Central Composite Response Surface Methodology Research Articles

Design of fixture for ultrasonic assisted gas tungsten arc welding using an integrated approach

Abstract The welding fixture greatly impacts the weld quality matrixes. In this work, the welding fixture for ultrasonic-assisted gas tungsten arc welding to reduce the hot cracking behaviour in weldments was designed using the finite element analysis approach. A three-level, five-factor central composite design-based response surface methodology analysis was followed to vary the dimensions of the fixture for the modal and harmonic analysis of the fixture using Ansys software. The optimum fixture dimensions to achieve maximum displacement amplitude and minimum von-Mises stress have been optimized using a genetic algorithm approach. The model predictions for maximum displacement amplitude and minimum von-Mises stress were compared to the experimental findings at optimal conditions. A strong consensus between the model prediction by genetic algorithm and experimental findings indicates the correctness of the developed model.

Optimization of fermentative parameters to improve hydrogen production: Is the co-fermentation of waste from the citrus agroindustrial an interesting alternative for energy recovery?

The co-fermentation of peel and wastewater from citrus processing is a proposal to promote the complementation of the individual characteristics of these substrates, making it possible to obtain higher efficiency in hydrogen (H2) production, in addition to equating problems related to the logistics of destination and treatment of these waste. To build a model for optimizing hydrogen production, based on the variables of citrus peel waste concentration (9.9 – 35.1 gTVS.L-1), citrus processing wastewater concentration (0.3 – 8.7 gCOD.L-1), and calcium carbonate (CaCO3) concentration (0.3 – 7.3 g.L-1), the Rotational Central Composite Design and Response Surface Methodology (RSM) were applied, using a mesophilic granular sludge as inoculum for batch assays subjected to thermal treatment. Hydrogen production from 199.2 to 1241.9 mLH2.L-1 was obtained in the assays, with the lowest production obtained with 22.5 gTVS.L-1 of citrus peel waste, 4.5 gCOD.L-1 of citrus processing wastewater, and 0.3 g.L-1 of calcium carbonate, for a gCaCO3/gCarbohydrate ratio of 0.03. In the optimized condition with 21.4 gTVS.L-1 of citrus peel waste, 3.4 gCOD.L-1 of citrus wastewater and 4.5 g.L-1 of calcium carbonate, which resulted in a gCaCO3/gCarbohydrate ratio of 0.53, 1249.0 mLH2.L-1 were obtained. In the hydrogen optimized condition assay a relative abundance of 95% was observed for Clostridium Sensu Stricto 1, and therefore the Clostridial metabolic pathway was inferred as predominant, with a maximum butyric acid and acetic acid production of 2230.8 mg.L-1 and 1213.6 mg.L-1, respectively. For the lowest hydrogen production assay, there was a significant reduction in the Clostridium sensu stricto 1 (51.2%) abundance, and an increase in the Paraclostridium (20.0%) and Lactobacillus (21.9%) abundances, inferring lactic acid fermentation (6367.8 mg.L-1) as the predominant pathway. An energy potential of 523.2 MJ.t-1 of citrus waste was estimated based on the hydrogen production for the optimized condition assay.

Utilization of Biowaste for Sustainable Production of Coal Briquettes

In energy scarcity, particularly in Agri-based developing economies, bio-coal briquetting is the most suitable means of meeting sustainable energy needs utilizing agricultural waste. In this study, briquettes were made from an indigenously designed briquetting machine for investigating coal–biomass proportion blend using coal from Dara Adam Khel, Khyber Pakhtunkhwa in Pakistan, and pomegranate/olive waste to analyze their resulting calorific value, strength, and geochemical properties. A central composite design (CCD) and response surface methodology (RSM) were employed to design the experiments and analyze the data. Regression models were developed for each biomass type, demonstrating their adequacy and reliability for further analysis and prediction. Energy Dispersive X-ray Spectroscopy (EDX) analysis provided insights into the elemental composition of the coal briquettes. Mechanical analysis was performed to assess the strength of the briquettes, with varying compositions showing different levels of strength. Optimization using a composite desirability function yielded an optimal calorific value of 6728 kJ/kg. In summary, this study underscores the viability of bio-coal briquetting as a transformative solution to alleviate energy scarcity. Repurposing agricultural waste curtails resource depletion while mitigating waste disposal challenges. The optimized calorific value aligns with eco-friendly energy initiatives, advancing a greener path toward energy security.

