Response Surface Central Composite Design Research Articles

A new robust theoretical prediction model for flange wrinkling in conventional spinning

Flange wrinkling is one of the most common defects affecting the forming quality of workpieces in conventional spinning. To this end, the flange wrinkling mechanism is analyzed and a new robust theoretical prediction model for the flange wrinkling is developed in this work. It is found that the initiation of flange wrinkling is closely related to the excessive circumferential compressive stress in the zone affected by the roller action rather than the whole flange. Then, a theoretical model for the critical circumferential stress producing flange wrinkling is developed based on the generalized variational principle of limit analysis. By comparing the instant maximum circumferential stress in the zone affected by the roller action with the calculated critical stress, the flange wrinkling can be predicted. Compared with the prediction model based on energy method, the main improvements of the new model can be summarized as follows. First of all, the incremental displacement amplitude of deflection mode in the effective compressive region, which dramatically affects the critical stress but overlooked in the model based on energy method, is considered in the new model. Secondly, the sheet blank is regarded as a rigid plastic material in the new model, so the calculation of elastoplastic matrix which is very sensitive to the mechanical states does not need to be considered, thereby avoiding the adverse effect of the extraction deviation of mechanical states on prediction accuracy. Thus, compared with the prediction model based on energy method, the new model has higher prediction accuracy and better robustness under the extraction deviation of mechanical states. In addition to realizing the prediction of flange wrinkling, the new model can also be used to analyze the influence of sheet blank geometric parameters and material parameters on the initiation of flange wrinkling under various forming conditions. In view of this, the new model is applied to reveal the influence of material parameters (material strengthening coefficient K, hardening index n and elastic modulus E) on the initiation of flange wrinkling by combining response surface methodology and central composite design (CCD). The results show that K has the greatest influence on the initiation of flange wrinkling, followed by E and n. Considering the interaction between the parameters, the interaction between K and E also has a greater effect on the initiation of flange wrinkling. The smaller E and larger K are helpful to reduce the risk of flange wrinkling. Changing the value of n has no significant effect on delaying the occurrence of flange wrinkling. The results can deepen the understanding on the prediction and rules of flange wrinkling in conventional spinning.

Preparation and in vitro quality evaluation of curcumin supersaturated self-nanoemulsion

In order to improve the supersaturation and maintenance time of drug dispersion in curcumin self-nanoemulsion(CUR-SNEDDS), precipitation inhibitors(PPIs) were introduced to prepare curcumin supersaturated self-emulsion(CUR-SSNEDDS). The composition of CUR-SNEDDS prescriptions was selected through the solubility test, the compatibility of oil phase and surfactant, the investigation of the emulsifying ability of the surfactant and the drawing of the pseudo-ternary phase diagram. Analytic hierarchy process was used in combination with central composite design-response surface method to optimize the prescription. The type and dosage of precipitation inhibitors(PPIs) were selected to maintain the supersaturated concentration and duration of CUR in artificial gastrointestinal fluids. At the same time, polarizing microscope was used to evaluate the crystallization inhibition effect and the quality and in vitro release behavior of CUR-SSNEDDS. The prepared CUR-SSNEDDS prescription was capryol 90-kolliphor RH40-transcutol HP-Soluplus(7.93∶66.71∶25.36∶5), with the drug loading of(65.12±1.25) mg·g~(-1). CUR-SSNEDDS was transparent yellow, and the nanoemulsion droplets were spherical with uniform distribution. The emulsification time was(21.02±0.13) s, the average particle size was(57.03±0.35) nm, the polydispersity index(PDI) was(0.23 ± 0.01), and the Zeta potential was(-18.10±1.30) mV. CUR-SSNEDDS significantly inhibited the generation and growth of crystals after in vitro dilution. The supersaturation could be maintained above 10 within 2 h, and the dissolution rate and degree of CUR in artificial gastrointestinal fluid were significantly increased. Soluplus could effectively maintain the supersaturated state of CUR and enhance CUR dissolution in vitro.

