Response Surface Experimental Design Research Articles

Molecularly imprinted polymers (MIPs) as efficient catalytic tools for the oxidative degradation of 4-nonylphenol and its by-products.

Water pollution is a current global concern caused by emerging pollutants like nonylphenol (NP). This endocrine disruptor cannot be efficiently removed with traditional wastewater treatment plants (WTPs). Therefore, this work aimed to evaluate the adsorption influence of molecularly imprinted polymers (MIPs) on the oxidative degradation (ozone and ultraviolet irradiations) of 4-nonylphenol (4-NP) and its by-products as a coadjuvant in WTPs. MIPs were synthesized and characterized; the effect of the degradation rate under system operating conditions was studied by Box-Behnken response surface design of experiments. The variables evaluated were 4-NP concentration, ozone exposure time, pH, and MIP amount. Results show that the MIPs synthesized by co-precipitation and bulk polymerizations obtained the highest retention rates (> 90%). The maximum adsorption capacities for 4-NP were 201.1mg L-1 and 500mg L-1, respectively. The degradation percentages under O3 and UV conditions reached 98-100% at 120s of exposure at different pHs. The degradation products of 4-NP were compounds with carboxylic and ketonic acids, and the MIP adsorption was between 50 and 60%. Our results present the first application of MIPs in oxidation processes for 4-NP, representing starting points for the use of highly selective materials to identify and remove emerging pollutants and their degradation by-products in environmental matrices.

Dialysis is a key factor modulating interactions between critical process parameters during the microfluidic preparation of lipid nanoparticles

Manufacturing lipid nanoparticles through microfluidic mixing can be approached from a Quality by Design perspective. Research involving critical process parameters seems to focus on the total flow and flow rate ratio, thus other process variables, such as dialysis, are underestimated. This study used a Design of Experiments to identify the influence of critical process parameters on particle size, polydispersity index, and zeta potential. A response surface Design of Experiments modeled the influence of: total flow (400 to 4000 μL min-1); flow rate ratio (3 to 9) and dialysis (yes/no). Results suggest that dialysis is a crucial parameter that strongly influences particle size and zeta potential and moderately affects polydispersity index. The flow rate ratio's relevance decreases when dialysis is performed. As the purification method can change the influence of other process parameters, it should be an integrated part of the microfluidic manufacturing of lipid nanoparticles instead of an extra step.

Impact of process parameters on the specific volume of wholemeal wheat bread made using sourdough- and baker's yeast-based leavening strategies

The final quality of wholemeal wheat bread is determined by the process parameter settings and leavening strategy. We hypothesise that the used leavening strategy may influence the optimal process parameter settings and, as such, the specific volume of the bread loaf. To analyse this interaction, bread was leavened with (i) a type 1 sourdough (SB), (ii) a type 1 sourdough combined with baker's yeast (YSB), or (iii) baker's yeast (YB). For each leavening strategy, the specific volume of bread, in response to variations in mixing time (4–10/4–14 min), water absorption (60–85 %), and proofing time (1–7/1–3 h), was analysed using an I-optimal response surface experimental design. Data modelling identified a substantially lower maximal specific volume of SB (2.13 mL/g), compared to YSB (3.30 mL/g) and YB (3.26 mL/g). The proofing time and water absorption mostly influenced the specific volume of the SB and YSB, respectively. However, the mixing and proofing times mainly affected the specific volume of YB. The type 1 sourdough reduced the mixing time and water absorption required for an optimal specific volume of bread compared to baker's yeast. These results challenge the idea of yielding higher volumes upon using sourdough compared to baker's yeast and highlight the importance of optimisation of bread dough formulations and breadmaking processes.

