Modified response surface methodology (MRSM) for phase equilibrium-theoretical background

The effect of molecular interaction energy among different molecules in the mixed solutions significantly depends upon the size of individual molecule size and molecular arrangement. In order to compensate these effects on the existing method, a new method of representing the relationship of temperature and compositions of each phase (vapor and liquid phases in equilibrium) and azeotropic mixture is proposed. The optimized models of the RSM (response surface methodology) and MRSM (modified response surface methodology) are briefly described. The applications of these models to the solution thermodynamics are also explained.     

应用响应曲面优化交联淀粉微球的合成工艺

为了优化采用反相悬浮法合成的交联淀粉微球(CSM)的工艺,采用响应曲面法(RSM)分析了交联剂质量分数、反应温度和引发剂浓度对于CSM品质(溶胀度、平均粒径)的影响,并建立了相应的预测模型。方差分析的结果表明:交联剂质量分数、反应温度和引发剂浓度对于CSM溶胀度和平均粒径这2项指标都有着极为显著的影响。优化所得的较优工艺参数:交联剂质量分数为0.5%,交联温度为48℃,引发剂浓度为3.7 mmol/L。对应的CMS溶胀度及平均粒径的预测值分别为246%和16.5μm。经实验证明:应用响应曲面法所得到的CMS合成工艺参数是可行的。     

Optimization of a continuous ultrasound assisted oxidative desulfurization (UAOD) process of diesel using response surface methodology (RSM) considering operating cost

A continuous-flow ultrasound-assisted oxidative desulfurization(UAOD) of partially hydro-treated diesel has been investigated using hydrogen peroxide-formic acid as simple and easy to apply oxidation system. The effects of different operating parameters of oxidation stage including residence time(2–24 min), formic acid to sulfur molar ratio(10–150), and oxidant to sulfur molar ratio(5–35) on the sulfur removal have been studied using response surface methodology(RSM) based on Box–Behnken design. Considering the operating costs of the continuous-flow oxidation stage including chemical and electrical energy consumption, the appropriate values of operating parameters were selected as follows: residence time of 16 min, the formic acid to sulfur molar ratio of 54.47, and the oxidant to sulfur molar ratio of 8.24. In these conditions, the sulfur removal and the volume ratio of the hydrocarbon phase to the aqueous phase were 86.90% and 4.34, respectively. By drastic reduction in the chemical consumption in the oxidation stage, the volume ratio of the hydrocarbon phase to the aqueous phase was increased up to 10. Therefore, the formic acid to sulfur molar ratio and the oxidant to sulfur molar ratio were obtained 23.64 and 3.58, respectively, which lead to sulfur removal of 84.38% with considerable improvements on the operating cost of oxidation stage in comparison with the previous works.     

Optimization of adhesive strength to plywood of gelatin processed from dorsal skin of yellowfin tuna (<Emphasis Type="Italic">Thunnus albacares</Emphasis>)

Gelatin from yellowfin tuna (Thunnus albacares) dorsal skin was optimized for adhesive strength to plywood using surface response methodology of a central composite design with a dependent variable of adhesive strength (Y, kg _f /cm²) and two independent variables of gelatin concentration (X₁, %) and hardening time (X₂, hrs). From the above design, a maximum adhesive strength of 49.84 kg _f /cm² was obtained under the optimal treatment condition of 15.85% gelatin concentration and 25.68 hr hardening time. The adhesive strength under optimum conditions was 50.93 kg _f /cm². The adhesive strength of the tuna gelatin was shown to be superior to that of bovine and porcine gelatins which had adhesive strengths of 34.75 and 34.9 kg _f /cm², respectively.     

Optimization of ozone bleaching conditions for improving wheat straw pulp quality using response surface methodology

Ozone bleaching conditions for wheat straw soda pulp were optimized using response surface methodology with central composite design. Effect of pH, consistency, and ozone dose on kappa number, brightness, and viscosity was investigated. Optimized process conditions to get minimum kappa number, maximum viscosity, and brightness were obtained as follows: pH 2.08–2.25, pulp consistency 27.4–30.0%, and ozone dose 0.4%. Validation of the model predicted values and experimental values obtained for optimum conditions has the difference of 0.5–2.0%, which shows that the developed model for ozone bleaching of wheat straw pulp is satisfactory.     

