Volume Of Toluene Research Articles

Independent concentration extraction as a novel green approach resolving overlapped UV–Vis binary spectra and HPTLC-densitometric methods for concurrent determination of levocloperastine and chlorpheniramine

BackgroundThe proposed research study introduces independent concentration extraction (ICE) as a novel UV–Vis spectrophotometric approach. The approach can be used for extracting the concentration of two analytes with severely overlapped spectra from their binary mixtures. ICE is based on spectral extraction platform involving simple smart successive methods that can directly extract the original zero order spectra of the analytes at their characteristic (λmax). Chlorpheniramine maleate (CPM) and Levocloperastine fendizoate (LCF) are two commonly co-formulated drugs in cough preparations. The combined mixture was used to confirm the validity of the developed ICE tool. Another less green HPTLC was developed for the first time to separate both drugs and help also in confirming the proposed tool.MethodsFor the simultaneous determination of CPM and LCF, two ecologically friendly techniques were employed. The first approach encompasses the use of the ICE spectrophotometric method that could be successively applied for extracting the concentration of two analytes with severely overlapped unresolved spectra in their binary mixtures. Other complementary methods aiming at original spectral extraction; including spectrum subtraction (SS) and unity subtraction (US) were also successfully employed to resolve the zero order spectra of the combined drugs with all their characteristic features and peaks. The second technique used, a high-performance TLC-densitometric one, was performed on silica plates with silica plates F254 and a mobile phase with a ratio of 3:3:3:1 by volume of toluene, ethanol, acetone, and ammonia as a developing system at 230 nm.ResultsThe presented extraction approach was executed without any optimization steps or sample pretreatment for the simultaneous determination of CPM and LCF. The method was found to be valid for their determination within concentration range of 3.0–30.0 μg mL−1 for both drugs. For HPTLC method, the resulting Rf values of CPM and LCF were 0.37 and 0.78, within concentration ranges of 0.3–4.0 μg/spot and 0.8–10.0 μg/spot, respectively. Greenness assessment of both developed methodologies showed that the HPTLC method is less green than the spectrophotometric method, yet with comparable sustainability when it comes to the used technique.ConclusionThe procedures were found to be selective, accurate, and precise for analysis of the studied binary mixture. Furthermore, the environmental impact of the introduced methods was assessed using novel greenness metrics, namely AGREE and Green Analytical Procedure Index (GAPI) to prove their ecological safety. In addition, white analytical chemistry (WAC) evaluation metric was employed to ensure the synergy and coherence of analytical, practical, and ecological attributes.

Rationally controlling interfaces and oxygen vacancies of CeO2@C core–shell nanorods/nanofibers for superior microwave absorption and thermal conduction

High-performance thermally conductive-microwave absorbing integrated materials are highly required to mitigate the severe electromagnetic pollution and overheating generated in electronic devices. However, the incompatibility between thermal conduction and microwave absorption impedes their collaborative development. Herein, an adjustment strategy for interface- and oxygen-vacancy-linkage was adopted to rationally construct CeO2@C core–shell nanorods/nanofibers (CSNRs/NFs) and cooperatively boost their electrical, thermal, and microwave absorption properties. A hydrothermal-annealing technique was employed to synthesize CeO2@C CSNRs/NFs. Their core–shell structure, oxygen vacancies/lattice defects, and length-to-diameter ratio were accurately adjusted by changing the annealed temperature (Ta) and toluene volume (V). The CeO2@C CSNRs/NFs produced under Ta = 600 °C and V = 1.5 mL exhibit high thermal conductivity (TC = 2.94 W/(m·K)) at a small load of 40 wt%. The large TC is mainly due to the weak phonon defect/interface scattering and electron/phonon co-transfer in a 3D continuous path consisting of a 1D structure. Furthermore, the CeO2@C CSNRs/NFs display strong microwave absorption (EABmax/d = 3.27 GHz/mm; RLmin=− 50.98 dB) due to their various polarizations, tunable conduction loss, and multiple internal reflections. These results demonstrate that the CeO2@C CSNR/NFs are an ideal multifunctional material that protects against concurrent EM interference and excess heat in electronic packaging materials.