Influence of Cooling and Lubrication Parameters on Robot Bone Grinding Temperature and Prediction Modeling

In the process of robot bone grinding, a large amount of heat is generated, which will cause mechanical and thermal damage to bone tissues and nerves. It is necessary to study the influence of cooling and lubrication parameters on the robot bone grinding temperature and establish the prediction models among them. The FE model of single abrasive bone grinding was established to explore the influence of cooling and lubrication parameters on the bone grinding temperature. Response surface design of experiment was carried out to obtain the simulation results, and Design-Expert was used to establish a multiple regression prediction models of grinding temperature under the condition of different cooling and lubrication. Through the variance and response surface comparative analysis of the prediction model, the influence rules of the bone grinding parameters and the cooling and lubrication parameters on the bone grinding temperature was obtained. A robot bone grinding experiment was performed to prove the accuracy of FE simulation and prediction model. The research results show that the relationship between grinding temperature and cooling lubrication parameters obtained by FE simulation, RSM prediction and experiment verification is consistent, and the simulation model and prediction model of cooling and lubrication parameters are proven to be correct and effective. The influence rules and prediction effects obtained in this study will provide a reasonable scheme for doctors to implement robot bone grinding with high efficiency and low damage, and establish the theoretical basis for the effective control of robot bone grinding force thermal damage.

Optimization of the Epimedii Folium Mutton-Oil Processing Technology and Testing Its Effect on Zebrafish Embryonic Development.

As a traditional Chinese medicine (TCM), Epimedii folium (EF) has a history in medicine and food that is > 2,000 years old. Clinically, EF processed with mutton oil is often used as a medicine. In recent years, reports of safety risks and adverse reactions of products that use EF as a raw material have gradually increased. Processing can effectively improve the safety of TCM. According to TCM theory, mutton-oil processing can reduce the toxicity of EF and enhance its tonifying effect on the kidneys. However, there is a lack of systematic research and evaluation of EF mutton-oil processing technology. In this study, we used the Box-Behnken experimental design-response surface methodology to optimize the key parameters of the processing technology by assessing the contents of multiple components. The results showed that the optimal mutton-oil processing technology of EF was as follows: heating the mutton oil at 120 °C ± 10 °C, adding the crude EF, stir-frying it gently to 189 °C ± 10 °C until it is evenly shiny, and then removing it and cool. For every 100 kg of EF, 15 kg of mutton oil should be used. The toxicities and teratogenicities of an aqueous extract of crude and mutton-oil processed EF were compared in a zebrafish embryo developmental model. The results showed that the crude herb group was more likely to cause zebrafish deformities, and its half-maximal lethal EF concentration was lower. In conclusion, the optimized mutton-oil processing technology was stable and reliable, with good repeatability. At a certain dose, the aqueous extract of EF was toxic to the development of zebrafish embryos, and the toxicity was stronger for the crude drug than for the processed drug. The results showed that mutton-oil processing reduced the toxicity of crude EF. These findings can be used to improve the quality, uniformity, and clinical safety of mutton oil-processed EF.

Modelling and Optimizing the Effect of pH on Remediation of Crude Oil Polluted Soil with Biochar Blend: RSM Approach

This research modelled the effect of pH on the remediation of crude oil-polluted soil using biochar blend. The biochar blends, PL-500, pW-500, and RS-400, were made by pyrolyzing poultry litter, pine wood, and rice straw at varied temperatures and times. The pH of the crude oil polluted soil was 4.72. Response surface experimental design mixed biochar to remediate total petroleum hydrocarbons (TPH). Following 30 days of bioremediation, 15g PL-500, 3g PW-500 and 6g RS-400, removed a maximum of 46% TPH. The experimental data were statistically modelled and optimized using design expert software and response surface methods. Analysis of variance (ANOVA) was used to determine the significance of each regression coefficient. Biochar blend improved soil pH to 6.9 following remediation. ANOVA indicated that PL-500 was significant for predicting TPH % degradation at p =0.0290, suggesting that its high pH, nutrient, and soil water conservation values made it more effective in remediating TPH. The quadratic model predicts with R2 =0.8567. A model fit statistics were used to examine soil pH influence on TPH remediation. RSM study indicated a good positive association between statistical model and experiment with R2 = 0.7612. The model fits experimental data and predicts that . Remediation requires soil pH and biochar's alkalinity raised soil pH to 6.9, which promoted hydrocarbon-utilizing bacteria.