Coupled CAD-CFD automated optimization for leading and trailing edge of an axial impulse turbine blade

A bidirectional impulse turbine with fixed guide vanes is used in an oscillating water column to extract wave energy. The turbine suffers from low aerodynamic efficiency, and it is required to improve performance. In the present study, coupled CAD-CFD automated optimization of the blade leading and trailing edge ratio was performed to maximize the efficiency. The design points were generated using a central composite design sampling technique and response surface optimization method estimated the optimum design. The optimization pipeline was automated using the Ansys Design Exploration module. Ansys Turbo Grid was used for generating structured hexahedral elements in the computational domain, and the problem was solved in Ansys CFX® v16.2. The results showed that the modified leading and trailing edge enhanced the performance compared to the reference blade by minimizing the pressure drop. The optimized design improved the relative peak efficiency and torque by 3.4% and 2% respectively. Additionally, a detailed flow analysis has been reported in this paper.

Media optimization for C-phycocyanin production in Plectonema sp. using response surface methodology and central composite design

Cyanobacteria represent the richest sources of phycobiliproteins with especial reference to C-phycocyanin (C-PC), which in turn holds exhaustive therapeutic implications. Screening of several cyanobacterial strains namely Anabaena sp., Nostoc muscorum, Cylindrospermum sp., Plectonema sp., Scytonema sp., Spirulina sp., Synechococcous sp. and Tolypothrix sp. was carried out for their C-PC producing capacity, however the produced quantity of C-PC varies greatly among different strains. Owing to the crucial role of different media constituents on productivity of C-PC the current study was designed to optimize most appropriate media composition for augmented CPC production by selected superior producer. 36 factorial central composite design (CCD) dependent response surface methodology (RSM) was utilized to estimate the important medium components attributed with influencing C-PC productivity. RSM analysis of five independent coded factors including Na2CO3, K2HPO4, NaNO3, citric acid and EDTA were analyzed preceded by recognition of efficient variables for algal components production by Plectonema sp. Investigation of results revealed that the eminent medium components were NaCO3 (0.4 g/L); NaNO3 (0.5 g/L); K2HPO4 (2.8 g/L); citric acid (0.08 g/L) and EDTA (0.01 g/L) respectively. The optimized combination yielded 0.5536 mg/ml of C-PC. The increment of C-PC yield is R-Sq = 88.2%. Thus, our study led to the recognition of critical nutritional component that can be used further for enhanced productivity of C-PC.

Generating Organic Liquid Products from Catalytic Cracking of Used Cooking Oil over Mechanically Mixed Catalysts

Used cooking oil is unsuitable to use again in the food process, but it may be harnessed as raw material in biofuel production. In this work, used palm oil was reactedvia cracking over mechanically mixed catalystsbetween ZSM-5 and Y-Re-16to generate organic liquid products (OLP). The catalysts used were known for highacidity and lowcost for decomposition, degradation,and deoxygenation of triglycerides. The cracking experiments were conducted in a flow reactor. The experimental variables included reaction temperature between 300-500°C, catalyst loading between 5-20 % w/w, and ratio of mixed catalyst between ZSM-5 and Y-Re-16 from 0-100 % w/w. They were setvia response surface methodology and central composite design of experiments. Both catalysts showed good cracking reaction. The optimum condition for generating the OLP of about 85 % w/w was found at 300°C, 5 % catalyst loading, 97 % ratio of mixed catalyst. The OLPs with different short-chain hydrocarbons between C7-C21 were identified. The main components were 71.43% of diesel, 12.11% of gasoline, and 8.95% of kerosene-like components.

Optimization and validation of automated solid-phase microextraction arrow technique for determination of phosphorus flame retardants in water.

