all results were in agreement at a 95% confidence level using a paired Student's t-test. For validation purposes, three crude oil samples have been mineralized using an open-vessel acid digestion, and the results were in agreement with those found with direct sampling and with emulsion sampling using FF according to ANOVA test. Both methods are simple, fast and reliable, being appropriated for routine analysis; however, the direct method using SS technology should be preferred because of its simplicity, speed and commercial availability.     

Adsorption of benzoic acid from organic solvents on calcite and dolomite: Influence of water

A study has been carried out of the adsorption of benzoic acid from cyclohexane solution onto the hydrophilic surface of calcite.

We determined initially the chemical and mineral composition of the solid, its specific surface area and its granulometry. This was followed by the determination of the enthalpies of immersion of calcite in different solvents. These thermodynamic properties gave information on the energetics of calcite—solvent interactions. In this way, we could construct a scale of affinities of the different organic molecules and water for the calcite surface. It was noted that the enthalpies were higher in unsaturated than in saturated organic solvents, and higher in water than in the organic solvents.

The adsorption isotherms and the differential molar enthalpies of displacement were determined in the presence and the absence of water. The role played by water in the adsorption of polar organic molecules from the oil phase has not been clearly explained previously. In this paper, we indicate how the presence of water can modify the adsorption of aromatic compounds on the surface of calcite. As regards the adsorption isotherms, the presence of water essentially increases the amount of adsorption. The results of the calorimetric studies were found to be surprising; we observed that the differential molar enthalpies of displacement were endothermic.

Similar experiments were carried out with dolomite and n-heptane solution and the results compared with those obtained with calcite and cyclohexane, leading to the formulation of a general model concerning the adsorption of small polar organic molecules from organic solvents onto the surfaces of the carbonates.     

Evaluation of tetracycline removal by magnetic metal organic framework from aqueous solutions: Adsorption isotherm,kinetics, thermodynamics,and Box-Behnken design optimization

In our current research, an intriguing magnetic nano sorbent Fe₃O₄@Zr-MOF was synthesized in the lab. We used this adsorbent for successfully removing tetracycline (TC) from water. We performed a number of experiments and studies to further support this, including the following: vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), X-ray diffraction (XRD), and Brunauer-Emmett-Teller surface area (BET). Our studies have determined that the Fe₃O₄@Zr-MOF boasts a considerable surface area of 868 m²/g with the highest adsorption capacity (q_max) of 942.12 mg/g. Study the factors that effect on adsorption process such as pH, TC concentration, adsorbent dose, and temperature. The adsorption isotherm was fitted to the Langmuir equation, whereas the kinetic isotherm to the pseudo-second-order equation. The adsorption process was chemisorption as well as the adsorption energy was 20 kJ/mol. Adsorption thermodynamics indicated that the adsorption process was both endothermic and spontaneous. As temperatures increased, the amounts of materials absorbed also increased. The Fe₃O₄@Zr-MOF has magnetic properties as it easily to remove from the solution after adsorption process. The adsorbent was used for five cycles with high efficiency and without change in the chemical composition as well as the XRD was the same before and after reusability. The mechanism of the interaction between Fe₃O₄@Zr-MOF and TC was expected on: Electrostatic interaction, π-π interaction, hydrogen bonding, and pore filling. The adsorption results were optimized using Box Behnken-design (BBD).     

Preparation of Quercus mongolica leaf-derived porous carbon with a large specific surface area for highly effective removal of dye and antibiotic from water

Quercus mongolica leaf (QL), an easily available biomass, was used as the precursor for preparing the hierarchical porous carbon with a large specific surface area and high adsorption capacities toward the representative dye and antibiotic. After being carbonized, QL was further chemically activated, and potassium hydroxide was proved to be a better activator than sodium hydroxide. The QL-derived porous carbon (PCQL) exhibited abundant micro- and mesopores, and the specific surface area reached 3275 m² g^?1. The performances of PCQL were evaluated through adsorbing rhodamine B (RhB) and tetracycline hydrochloride (TC) from water. Four adsorption isotherm models (the Langmuir, Freundlich, Sips, and Redlich-Peterson models), three adsorption kinetic models (the pseudo-first-order, pseudo-second-order, and intra-particle diffusion models), and the thermodynamic equations were used to investigate the adsorption processes. The pseudo-second-order kinetic model and the Sips isotherm model fitted the experimental data well, which indicates that the adsorption processes were controlled by the amount of adsorption active sites on the surface of PCQL, and these adsorption active sites had different affinities for the adsorbates. The maximum adsorption capacities of PCQL toward RhB and TC were 1946.0 and 1479.6 mg g^?1, respectively, based on the Sips model. The thermodynamic analysis indicates that the adsorption of PCQL toward adsorbents was spontaneous physical processes accompanied by the increasing disorder degree. The adsorption mechanism was attributed to the combination of the pore-filling, hydrogen bond, and π-π interactions. Moreover, in the fixed-bed experiments, the Yoon-Nelson model fitted the breakthrough curves well, and about 8 L wastewater containing RhB (200 mg L^?1) may be effectively treated by 1.0 g of PCQL. Above results indicate that QL is a promising precursor for preparing functional porous carbon materials.     

