HCl Ratio Research Articles

Study of the process of obtaining zinc chloride from zinc-containing concentrate

The article presents data on the production of zinc chloride by autoclave leaching of zinc from zinc concentrate with hydrochloric acid. The influence of the Zn : HCl ratio on the chemical composition of the liquid and solid phases, and the degree of zinc extraction by 28 % hydrochloric acid at a process duration of 10 hours was studied. The liquid phase contains mainly zinc chloride, concentrate impurities, of which calcium, iron, copper, cadmium, and lead predominate, with the their contents of 0.181–0.314 % for calcium and 0.951–1.654 % for lead. The temperature of the leaching process in this case is 65-75°C, the pressure is 1.72 MPa. The recovery rate at these parameters is 71.22–90.10 % depending on the Zn:HCI ratio. The optimal ratio is 1 : 1.1. It has been established that the interaction of zinc concentrate occurs in the kinetic region and continues in the diffusion region, where the duration of the process has a significant effect. The reaction rate constant versus temperature obeys the Arrhenius equation and the average activation energy is 4.05 kJ/mol.

Effect of L-arginine and L-Lysine HCl ratio on growth performance and ileum morphology of native chickens aged 2-14 weeks.

Background and Aim:Micronutrients such as essential amino acids in chicken feed must be balanced to promote optimal development. The balance of the amino acids arginine and lysine in chicken feed is particularly important. This study aimed to examine the effect of the ratio of L-arginine to L-Lysine HCl on growth performance and ileum morphology of native chickens aged 2-14 weeks-old.Materials and Methods:One hundred and eighty 2-week-old native chickens which initial weight 78.10±4.97 g were classified into six treatments and five repetitions using a completely randomized design.Treatments were based on the ratio of arginine to lysine in the feed:T1 (0.50% L-arginine: 0.85% L-lysine HCl); T2 (0.75% L-arginine: 0.85% L-lysine HCl); T3 (1.00% L-arginine: 0.85% L-lysine HCl); T4 (0.50% L-arginine: 1.00% L-lysine HCl); T5 (0.75% L-arginine: 1.00% L-lysine HCl); and T6 (1.00% L-arginine: 1.00% L-lysine HCl).Results:Groups T3 and T6 had the highest feed consumption (42.06±0.29 and 42.78±0.72 g/bird/day, respectively), while Group T6 had the highest body weight and body weight gain rate (1505.60±103.20 kg/bird and 16.99±1.24 g/bird/day, respectively). Groups T3 and T6 also had the highest carcass weight (916.16±46.99 and 947.18±62.32 g/bird, respectively). The best feed conversion was seen for Groups T3, T5, and T6 (2.55±0.14, 2.50±0.20, and 2.53±0.19, respectively). For ileum morphometry, the highest villus height occurred in Groups T2, T3, T5, and T6 (962.80±23.31, 982.80±10.03, 972.80±18.99, and 989.80±10.69 μm, respectively); and Group T6 had the highest crypt depth and villus width (340.80±11.52 and 302.00±4.00 μm, respectively). Statistical analysis indicated significant differences among the treatment groups for all variables examined (p<0.05).Conclusion:The highest ratio of arginine-lysine was associated with the largest increase in native chicken feed consumption, body weight gain, feed conversion, and carcass weight, as well as villus height and width, and crypt depth in the ileum. Overall, an arginine-lysine ratio of 0.8-1.20 promoted optimal growth of native chickens aged 2-14 weeks. In the future, it is important to increase the arginine-lysine ratio with low feed protein levels in native chickens.