In the present work, a very sensitive and fully automated direct immersion PAL SPME Arrow procedure, coupled with GC-MS, has been developed and validated for determination of nine phosphorus flame retardants in different types of water samples (river, drinking and rainwater). PDMS/DVB was selected among three commercially available SPME Arrows (PDMS/DVB, DVB/PDMS/CWR and PDMS/CWR), since it resulted in the best sensitivity. The important experimental parameters were optimized via a central composite design response surface methodology and as result, extraction time of 65min, extraction temperature of 80 °C and added salt concentration of 19% (w/v), were selected as the optimum values. The optimized method showed linear response over the calibration range (2 - 500ng L-1), with R2-values higher than 0.9937. The precision (RSD%) measured by replicate analyses (n=7) was estimated at 2 and 100ng L-1 and was less than 29% and 21%, respectively. The LOQ of PAL SPME Arrow, calculated as S/N=10, was between 0.2 and 1.2ng L-1 (for triphenyl phosphate and tris-(1‑chloro‑2-propyl) phosphate, respectively) with extraction efficiencies between 5.9 and 31% (for tris-(1,3-dichloro-2-propyl) phosphate and tri-n‑butyl phosphate, respectively). To assess the performance of the developed technique for real samples, two river water samples, tap water from two regions and a rainwater sample were analyzed. Most of the target analytes were observed in the river samples with concentrations of 1.0 - 250ng L-1 and the obtained recoveries at 50ng L-1 ranged between 60 and 107%. Considering the figures of merit of the optimized method, PAL SPME Arrow-GC-MS showed to be the most sensitive analytical approach for determination of phosphorus flame retardants in water, with satisfying precision and accuracy, compared with conventional SPME-NPD, LLE-GC-MS and SPE-LC-MS/MS.

Concentrated Leachate Treatment by Electro-Fenton and Electro-Persulfate Processes Using Central Composite Design

Current work deals with the treatment of leachate nanofiltration concentrate which was exposed to ultrafiltration membrane treatment following anaerobic biological process and nitrification–dentrification process before. Advanced electrocoagulation processes [electro-Fenton (EF) and electro-persulfate (EF)] were applied to the wastewater characterized by high inert COD content arising from resistant organic matter. Response surface methodology and central composite design were employed for modeling and optimizing the processes. Adequacy of the model was examined by application of variance analysis that verified the conformity of experimental and predicted data. Under statistically obtained optimized conditions for COD removal (H2O2/COD ratio 1.42, current 2.27 A, pH 2.9, and reaction time 30.3 min for EF; and S2O8−2/COD ratio 1.72, current 1.26 A, pH 5.0 and reaction time 34.8 min for EP processes), predicted COD removal efficiencies were determined to be 67.1% and 72.6% for EF and EP treatments, respectively. By performing experimental sets for validation, 60.8% and 71.4% COD removals through EF and EP processes were obtained under these conditions. NF concentrate COD fractions were also determined before and after treatment processes. Soluble COD fraction increased from 71.4 to 83.2% and 87.7% whereas biodegradable COD fraction increased from 12.2 to 19.2% and 32.5% after EF and EP processes, respectively. Results of the study showed that both EF and EP processes were efficient alternatives for leachate NF concentrate treatment but EP process can be preferred due to lower energy consumption.

Modeling of chromium (VI) removal from aqueous solution using modified green-Graphene: RSM-CCD approach, optimization, isotherm, and kinetic studies.

The aim of this study was to investigate the removal of Cr (VI) using Green-Graphene Nanosheets (GGN) synthesized from rice straw. Synthesis of the GGN was optimized using response surface methodology and central composite design (CCD). The effect of two independent variables including KOH-to-raw rice ash (KOH/RRA) ratio and temperature on the specific surface area of the GGN was determined. To have better removal of Cr (VI), GGN was modified using the grafting amine group method. In the Cr (VI) removal process, the effects of four independent variables including initial Cr (VI) concentration, adsorbent dosage, contact time, and initial solution pH were studied. The results of this study showed that the optimum values of the KOH/RRA ratio and temperature for the preparation of GGN were 10.85 and 749.61°C, respectively. The maximum amount of SSA obtained at optimum conditions for GGN was 551.14 ± 3.83m 2 /g. The optimum conditions for Cr (VI) removal were 48.35mg/L, 1.46g/L, 44.30min, and 6.87 for Cr (VI) concentration, adsorbent dosage, contact time, and pH, respectively. Based on variance analysis, the adsorbent dose was the most sensitive factor for Cr (VI) removal. Langmuir isotherm (R2 = 0.991) and Pseudo-second-order kinetic models (R2 = 0.999) were the best fit for the study results and the Q max was 138.89mg/g. It can be concluded that the predicted conditions from the GGN synthesis model and the optimum conditions from the Cr (VI) removal model both agreed with the experimental findings.