Inactivation of Listeria monocytogenes by pulsed light in packaged and sliced salpicão, a ready-to-eat traditional cured smoked meat sausage

The efficacy of pulsed light (PL) for the surface decontamination of a sliced ready-to-eat cured meat product, salpicão, was studied. The surface of the slices was inoculated with Listeria monocytogenes (107 cfu/g), and then PL treatment was applied. Microbial analyses (L. monocytogenes, coagulase-negative Staphylococci (CNS), Lactic acid bacteria (LAB) and Enterobacteriaceae) were performed immediately after the treatment. pH, aw, colour and volatile profile were also evaluated. Response Surface experimental Design was applied regarding factors voltage (ranging from 1828 to 3000 V) and distance (ranging from 2.6 to 5 cm) to the light source, and a maximum of 16.11 J/cm2 energy dose was achieved. A reduction of 1.58 log cfu/g in L. monocytogenes count was obtained when a fluence of 5.31 J/cm2 was applied. Enterobacteriaceae, LAB and CNS endogenous microbial populations were not influenced by PL treatment. PL application reduced a* values and influenced b* values without impacting the sample ΔE or L* values. The potential oxidative effect of this technology was evaluated by solid-phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS), and no significant changes were verified after its application in this sliced cured meat product.

Flame-Assisted Laser Polishing of Alumina Ceramic Surface Properties

Laser polishing was used to reduce the surface roughness and improve the surface properties of alumina ceramics. In this paper, a response surface experimental design scheme is used to establish a mathematical model based on the Box-Behnken central combination principle, with the surface roughness as the optimization target to optimize the optimal process parameters for the laser polishing of alumina ceramics, to suppress the polished surface cracks by preheating the material, and to study the changes of surface properties of laser-polished alumina ceramics under different preheating temperatures. The optimal laser polishing process parameters were optimized by response surface experiments with a scanning speed of 323.5 mm/s, a laser power of 73.63 W, a pulse frequency of 2.3 kHz, and a scanning spacing of 0.09 mm; compared with the initial surface roughness of 4.67 μm, the polished surface roughness was 0.96 μm under the experimentally optimized polishing parameters, and the surface cracks were suppressed after the preheating treatment. The surface roughness was further reduced to 0.74 μm, and the surface wear coefficient was reduced from 0.5939 to 0.5725, while the surface hardness was increased from 1810 to 2063 HV. Optimization of the laser polishing process parameters through the response surface can significantly reduce the surface roughness of the material, while the flame preheating, assisted by the laser-polished surface wear resistance and hardness, is improved.

Efficient ultrasound-assisted extraction of platycodin D and lobetyolin from Platycodon grandiflorus with polyethylene glycol (PEG) solution

This study describes an enhanced technique for extracting platycodin D and lobetyolin from the roots of Platycodon grandiflorus using an ultrasound-assisted approach with polyethylene glycol (PEG) as an additive. The optimization conditions were obtained by combining single-factor and Box Behnken design experiments and included the following results: The extraction solvent was 10% polyethylene glycol (PEG200-PEG400, 1:1), the liquid-to-material ratio was 24 mL/g, the ultrasonic irradiation power was 288 W, the ultrasonic irradiation time was 44 min, the reaction temperature was 30 °C, the cavitation time was 1.5, and the buffer time was 1.5 s. Under these conditions, the yield of platycodin D was 5.22 ± 0.13 mg/g, and the yield of lobetyolin was 0.15 ± 0.01 mg/g. The total yield of platycodin D and lobetyolin were significantly higher than those obtained with ethanol solution as the extraction solvent. In summary, the ultrasound-assisted method in conjunction with response surface experimental design is a quick and effective sample extraction technique for platycodin D and lobetyolin that can also be used to extract substances from other plants. • Use ultrasonic-assisted extraction of platycodin D & lobetyolin from P. grandiflorus. • Polyethylene glycol was first added to extract triterpenoid and alkynyl glycosides. • 10% PEG200-PEG400 (1:1, v/v) was chosen as the extraction solvent. • Determine optimum conditions of platycodin D & lobetyolin by response surface method. • Compared with ethanol as solvent, PEG has obvious advantages in terms of yield and safety.