Optimization of fermentation condition to produce liquid organic fertilizer (LOF) from rotten vegetable waste using response surface methodology

This study aims to optimize fermentation process of vegetable waste into liquid organic fertilizer (LOF). Materials used in this study are rotten vegetables obtained from the local market and bio-activator from the biogas pilot plant. Level of variables for LOF fermentation such as fermentation time and activator volume were adjusted by central composite design (CCD) and response surface methodology (RSM) was used to optimize process variables using JMP Pro ver. 13 software. This study observed except for yield of phosphorus (P) which is significantly correlated with fermentation time and bio-activator volume, other parameters such as pH, nitrogen (N), potassium (K), and carbon (C) are associated with time significantly but less significant with bio-activator volume. RSM predicted the best fermentation time to produce LOF was 11.17 days using bio-activator volume of 5.15 mL and pH level should be around 6 to 7.5. The LOF product under those optimum condition was predicted containing N, P K, and C approximately 0.15%, 0.042%, 0.27% and 0.58% respectively. Experimental verification had been carried out and t-test was used to compare the means of the observed and predicted data in this study. The experimental values were found significantly in agreement with the predicted N and P, but less significant for K with respect to t-Table. The t-test value indicates the predictive models were accepted. © 2001 Elsevier Science. All rights reserved.

Optimization of Long-Chain Fatty Acid Synthesis from CO 2 Using Response Surface Methodology

A microbial electrosynthesis cell (MES) is an electrochemical technique in which electrolithoautotrophic electroactive microbes fix carbon dioxide (CO2) to longer-chain volatile fatty acids (VFAs). The synthesis of VFAs from CO2 requires optimization to improve the MES performance for industrial feasibility. This work studied the effect of different parameters, such as pH, headspace gas pressure, ethanol concentration, electrolyte, and trace element concentrations, on VFA synthesis from CO2 that used mixed anaerobic consortia in serum bottles. The operational parameters were varied according to a central composite design (CCD) and response surface methodology (RSM). A global optimum for the response variables was determined. The optimum values of different operating factors to maximize VFA production that was obtained from the optimizations were 1.12 × 105 Pa pressure, pH 7.149, ethanol = 2,318.7 mg/L, three times the standard Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ) 300 electrolyte concentration and five times the standard DSMZ 300 trace elements concentration. The experimental study was validated in triplicate, which considered the optimal values. The rate of total VFA production that was obtained from the operational parameters experimental study was 43.7 ± 5.9 mg/L/day under this optimized condition, which agreed with the predicted value of 30.39 mg/L/day. For the media optimization, validation of the experimental study was conducted at the optimal values, and their experimental response was 79.75 ± 19.26 mg/L/day, and the predicted response was 75.89 mg/L/day for total VFA production rates.

RESPONSE SURFACE METHODOLOGY APPLIED TO ELECTRO-FENTON PROCESS FOR DEGRADATION OF RED BEMACID AS TEXTILE DYE MODEL

The textile industry produces persistent organic pollutants (POPs) that pose significant risks to ecosystems because of their toxic and hazardous nature. Consequently, there is an urgent requirement for the development of effective techniques to treat the effluents and remove these compounds. This work studied the viability of the Electro-Fenton (EF) process as a potential alternative for treating textile wastewater contaminated with POPs. A batch electrochemical reactor, equipped with a platinum grid cathode and stainless-steel sacrificial anode, was utilized to eliminate Red Bemacid (RB) dye. The study investigated the impact of four key operational parameters: (i) stirring speed (rpm), (ii) oxygen flow rate (L/min), (iii) supporting electrolyte concentration [Na2SO4] (mg/L), and (iv) current intensity (A), as well as their interactions on RB removal. To perform this, Central Composite Experimental Design (CCD) and Response Surface Methodology (RSM) were employed. Under optimized EF conditions for RB removal (stirring speed = 205.09 rpm, oxygen flow rate = 0.20 L/min, current intensity = 0.306 A, and supporting electrolyte concentration = 0.09 M), the EF process demonstrated exceptional removal efficiency, achieving approximately 94.51% removal of RB. The obtained results showed that the kinetic data of RB removal were in good agreement with the Behnajady-Modirshahla-Ghanbery (BMG) model. The CCD analysis revealed that the main effect of the current intensity had a significant impact on RB removal, as well as the interaction of all paired variables.