Development of carbon fibre reinforced polymer matrix composites and optimization of the process parameters for railcar applications

The potential use of carbon fibre for railcar application stems from its excellent properties such as high strength to weight ratio and fire retarding abilities. This work studies the development of carbon fibre reinforced epoxy matrix composites and the optimization of the process parameters for railcar applications. Using the transfer moulding process, the composite comprising of mixture of double layers of polyacrylonitrile (PAN) based carbon fibre as reinforcement, epoxy resin which serves as the binder to form the matrix and silica additives were prepared and cured in a mould. The numerical experiment was performed using the Response Surface Methodology (RSM) and central composite design (CCD) comprising of two factors namely; the curing temperature (100–180 °C) and curing time (6–24 h). The statistical analysis of the numerical and physical experimentations were used to obtain a predictive model that correlates the tensile strength as a function of the curing temperature and curing time. There is a high degree of correlation between the results obtained from both the numerical and physical experimentations which implies that the developed model is suitable for predictive and correlative purposes. In addition, the results of the mechanical properties of the developed composite material indicate high tensile strength under varying loading conditions. This is an indication that the material possesses good strength and stiffness which makes the composite suitable for railcar applications. This work bring about the development of carbon fibre reinforced polymer and the determination of its mechanical properties for railcar applications.

Design characteristics of perforated tray aerator

AbstractThe performance of the perforated tray aerator (PTA) was evaluated by conducting experiments in a tank of size 4 m × 4 m × 1.5 m. Based on the dimensional analysis, non-dimensional numbers related to geometric variables, viz. numbers of trays (n), ratio of consecutive width of tray to total height of aerator , ratio of perforation diameter to total height of aerator and ratio of the volume of water in the tank to total height of aerator were developed. Experiments were conducted with different numbers of trays (n): 1, 2, 3 and 4, keeping = 0.33, = 2.5 × 10−4, = 2,500 and pump flow rate (Q) = 0.010 m3/s as constants. The optimum number of perforated trays was found to be 3. Response surface methodology (RSM) and central composite rotatable design (CCRD) were used to further optimize the geometric variables with combinations of non-dimensional geometric variables , and . The flow rate (Q) of 0.013 m3/s and number of trays (n) as 3 were kept as constants. The optimum performance of PTA was obtained at = 0.665, = 1.85 × 10−4 and = 312.50 with the maximum non-dimensional standard aeration efficiency (NDSAE) and standard aeration efficiency (SAE) of 35.58 × 10−3 and 1.45 kgO2/kWh.

Hydrothermal pretreatment and acid hydrolysis of coconut pulp residue for fermentable sugar production

Coconut pulp residue is the waste generated after the extraction of milk and oil. This material became an interest as feedstock for the production of biofuels and other bioproducts in a biorefinery context. The present study aimed to improve the release of sugar from coconut pulp residue through the optimization of sequential hydrothermal and acid pretreatment. An experimental design was constructed with the central composite design (CCD) response surface method using factors of the hydrothermal residence time of 20, 40, 60min and post-acid treatment concentration of 1%, 2% and 3% (v/v) in constant temperature and time of 121°C and 20min. Total sugar yields of 32.47, 27.51 and 26.72g/L were observed after hydrothermal pretreatment time of 20, 40 and 60min, respectively. Furthermore, when the pretreated solid residues were subjected to acid pretreatment, the results revealed an increment of 90% on reducing sugars after reaction with 1%, 2% and 3% H2SO4. Statistically, the optimum condition for the two-stage hydrolysis of coconut pulp residue was 60min hydrothermal pretreatment followed by 3% H2SO4 acid hydrolysis with maximal reducing sugar release of 120.71g/L. In addition, the degree of polymerization achieved was 1.2, indicating no further hydrolysis required. The current study demonstrates that two-stage pretreatment improves saccharification and provide sufficient sugars for the fermentation process.