玉米籽粒收获机清选装置作业机理分析与优化试验

Aiming at the current problem of the high rate of impurity and loss in the cleaning device of corn seed harvesters in China, this paper took the cleaning device of 4YZL-6 self-propelled corn seed harvester as a sample and analyzed the movement law of the material on the sieve. Box-Behnken response surface experimental design theory was used for the orthogonal tests. Wind inlet angle, airflow velocity, and crank angular velocity were selected as influencing factors, and the impurity rate and loss rate as the evaluation index of operation quality. A regression mathematical model between each influencing factor and indicator was established, and the model was also integrated and optimized. The optimal parameter combination was obtained as follows: the wind inlet angle was 37.95o, the airflow velocity was 11.3 m/s, and the crank angular velocity was 4.1 r/s. The corresponding impurity rate was 0.87% and the loss rate was 0.34%. Verification tests were conducted on the optimization results, and the test results showed that under the optimal combination of parameters, the impurity rate was 0.89% and the loss rate was 0.35%. The relative errors of each evaluation index and its model prediction were 2.29% and 2.94%, respectively.

An efficient removal approach for degradation of metformin from aqueous solutions with sulfate radicals

Metformin consumption for diabetes treatment is increasing, leading to its presence in wastewater treatment plants where conventional methods cannot remove it. Therefore, this work aims to analyze the performance of advanced oxidation processes using sulfate radicals in the degradation of metformin from water. Experiments were performed in a photoreactor provided with a low-pressure Hg lamp, using K2S2O8 as oxidant and varying the initial metformin concentration (CA0), oxidant concentration (Cox), temperature (T), and pH in a response surface experimental design. The degradation percentages ranged from 26.1 to 87.3%, while the mineralization percentages varied between 15.1 and 64%. Analysis of variance (ANOVA) showed that the output variables were more significantly affected by CA0, Cox, and T. Besides, a reduction of CA0 and an increase of Cox up to 5000 μM maximizes the metformin degradation since the generation of radicals and their interaction with metformin molecules are favored. For the greatest degradation percentage, the first order apparent rate constant achieved was 0.084 min−1. Furthermore, while in acidic pH, temperature benefits metformin degradation, an opposite behavior is obtained in a basic medium because of recombination and inhibition reactions. Moreover, three degradation pathways were suggested based on the six products detected by HPLC-MS: N-cyanoguanidine m/z = 85; N,N-dimethylurea m/z = 89; N,N-dimethyl-cyanamide m/z = 71 N,N-dimethyl-formamide m/z = 74; glicolonitrilo m/z = 58; and guanidine m/z = 60. Finally, it was shown that in general the toxicity of the degradation byproducts was lower than the toxicity of metformin toward Chlamydomonas reinhardtii.

Simultaneous cellulose nanocrystals extraction and organic halides removal from paper mill excess sludge via alkali-oxygen cooking and ultrasonication

Pulp mill excess sludge (PMES) is an industrial biomass waste containing high moisture, many organic compounds, and highly concentrated adsorbed organic halides (AOX). The safe disposal and recycling of PMES using an environmentally friendly and sustainable treatment represents a major challenge. In this study, alkali-oxygen cooking was used to recover cellulose nanocrystals (CNC) from PMES while removing AOX in a one-pot process. Single-parameter experiments showed that more than 95% of AOX was effectively removed, meeting sewage emission standards, and greater than 70% of cellulose was recovered as CNC. A response surface experimental design was then applied to determine the optimal reaction conditions. A temperature of 200 °C, alkali dosage of 35 wt%, and reaction time of 5 h resulted in an AOX removal rate of 96.57% and CNC recovery rate of 73.78%. The results of this study not only demonstrate an environmentally friendly, sustainable strategy for the treatment and recycling of PMES into CNC, And the alkali-oxygen cooking process can be applied other cellulose-rich industrial wastes to recover value-added products.

