Modelling the Kinetics of Color and Texture Changes of Dabai (Canarium odontophyllum Miq.) during Blanching

Dabai (Canarium odontophyllum Miq.) is a fruit that is often eaten by first blanching in hot water to make the flesh creamier and softer, before it is served as a snack or side dish. In this study, Dabai fruit was blanched at different temperatures between 60 and 100 °C, with an increment of 10 °C, for up to 10 min, and the kinetics of quality changes (color and texture) were studied. Kinetic models that were assessed for changes of color and texture were zero-order, first-order, and fractional conversion model. The results showed that L parameter had no change throughout the blanching process, while parameters a*, b*, chroma (C), and total color difference (TCD) resulted as significantly increased as the temperature and duration of blanching increased. However, the change of firmness was not significant due to minor changes of firmness as the temperature and time increased. In terms of kinetic models, zero and fractional-conversion order well described the changes of a* parameter; while zero, first and fractional conversion well described parameters b*, C and TCD. Change of firmness did not fit with zero or first-order. All of the kinetic models obeyed the Arrhenius equation. Thus, the fitted kinetic models can be used to design the blanching process of Dabai fruit.

Photocatalytic H2 Production from Naphthalene by Various TiO2 Photocatalysts: Impact of Pt Loading and Formation of Intermediates

This work presents a comparative study of the efficiency of two commercial TiO2 photocatalysts, Aeroxide P25 (ATiO2) and Sachtleben Hombikat UV100 (HTiO2), in H2 production from an aqueous solution of naphthalene. The TiO2 photocatalysts were platinized by the photodeposition method varying the platinum content of the suspension to 0.5, 1.0, and 5.0 wt%. A full physicochemical characterization for these materials was performed, showing no structural effects from the deposition method, and confirming a well dispersion of nanosized-Pt0 particles on the surface of both photocatalysts. Pristine ATiO2 shows around 14% higher photocatalytic fractional conversion of naphthalene than pristine HTiO2 after 240 min of irradiation, while both materials exhibit negligible activity for H2 formation. The 0.5 wt% Pt- HTiO2 increases the photocatalytic fractional conversion of naphthalene from 71% to 82% and produces 6 µmol of H2. However, using a higher Pt content than the optimal platinization ratio of 0.5 wt% dramatically inhibits both processes. On the other hand, regardless of the fractional ratio of Pt, the platinization of ATiO2 results in a decrease in the fractional conversion of naphthalene by 4% to 33% of the pristine value. Although the presence of Pt islands on the surface of the ATiO2 is essential for the H2 evolution, no dependency between the Pt ratio and the H2 formation rate was observed since all the platinized materials show a similar H2 formation of around 3 µmol. Based on the EPR results, the higher photocatalytic activity of the Pt-HTiO2 is attributed to the efficient charge carrier separation and its larger surface area. The recyclability test confirms that the inhibition of the photocatalytic process is related to the deactivation of the photocatalyst surface by the adsorption of the photoformed intermediates. A strong relationship between the photocatalytic activity and the kind of the aromatic compounds was observed. The H2 evolution and the photooxidation of the aromatic hydrocarbons exhibit higher photonic efficiencies than that of their corresponding hydroxylated compounds over the Pt-HTiO2.

Storage and handling of pretreated lignocellulose affects the redox chemistry during subsequent enzymatic saccharification

The decomposition of lignocellulose in nature, as well as when used as feedstock in industrial settings, takes place in a dynamic system of biotic and abiotic reactions. In the present study, the impact of abiotic reactions during the storage of pretreated lignocellulose on the efficiency of subsequent saccharification was investigated. Abiotic decarboxylation was higher in steam-pretreated wheat straw (SWS, up till 1.5% CO2) than in dilute-acid-catalysed steam-pretreated forestry residue (SFR, up till 3.2% CO2) which could be due to higher iron content in SFR and there was no significant CO2 production in warm-water-washed slurries. Unwashed slurries rapidly consumed O2 during incubation at 50 °C; the behaviour was more dependent on storage conditions in case of SWS than SFR slurries. There was a pH drop in the slurries which did not correlate with acetic acid release. Storage of SWS under aerobic conditions led to oxidation of the substrate and reduced the extent of enzymatic saccharification by Cellic® CTec3. Catalase had no effect on the fractional conversion of the aerobically stored substrate, suggesting that the lower fractional conversion was due to reduced activity of the lytic polysaccharide monooxygenase component during saccharification. The fractional conversion of SFR was low in all cases, and cellulose hydrolysis ceased before the first sampling point. This was possibly due to excessive pretreatment of the forest residues. The conditions at which pretreated lignocellulose are stored after pretreatment significantly influenced the extent and kind of abiotic reactions that take place during storage. This in turn influenced the efficiency of subsequent saccharification. Pretreated substrates for laboratory testing must, therefore, be stored in a manner that minimizes abiotic oxidation to ensure that the properties of the substrate resemble those in an industrial setting, where pretreated lignocellulose is fed almost directly into the saccharification vessel.