The effects of acid leaching on porosity and surface functional groups of cocoa (Theobroma cacao)-shell based activated carbon

Cocoa shell pellets were converted into activated carbon (CSAC) by carbonization at 800 °C followed by activation at 850 °C in CO₂ flow until reaching burn off at approximately 48%. The CSAC was treated with hydrochloric acid (HCl) using response surface methodology (RSM), where the effect of soaking times (1, 2 and 4 h), temperatures (30, 50, 70 °C) and concentration of HCl (0.1, 1 and 2 M) were studied. CSAC treated with 1 M HCl at higher temperatures (>60 °C) yielded CSAC with low ash content (<10%). Acid-treatment process parameters, particularly the reaction temperature, determined the composition and types of functional groups existing in the CSAC. High concentrations of oxygen functional groups were detected in both untreated CSAC and CSAC treated at low acid concentration (1 M). High concentrations of nitrogen functional groups were detected only in CSAC treated at acid concentration (2 M).     

Cr(III) removal from simulated solution using hydrous magnesium oxide coated fly ash: Optimization by response surface methodology (RSM)

Hydrous magnesium oxide coated fly ash (MFA) has environmental remediation potential by providing a substrate for the adsorption of aqueous Cr(Ⅲ). Aqueous Cr(Ⅲ) adsorption onto MFA was examined as a function of MFA dosage, pH and initial Cr(Ⅲ) concentration with the Box-Behnken approach used for experimental design and optimization using response surface methodology (RSM). pH and dosage (dosage and concentration) have significant interactive effects on Cr(Ⅲ) adsorption efficiency. Analysis of variance shows that the response surface quadratic model is highly significant and can effectively predict the experimental outcomes. Cr(Ⅲ) removal efficiency of 98% was obtained using optimized conditions of MFA dosage, pH and initial Cr(Ⅲ) concentration of 1.57 g·L^-1, 4.11 and 126 mg·L^-1, respectively. Cr(Ⅲ) adsorption onto MFA is mainly attributed to the interaction between Cr(Ⅲ) and the functional group -OH of the hydrous magnesium oxide, in all probability caused by chemisorptions. The results of this study can conduce to reveal the interactions between Cr(Ⅲ) pollutant and MFA characteristics, posing important implications for the cost-effective alternative adsorption technology in the treatment of heavy metal containing wastewater.     

Optimizing adsorption of arsenic(III) by NH2-MCM-41 using response surface methodology

Response surface methodology (RSM) was used to optimize process parameters for arsenic (As(III)) removal from aqueous solution using amine-functionalized MCM-41 (NH₂-MCM-41). Four independent variables such as pH, initial metal concentration, temperature and adsorbent dosage were investigated. The optimal conditions to remove As(III) by NH₂-MCM-41 was found to be pH 5.62, initial As(III) concentration 5.00 mg/L, temperature 20 °C and NH₂-MCM-41 dosage 5.00 g/L. XRD, FTIR and SEM analyses testified to the obvious change of the surface morphology and the presence of metal on the sorbent after adsorption.     

Use of surface response methodology to optimize culture conditions for iturin A production by Bacillus subtilis in solid-state fermentation