Removal of malachite green by polyacrylamide-g-chitosan γ-Fe2O3 nanocomposite-an application of central composite design

The material PACT@γ-Fe2O3 was synthesized via oxidative free radical polymerization of acrylamide monomer in presence of γ-Fe2O3 nanoparticles as a filler by grafting with chitosan biopolymer. The utility of the material was explored towards the removal of malachite green (MG) dye from the wastewater. Various kind of process variables were optimized by well-known statistical tool termed as response surface methodology (RSM) and central composite design (CCD). The optimized variables obtained by CCD were found to be contact time 170.28 min, pH 6, adsorbent dose 0.75 g, MG concentration of 60 mg L−1. Under these optimized conditions, the predicted removal percentage of MG dye by PACT@γ-Fe2O3 was calculated 77% which agrees well with the experimental value of 73% with desirability of 1.0. Based on the mathematical model application, it was observed that the experimental data verily inclines in direction of the Langmuir model with variable temperature conditions (298–318 K). The dynamics of the reaction defines that the mechanism of uptake of MG molecules by using PACT@γ-Fe2O3 take place through the formation of a coordination bonds between the solute and the material within the liquid perimeter.

Extraction of pectin from agroindustrial residue with an ecofriendly solvent: use of FTIR and chemometrics to differentiate pectins according to degree of methyl esterification

Pectins are members of the more complex class of high molecular weight heteropolysaccharides. They consist mainly of (1 → 4)-linked α-d-galacturonic acid residues, which may be partially methyl esterified. The quantity of methyl esterified groups throughout the chain influences the physico-chemical characteristics of the pectin, especially in terms of complexation and gel formation. There have been many studies of pectin extraction, but each experimental condition confers different characteristics to the product. This work used a green solvent (citric acid solution) and an ultrasonic bath to extract pectin from passion fruit peel, an important agroindustry waste. Response surface methodology and central composite design were used to evaluate the yield of pectin. Principal component analysis was applied to FTIR spectra in order to distinguish pectins according to their degree of methyl esterification.

Optimization of rare earth carbonate reactive-crystallization process based on response surface method

Rare earth carbonate precipitation is mainly amorphous, of large volume and difficult to filter. To prepare crystalline rare earth carbonate, mother liquor of heavy rare earth was taken as research object, and the experimental scheme was designed based on the response surface central composite design (CCD) method. The concentration of mother liquor, aging time and seed crystal dosage were taken as independent variables, and the particle size of rare earth carbonate was taken as the response value to establish a quadratic polynomial numerical model to optimize the reactive-crystallization process of rare earth carbonate. The results show that these three factors have significant effect on the particle size of rare earth carbonate, and the influence order is mother liquid concentration > aging time > seed crystal dosage. Moreover, the interaction between mother liquor concentration and seed crystal dosage has a significant effect on the size of rare earth carbonate particles. The optimal parameters predicted by the model are as follows: the concentration of mother liquid is 1.75 g/L, seed crystal dosage is 13.56 wt%, and aging time is 8 h. Under these conditions, the predicted particle size is 28.74 μm, and the experiment particle size is 28.23 μm, between both, the relative error is 0.73%, which indicates that the established response surface model has a good prediction effect and a certain practical significance to guide the reactive-crystallization process of rare earth carbonate. The obtained rare earth carbonate has a crystallinity of 97.82%, uniform particles size, and low-hydrated crystals with a tengerite structure.