Conversion of biomass-derived oil over promoted ZSM-5 based catalysts

Crude canola oil was thermo-catalytically converted to unsaturated hydrocarbons and aromatics. The major products were: 1,5-Heptadien-3-yne, 1,3-Hexadien-5-yne, 1- ethenyl-3-methylene-cyclopentene and Xylenes for Ni-ZSM-5, Benzene, Toluene, and other Aromatics including Ethylbenzene for Sn-ZSM-5 samples. The preparation of Ni and Sn-HZSM-5 was achieved by calcining the commercial NH4-ZSM-5, Si/Al ratio of 50, and promoting the material with Ni and Sn chlorides. Various techniques were used to promote the catalysts, namely, mechanical mixing promotion (MM), incipient wetness promotion (IW) and aqueous promotion (AQ). All the reactions were carried out at a WHSV of 10.6 hr-1 and temperature of 450°C. A fixed bed reactor system was used. To understand the reactions involved in the process, the characterization of the feed was done by GC-FID to identify the fatty acid composition of the Canola oil. The analysis showed that the feed was mainly composed of C18-16 fatty acids. The Gas products were characterized by GC-TCD and revealed the presence of C1 gases: CO, CO2 and CH4. No H2 was detected in the gas products. The selectivity in the gas fraction was barely influenced by the composition of the HZSM-5 based samples and the results show a mean difference within ±1.0%. A fractional conversion of close to 100% for all the tested Ni-loaded samples was observed, no fatty acids were detected in the OLP. Since the detected C18-16 fatty acids are liquids at room temperature, it was concluded that the amount of C18 fatty acids in the gas product was zero. When the HZSM-5 was loaded with Sn (atomic radius = 145pm), at higher loading %, (2.99 and 3.82%) of Sn, the conversion was lowered up to 77.9 and 91.4% from 100% that was observed for lower loading of 0.25 – 1.77%. The organic liquid product fraction was characterized using GC-MS. An analysis was done for the thermo-catalytic products of six different groups of catalysts, namely: Ni- Aqueous promotion; Ni-AQ, Ni-Incipient Wetness promotion Ni-IW; Ni-Mechanical Mixing promotion; Ni-MM; Sn-Aqueous promotion; Sn-AQ, Sn-Incipient Wetness promotion; Sn-IW, and Sn-Mechanical Mixing promotion; Sn-MM. Each of these different metal loading/ promotions were done to understand how the products were affected by increasing the Metal Loading/ promotion. For each of the product streams, the metal loading/ promotion targets of 0.5%, 1%, 3%, 5% and 7% were used. Trends to relate the Metal loading/ promotion to the product output and fractional conversion were done for each metal for comparison of the different product streams. It was observed that for Ni-AQ, Ni-IW and Ni-MM the average amount of aromatics in the organic liquid product for the Metal loading/ promotion was 68.3%, 80.6% and 63.3% respectively. From results it was observed that the activity of the Sn loaded samples increases in the production of various products groups such as Benzene, Toluene and Xylene (BTX) among other aromatics and, Ni activity was more towards Cyclopentane derivatives and Alkynes (XCA). The unpromoted commercial HZSM-5 catalyst produced 7.18% Xylenes, with no Cyclopentane Deravatives and Alkynes detected. Ni-loading exhibited increased catalytic activity towards XCA production for samples loaded using AQ and MM techniques. The samples loaded by IW technique showed activity towards producing Xylene but not Cyclopentane Derivatives or Alkynes. The introduction of Ni has increased the production of unsaturated hydrocarbons lighter than the C18 hydrocarbons such as: 1,5-Heptadien-3-yne, 1,3-Hexadien-5-yne, and 1- ethenyl-3-methylene-cyclopentene. The results obtained from this study show the selectivity toward BTX and other aromatics was lifted when HZSM-5 was promoted with Sn in comparison to the unpromoted HZSM-5 and Ni-HZSM-5. No Cyclopentane Derivatives and Alkynes were detected in any of the products of the Sn loaded samples.