Modified air-Fenton with MIL-88A for chemical oxygen demand treatment in used coolant oil.

Coolant oil from auto part manufacturing contains additives resulting in high chemical oxygen demand (COD) in wastewater. In this study, COD treatment of coolant oil was investigated in a metal-organic framework (MOF) with MIL-88A by a modified air-Fenton (MAF) process by varying synthetic coolant oil concentrations (1-5%), pH (3-9), air-flow rate (1-2 L/min), amount of MIL-88A (0.2-1.0g), and reaction time (30-180min). The results were analyzed using central composite design (CCD) and response surface methodology (RSM) using Minitab ver. 19. The characteristic MIL-88A was characterized by XRD that showed a spindle-like shape with 2θ at 10.2° and 13.0°. The FTIR spectrum revealed the vibrational frequencies at Fe-O (564cm-1), C-O (1391 and 1600cm-1), and C = O (1216 and 1710cm-1). The optimum treatment efficiency was studied from 30 CCD conditions in the presence of coolant oil (5%, COD ~ 132,000mg/L), pH (9), air flow rate (2 L/min), and MIL-88A (1g) within 177min. The results obtained from the experiment and the COD prediction were found to be 92.64% and 93.45%, respectively. The main mechanism of iron(III) in MIL-88A is proposed to be the production of hydroxyl radical (·OH) that oxidizes the organic matter in the coolant oil. Moreover, the MAF process was applied to the used industrial coolant oil and was found to be 62.59% efficient.

Treatment of salt from hides curing stage by electrocoagulation for use in the pickling stage of the tanning industry

The raw materials for the tanning industry, namely hides and skins, are preserved (curing stage) and carried with common salt, i.e., sodium chloride (NaCl). Proceeding to conversion into leather, pickling is a key stage of the tannery process, which entails high demand of water and salt. In this work, the salt-derived brine (SdB) generated from the curing of hides was treated by iron-driven electrocoagulation (EC), aiming at its later application in the pickling stage of the tanning industry, promoting a transition to zero waste emission policy. Focusing on reducing the brine's total organic carbon (TOC), central composite rotational design and response surface methodology were adopted to study the effect of electrolysis time (6.2–14.2 min) and current density (74–431 A·m−2) on the treatment of the SdB (≅ 7.5 % wt. NaCl). The quality of the treated brines was then assessed in pickling trials and compared with virgin brine. 68–83 % removal of TOC from the SdB were achieved under electrolysis time ranging 6.2–14.2 min and current density ranging 126–252 A·m−2. Under these operating ranges the quality of the wet-blue leathers was guaranteed. Lowest power consumption (0.44 kWh·m−3) was achieved under electrolysis time of 6 min and current density of 126 A·m−2, yielding 68 % removal of TOC. Moreover, the shrinkage temperature of the hides was improved with treated brine (103.5 °C–110.5 °C) compared to virgin brine (103.0 °C). The present study provides strong evidence that contaminated salt from the curing stage can be valorised within the tanning industry through electrocoagulation treatment and then used in another production stage, instead of being landfilled.

Optimization of Enzyme-Assisted Extraction of Bioactive Compounds from Sea Buckthorn (Hippophae rhamnoides L.) Leaves: Evaluation of Mixed-Culture Fermentation.