Determination of voidage of palm nuts in a vessel

Inaccurate estimation of nuts volume in a hopper may likely influence the design of some components of palm nut processing system such as shaft, rotor, electric motor power, hopper supporting rods, etc. In an effort to address this challenge the voids/ spaces were considered as inherent in palm nuts when stored in a vessel. In this study, 5 kg of dried and ready to crack mixed varieties of palm nuts were grouped based on their minor diameter (d_1) as small size: d_1 < 13.00 mm; medium size: 13.00 ≤ d_1 < 17.00 mm and large size: d_1 ≥ 17.00 mm for each size range, nuts were randomly selected and each range placed into different 100 ml beaker. Toluene was poured into each of the beaker until the nuts at the top were tipped covered. The volume of toluene (V_toluene) used in filling to the tip of the top nuts was quantified as void / space unoccupied by the nuts. The experiment was repeated using 150, 200, 250 and 300 ml beaker respectively. Each experiment was carried out in duplicate and their mean and standard deviation computed. Result showed that voidage of palm nut in a processing vessel was 45 ± 4%. This designates that the actual volume of palm nuts occupied in a processing vessel such as hopper would likely be 55% of its container’s volume. Hence, could be used in the design of storage facilities such as silo, bin, etc.

Experimental study of the thermal and burning characteristics of 15 cm pool fires fueled by heptane-toluene mixtures

This article presents an experimental investigation of the effects of the fuel sooting propensity on the thermal and burning characteristics of 15 cm diameter pool fires burning in air. Heptane is used as reference fuel and two other heptane/toluene blends with toluene volume concentration of 5% and 10% are considered to vary the fuel sooting propensity. An exhaustive characterization of the pool fires is performed with measurements of the flame geometry, puffing frequency, mass burning rate, combustion efficiency, local temperature statistics from a dual thermocouple technique, local mean soot volume fraction from laser light extinction, radiative loss to the surroundings and total heat flux to the center of the pool surface. This comprehensive dataset can be used to develop and validate models for soot formation and radiative heat transfer. The experimental results show that the increase in fuel sooting propensity, characterized by a smoke point height decreasing from 12.5 cm to 4.9 cm, results in a significant enhancement in soot production, with the peak of mean soot volume fraction increasing from 0.62 ppm to 1.11 ppm. Radiative loss to the surroundings is also affected, as radiant fraction and total heat flux to the center of the fuel surface increase from 0.37 to 0.45 and 18.5 to 22.2 kW/m2 respectively. This is accompanied by a significant reduction in combustion efficiency from 0.95 to 0.83. In an opposite way, the impact on the temperature statistics is minor.

An HP-TLC densitometric method and fingerprinting for estimating capecitabine and thymoquinone simultaneously and its application in nanoscience using Box–Behnken design

World Health Organization estimates that 10% of medications are of inferior quality, thus dangerous to human health. One way to avoid such a problem is to create an adequate, economical, and competitive analytical system. As a result, the study’s goal is to create a High-Performance Thin Layer Chromatography (HP-TLC) method for determining capecitabine (CAP) and thymoquinone (TQ) simultaneously. To the best of our knowledge, no such method for determining CAP and TQ simultaneously exists today. The method was created by implementing an analytical quality-by-design approach based on the Box–Behnken design (BBD) to optimize the chromatographic conditions and a combination of factors such as toluene volume (A), solvent front (B), and chamber saturation time (C), all of which were likely to affect the R f of CAP and TQ, respectively, later validated using TLC-silica coated plate 60 F254. The validated parameters were within an acceptable range, according to ICH guidelines. BBD design revealed that the volume of toluene and solvent front had a greater effect on all of the responses studied and thus needs to be controlled. The developed method of the analysis was found to be facile, dependable, expeditious, cost-effective, and could be used to quantify CAP and TQ in Nanoformulation.