Eggshells Calcium Extraction and the Application in Food Fortifications

Eggshells are the hard, outer covering of eggs. It is known that eggshells are discarded as waste materials, although they contain a significant amount of calcium. The study was aimed to extract and quantify calcium from the eggshells and fortification on the biscuit and yogurt products. The extraction of calcium was done using calcium chloride with HCL solution at different propositions (1:1, 1:5, 1:10, 1:15, and 1:20). After extraction, the sample was dried at 50 °C temperature for 3 hours to obtain dry calcium chloride. Calcium was fortified at a concentration of 100 ppm, 1000 ppm, and 2000 ppm in both the biscuits and yogurt, respectively. The calcium-fortified samples were analyzed for sensory properties and chemical composition. The ash content of calcium-fortified yogurt (0.47) was slightly higher than normal yogurt (0.44), while the other chemical components remains similar to the control. For the sensory evaluation result, the biscuit with 2000 ppm calcium-fortified biscuit and 1000 ppm calcium-fortified yogurt was found to be highly acceptable among the calcium-fortified samples. The extraction of calcium chloride from eggshells was obtained the highest for eggshells on HCl ratio 1:20 (w/v) where calcium chloride was found 32.92%, 26.95%, and 23.63% for duck, layer chicken, and local chicken eggshells, respectively. The extraction rate of calcium chloride of duck eggshells was higher than the local and layer chicken’s eggshells. Therefore, it may be opined that the fortified products (2000 ppm Ca) contained a considerably higher amount of calcium content than the control sample.

A facile and controllable one-pot synthesis approach to amino-functionalized hollow silica nanoparticles with accessible ordered mesoporous shells

The development of a practical synthetic method to functionalize hollow mesoporous silica with organic groups is of current interest for selective adsorption and energy storage applications. Herein, a facile and controllable one-pot approach for the synthesis of monodisperse amino-functionalized hollow mesoporous silica nanoparticles is presented. A novel solid-to-hollow structural transformation procedure of the silica nanoparticles is presented. The structural transformation is easily designed, as observed through transmission electron microscopy, by tailoring the HCl and N-lauroylsarcosine sodium molar ratio and the water content in the sol-gel. Ordered and radially oriented in situ amino-functionalized mesochannels were successfully introduced into the shells of the hollow silica nanoparticles. A formation mechanism for the hollow mesoporous silica materials is discussed.

A one-pot synthesis of a monolithic Cu2O/Cu catalyst for efficient ozone decomposition.

Nowadays, it is necessary and challenging to prepare monolithic catalysts, which are ready for use, preventing the tedious and complicated integration procedure of the powder materials onto a porous substrate. Herein, Cu2O nanoparticles are successfully synthesized onto a porous Cu foam in one pot via the surface oxidation, coordination and precipitation reactions in a NH4OH and HCl solution, and the optimum synthesis conditions are a NH3 : HCl ratio of 1 : 0.9, oxidation temperature of 80 °C and time of 18 h. The obtained Cu2O/Cu catalyst (mostly <100 nm) shows a highly active O3 decomposition performance with >98% and >80% conversion efficiency in dry and 90% relative humidity air for >10 h at an O3 concentration of 20 ppm and a gas hourly space velocity of 12 500 h−1. The high efficiency can be attributed to the porous Cu foam providing a large contact area, abundant crystal defects in the nanometer-sized Cu2O materials serving as the active sites, and also to the Schottky barrier formed in the Cu2O/Cu interface facilitating the electron transfer for O3 degradation. All these results show the potency of the easily fabricated monolithic Cu2O/Cu catalyst for the highly efficient O3 contaminant removal.

EXTRACTION OF FUKOIDAN CHARACTERIZATION FROM CHOCOLATE ALGAE Sargassum sp

Fucoidan were recovered from Sargassum polycystum by single-step extraction with ultrasonic wave pretreatment. Extraction were optimized using central composite design of respon surface method. Ultrasonic wave pretreatment conditions were 80% amplitude, for 15 minute. Alga solution in 0.03 M HCl ratio 1:20 (b/v) at 70-90 o C for 3-5 hour were evaluated during this process to establish a condition to maximize the extraction. The aim this research is getting the optimum conditions extraction yield fucoidan Sargassum sp. Result this reseacrh all extraction factors had significant effects on fucoidan yield (p<0,05). The optimum conditions were extracting temperature 81 o C, extracting time 4,04 h. Under this condition, the experimental yield of crude fucoidan 7,15±5,58%. Based on the characterization result of fucoidan by fourier transform-infrared spectroscopy, we foundthat fucoidan Sargassum sp.is composed sulfate group.