Formulation and characterization of voriconazole nanospray dried powders

Purpose: Voriconazole nanoparticles (API-NPs) were prepared by nanospray drying to improve the solubility of voriconazole and reduce its interindividual variability.Methods: The preparation procedure was optimized by central composite design-response surface methodology. The properties of the nanoparticles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) analyses. The solubility, dissolution, and stability of the API-NPs were determined experimentally. The pharmacokinetics were assessed based on rat plasma levels of voriconazole. An acute oral toxicity test of the API-NPs was performed in mice.Results: The powers were formulated using cetyltrimethylammonium chloride (CTAC) as the carrier material. SEM and particle size results showed that the API-NPs had a narrow particle size distribution. The XRD, DSC, and FTIR analyses show a decrease in crystallinity and a polymorphic transformation of the nanoparticles after nanospray drying. The solubility in water was approximately 15 times higher than that of voriconazole. The API-NP tablets exhibited significantly higher plasma exposure, namely, longer acting times and lower variability. The acute administration of voriconazole showed no toxic histopathological effects on organ tissue.Conclusion: The solubility of voriconazole was greatly improved, it showed higher bioavailability and safety, and the interindividual variability in voriconazole pharmacokinetics was reduced by nanospray drying.

Influence of different yeast strains on the quality of fermented greengage (Prunus mume) alcoholic beverage and the optimization of fermentation conditions

Three commercial yeast strains (Saccharomyces cerevisiae), namely Angel RV171, Lalvin 71B and Angel BV818, were used for greengage alcoholic beverage (GAB) fermentation. To determine the most suitable yeast strain for the production of GAB, the main physicochemical properties of GAB were monitored, and the sensory characteristics were evaluated. Out of the three strains, Lalvin 71B-fermented GAB with a higher alcohol concentration of 14.31 ± 0.22%, residual sugar content of 5.72 ± 0.16 g/L and total acid content of 9.72 ± 0.12 g/L, presented the highest efficiency and a suitable sugar-acid ratio. The most abundant volatile flavor compounds were detected in the 71B-fermented GAB (290.67 ± 12.75 mg/L). However, the GABs by RV171 and BV818 showed stronger antioxidant and radical scavenging capacity. Combined with the comprehensive sensory evaluation, Lalvin 71B was suggested to be a more suitable strain to produce fermented GAB. Furthermore, response surface design and central composite design were employed to optimize fermentation conditions. The results demonstrated that GAB with higher alcohol content (14.21%) and lower total acid content (8.74 g/L) was produced, under the optimized condition of the juice-water ratio of 3:5, inoculum amount of 0.67 g/kg glutinous rice and fermentation temperature of 24 °C.

Empirical prediction model based process optimization for droplet size and spraying angle during pharmaceutical fluidized bed granulation

The objective of this study was to predict the droplet size and the spraying angle during the process of binder atomization in pharmaceutical fluidized bed granulation using an empirical model. The effects of the binder viscosity, the atomization pressure, and the spray rate on the droplet size and the spraying angle were investigated using a response surface central composite design and analysis of variance. Prediction models for droplet size and spraying angle were then established using stepwise regression analysis and were validated by comparing the measured and predicted values. The results showed that the droplet size model and the spraying angle model were well established, with an R2 of 0.93 (p < 0.0001) and a root mean square error (RMSE) of 10.10, and an R2 of 0.82 (p < 0.0001) and an RMSE of 3.69, respectively. The error between the measured and predicted values of the droplet size and the spraying angle were less than 10%, indicating that the established models were accurate. The results of the present study were significant in predicting the droplet size and spraying angle in the process of pharmaceutical fluidized bed granulation.

Sonophotocatalytic treatment of AB113 dye and real textile wastewater using ZnO/persulfate: Modeling by response surface methodology and artificial neural network