A New Series of Tungstophosphoric Acid-Polymeric Matrix Catalysts: Application in the Green Synthesis of 2-Benzazepines and Analogous Rings

A new series of composite materials (PLMTPA) based on tungstophosphoric acid (TPA) included in a polymeric matrix of polyacrylamide (PLM), with a TPA:PLM ratio of 20/80, 40/60, and 60/40, were synthesized and well characterized by FT-IR, XRD, 31P MAS-NMR, TGA-DSC, and SEM-EDAX. Their acidic and textural properties were determined by potentiometric titration and nitrogen adsorption–desorption isotherms, respectively. Considering 31P MAS-NMR and FT-IR analyses, the main species present in the samples is the [PW12O40]3− anion that, according to XRD results, is highly dispersed in the polymeric matrix or appears as a noncrystalline phase. The thermogravimetric analysis revealed that PLMTPA materials did not undergo any remarkable chemical changes up to 200 °C. Additionally, the PLMTPA materials showed strong acid sites whose number increased with the increment of their TPA content. Finally, PLMTPA materials were used as efficient and recyclable noncorrosive catalysts for the synthesis of 2-benzazepines and related compounds. Good yields (55–88%) and high purity were achieved by a Pictet-Spengler variant reaction between N-aralkylsulfonamides and s-trioxane in soft reaction conditions: low toluene volume, at 70 °C, for 3 h. The described protocol results in a useful and environmentally friendly alternative with operative simplicity. The best catalyst in the optimized reaction conditions, PLMTPA60/40100, was reused six times without appreciable loss of activity.

Effective separation of toluene from n-heptane with imidazolium-based deep eutectic solvents

In this work, the selective extraction of toluene from toluene/n-heptane mixtures by using a series of deep eutectic solvents (DESs) with imidazolide-based ionic liquids as the hydrogen bond acceptor (HBA) and lactams as the hydrogen bond donor (HBD) was assessed. Investigation of the HBA alkyl chain length, HBA:HBD molar ratio, and HBD structure showed that the optimum extraction agent was EmimCl:1,3-dimethylurea (2:1). The feasibility of using DESs to separate toluene and n-heptane was confirmed by quantum chemistry calculations. The effects of toluene concentration, operating temperature, and DES:toluene volume ratio on the toluene selectivity were determined. The DES was recovered by distillation and reused. The Othmer-Tobias correlation was used to check the reliability of the experimentally obtained liquid–liquid extraction data. The liquid–liquid equilibrium data for the ternary system {toluene + n-heptane + DES} were obtained and fitted to a non-random two-liquid model.

Stability-Indicating Analytical Method Development Using Quality by Design (QbD) Approach for Simultaneous Estimation of Budesonide and Levosalbutamol.

Budesonide is a corticosteroid; levosalbutamol is bronchodilator. In combination, they are used in the treatment of asthma and chronic obstructive pulmonary disease. The present article portrays the development of a stability-indicating high-performance thin-layer chromatography (HPTLC) method for the simultaneous estimation of budesonide and levosalbutamol using design of experiment (DOE) principles. DOE was applied in development part in which a Box-Behnken design was used to study the effect of factors on the Rf value of the drugs. Twenty-five experimental runs were performed to optimize the chromatographic conditions. Aluminum sheets precoated with silica gel 60 F254 were used as the stationary phase. The optimized mobile phase composition was found to be toluene-ethyl acetate-methanol-ammonia (4:1.8:1.8:0.2) and saturation time 20 min, quantified by densitometric analysis at 231 nm. Moreover, the drugs were subjected to acid and alkali hydrolysis, oxidation, thermal, and photodegradation. The drugs undergo degradation under mainly acidic and basic conditions. Also, the degraded products were well resolved from the pure drug with significantly different Rf values. Linearity was performed in the ranges of 224-1120 ng/band for budesonide and 280-1400 ng/band for levosalbutamol. The method was validated according to the International Conference on Harmonization guidelines. This approach is useful to expedite method development and optimization activities in analytical laboratories. The experimental data revealed that the volume of toluene and methanol in the mobile phase significantly affected the Rf value of both the drugs, and ammonia significantly affected the Rf value of levosalbutamol.