Acid-Assisted Recycling of Iron Hydroxide Sludge as a Coagulant for Metalworking Fluid Wastewater Treatment

Coagulation is capable of treating metalworking fluid (MWF) wastewater after MWF oil recovery, as an alternative fuel by dissolved-air flotation, but it yields a substantial amount of oil-contaminated sludge. The oil-contaminated sludge is a resource of coagulant recovery, which reduces the sludge disposal and coagulant cost. This study examined the acid recovery and reusability of iron coagulant for MWF wastewater treatment. Ferric chloride (FeCl3) was used as a coagulant, while hydrochloric acid (HCl) was used in the solubilisation process. Without MWF contamination, the iron hydroxide (Fe(OH)3) to HCl ratio of 3:1 was required to completely dissolve the Fe(OH)3 sludge within 5 min. The presence of MWF oil on the sludge substantially decreased the acid recovery of Fe(OH)3. Even at 30 min, the Fe(OH)3 to HCl ratio of 3:1 could recover only 87.07% by mass of iron. The use of anionic polymer (polyacrylate) as a coagulant aid for MWF treatment made the acid recovery of iron coagulant less effective. Acid-recovered iron coagulant can be reused for four cycles to treat the MWF wastewater because increasing the cycles of reuse lowers the treatment efficiency. The use of HCl waste in this approach reduces both the operational cost and potential global warming effect.

Synthesis of hexagonal aluminosilicate from liquid-crystalline mesophase using zeolitic nanoclusters: bottom-up versus top-down approach

An amorphous porous hexagonal aluminosilicate Al-ZAT was prepared using liquid crystal phase of Brij-56 and preformed MFI zeolite nanoclusters solution through bottom-up approach. The HCl concentration (0.5–2.0 M), HCl to Brij-56 ratio and zeolitic seed solution wss varied for the mesoporous system at ambient synthesis condition. The optimum Brij-56 to HCl ratio was found to be 1 Brij 56: 9–19 HCl (0.5 M) by mass. The addition of preformed zeolite seed (7–14 ml) as precursor solution instead of conventional silica source tetramethyl orthosilicate (TMOS) generate uniform mesophase and subsequently avoids formation of methanol (from TMOS hydrolysis) that affects liquid crystalline mesophase. MCM-41 (ZMCM-41) and SBA-15 (ZSBA-15) derived from similar zeolite precursor solution was synthesized for comparative study. The porous textural characteristics, and type of surface acidity were studied. The analysis showed a highly porous hexagonal structure of Al-ZAT. ZMCM-41 prepared through top-down approach, showed formation of ordered nanostructured mesoporous (disordered hexagonal). Al-ZAT and ZSBA-15 shows weaker Bronsted acid sites compared to ZMCM-41.

Activated carbon supported VN, Mo 2 N, and W 2 N as catalysts for acetylene hydrochlorination

Abstract The development of green catalysts for the calcium carbide acetylene method synthesis of vinyl chloride monomer (VCM), is essential material to industrial polyvinyl chloride production. The original catalyst HgCl2 easy to volatile during the reaction lead to environmental pollution. Here we present three different transition metal nitride load into activated carbon (AC): VN/AC, Mo2N/AC, and W2N/AC as novel catalysts. W2N/AC and Mo2N/AC was a relatively stable catalyst to compared with VN/AC. All of them VCM selectivity can maintain 98%. More HCl ratio for Mo2N/AC lead its acetylene conversion reach 80%. The former two catalysts are promising candidates for acetylene hydrochlorination.

Some Nutritional Characteristics of Enzymatically Resistant Maltodextrin from Cassava (Manihot esculenta Crantz) Starch.

Cassava (Manihot esculenta Crantz) native starch was treated with pyroconversion and enzymatic hydrolysis to produce a pyrodextrin and an enzyme-resistant maltodextrin. Some nutritional characteristics were quantified for both compounds. Pyroconversion was done using a 160:1 (p/v) starch:HCl ratio, 90°C temperature and 3h reaction time. The resulting pyrodextrin contained 46.21% indigestible starch and 78.86% dietary fiber. Thermostable α-amylase (0.01%) was used to hydrolyze the pyrodextrin at 95°C for 5min. The resulting resistant maltodextrin contained 24.45% dextrose equivalents, 56.06% indigestible starch and 86.62% dietary fiber. Compared to the cassava native starch, the pyrodextrin exhibited 56% solubility at room temperature and the resistant maltodextrin 100%. The glycemic index value for the resistant maltodextrin was 59% in healthy persons. Its high indigestible starch and dietary fiber contents, as well as its complete solubility, make the resistant maltodextrin a promising ingredient for raising dietary fiber content in a wide range of foods, especially in drinks, dairy products, creams and soups.