Economic Optimization of Rare Earth Element Leaching Kinetics from Phosphogypsum with Sulfuric Acid

Frequently optimizations of chemical processes are presented in terms of the maximization of fractional conversion, but the primary concern when implementing a process is much more likely to be the economic viability. These are distinct optima that tend to occur at very different points. It was the purpose of this paper to integrate leaching experimental data with cost analysis to arrive upon economically optimized leaching conditions for the recovery of rare earth elements from phosphogypsum, a water phosphate byproduct. The variables under consideration were the number of leaching reactors and the residence time of each reactor. The modeling results indicated that the optimum residence time was 270 minutes and that the optimum number of stages was one.

Modified Optimal Class of Newton-Like Fourth-Order Methods for Multiple Roots

Here, we propose optimal fourth-order iterative methods for approximating multiple zeros of univariate functions. The proposed family is composed of two stages and requires 3 functional values at each iteration. We also suggest an extensive convergence analysis that demonstrated the establishment of fourth-order convergence of the developed methods. It is interesting to note that some existing schemes are found to be the special cases of our proposed scheme. Numerical experiments have been performed on a good number of problems arising from different disciplines such as the fractional conversion problem of a chemical reactor, continuous stirred tank reactor problem, and Planck’s radiation law problem. Computational results demonstrates that suggested methods are better and efficient than their existing counterparts.

Modelling Cow-Dung and Grass- Clippings Isothermal Continuous Stirred Co-digester for Biogas Production using Modified Gompertz Rate Equation

The continuous search in renewable energy sources for industrial and domestic utilization is very imperative and motivated this study. The study of Cow- dung and grass clippings Co-digestion are important due to the fact that successful outcome of the studies will provide a basis for waste minimization and enhance renewable energy production for global consumption. This work therefore is focused by exploiting the modified Gompertz kinetic equation in developing design models for the simulation of continuous stirred co-digester(CSC) at isothermal condition. Co-digester functional dimensions such as volume, length, space time, space velocity and heat generation per unit volume were developed for Continuous Stirred Co-digester type..The developed models were simulated using Matlab codes programming technique using design basis of 50,000 metric tons of biogas per annum at 37oC isothermal condition. The developed performance models were solved numerically using MATLAB version 7.1 within the operational limit of conversion degree, XA = 0.1 to 0.9.The results obtained showed that increase in fractional dimensions of Co-digester volume VR, length LR and Space time SV­ increases with increase in fractional conversion at constant radius. Results of space velocity (SV­) and heat generation/per unit volume (q) showed inverse characteristic behavior as increase in fractional conversion decreases space velocity and heat generation per unit volumes.. Further careful examination of the results, demonstrated that at optimal yield of 0.9 degree of conversion, Co-digester volume value of 10.0m3 at constant radius was feasible. The results as obtained in this work proved dependable relationship with fractional conversion.

New Iterative Methods for Solving Nonlinear Problems with One and Several Unknowns

In this manuscript, a new type of study regarding the iterative methods for solving nonlinear models is presented. The goal of this work is to design a new fourth-order optimal family of two-step iterative schemes, with the flexibility through weight function/s or free parameter/s at both substeps, as well as small residual errors and asymptotic error constants. In addition, we generalize these schemes to nonlinear systems preserving the order of convergence. Regarding the applicability of the proposed techniques, we choose some real-world problems, namely chemical fractional conversion and the trajectory of an electron in the air gap between two parallel plates, in order to study the multi-factor effect, fractional conversion of species in a chemical reactor, Hammerstein integral equation, and a boundary value problem. Moreover, we find that our proposed schemes run better than or equal to the existing ones in the literature.

An alternative to hydrogenation processes. Electrocatalytic hydrogenation of benzophenone

The electrocatalytic hydrogenation of benzophenone was performed at room temperature and atmospheric pressure using a polymer electrolyte membrane electrochemical reactor (PEMER). Palladium (Pd) nanoparticles were synthesised and supported on a carbonaceous matrix (Pd/C) with a 28 wt % of Pd with respect to carbon material. Pd/C was characterised by transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). Cathodes were prepared using Pd electrocatalytic loadings (LPd) of 0.2 and 0.02 mg cm−2. The anode consisted of hydrogen gas diffusion for the electrooxidation of hydrogen gas, and a 117 Nafion exchange membrane acted as a cationic polymer electrolyte membrane. Benzophenone solution was electrochemically hydrogenated in EtOH/water (90/10 v/v) plus 0.1 M H2SO4. Current densities of 10, 15 and 20 mA cm−2were analysed for the preparative electrochemical hydrogenation of benzophenone and such results led to the highest fractional conversion (XR) of around 30% and a selectivity over 90% for the synthesis of diphenylmethanol upon the lowest current density. With regards to an increase by ten times the Pd electrocatalytic loading the electrocatalytic hydrogenation led neither to an increase in fractional conversion nor to a change in selectivity.