Pulsed Light Application for Campylobacter Control on Poultry Meat and Its Effect on Colour and Volatile Profile.

Campylobacter on poultry meat needs to be controlled to reduce the risk of infection caused by the consumption of chicken meat. Pulsed light (PL) application on poultry meat was studied to control Campylobacter spp. The effect of this technology was evaluated regarding poultry meat colour and volatile compound changes. Two breast sample groups were prepared: inoculated with Campylobacter (107 bacteria of Campylobacter jejuni strains) and not inoculated. Samples were submitted to PL, five pulses/s of 300 ms, 1 Hz, and 1 J/cm2 in the apparatus, PL Tecum unit (Claranor). A response surface experimental design was applied regarding the factors of voltage (1828 to 3000 W) and distance to the source UV lamp (2.6 to 5.4 cm). The binomial factorial treatment (voltage and distance) with PL induced different energy doses (fluence J/cm2) received by samples, 2.82 to 9.67 J/cm2. Poultry meat pulsed light treated had a significant decrease of Enterobacteriaceae counts. The treatments applied were unable to reduce 1 log Campylobacter cfu/g of poultry meat. The poultry meat PL treated became slightly light, redder, and yellower than those not treated. PL can decrease the proportion of aldehydes on total volatiles in meat, particularly on those associated with chicken-like, chicken skin-like, and sweet odour notes in fresh poultry meat. Further studies of PL with higher energy doses will be necessary to confirm if there are Campylobacter reductions and about poultry meat treated under storage to evaluate if volatile compounds can affect the flavour of PL-treated meat samples.

Influence of Tool Thread Pitch During Friction Stir Welding of High-Density Polyethylene Plate

AbstractThis study utilizes a face-centered central composite response surface design of experiments to determine the effects of thread pitch when friction stir welding high-density polyethylene. The tool pin thread pitch, along with rotation and traversing speed, was varied so that models of the maximum tensile strength, tool temperature, and tool forces could be analyzed. Coarser thread pitches facilitated higher tensile strength than finer threads due to greater material velocity and overlap between the stir zone and base material. In the tested range, the thread pitch provided a 6% linear contribution to ultimate tensile strength, whereas welds with coarse threads had on average a 2.83 MPa increase in tensile strength over the fine thread tool. The greater circumferential pin surface area of fine threads caused a greater increase in tool temperature, though this did not correlate to stronger welds. Ultimately, the most interdiffusion across the polymer joint occurred with the coarser thread pitch and slow traverse speed due to prolonged joint exposure to the molten polymer weld pool.

Preparation of hierarchical porous carbon by pyrolyzing sargassum under microwave: The internal connection between structure−oriented regulation and performance optimization of supercapacitors

To find an effective correlation between the preparation process and the application performance of symmetric supercapacitors, the relationship between the structural characteristics of biomass porous carbon and the electrochemical performances of supercapacitors was studied. Based on a response surface experimental design, the pore structure of biochar produced by the microwave pyrolysis of sargassum was adjusted through the collaborative optimization of key parameters, and graded sargassum porous carbon (SPC) with different pore characteristics was successfully prepared. Three representative samples, SPC−1, SPC−2, and SPC−3, were selected by systematically exploring the effects of the specific surface area (SSA), pore volume (Vtotal), and pore size distribution on the electrochemical performances. The SSA and Vtotal values of SPC−1 were 1500.50 m2 g−1 and 1.0513 cm3 g−1, respectively. The large number of micropores provided space for electronic storage, allowing it to have an excellent electronic storage capacity. The SSA of SPC−2 was 2019.90 m2 g−1, and Vtotal was 1.2241 cm3 g−1. The rich micropores resulted in a good charge–discharge rate. The SSA of SPC−3 was as high as 2103.20 m2 g−1, and Vtotal was 1.4756 cm3 g−1. The micron−level mesopores between the SPC−3 carbon skeletons acted as ion buffer reservoirs to shorten the ion diffusion distance and produce excellent rate performances. Subsequently, the morphology and surface properties of porous carbon samples were characterized. The study revealed that hierarchical porous carbon materials with excellent properties must achieve a balance of the microstructure and surface properties and their influence on the electrochemistry. A higher degree of graphitization could bring about a high pore regularity, thereby optimizing the ion transport kinetics. Heteroatoms could increase redox active surface sites and provide additional pseudocapacitance, but the resulting defect structure formed a large number of pores with high edge roughness in the carbon material, which had a certain negative impact on the capacity properties of the materials. The above findings can provide technical support and a theoretical basis for controlling the pore networks and directionally optimizing the performances of supercapacitors by adjusting the pore structure of biochar.