Effects of pyroconversion and enzymatic hydrolysis on indigestible starch content and physicochemical properties of cassava (Manihot esculenta) starch

Cassava (Manihot esculenta Crantz) root is the second most important starch source worldwide and its cultivation could be potentially much greater. Pyrodextrins and enzyme-resistant maltodextrins were produced from cassava starch by pyroconversion and enzymatic hydrolysis. Changes in indigestible starch content and some physicochemical properties were analyzed. The best results were produced with a 160:1 (m/v) starch:HCl ratio, 90°C temperature, and 3 h reaction time. These conditions produced a pyrodextrin with 45.98% indigestible starch content and a color difference of 1.89. Optimum hydrolysis conditions were a 0.01% α-amylase concentration and 5 min reaction time, which produced a resistant maltodextrin with 24.45% dextrose equivalents and 56.06% indigestible starch content. Compared to the native starch, the pyrodextrin exhibited 93% solubility at 60°C, and 100% at 70–90°C. The resistant maltodextrin was completely soluble at all temperatures. The pyrodextrin had low water-absorption capacity (0.16–0.34 g water/g gel) and some swelling power, while the resistant maltodextrin had neither property, even at low temperatures. None of the compounds exhibited a gelatinization transition. The resistant maltodextrin's high indigestible starch content and solubility make it a promising ingredient for increasing dietary fiber content in a wide range of foods, particularly beverages, creams, soups, dairy and bread products.

IgA Hevylite® Test As a Surrogate to Serum Protein Electrophoresis (SPEP) or Nephelometry in the Management of IgA Myeloma

AbstractAbstract 3970 Background:Measurement of serum M-spike is used to assess response to therapy and treatment-free survival in IgA myeloma. However, its resolution on SPEP and the presence of IgA-dymers can make accurate measurement difficult. The more the M-spike decreases on SPEP, the more imprecise the M-spike measurement is using SPEP. IgA M-spike often migrates in the betaglobines that renders the M-spike measurement often complicated to analyze. Furthermore, quantification of the clonal IgA chain by nephelometry (IgAneph), which inherently includes monoclonal and polyclonal immunoglobulins, does not accurately reflect the tumour burden. Currently, there is a need in myeloma with IgA isotype (approximately 30–40% of patients) to identify new markers that better reflect the disease burden and the response to treatment, and correlate to patients’ outcome. Hevylite® measures IgAkappa and IgAlambda and might provide precise quantitative measurement of the IgA M-spike. We sought to determine whether Hevylite® can be used as a reliable marker for diagnosis and response to therapy in IgA myeloma as compared to the M-spike measurement on SPEP and nephelometry. Methods:We conducted a retrospective analysis on 113, smoldering or symptomatic, IgA myeloma patients at diagnosis referred to our department from 1997 to 2011. All serum samples were collected prior to treatment or at relapse (for sequential data) and were kept frozen since collection. Hevylite® measurements were made at The Binding Site Ltd, Birmingham, UK. A normal range was produced from normal (blood donor) sera (n=138), and were for IgA kappa 0.48–2.82g/L, IgA lambda 0.36–1.98g/L and IgA K/L ratio 0.80–2.04. For ease of comparison we have studied the IgA hevylite ratios expressed as IgA K/L ratio. Results:The median age at diagnosis was 65 years (range: 33–93) and the M/F sex ratio was 0,91. Forty-eight percent of patients had an ISS greater than 2 (n=86). On nephelometry the median IgA level was 22g/L (range min-max, 0–100). Fifty patients had M-spikes migrating among the betablobulines, 27 among the gammaglobulines, 10 migrated in both and 23 unspecified. Fourteen patients had oligosecretory disease (M-component < 10g/L). Forty-two patients had an IgA kappa clonal chain, 70 others an IgA lambda and for one patient the data was not available. Among IgA kappa patients the mean HCLratio was 616.6 (median 117.7 [0.021–4323.7]) whereas it was 0.61 (0.21 [0.004–0.455]) among the IgA lambda patients.Across the entire population, 58 patients were identified by SPEP and HCL ratios. Among the 55 patients whose M-component was not quantified on SPEP, HCL ratios were abnormal in 53/55 (96%) cases. In the subgroup of patients whose M-protein migrates in the beta-region 29 out of 50 are identified by HCL ratios and SPEP. Another 19 patients (38%) had abnormal HCL ratios while unquantified on SPEP. The same was seen in patients whose M-protein migrates among the gammaglobulins with 16/27 and 11/27 (40%), respectively. In the last subgroup of patients with beta and gamma migrating M-proteins, all (10/10) were identified by HLC and SPEP. More interestingly, among the oligosecretory MM patients identified by an M-component < 10g/L, all (14 patients) had an abnormal HCL ratio. In our series of IgA myeloma, 51% of patients were accurately quantified on SPEP. When using HCLratios, an extra 47% of patients became measurable, with an abnormal HLC ratios allowing IgA myeloma in up to 98% of cases.When considering IgA measurement using nephelometry, 102 patients had both high IgA levels (90%) and abnormal HCL ratios. Interestingly, 7 patients had normal IgA levels with IgAneph and abnormal HCL ratio offering a useful diagnostic tool for 96% of patients as compared to IgAneph.In our series, IgA myeloma was neither associated with a poor outcome (median [range] OS: 119 months [0,5–604]) nor a poor response to therapy (median [range] TTP: 16 months (1–92). HCL involved chain ROC analysis identified a 37g/L cut-off as prognostic in IgA myeloma(p=0.039). Conclusion:Hevylite® is a new and reliable marker for diagnostic and monitoring of IgA myeloma. It enables to quantify accurately up to 98% of IgA-MM patients. These preliminary data need confirmation in further prospective trials in order to monitor further the impact of this marker in IgA myeloma patients before it becomes the gold standard to monitor the IgA M-protein in years to come. Disclosures:Boyle:Chugai: Consultancy, Honoraria. Combat:The Binding Site: Employment. Pietrantuono:The Binding Site: Employment. Facon:onyx: Membership on an entity's Board of Directors or advisory committees; celgene: Membership on an entity's Board of Directors or advisory committees; janssen: Membership on an entity's Board of Directors or advisory committees; millenium: Membership on an entity's Board of Directors or advisory committees. Harding:The Binging Site: Employment. Leleu:Celgene: Honoraria, Research Funding, Speakers Bureau; Janssen: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Sanofi: Honoraria; Onyx: Honoraria, Speakers Bureau; LeoPharma: Honoraria, Speakers Bureau.