Preparation of CoFe2O4/sawdust and NiFe2O4/sawdust magnetic nanocomposites for removal of oil from the water surface

In this study, CoFe₂O₄/Sawdust and NiFe₂O₄/Sawdust magnetic nanocomposites were synthesized using a hydrothermal method, and then characterized using X-ray powder diffraction, Infrared, scanning electron microscopy, Brunauer–Emmett–Teller/Barrett–Joyner–Halenda, and vibrating-sample magnetometer techniques. In this study, unmodified sawdust (US), modified sawdust (MS), unmodified CoFe₂O₄/sawdust (UCS), modified CoFe₂O₄/sawdust (MCS), unmodified NiFe₂O₄/sawdust (UNS), and modified NiFe₂O₄/Sawdust (MNS) magnetic nanocomposites, which are inexpensive, economical, environmentally friendly absorbents, and have a high selective hydrophobic, were used for the removal of oil from the water surface. The results show that the UCS, MCS, UNS, and MNS magnetic nanocomposites can selectively absorb the oil spreading on the water surface, due to its superhydrophobicity and superoleophilicity, and can be easily collected from water under the influence of a magnetic field. In addition, the results showed that the absorbents reach their equilibrium at the 30-min mark. Among all the absorbents, the MNS magnetic nanocomposite showed the maximum absorption capacity (18.172 g/g) at the 40-min mark. The results of the kinetic studies showed that the second-order kinetic equation with the highest correlation coefficient had the best fit with the experimental results.     

Fast removal of heavy metal ions and phytic acids from water using new modified chelating fiber

The graft copolymerization of acrylic acid(AA) onto polyethylene glycol terephthalate(PET) fiber initialed by benzoy peroxide (BPO) was carried out in heterogeneous media.Moreover,modification of the grafted PET fiber(PET-AA) was done by changing the carboxyl group into acylamino group through the reaction with dimethylamine.The modified chelating fiber(NDWJN1) was characterized using elementary analysis,SEM and FT-IR spectroscopy.Adsorption kinetic curves indicated that NDWJNl could fast remove heavy metal ions and phytic acids from water effectively.Furthermore,batch kinetic studies indicated that heavy metal ions adsorbed to NDWJNl could be filted well by both pseudo-first-order and pseudo-second-order adsorption equations,but the intra-particle diffusion played a dominant role in the adsorption of phytic acids.     

Investigation and optimization of the recovery of coal fines using oil agglomeration process: Use of waste oils from different sectors

The high cost of the bridging liquid subdues the implementation and commercialization of oil agglomeration process. To overcome this problem, waste oils from different sectors were used in this present study. The performance of the process was assessed based on the responses like ash rejection and organic matter recovery. The aim of the present study was to investigate the usage of waste oils from different sectors and to optimize and analyze the behavioral pattern showcased by different variables (pulp density, oil dosage, agglomeration time and oil type) using response surface methodology (Box-Behnken design). Experimental investigation shows that the optimum pulp density, oil dosage, agglomeration time and oil type condition obtained as 3%, 15%, 15?min and waste engine oil, respectively. At optimum condition, the % ash rejection and % organic matter recovery obtained as 63.94% and 81.8%, respectively.     

Super-hydrophobic carrageenan cross-linked graphene sponge for recovery of oil and organic solvent from their water mixtures

A novel ultra-light, superhydrophobic graphene based carrageenan sponge (GCS) absorbent was synthesized by one pot hydrothermal method, for the use of selective adsorption of oils and organic solvents from their water mixtures. The GO nanosheets were reacted in the presence of formaldehyde by the insertion of carrageenan, forming hydrophobic cross-linked structure in between them. The structure and properties of this GCS are well characterized by Fourier transform infrared spectroscopy, X-ray diffraction, Thermal gravimetric analysis, Scanning electron microscopy, and Water contact angle. The as-prepared GCS has good thermal stability (400 °C), low density (20 mg/cm⁻³), excellent hydrophobicity (water contact angle of 136.24°), and selective absorption capacity (25.2–35.95 g/g) of oils and organic solvents from their water mixtures. GCS has excellent oil sorption capacity in the range of 25.2–50 g of oil per gram of adsorbent. GCS could be easily reused by simple solvent treatment. Therefore, the adsorption capacity still retained even after 10 cycles. The present work suggests that GCS using biobased resources has high potentials for many widespread applications in industry to control environmental pollution.     