Hippophae rhamnoides L. leaves possess a remarkable amount of polyphenols that could serve as a natural remedy in various applications. In comparison, numerous techniques, such as conventional and high-pressure techniques, are available for extracting the bioactive fractions from sea buckthorn leaves (SBL). However, enzyme-assisted extraction (EAE) of SBL has not been comprehensively studied. The aim of this study was to optimize critical EAE parameters of SBL using the cellulolytic enzyme complex, Viscozyme L, to obtain a high-yield extract with a high concentration of bioactive compounds. In order to determine the optimal conditions for EAE, the study employed a central composite design and response surface methodology to analyze the effects of four independent factors (pH, temperature, extraction time, and enzyme concentration) on two different responses. Our findings indicated that under optimal conditions (3:15 h extraction, temperature 45 °C, pH 4.9, and 1% Viscozyme L v/w of leaves DW), EAE yielded 28.90 g/100 g DW of the water-soluble fraction. Furthermore, the EAE-optimized liquid extract was continuously fermented using an ancient fermentation starter, Tibetan kefir grains, which possess lactic acid bacteria (LAB) and have significant potential for use in biopreservation. Interestingly, the results indicated various potential prebiotic characteristics of LAB. Additionally, alterations in the cell wall morphology of the SBL residue after EAE were examined using scanning electron microscopy (SEM). This study significantly optimized EAE parameters for sea buckthorn leaves, providing a promising natural source of bioactive compounds for various applications, such as nutraceuticals, functional foods, and high-value products.

Super-high interface adhesion through silver/polyimide heterojunction

Metallized polymer film is becoming increasingly common in cutting-edge technology fields, and interface adhesion is the key factor affecting service performance. In this article, we used all-wet process to prepare Ag/Polyimide composite film with ultra-high interface adhesion (Over 25 N/cm). The influence of etching and reduction on interface adhesion was analyzed using central composite experiments and response surface methodology. Microcracks on polyimide (PI) surface were the basis for the formation of mechanical interlocks. And combined with SEM, EDS, and XPS data, the effect of Ag structure and composition on interface adhesion during reduction was summarized. The role of Ag aggregations at interface was explained, and concluded the detachment of Ag aggregations during peeling and high temperature was the main reason of failure. RFID tag, Circuit, and Cu/Ag/PI film (Resistivity: 9.3 × 10−6 Ω·cm) were made, which confirmed the compatibility and usability of Ag/PI film.

NITROGEN, POTASSIUM, AND SILICON FERTILIZATION TO ACHIEVE LOWER PANICLE BLAST SEVERITY AND IMPROVE YIELD COMPONENTS OF RICE USING RESPONSE SURFACE METHODOLOGY

Rice blast is one of the most critical limiting factors for rice plant growth performance, and it occurs in 85 countries, causing 10-35% grain yield losses. Several findings have indicated the positive benefits of nitrogen (N), potassium (K), and Silicon (Si) fertilization on plant development, yield, and biotic stress relief. However, due to rice blast attacks, its growth, development, and yield may be restricted or limited by insufficient or unbalanced N, K, and Si fertilizers. This study was conducted to optimize the fertilization strategies for rice panicle blast control and improve rice grain yield. The methods used were Central Composite Design and Response Surface Methodology. The application of N, K and Si did not influence the number of spikelets per meter square, filled grain (%) and 1000- grain weight (g). An increase in K and Si significantly reduced the rice blast severity in the off-season 2021 and the main-season 2021/2022. On the other hand, only Si had influenced rice grain yield production. An increase in Si showed a positive linear trend in rice grain yield. Based on these results, panicle blast disease is expected to be controlled with the recommended rate of 104 N kg/ha, 42 P2O5, 80 kg K2O, and an additional 200 Si kg/ha, which minimizes the rice blast severity (%) but at the same time maximizes the rice grain yield. The findings of this study provide a scientific base and technical advice for high-yield rice grain-growing under panicle blast disease hot spot areas.

Electric Discharge Machining of Titanium Alloy under Cu Mixed Dielectric Medium

Introduction: In the current research work, an attempt has been made to machine Ti6Al4V using Powder Mixed Electric Discharge Machining (PMEDM) technique. methods: The experiments were designed utilizing central composite response surface methodology by varying current, pulse on time, gap distance, and powder concentration at five different levels, whereas Material Removal Rate (MRR), Tool Wear Rate (TWR), and Surface Roughness (Ra) were documented as responses. The MRR reduced with an increase in powder concentration until the concentration reached 7.5g/l because incorporated particles observed the major proportion of heat, and at 10g/l, MRR increased due to the bridging effect. results: The TWR and Ra reduced with an escalation in powder concentration due to expansion in the spark gap, facilitating the flushing of machined debris. The surface topography revealed cracks, pits, globules, and craters. Moreover, with the addition of particles, surface quality improved owing to the elimination of re-melted layers. conclusion: The parameters were optimized using the Grey Relational Analysis (GRA), and the combination of 2.5g/l powder concentration, 20A current, 50µs ton, and 4mm gap distance offers the best machining performance.