Effects of sulfur on PCDD/F formation under stable and transient combustion conditions during MSW incineration

SO 2 levels in the flue gas from a laboratory-scale fluidized bed reactor combusting artificial municipal solid waste (MSW) were varied (resulting in four different SO 2:HCl ratios 0, 0.2, 0.7 and 2.7 (by mass)) to study the effects of sulfur on the formation of polychlorinated dibenzo- p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzothiophenes (PCDTs). Sampling was performed simultaneously at three fixed points in the post-combustion zone with temperatures of 400, 300 and 200 °C, under normal combustion conditions and both during and after transient combustion conditions. The findings indicate that sulfur has a greater inhibitory effect on PCDF formation than on PCDD formation and that the PCDD/PCDF ratio in the flue gas depends on both the SO 2:HCl ratio in the flue gas and memory effects arising from transient combustion conditions. The results also indicate that the relative importance of different pathways shifts in the post-combustion zone; condensation products increasing with reductions in temperature and increases in residence time. However, these changes appear to depend on the SO 2:HCl ratio in the flue gas and combustion conditions. Sulfur seems to inhibit the chlorination of PCDFs. A tendency for increased SO 2 levels in the flue gas to increase levels of PCDTs was also detected, but the increases were much less significant than the reductions in PCDF levels.