Molecular Structural Evolution of Near-Infrared Cationic Aggregation-Induced Emission Luminogens: Preclinical Antimicrobial Pathogens Activities and Tissues Regeneration

Molecular Structural Evolution of Near-Infrared Cationic Aggregation-Induced Emission Luminogens: Preclinical Antimicrobial Pathogens Activities and Tissues Regeneration

On the Mechanism of Swelling of Gel-Type, Macroporous and Hypercrosslinked Copolymers of Styrene

Gel type polymers, polymers of expanded structure and macroporous polymers of styrene mostly with 6 mole% of divinylbenzene have been obtained by suspension polymerization, expanded and macroporous structures being prepared in the presence of 1.5 volumes of toluene or iso-octane, respectively. All three types of copolymers were further converted into highly porous hypercrosslinked products by their intensive post-crosslinking with monochlorodimethyl ether. For all samples obtained, the inner specific surface area, total pore volume, apparent density, and uptake of toluene, methanol and water have been measured. It was found that the swelling of macroporous and hypercrosslinked porous polymers results in an increase in the volume of the polymeric phase and decrease in the volume of large pores with insignificant rise in the total size of the polymeric beads. Swelling of porous polymers thus mainly proceeds at the expense of space of internal voids.

Solvent-induced deflection of polydimethylsiloxane plates: Effects of dimensions and solvent volume.

The development of flexible electronics and robots has stimulated interest in the deformation behavior of polymers under liquid environments. In this work, we introduce a "local" method to study the toluene-induced deflection of polydimethylsiloxane (PDMS) plates. Placing a graphite rod on the surface of a PDMS plate, we are able to confine the spreading and evaporation of toluene and the uptake of toluene by the PDMS plate. The local uptake of toluene by a PDMS plate causes the deflection of the PDMS plate, which is dependent on the geometric dimensions of the plate and the toluene volume. An empirical relationship is proposed to correlate the largest deflection of a PDMS plate induced by local uptake of toluene to geometric dimensions of the plate and toluene volume. The approach used in this work provides a simple approach to study the kinetics of the solvent-induced deformation of a polymer, which can contribute to the design and applications of a stimuli-sensitive self-shaping polymer.

Thiol-ene photo-click immobilization of a chiral chromatographic ligand on silica particles

This work reports procedures for the immobilization of vinyl ligands on silica particles by UV-initiated thiol-ene radical addition reaction (photo-click immobilization). tert‑Butylcarbamoyl quinine was the functional ligand (ene component) for the synthesis of chiral stationary phases. Two distinct surface chemistries were evaluated. In one approach, the ligand was directly attached to 3-mercaptopropyl-silica triggered by radicals generated by UV irradiation from a photoinitiator. In another approach, the ligand was immobilized onto vinyl silica via poly(3-mercaptopropyl-methylsiloxane) (PMPMS) as crosslinker by a photoinitiated double click reaction in which functionalization with chiral ligand and crosslinking to vinylsilica occurred simultaneously in one synthesis step. PMPMS-bonded CSPs were prepared from suspension (slurry method) or solventless after coating of the polythiol onto the vinylsilica surface (film method). Optimization by a design of experiment approach showed that the reaction time is the prime variable to optimize the surface coverage of chiral selector which also increased with PMPMS concentration. When the film formation of the latter approach was assisted by a minute volume of toluene during photo-click immobilization, selector coverage could be significantly increased to 0.73 µmol/m2 in a 2 h synthesis compared to 0.44 µmol/m2 by the solventless film method and 0.47 µmol/m2 by the slurry method under otherwise comparable conditions. The solvent assistance improved the chromatographic efficiency of the film method and resulted equal minimal reduced plate height of 2.6 as the slurry method for a chiral probe (Fmoc-Phe). The mass transfer resistance was around factor 2 smaller with the solvent-assisted film method as compared to the film approach without toluene, presumably due to a more homogenous distribution of the thin polymer film owing to lower dynamic viscosity in presence of toluene.

Central composite design expert-supported development and validation of HPTLC method: Relevance in quantitative evaluation of protopine in Fumaria indica

The current study was executed for method development, validation and to estimate the concentration of protopine in methanolic extract of Fumaria indica by high-performance thin-layer chromatography (HPTLC). Isolation of bioactive compounds was carried out using the mobile phase, toluene:ethyl acetate:diethyl amine (8:2.5:0.5 v/v/v), and detected at wavelength 290 nm. This method was validated for precision, specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), etc. The calibration range was found to be 500–5000 ng/spot for the bioactive compound. Protopine was separated with an Rf value of 0.22 ± 0.03. The method was validated for linearity (r2 ≥ 0.996 ± 0.082), accuracy 98.75–102.12%), and RSD of precision (0.49–2.07) with a calibration curve range of 500.00–5000.00 ng/spot. The LOD and LOQ were found to be 83.92 ng/spot and 254.30 ng/spot., respectively. The Central Composite design expert was applied for the validation of robustness. Three independent variables such as the volume of toluene in solvent system, chamber saturation time and wavelength were investigated. The results indicated that a slight change in these variables had no significant effect on the peak response. This developed HPTLC method is simple, precise, robust, specific, rapid, and cost effective. It could be used for quality control study and quantification of protopine in the plant extract and different herbal formulations containing the plant species.