Experimental Investigation and Prediction of Mechanical Properties in a Fused Deposition Modeling Process

Additive manufacturing, also known as three-dimensional printing, is a computer-controlled advanced manufacturing process that produces three-dimensional items by depositing materials directly from a computer-aided design model, usually in layers. Due to its capacity to manufacture complicated objects utilizing a wide range of materials with outstanding mechanical qualities, fused deposition modeling is one of the most commonly used additive manufacturing technologies. For printing high-quality components with appropriate mechanical qualities, such as tensile strength and flexural strength, the selection of adequate processing parameters is critical. Experimentally, the influence of process parameters such as the raster angle, printing orientation, air gap, raster width, and layer height on the tensile strength of fused deposition modeling printed items was examined in this work. Through analysis of variance, the impact of each parameter was measured and rated. The system’s response was predicted using an adaptive neuro-fuzzy technique and an artificial neural network. In Minitab software, the Box-Behnken response surface experimental design was used to generate 46 experimental trials, which were then printed using acrylonitrile butadiene styrene polymer materials on a three-dimensional forge dreamer II fused deposition modelling printing machine. The results revealed that the raster angle, air gap, and raster width had significant impacts on the tensile strength. The adaptive neuro-fuzzy approach and artificial neural network predicted tensile strength accurately with an average percentage error of 0.0163 percent and 1.6437 percent, respectively. According to the findings, the model and experimental data are in good agreement.

Optimization and troubleshooting of preparative liquid chromatography using statistical design of experiments: Four small-molecule case studies

Statistical design of experiments (DoE) is used to aid in the development and execution of preparative liquid chromatography (LC) for large-scale purification of active pharmaceutical ingredients (API) and pharmaceutical intermediates. Four purification case studies were undertaken. In case study 1, a normal phase preparative silica method is developed and modeled. After initial method screening, DoE results were used to set mobile phase composition, flowrate, and sample diluent. Of the three particle sizes studied (10 µm, 20 µm, 50 µm) only 10 µm silica resin was able to produce purified API at the yield (>96%) and productivity (> 1 kg/kg-resin/day) necessitated by the project. The second case study uses DoE studies to identify critical process parameters of column load, mobile phase solvent ratio and basic modifier level for a low-resolution, preparative, chiral separation. Trade-offs between purity, yield and productivity are quantified in a tight separation which made compromising on process outcomes a necessity. The third case study troubleshoots a loss of yield experienced during operation of a process-scale reverse-phase LC purification. DoE is used to identify a critical interaction between levels of acetonitrile and phosphoric acid in the mobile phase. An operating region which increased yield from around 85% to 97% was defined and implemented. The fourth case study was initially designed as a preparative chromatography purification of API. DoE was used to screen mobile phase solubility. These experiments uncovered conditions where API is soluble, and impurities are not. The solubility model in acetonitrile/water mixtures is further defined via a response surface DoE. The resulting targeted solvent mixture allows bulk purification via dissolution of API while three less-polar impurities remain in the solid phase and are removed by filtration. These four case studies demonstrate the efficiency of DoE and response surface modeling as tools for process development and optimization.