Simplified method for determining cadmium concentrations in rice foliage and soil by using a biosensor kit with immunochromatography

AbstractBACKGROUND: The behavior of cadmium in ecosystems needs to be monitored because of the human toxicity of this heavy metal. The need recently arose for a simple and quick on‐site test for trace levels of Cd in food and environmental samples. In response, an immunochromatographic assay kit for detecting Cd was manufactured by Kansai Electric Power Co. of Japan. This kit uses the antigen–antibody complex reaction between the Cd–EDTA complex and an anti‐Cd–EDTA antibody and shows the results in terms of the degree of color developed on a test paper. We previously reported the successful use of this kit to determine Cd concentrations in brown rice. Here, we applied the kit to the determination of Cd concentrations in rice foliage and soil.RESULTS: Cadmium in rice foliage was not extracted successfully by the method used for brown rice. However, it was successfully extracted by 0.1 mol L−1 HCl solution at a rice foliage:HCl ratio of 1:20, and coexisting metals were removed sufficiently by the column treatment. The Cd concentrations determined by immunochromatographic assay were well correlated with the values obtained by acid decomposition and inductively coupled plasma mass spectrometry. The 0.1 mol L−1 HCl‐extractable Cd concentration in soil was also determined successfully with the kit.CONCLUSION: Approximate Cd concentrations in rice plants and 0.1 mol L−1 HCl‐extractable Cd concentrations in soil can be monitored easily and quickly by this method at locations where facilities for acid digestion and precision analysis are not available. Copyright © 2009 Society of Chemical Industry

Easy route for the synthesis of Fe-SBA-16 at weak acidity and its catalytic activity in the oxidation of cyclohexene

The synthesis of Fe-SBA-16 with isolated framework Fe species was achieved by simple adjustment of molar ratio of co-surfactant n-butanol, TEOS, n H 2 O / n HCl ratio, Si/Fe ratio, and aging condition, respectively. The extent of mesopore structural ordering and the coordination of iron are confirmed by X-ray diffraction, N 2 physisorption, 29Si-MAS NMR, SEM, TEM, electron spin resonance (ESR), and NH 3-TPD analysis. The material obtained constitutes micro- (∼316 m 2/g) and mesopore surface area (∼1000 m 2/g), with high-mesopore sizes (∼9.8 nm). The micropore volume present up to 0.28 cm 3/g, while the total pore volume range ∼0.90 cm 3/g at the maximum. Among various Si/Fe ratios synthesized, Fe-SBA-16 with Si/Fe ratio 19 exhibited good catalytic activity for the oxidation of cyclohexene at the optimized reaction condition.

The behaviour of phosphorus and heavy metals in sewage sludge ashes

The effect of the combustion atmosphere and the additives (CaO and HCl) on the behaviour of phosphorus and heavy metals during sewage sludge combustion was investigated. The results demonstrated that the reduction combustion promoted the vapourisation of phosphorus and heavy metals during sewage sludge combustion. Moreover, the concentrations of phosphorus and heavy metals in the bottom ash decreased with increasing HCl ratio, and the addition of CaO can stabilise heavy metals and phosphorus. It was also observed that phosphorus and heavy metals increased with increasing CaO ratio. Lastly, the difference of the TG-DTA curves with and without additives is discussed.

Direct hydrothermal synthesis of mesoporous Sn-SBA-15 materials under weak acidic conditions

A direct synthetic route for the preparation of Sn-SBA-15 materials with n Si/ n Sn ratios ranging from 100 to 10 under milder acidic conditions than normally employed for the preparation of Si-SBA-15 is reported. The changes in the pH conditions of the gel were made through an adjustment of the molar ratio of n H 2 O to n HCl (<1 pH <2) during preparation. The samples prepared under three different acidic conditions have been characterized by various techniques. An expansion of the lattice (powder XRD) and an increase in mesopore area (low temperature N 2 adsorption) indicate that the hexagonal structure of the SBA-15 is maintained with no loss of long range ordering. The UV–vis reflectance spectra of Sn-SBA-15 samples show the presence of Sn 4+ ions both in tetrahedral and octahedral environment. 29Si MAS NMR spectra of samples prepared under an intermediate acid condition show the presence of Q 3 and Q 4 species. Their ratio increases with a decrease in tin content. The presence of Si in (2Si, 2Sn) i.e., Q 2 environment may point to incorporation of considerable Sn 4+ ions in tetrahedral positions. Sn-Mössbauer spectroscopic studies reveal that Sn 2+ species form upon reductive treatments and can probably be stabilized in the pore wall upon reoxidation. This to some extent is an indication of the formation and stabilization of Si–O–Sn–O–Si linkages in Sn-SBA-15. A progressive increase in the pH of the medium (increasing the n H 2 O to n HCl ratio) results in the location of Sn 4+ ions, (a) at the surface of the mesopores (surface of the corona region) as a thin film of SnO 2 or small aggregates (loss in mesopore area) depending on the concentration of Sn; (b) at the walls of the mesopore structure, substituting Si 4+ ions (some lattice expansion and tetrahedral Sn 4+ ions); and/or (c) as a part of the corona region, neutralizing the resulting Si–OH groups (a loss of micropore area and octahedral Sn 4+ ions). The studies reveal that the method of preparation, n H 2 O / n HCl ratio and the n Si/ n Sn ratio (concentration of SnCl 4) of the gel significantly influence the type of tin species in the resulting Sn-SBA-15 samples.