Response surface methodology (RSM) was employed to optimize the cultivation conditions of Bacillus subtilis S3 for the enhancement of iturin A, a lipopeptide antibiotic used as biological pesticide, production in solid-state fermentation (SSF). The statistic experimental model predicted a maximum iturin production of 11.435 mg/g-wet solid material. Verification of the calculated maximum was done with experiments that were performed in the culture media representing the optimum combination found, and the iturin A production of 11.447 mg/g-wet solid material (average of three repeats) was obtained when B. subtilis S3 was cultivated at 25 °C for 5 days in solid fermentation containing high gluten flour 10 g and rice bran 50 g in addition to glucose 1.15%, KH₂PO₄ 1.27 mM, MgSO₄ 5.08 mM, peanut oil 1.01%, inoculum 19.49% and water content 44.97%. The iturin A production by B. subtilis S3 was increased significantly by 23%, from 9.26 mg/g-wet solid material to 11.447 mg/g-wet solid material when the strain was cultivated in the optimal medium developed by surface response methodology, as compared to medium conventionally developed by one-factor-at-a-time. The yield of iturin A (11.447 mg/g-wet solid material, with 45% moisture content) produced by B. subtilis S3 reported in this study is the highest reported to date for B. subtilis species in SSF. In addition, the use of rice bran as a substrate in solid-state fermentation for iturin A production by B. subtilis is unique.     

响应面法优化产低温脂肪酶工程菌Cl02的发酵条件

目的采用响应面法优化产低温脂肪酶工程菌Cl02的发酵条件。方法通过单因素试验考察培养基中酵母氮源含量、pH值、甘油含量和甲醇含量对酶活的影响,确定产酶的主要影响条件,在此基础上,根据Box-Benheken中心组合试验设计原理,采用三因素三水平的响应面分析法,综合考察各因子对低温脂肪酶酶活的影响,建立低温脂肪酶酶活的二次回归模型。结果培养基中酵母氮源含量、pH值和甲醇含量对酶活的影响显著。最适产低温脂肪酶条件为:酵母氮源含量7.3 g/L、pH 6.0、甲醇含量9.1 g/L,在此条件下,低温脂肪酶酶活可达42.25 IU/ml,比优化前(28.0 IU/ml)提高了50.9%。结论利用响应面法优化的发酵条件可显著提高工程菌的产酶能力,为规模化生产低温脂肪酶奠定了基础。     

Experiment research on mix design and early mechanical performance of alkali-activated slag using response surface methodology (RSM)

To enhance the quality of alkali-activated slag (AAS) materials, scientific and efficient mix design method is preferred. This paper presents an optimization of AAS materials using Response Surface Methodology (RSM). Three factors related to early strength such as modulus (n), concentration of alkali activator (CAA) and liquid–solid ratio (LSR) were investigated. Specimens with different mix ratios were prepared based on RSM design. The early mechanical performance was assessed, after 2 or 3 h of curing. Then response surface models were established and the effect law of each factor was systemically analyzed. The result shows that both n and CAA have a significant effect on the early strength, while LSR affects slightly. By adjusting the mix design parameters, the early performance of AAS can be effectively improved. This study verifies that RSM is efficient in the preparation of AAS and it can control the early strength of AAS accurately.     

Optimization of photooxidative removal of p-nitrophenol in a spinning disc photoreactor using response surface methodology

In this article, response surface methodology (RSM) was used to obtain optimum conditions for removal of p-nitrophenol (PNP) by UV/H₂O₂ process using spinning disk photoreactor (SDP). For this purpose, the effect of five independent variables, the initial concentration of PNP, the initial concentration of H₂O₂, pH, solution volume, and irradiation time on the PNP removal percent, was investigated. Central composite design, one of the response surface techniques used for process optimization. The results showed a good agreement between the RSM predicted and experimental data with “R²” and “Adjusted R²” of 0.9692 and 0.9480, respectively. In addition, “Predicted R²” of 0.8909 is in reasonable agreement with “Adjusted R²” of 0.9488. At optimal conditions, that is, PNP concentration of 20.78?mg L^?1, H₂O₂ concentration of 1355.83?mg L^?1, solution volume of 566.08?mL, irradiation time of 12.30?min, and pH of 4.59 the removal percent predicted by RSM is 100% which has good correspondence with its experimental value (98.67%).     