Insight into the adsorption of acid fuchsin using CoAl layered double hydroxide: Central composite design, kinetics, isotherms and thermodynamic studies

Massive amounts of wastewater contaminated by hazardous and synthetic dyes are produced by the textile industry. Therefore, it is crucial to develop innovative techniques for removing these pollutants. In the present study, CoAl- LDH with excellent adsorption ability was synthesized via coprecipitation method at ambient temperature. The surface morphology and composition of the resulted compound were evaluated using several methods including X-ray diffraction (XRD), Fourier Transform Infrared spectrometry (FTIR), scanning electron microscopy (SEM), Thermogravimetric analysis (TGA), differential thermogravimetry (DTG), and Differential scanning calorimetry (DSC). The results given by Brunauer, Emmett and Teller theory (BET) showed that the material has a specific surface area of 48 m2.g−1 and pore volume of 0.42 cm3.g−1. The as-synthesized material was tested for the acid fuchsin removal from an aqueous medium and the impact of several parameters was investigated. The experimental parameters such as the pH, the initial concentration, the adsorbent dose and the time were optimized using the central composite response surface methodology. The optimal adsorption capacity is attained at pH = 4.5, Initial concentration C0 = 96.71 ppm, adsorbent dose d = 0.40 g.L−1 and time t = 180 min. The adsorption process fitted well with the pseudo-second order reaction, and followed Langmuir adsorption isotherm providing a considerable Langmuir adsorption capacity of 384.6 mg. g−1. The effect of different temperatures reveals the thermodynamic parameters, i.e., the free Gibbs energy ΔG° (−4.86 to −1.16 kJ.mol−1), enthalpy change (ΔH° = 79.69 kJ.mol−1) and entropy (ΔS° = 137.61 JK−1.mol−1), the negative ΔG° and positive ΔH° values signify that the fuchsin acid adsorption is spontaneous and endothermic.

Utilization of Out-of-specification Unripe Cavendish Banana [Musa acuminata (AAA)] as Banana Powder

Around 5–20% of the total banana crop in the Philippines is rejected because it does not meet the specifications for export as fresh fruit. This study aimed to utilize the out-of-specification unripe Cavendish banana of local exporters into banana powder. The effects of different pre-drying treatments such as blanching time and concentrations of citric acid and ascorbic acid on the properties of the resulting Cavendish banana powder in terms of moisture content, water activity, color, solubility, water absorption capacity, bulk density, water holding capacity, and % yield were determined using a central composite face-centered response surface methodology design. Significant mathematical models were generated that predicted the effects of individual and combined influences of pre-drying treatments. Results showed that ascorbic acid was the main factor that influence the lightness, water activity, swelling power, bulk density, and water absorption capacity of banana powder. Results of the optimization process suggested that the desirable pre-drying treatments for banana powder were a blanching time of 0–5 min, as well as soaking in ascorbic acid ranging from 0.01–0.10% and in citric acid ranging from 0.07–0.10%. The identified optimal treatment ranges for blanching time, ascorbic acid concentration, and citric acid concentration provide valuable insights for producing acceptable, safe, and high-quality banana powder. By utilizing out-of-specification bananas and transforming them into value-added intermediate products like powder, the banana industry can reduce waste, maximize resource utilization, and create a more environmentally friendly and economically viable approach to banana production.

Applicability of central composite design and response surface methodology for optimizing treatment of landfill leachate using coagulation-flocculation

Without proper treatment, leachate can contaminate adjacent groundwater, soils, and streams, resulting in potential risks to public health, the environment, and surrounding biodiversity. This work aims to treat landfill leachate by coagulation-flocculation and optimize the results using the central composite design in combination with the response surface methodology in the Mohammedia-Benslimane landfill in Morocco. The optimization of the process allowed us to find optimal removal efficiencies of color, polyphenols, and nitrates, which reached 68.8%, 77.5%, and 81.0%, respectively. The optimum conditions in this study were pH 7.66, 9.5 g/L of coagulant dose, 9.1 ml/L of flocculant dose, and 10 min of agitation time. The models obtained for the 3 responses are reliable, reproducible, and well-fitted. By optimizing the leachate treatment at the Mohammedia-Benslimane landfill using coagulation-flocculation and the response surface methodology, our study offers an efficient and reliable approach to address the challenges of landfill leachate treatment. The results obtained from this research have significant implications for liquid waste management, particularly in the context of landfill leachate treatment.