Determination of Mo, Zn, Cd, Ti, Ni, V, Fe, Mn, Cr and Co in crude oil using inductively coupled plasma optical emission spectrometry and sample introduction as detergentless microemulsions

A procedure to prepare crude oil samples as detergentless microemulsions was optimized and applied for the determination of Mo, Zn, Cd, Si, Ti, Ni, V, Fe, Mn, Cr and Co by ICP OES. Propan-1-ol was used as a co-solvent allowing the formation of a homogeneous and stable system containing crude oil and water. The optimum composition of the microemulsion was crude oil / propan-1-ol / water / concentrated nitric acid, 6 / 70 / 20 / 4 w/w/w/w. This simple sample preparation procedure together with an efficient sample introduction (using a Meinhard K3 nebulizer and a twister cyclonic spray chamber) allowed a fast quantification of the analytes using calibration curves prepared with analyte inorganic standards. In this case, Sc was used as internal standard for correction of signal fluctuations and matrix effects. Oxygen was used in the nebulizer gas flow in order to minimize carbon building up and background. Limits of detection in the ng g^− 1 range were achieved for all elements. The methodology was tested through the analysis of one standard reference material (SRM NIST 1634c, Residual Fuel Oil) with recoveries between 97.9% and 103.8%. The method was also applied to two crude oil samples and the results were in good agreement with those obtained using the acid decomposition procedure. The precision (n = 3) obtained was below 5% and the results indicated that the method is well suited for oil samples containing low concentrations of trace elements.     

Experimental study and modelling of effective parameters on removal of Cd(II) from water by halloysite/graphene quantum dots magnetic nanocomposite as an adsorbent using response surface methodology

Graphene quantum dots (GQDs) were covalently immobilized onto the NiFe₂O₄-halloysite nanotubes (NiFe₂O₄-HNTs) surface to fabricate a nanocomposite material utilized as an active adsorbent to eliminate Cd(II) ions from water. NiFe₂O₄ nanoparticles were synthesized and simultaneously deposited on HNTs. Then, the material surface was coated by APTES (aminopropyltriethoxysilane) to cause GQDs be connected to the external layer via an amide bond. The prepared nanomaterial structure was identified by TEM, XRD, FT-IR, BET isotherm, EDS analysis and VSM (vibrating sample magnetometry). Box–Behnken design incorporated with response surface method (RSM) was utilized to find out the impact of pH, time, initial concentration of Cd(II) and adsorbent dose on cadmium removal. Study discovered that adsorption operation is the quasi-second-order kinetic model and adapted more precisely with Langmuir adsorption model. The Langmuir highest uptake capacity of 34.72 mg/g at 298 K was acquired. The Elovich model recommended that the process is a kind of chemisorption. The calculated thermodynamic variables verified that the uptake process is endothermic and spontaneous. Additionally, the adsorbent can be simply separated with the aid of a magnet. In this study, we have suggested a practical method for the synthesis of the NiFe₂O₄/halloysite nanotubes/graphene quantum dots magnetic nanoparticles for cadmium removal from water.     

MEKC determination of vanadium from mineral ore and crude petroleum oil samples using precapillary chelation with bis(salicylaldehyde)tetramethyl‐ethylenediimine

An analytical procedure has been developed for the separation of Cu(II), Ni(II), Co(II), Fe(II), Pd(II), Th(IV), V(IV), and determination of Fe(II), Co(II), Ni(II), and V(IV) by MEKC after chelation with bis(salicylaldehyde)tetramethylethylenediimine (H₂SA₂Ten). Uncoated fused silica capillary was used with an applied voltage of 30 kV with photo‐diode array detection at 228 nm. SDS was added as micellar medium at pH 8.2 with sodium tetraborate buffer (0.1 M). Linear calibrations were established within 0.015–1000 μg/mL of each element with LOD within 5–67 ng/mL. The method was applied for the determination of vanadium from crude oil and ore samples in the range 0.34–2.40 and 114.2–720.7 μg/g with RSD 1.7–3.8 and 0.98–2.30% (n = 3), respectively. Fe, Ni, and Co present in crude oil and ore samples were also determined with RSD 1.3–2.8, 1.1–4.1, and 1.2–3.5% (n = 3), respectively. The results were compared with that of supplier's specifications and atomic absorption spectrometry (AAS). Method was evaluated by standard addition technique.