Optimization by response surface methodology (RSM) for toluene adsorption onto prepared acid activated clay

Adsorption of toluene onto acid activated clay was carried out. Modified clay was prepared by acid attack (H₂SO₄) on raw material. Response surface methodology based on a 2‐level, 4‐variables central composite orthogonal design was used to evaluate the effects of important parameters on the adsorption of toluene on to activated clay. Temperature (53.8–96.2°C), contact time (0.57–6.93 h), mass ratio of liquid/solid (3.38–7.62) and strength of acid (7.75–57.24%) were chosen as process variables for the optimization. Of these parameters, temperature reaction and time had greater impact on toluene adsorption than did the other parameters. Analysis of variance (ANOVA) shows a good agreement between theoretical analysis and experimental data. The validity of model is verified by an experiment at the optimum conditions. The optimum conditions for the maximum adsorption of toluene onto activated clay are: temperature of 96.2°C, a contact time of 6.93 h, a liquid/solid ratio of 5.98 and strength of acid of 32.94%. Since the predicted values and the actual experimental value obtained for the maximum adsorption of toluene are within 95% confidence intervals, the final model is considered valid and has satisfactory predictive ability.     

Optimization of CO2 capture process with aqueous amines using response surface methodology

Amine is one of candidate solvents that can be used for CO₂ recovery from the flue gas by conventional chemical absorption/desorption process. In this work, we analyzed the impact of different amine absorbents and their concentrations, the absorber and stripper column heights and the operating conditions on the cost of CO₂ recovery plant for post-combustion CO₂ removal. For each amine solvent, the optimum number of stages for the absorber and stripper columns, and the optimum absorbent concentration, i.e., the ones that give the minimum cost for CO₂ removed, is determined by response surface optimization. Our results suggest that CO₂ recovery with 48 wt% DGA requires the lowest CO₂ removal cost of $43.06/ton of CO₂ with the following design and operating conditions: a 20-stage absorber column and a 7-stage stripper column, 26 m³/h of solvent circulation rate, 1903 kW of reboiler duty, and 99°C as the regenerator-inlet temperature.     

Optimization of process conditions using response surface methodology for the microwave-assisted transesterification of Jatropha oil with KOH impregnated CaO as catalyst

A transesterification reaction of Jatropha curcas oil with methanol in the presence of KOH impregnated CaO catalyst was performed in a simple continuous process. The process variables such as methanol/oil molar ratio (X₁), amount of catalyst (X₂) and total reaction time (X₃) were optimized through response surface methodology, using the Box–Behnken model. Within the range of the selected operating conditions, the optimal ratio of methanol to oil, amount of catalyst and total reaction time were found to be 8.42, 3.17% and 67.9 min, respectively. The results showed that the amount of catalyst and total reaction time have significant effects on the transesterification reaction. For the product to be accepted as a biodiesel fuel, its purity must be above 96.5% of alkyl esters. Based on the optimum condition, the predicted biodiesel conversion was 97.6% while the actual experimental value was 97.1%. The above mentioned results demonstrated that the response surface methodology (RSM) based on Box–Behnken model can well predict the optimum condition for the biodiesel production.     

Lipase-catalyzed synthesis of isoamyl butyrate: Optimization by response surface methodology

Immobilized lipase from Mucor miehei (Lipozyme IM-20) was employed in the esterification of butyric acid and isoamyl alcohol to synthesize isoamyl butyrate in n-hexane. Response surface methodology based on five-level, five-variable central composite rotatable design was used to evaluate the effects of important variables—enzyme/substrate (E/S) ratio (5–25 g/mol), acid concentration (0.2–1.0 M), alcohol concentration (0.25–1.25 M), incubation period (12–60 h), and temperature (30–50°C)—on esterification yield of isoamyl butyrate. In the range of parameters studied, the extent of esterification decreased with temperature, lower E/S ratios, and incubation periods. Excess acid and alcohol concentrations (i.e., acid/alcohol >1.4 or alcohol/acid >1.4) were found to decrease yield probably owing to inhibition of the enzyme by acid or alcohol, the former being more severe. The optimal conditions achieved are as follows: E/S ratio, 17 g/mol; acid concentration, 1.0 M; incubation period, 60 h; alcohol concentration, 1.25 M; and temperature, 30°C. With these conditions, the predicted value was 1.0 M ester, and the actual experimental value was 0.98 M.     