Multivariate and machine learning approaches for prediction of antioxidant potential in Bertholletia excelsa barks

ObjectivesSpecialised metabolites in plants are essential in developing new products since these compounds with antioxidant activity can be incorporated into pharmaceutical and food matrices. However, optimising the extraction processes of these bioactive compounds is necessary for a practical application. The current study aims to obtain optimal models to predict the total phenolic content (TPC) and antioxidant activity (AA) of Bertholletia excelsa barks by the ABTS, DPPH and FRAP methods. MethodsDifferent algorithms were applied by Machine-Learning (ML), such as Random Forest (RF) and Partial Least-Square Regression (PLSR). Central composite rotational design (CCRD) and response surface methodology (RSM) were used to analyse the ethanol concentration, time and temperature effect on the extraction. This research used five levels for each factor to evaluate the assays. These response variables were used to generate second-order predictive models, and the best conditions for the extraction of bioactive compounds were established. A matrix correlated with the TPC and AA responses was used to generate predictive models by machine learning. ResultsThe best performance to extract phenolic compounds with antioxidant activity by the ABTS method was achieved when ethanol (50%) at a temperature of 60 °C was used for 30 min of extraction. The coefficient of determination of the generated models using RF varied from 85% to 99%, while for the PLSR, the variation was from 85% to 96%. The composition of RGB (red, green, blue) images can be used to determine the TPC and AA in extracts of B. excelsa. ConclusionThe results indicated that the current method was a powerful and effective tool for determining the AA and TPC on B. excelsa barks. In addition, this study permitted to development of a low operational cost method that can help determine the antioxidant activity of plant extracts by digital images.

Use of Bacteria to Recover Coagulant from Water Treatment Residue and Reuse for Turbidity Removal from Water

Aluminum is present in significant concentrations in water treatment residue (WTR), a waste product obtained during turbidity removal in drinking water treatment. This study aimed at exploring the potential for recovery of coagulant from WTR using Acidithiobacillus ferroxidans (ATF) and reusing the recovered coagulant (RC) for turbidity removal from water. The activity of ATF was measured by monitoring the pH and Al recovery (in %, AlR%). The effects of two factors (WTR and sulfur dose) on the activity of ATF were studied using central composite design (CCD) and response surface methodology (RSM). The results indicated that the bacteria activity decreased with an increase in WTR dose. The results also revealed that the sulfur dose does not have a significant effect on the ultimate AlR%; however, it significantly reduced the time required for achieving AlR%. ANOVA analysis indicated that the obtained model and factors were significant. The maximum AlR% around 70.9% was obtained with 10 g/L of WTR dose and 8 g/L of sulfur dose. The RC was reused for the turbidity removal from lake water and synthetic turbid water (STW) and compared with the turbidity removal achieved with 1% (w/v) aluminum sulfate. The doses of RC to bring the turbidity <5 NTU in lake water and STW were found to be 0.75 and 1 mL/L respectively. To obtain similar turbidity level, the dose required with aluminum sulfate was 2.5 and 1.5 mL/L for lake water and STW, respectively. There was no significant change in the pH and sulfate and metal concentrations in the effluent treated with RC. The results obtained indicate that the RC is efficient in turbidity removal. The RC, therefore, has potential to reduce the demand for fresh alum for water treatment purposes and provide an alternative use of a waste material.