Characterization and transformation of nanche stone (Byrsonima crassifolia) in an activated hydrochar with high adsorption capacity towards metformin in aqueous solution

Metformin (MET) is one of the main drugs to treat type 2 diabetes in humans, consequently its presence in the environment has increased in recent years. Therefore, in this work, hydrochars were synthesized from Byrsonima crassifolia stones using hydrothermal carbonization followed by cold chemical activation to enhance the removal of MET in aqueous solution. A response surface experimental design was employed to correlate the experimental adsorption capacity (qMET) with the synthesis conditions (hydrocarbonization time, activation time, and NaOH concentration) and the physicochemical properties of the adsorbents. The results showed that the hydrocarbonization and activation times are the most significant factors influencing the MET removal. According to the textural and physicochemical analyses, it was found that the combination of hydrothermal treatment and cold chemical activation increased both the presence of acid and basic active sites with the O/C ratio, which favored the removal of MET in lignin-rich hydrocarbonized materials. The adsorption equilibrium studies employing the best adsorbent evidenced that MET removal was favored at pH = 7 due to a reduction of repulsive electrostatic interactions that played a main role in the adsorption process. The maximum adsorption capacity obtained was 113.6 mg/g, which was the highest value reported in the literature. Finally, the transformation of the Byrsonima crassifolia stones suggests that the activated hydrochars synthesized by the method proposed in this work results in an effective adsorbent for MET removal in aqueous solution.

Evaluation of mass transfer in packed column for competitive adsorption of Tartrazine and brilliant blue FCF: A statistical analysis

Environmental pollution as the result effluents discharged by industry is increasing, principally owing to mixtures of pollutants, including dyes. The objective of the present study was to evaluate the adsorption process of the bicomponent mixture of Tartrazine (Y5) and Brilliant Blue FCF (B1) dyes in a dynamic regime (fixed-bed column), using rice husks (RH) as adsorbent material. A 3-level response surface design of experiments was employed to evaluate the adsorption process of the dyes in the mixture at the following initial concentrations: 0.0216, 0.0739, 0.1261, 0.1477 (mmol L−1). The response surface analysis of the experimental design made it possible to identify a competitive adsorption of both dyes. RH had higher affinity for B1, although the adsorption capacity changed depending on the concentration of each dye in the mixture. The highest RH adsorption capacity was 3.4 mg g−1 for B1 and 1.45 mg g−1 for Y5, respectively, under a monocomponent condition. It was considered that the interactions in the mechanism proposed for the adsorption process occurred because of the formation of hydrogen bonds between the sulfonate groups of the dyes and the –OH groups present on the surface of the adsorbent. B1 had a higher affinity towards RH because it had one more sulfonate group than Y5. The multiple-response optimization results make it possible to recommend the use of RH beds with low concentrations of B1 and Y5 in the same feed.

Optimization of the Subcritical Butane Extraction of Tung Oil and Its Mechanism Analysis

Tung oil is an important dry grease. In order to overcome the deficiencies of traditional processes in oil production, the preparation of tung oil was carried out by the butane-subcritical method. A response surface optimization experiment was carried out based on Design-Expert software, and the best process parameters were obtained. The extraction temperature was 42.98 °C, the extraction time was 43.77 min, the particle size of the raw material was 38.88 mesh, and the oil yield of tung oil under this condition reached 67.437%. The fatty acid composition of tung oil was analyzed by Gas Chromatography-Mass Spectrometry (GC-MS): the content of α-oleostearic acid was 74.99%, linoleic acid content was 8.83%, oleic acid content was 7.42%, palmitic acid content was 2.02%, and stearic acid content was 4.35%. Through the analysis of the oil sample obtained, five indicators showed that the process of obtaining oil products met the requirements of the national standard. By simulating the subcritical n-butane/tung oil dissolution equilibrium model, the miscible dynamic equilibrium of tung oil in subcritical n-butane was studied at temperatures in the range of 35–50 °C and an equilibrium time of 40 min, and the kinetic equations of oil extraction at different temperatures were obtained, with a coefficient of determination (R2) greater than 0.99. The oil extraction rate was up to 67.12 ± 0.05% under optimal extraction conditions through the optimization of univariate and response surface experimental design. Using 1stOpt data processing software, the data of tung oil extraction rate at different times were fitted, and it was found that the Patricelli model accurately elucidated the kinetic process of tung oil extraction through subcritical n-butane, with R2 greater than 0.99.