Thermodynamic study of binary mixtures of toluene with ionic liquids, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide

Abstract Densities, refractive indices and viscosities at 293.15, 298.15, 303.15, 308.15 and 313.15 K of binary mixtures of toluene with 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, 1-hexyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide and 1-butylpyridinium bis(trifluoromethylsulfonyl)imide have been measured over the miscible region at p = 0.1 MPa. From the experimental data, values of excess molar volume, excess thermal expansion, deviation in refractive index, deviation in viscosity and excess Gibbs energy of activation for viscous flow have been calculated. These properties have been fitted to the Redlich-Kister-type polynomial equation in order to analyse non-ideal behaviour of the studied mixtures. Moreover, partial and apparent molar volumes of toluene and ionic liquid in their binary systems have been calculated. Finally, the effects of temperature and cation of ionic liquid on the physicochemical properties were analysed and discussed in terms of intermolecular interactions occurring in the studied systems.

Simultaneous Raman and pyrometric temperature measurements in shock-wave-compressed toluene

We fielded experiments to compare temperatures measured simultaneously by pyrometry and Raman spectroscopy in toluene shocked to 9 GPa. A 0.5 mm thick toluene sample was compressed between sapphire windows by plate impact from a gas gun. As the shock wave reverberated between the windows, the pressure increased stepwise to about 9 GPa. While the sample was near its peak pressure, we measured the Raman spectrum and determined temperature from the ratio of the Stokes and anti-Stokes intensities. Simultaneously, we measured the sample thermal radiance from the C-H vibration bands that occur between 3.2 and 3.6 μm to determine temperature pyrometrically. The pyrometer used a biased indium antimonide detector paired with a custom transimpedance amplifier, a system capable of temperature measurements as low as about 400 K. The Raman measurements gave a temperature of 530 ± 25 K in the bulk volume of toluene. Pyrometry gave a temperature of 496 + 15/−20 K, which is in reasonable agreement with the Raman measurement. Comparisons of this type are necessary to validate pyrometry as a temperature diagnostic in dynamic experiments.

Application of mean-field theory to the spin casting of polystyrene and poly(methyl methacrylate) blend films from toluene

The Flory-Huggins free energy of mixing is shown to be appropriate for the analysis of the temporal evolution of a ternary blend of polystyrene and poly (methyl methacrylate) during spin-coating from toluene using an in-situ light scattering technique. For the range of concentrations studied, both the onset of film instability and the observation of a scattering ring occur at the same toluene volume fraction. The success of Flory-Huggins theory indicates that polymer chains retain random walk characteristics during spin-coating. It is also concluded that the thermodynamics of phase separation during film formation is independent of the initial solvent concentration.

Application of Novel Fe3O4–Polyaniline Nanocomposites in Asphaltene Adsorptive Removal: Equilibrium, Kinetic Study and DFT Calculations

Recent investigations have shown that surface modification can improve the colloidal stability and chemical properties of the metallic nanoparticles. In this study, poly aniline (PANI) coated Fe3O4 nanoparticles were synthesized and used for asphaltene adsorption. The prepared nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, field emission scanning electron microscopy, Fourier-transform infrared spectroscopy and vibrating-sample magnetometer techniques. The effects of adsorbent amount, initial asphaltene concentration and heptane to toluene volume ratio on the sorbents adsorptive capability were studied. The experimental sorption isotherm data was fitted to the Langmuir isotherm model for coated and uncoated adsorbents. The kinetic data was consistent with Pseudo second order kinetic model. Asphaltene adsorption on Fe3O4/PANI composite was much higher than pure Fe3O4 due to the significant π–π interactions between asphaltene and adsorbent and stability effect of PANI. The results indicated that PANI coated Fe3O4 is an appropriate candidate for crude oil upgrading. Moreover, density functional theory calculations confirm that the adsorption energy of asphaltene over the Fe3O4/PANI composite is larger than that over the bare Fe3O4. This can be mainly attributed to the more favorable orbital interactions as well as charge-transfer effects between asphaltene and PANI in the former system.