Synthesis and rheological properties of mesoporous nanocrystalline CeO 2 via sol–gel process

Cubic-phase CeO 2 with high surface area was prepared using sol–gel process. The effect of sol–gel parameters, viz. HCl:alkoxide and water:alkoxide molar ratios, indicated that the gelation time increased with acid concentration and the lowest gelation time was found at 55 water:alkoxide molar ratio. The XRD patterns of cerium dioxide at different calcination temperature (300–800 °C) and times (1–7 h) showed increasing crystallinity as a function of temperature and time, while the scanning electron microscope (SEM) micrographs showed the agglomeration of crystallites to form large particle cerium dioxide at higher calcination temperatures. The Brunauer–Emmett–Teller (BET) specific surface area increased with decreasing the HCl:alkoxide and water:alkoxide molar ratios, calcination temperature and time. The highest surface area was obtained at 0.8:1:55 HCl:alkoxide:water molar ratio and 400 °C calcination for 1 h (180 m 2/g). The viscoelastic properties of different HCl:alkoxide ratio solutions were studied using oscillatory shear. The fractal dimension determined from the frequency-scaling exponent of the modulus at the gel point indicated a dense critical gel structure at high HCl ratio and tight structure at low amount of acid. The gel strength increased as a function of acid molar ratio and the 0.8 molar ratio gave the highest gel strength.

Indigestible Starch of P. lunatus Obtained by Pyroconversion: Changes in Physicochemical Properties

AbstractLima bean (Phaseolus lunatus) starch was modified using pyroconversion to produce non‐digestible starch and the functional properties of the pyrodextrinized starches were evaluated. Reaction conditions included: starch/2.2 M HCl ratio (80:1 and 160:1, w/v); temperature (90°C and 110°C) and reaction time (1 and 3 h). “In vitro” indigestible starch and color difference (ΔE) were determined and used as response variables. The optimum product was recovered from native starch treated with a 160:1 starch/HCl ratio, at 90°C for 1 h, which produced modified starches containing 49.5% indigestible starch and ΔE of 18.86. Starch pyrodextrinization decreased the amount of enzymatically available starch through formation of atypical glycosidic bonds that are not digested by the amylases and maltooligosaccharidases in the small intestine of humans. Compared to the P. lunatus native starch, the pyrodextrinized starch exhibited increased paste and gel clarity (52.7%T), solubility (88.7%), and swelling power (26 g water/g starch), a higher gelatinization temperature range (72.5–89.8°C) and lower viscosity. This process can be considered a promising treatment for production of resistant starch (RS) from P. lunatus.

Effects of Synthesis Conditions on Macroscopic and Microscopic Properties of Ordered Mesoporous Silica Fibers

Experiments were conducted to prepare ordered mesoporous silica fibers under different conditions (precursor type, temperature, acid concentration, and growth time). The ordered mesoporous silica fibers can be obtained with tetrabutyl orthosilicate as the silica source under the following conditions: temperature at 300 K; and tetrabutyl orthosilicate, cetyltrimethylammonium bromide, HCl, and water molar ratio of 1.0, 0.5, 10−98, and 2000. Synthesis at temperatures above 300 K resulted in ordered mesoporous silica of nonfibrous geometry (films or particles) due to a fast transfer rate of silica source material. A variation in acid concentration in the range of 2.0−6.4 vol % accelerates the formation of fibers with more pore microstructural ordering. Higher acid concentration leads to formation of irregular nonfibrous silica forms besides fibers due to rapid silica hydrolysis/condensation. Under controlled conditions the fibers' diameter becomes larger with a broader distribution for samples with longer gr...