Catalytic Pyrolysis of Plastic Waste to Liquid Fuel Using Local Clay Catalyst

Plastics are nonbiodegradable, and safe disposal of this waste poses an environmental challenge all over the world. Catalytic pyrolysis is superior to thermal pyrolysis as it uses lower temperatures and hence less energy. The main objective of this study was to produce liquid fuel from plastic waste using indigenous clay as a catalyst through catalytic pyrolysis. The clay from Kisumu County was characterized through an X-ray fluorescence spectrometer (XRFS) and an X-ray diffractometer (XRD). The reaction setup consisted of a round-bottom flask reactor through which plastic feed and catalyst were heated in a temperature-controlled furnace. Vapor product was condensed using a Liebig type water condenser to give pyrolysis liquid product. Solid char was recovered from the flask at the end of the reaction. Optimization studies using central composite design (CCD) and response surface methodology (RSM) were performed in design expert software to predict optimal conditions of the operating variables for maximum yield of the liquid fuel. Results show that clay has a composition of silica and alumina at 64.5 wt% and 16.3 wt%, respectively, indicating high acidity of the clay, being a requirement for a good pyrolysis catalyst. For high-density polyethylene and polypropylene, the highest liquid yield of 87.23 wt% and 60.36 wt%, respectively, was at 300°C and a catalyst concentration of 10 wt%. Indigenous clay was established to be a suitable catalyst for catalytic pyrolysis of plastic waste, with the potential to replace imported catalysts since high yields of liquid fuel were obtained at lower reaction temperatures of 300-450°C, as compared to the 600°C required for thermal pyrolysis. In conclusion, waste plastics can be used to generate alternative fuel for industrial use. The liquid fuel can be used in diesel engines as a transport fuel, in turbines for electricity generation, and as a heating source in boilers and furnaces. Further studies on the modification of the surface and structure of clay are suggested to enhance its catalytic performance in the pyrolysis process for a better fuel yield.

Nanoencapsulation of Phenolic Extracts from Native Potato Clones (Solanum tuberosum spp. andigena) by Spray Drying.

Native potato clones grown in Peru contain bioactive compounds beneficial to human health. This study aimed to optimize the spray-drying nanoencapsulation of native potato phenolic extracts utilizing a central composite design and response surface methodology, obtaining the optimal treatment to an inlet temperature of 120 °C and an airflow of 141 L/h in the nano spray dryer B-90, which allowed maximizing the yield of encapsulation, antioxidant capacity (DPPH), encapsulation efficiency (EE), total phenolic compounds, and total flavonoids; on the other hand, it allowed minimizing hygroscopicity, water activity (Aw), and moisture. Instrumental characterization of the nanocapsules was also carried out, observing a gain in lightness, reddening of the color, and spherical nanoparticles of heterogeneous size (133.09-165.13 nm) with a negative ζ potential. Thermal, infrared, and morphological analyses confirmed the encapsulation of the core in the wall materials. Furthermore, an in vitro release study of phenolic compounds in an aqueous solution achieved a maximum value of 9.86 mg GAE/g after 12 h. Finally, the obtained nanocapsules could be used in the food and pharmaceutical industry.

Application of ozone to enhance the defluoridation property of activated alumina: A novel approach

Drinking water containing high fluoride concentrations may lead to serious health problems. Thus, aiming at water defluoridation through adsorption, several adsorbent materials have been studied worldwide. Due to its low cost and selectivity for fluoride ions, activated alumina (AA) is one of the most applied materials. At the same time, AA has low adsorption capacity, the pH of the aqueous solution must be less than 6.0 for fluoride adsorption, and it requires a long contact time to reach adsorption equilibrium. This study investigated the use of ozone to enhance the defluoridation property of AA. For this purpose, AA was treated under various ozonation conditions. Subsequently, the ozone-treated AA (OAA) samples were applied to adsorb fluoride from an aqueous solution. The influence of some ozonation parameters (AA concentration, pH, and contact time) was evaluated by carrying out adsorption experiments under fixed conditions. As a result, by full-factorial central composite rotational design (CCRD) and response surface methodology (RSM), it was found that the effect of initial pH during the ozonation is negligible on improving the defluoridation property of AA. At the same time, the decrease of AA concentration in the ozonation system significantly enhances the defluoridation property of AA. For example, the ozonation of 10 g L−1 of AA at a pH of 7.0 increased the fluoride removal efficiency of this material from 77.4% to 98.3%. Finally, the analysis of the ozonation time (0–120 min) showed that 90 min are sufficient to promote a significant rise in the fluoride removal efficiency of AA (from 78.3% to 97.4%). AA was characterized by FTIR, SEM, EDX NMR, and N2 physisorption methods to elucidate factors responsible for the increased fluoride removal efficiency when the material is ozonized.