Evaluation of solvents for in-situ asphaltene deposition remediation

Upon the formation and the accumulation of the deposits, cost-effective cleaning strategies should be applied to remediate and remove the organic solids. The injection of aromatic solvents, usually know as solvent wash, is one of the commonly used techniques to re-dissolve the deposited asphaltenes in the well. To select and develop the best solvents and the most appropriate solvent soaking conditions for asphaltene remediation, a re-dissolution test apparatus using a packed bed column was introduced to evaluate the solvents for in-situ asphaltene deposition remediation under more realistic production conditions. The solvency power of three aromatic solvents and four commercial solvents was determined and compared. Under the current experimental conditions, the injection of p-xylene re-dissolves 31.3% and 69.8% more deposits than the same volume of toluene and aromatic naphtha (A150). Additionally, the solvent wash by toluene/diesel mixture (50/50 by volume) and diesel significantly reduces the re-dissolution efficiency by 31.1% and 74.3% by comparing to toluene. Results also suggest that the screening of chemical solvents based on their solubility parameters may not provide accurate indication on the selection of the best solvent for asphaltene removal. Furthermore, the effects of aging time, occluded oil, soaking temperature, and soaking time were investigated on the removal of asphaltene deposition in the packed bed column. Results show that the existence of the occluded oil during the aging and soaking process weakens the solubility power of the toluene. The solvency power of toluene is enhanced by 11.4% and 24.2% when the soaking temperature increases from 25 °C to 120 °C and the soaking time extends from 1 h to 24 h, respectively. With the proposed technique to assess chemical solvents in the laboratory, the most cost-effective solvent wash strategy can be developed for the in-situ remediation of asphaltene deposition in the wellbore.

Gas chromatography–mass spectrometry determination of polycyclic aromatic hydrocarbons in baby food using QuEChERS combined with low-density solvent dispersive liquid–liquid microextraction

A sensitive GC–MS method is reported for the determination of twelve polycyclic aromatic hydrocarbons (PAHs) in baby food. The sample preparation involves QuEChERS extraction combined with low-density solvent dispersive liquid–liquid microextraction (LDS-DLLME) and ultra-low temperature (−80 °C). Plackett–Burman screening design was employed to identify the main sample preparation variables that affect the extraction efficiency, such as the volume of toluene used in LDS-DLLME. The suitability of proposed method was verified by analytical selectivity, linearity in solvent and matrix-matched calibration curves and adequate recoveries (72–112%) and precision (RSD values ≤11%), under repeatability and within-laboratory reproducibility conditions. High analytical sensitivity was achieved for the monitoring of PAHs at the strict limit of 1 µg kg−1 fixed by the European Commission for baby foods. The validated method was applied to thirty-two commercial baby food samples, and the investigated PAHs were not detected in any sample.

Experimental evaluation of asphaltene dispersants performance using dynamic light scattering

In this study, the asphaltene particle aggregation process is studied and effects of asphaltene concentration, n-heptane to toluene volume ratio, type and concentration of asphaltene aggregation inhibitor are investigated on onset of precipitation and asphaltene particle size distribution (APSD). The measurement of APSD is performed through dynamic light scattering technique. The results show that the concentration of asphaltene doesn't have significant effect on the onset point; however, it leads to form bigger particles. An increase in n-heptane volume ratio leads to increases the asphaltene particles size where 5% of particles are bigger than 6 μm after 40 min. Dodecyl benzene sulfonic acid component displaces the onset point reasonably and causes 7% rise in the amount of required n-heptane. Dodecyl resorcinol has the best performance at concentration of 50 ppm as an asphaltene dispersant and causes required n-heptane volume increment of 2%. It reduces the asphaltene particles size significantly and delays the asphaltene particles agglomeration process of about 30 min.