Synthesis and surface properties of N-dodecyl-N,N-bis[3-(aldonamido)propyl]amine-N-oxides

A new group of saccharide surfactants, N-dodecyl-N,N-bis[3-(aldonamido)propyl]amine-N-oxides (derivatives of d-gluconic, d-glucoheptonic, and lactobionic acids), were synthesized with high yields by one-step oxidation reaction of an appropriate N-dodecyl-N,N-bis[3-(aldonamido)-propyl]amine with an excess of 30 wt% of an aqueous solution of hydrogen peroxide. Their structures and purity were confirmed by means of elemental analysis, electrospray ionization mass spectrometry, and ¹H and ¹³C nuclear magnetic resonance spectroscopy. In comparison to an appropriate N-dodecyl-N,N-bis[3-(aldonamido)propyl]amine, the investigated N-oxides are more soluble in water with similar critical micelle concentration values and show higher surface effectiveness. They are low-foamable but in mixtures with sodium dodecyl sulfate form high-volume and stable foams in a wide range of mixture compositions.     

Growth rate,yield and nitrogen uptake response of grain sorghum (Sorghum bicolor (L) Moench) to nitrogen rates in humid subtropics

Field experiments were conducted during wet seasons (June to October) of 1974, 1976 and 1977 to determine the response of newly developed hybrids and varieties of grain sorghum to N fertilization under humid subtropical conditions of Pantnagar in India. In addition to the enhancement in flowering and maturity stages brought about by N application, it also resulted in increased plant dry weight, translocation coefficients, grain yield plant^–1 and grain yield ha^–1. Varietal differences existed with respect to their responses for yield and N uptake to N rates. Most of the entries responded up to 120 kg N ha^–1. Hybrid CSH 5 utilized applied N more efficiently than other varieties.Publication No 1612 of GBPUA and T, Experiment Station, Pantnagar.     

Chemical basis for interspecific responses to sex pheromones ofTrogoderma species (Coleoptera: Dermestidae)

Interspecific responses among severalTrogoderma species have been correlated with their pheromone components. The most important component emitted by four of the species is (Z)- or (E)-14-methyl-8-hexadecenal, which is not detectable in extracts of macerated beetles. The response to macerated beetles is probably due to the corresponding alcohol and ester. The recency of common origin of seven species is discussed.     

Optimization of the Culture Medium Composition to Improve the Production of Hyoscyamine in Elicited Datura stramonium L. Hairy Roots Using the Response Surface Methodology (RSM)

Traditionally, optimization in biological analyses has been carried out by monitoring the influence of one factor at a time; this technique is called one-variable-at-a-time. The disadvantage of this technique is that it does not include any interactive effects among the variables studied and requires a large number of experiments. Therefore, in recent years, the Response Surface Methodology (RSM) has become the most popular optimization method. It is an effective mathematical and statistical technique which has been widely used in optimization studies with minimal experimental trials where interactive factors may be involved. This present study follows on from our previous work, where RSM was used to optimize the B5 medium composition in [NO(3-)], [Ca(2+)] and sucrose to attain the best production of hyoscyamine (HS) from the hairy roots (HRs) of Datura stramonium elicited by Jasmonic Acid (JA). The present paper focuses on the use of the RSM in biological studies, such as plant material, to establish a predictive model with the planning of experiments, analysis of the model, diagnostics and adjustment for the accuracy of the model. With the RSM, only 20 experiments were necessary to determine optimal concentrations. The model could be employed to carry out interpolations and predict the response to elicitation. Applying this model, the optimization of the HS level was 212.7% for the elicited HRs of Datura stramonium, cultured in B5-OP medium (optimized), in comparison with elicited HRs cultured in B5 medium (control). The optimal concentrations, under experimental conditions, were determined to be: 79.1 mM [NO(3-)], 11.4 mM [Ca(2+)] and 42.9 mg/L of sucrose.