The present study investigates the synergistic performance of the sonophotolytic-activated ZnO/persulfate (US/UV/ZnO/PS) process in the decolorization of acid blue 113 (AB113) dye from aqueous solution and its feasibility for the treatment of real textile wastewater. Decolorization of AB113 solution was modeled by central composite design-response surface methodology (CCD-RSM) and artificial neural network (ANN) approaches and optimized by CCD-RSM and genetic algorithm (GA) approaches. Statistical metrics indicated that both CCD-RSM and ANN approaches seemed satisfactory. However, the results of statistical fit measures indicated a relative superiority of CCD-RSM as compared to the ANN approach. The results of optimization of the process parameters by CCD-RSM and GA approaches appeared to be similar as follows: pH = 6.1, reaction time = 25 min, US power density = 300 W/L, ZnO = 0.88 g/L and PS = 2.43 mmol/L. The synergistic effect of the hybrid US/UV/ZnO/PS process in comparison with its individual processes (US, UV, ZnO, and PS) was found to be 54.3%. Quenching experiments discovered that ▪ and HO are the main oxidizing radicals in a mildly acidic condition of the reaction solution. The removal efficiency of AB113 in the presence of some anions decreased in the order of bicarbonate > sulfate > phosphate > nitrate > chloride. Further, the reusability feasibility of ZnO showed that the ZnO material retained its photocatalytic property after five successive cycles of reusability test, while Zn2+ ion concentration in the reaction solution was measured to be 2.81 mg/L. The findings also indicated that the integrated process application suppresses extremely chemical and electrical costs. The study of the feasibility of the US/UV/ZnO/PS process in the treatment of real textile wastewater was done by determining COD, TOC and BOD5/COD ratio. Results demonstrated that the 96.6 and 97.1% reduction of COD and TOC was achieved after 5 and 7 h reaction time, respectively. The obtained BOD5/COD ratio changed from about 0.15 (for non-treated wastewater) to about 0.61 with increasing reaction time from zero to 90 min. In conclusion, the hybrid US/UV/ZnO/PS system can be proposed as a novel and promising approach to be utilized as a pretreatment technique before a biological treatment process to facilitate the biological treatment of recalcitrant textile wastewater.

Response Surface Methodology to Optimize Methane Production from Mesophilic Anaerobic Co-Digestion of Oily-Biological Sludge and Sugarcane Bagasse

Oily-biological sludge (OBS) generated from petroleum refineries has high toxicity. Therefore, it needs an appropriate disposal method to reduce the negative impacts on the environment. The anaerobic co-digestion process is an effective method that manages and converts organic waste to energy. For effective anaerobic digestion, a co-substrate would be required to provide a suitable environment for anaerobic bacteria. In oily-biological sludge, the carbon/nitrogen (C/N) ratio and volatile solids (VS) content are very low. Therefore, it needs to be digested with organic waste that has a high C/N ratio and high VS content. This study investigates the use of sugarcane bagasse (SB) as an effective co-substrate due to its high C/N ratio and high VS content to improve the anaerobic co-digestion process with oily-biological sludge. The sugarcane bagasse also helps to delay the toxicity effect of the methane bacteria. Batch anaerobic co-digestion of oily-biological sludge was conducted with sugarcane bagasse as a co-substrate in twelve reactors with two-liter capacity, each under mesophilic conditions. The interaction effect of a C/N ratio of 20-30 and a VS co-substrate/VS inoculum ratio of 0.06-0.18 on the methane yield (mL CH4/g VSremoved) was investigated. Before the anaerobic digestion, thermochemical pre-treatment of the inoculum and co-substrate was conducted using sodium hydroxide to balance their acidic nature and provide a suitable pH environment for methane bacteria. Design and optimization for the mixing ratios were carried out by central composite design-response surface methodology (CCD-RSM). The highest predicted methane yield was found to be 63.52 mL CH4/g VSremoved, under optimum conditions (C/N ratio of 30 and co-substrate/inoculum ratio of 0.18).

Optimization and Evaluation of the Thermosensitive In Situ and Adhesive Gel for Rectal Delivery of Budesonide.

Budesonide is a glucocorticoid for the treatment of ulcerative colitis (UC). The current study aims to develop a thermosensitive in situ and adhesive gel for rectal delivery of budesonide. HPMC K4M was selected as the adhesive agent based on the adhesive force and the effect on gel performance. The formulation of gel was optimized by using the central composite design-response surface methodology (CCD-RSM); a mathematical model was successfully developed to predict desired formulations as well as to analyze relationships between the amount of Pluronic F-127, Pluronic F-68, and HPMC K4M and the performances of gel. Based on CCD-RSM, a thermosensitive in situ and adhesive gel consisting of 0.002% budesonide, 0.74% HPMC, 4.87% F-68, and 19.0% F-127 was developed. Furthermore, the in vivo behavior of gel was evaluated in Sprague-Dawley rats. In comparison with budesonide solution, rectal administration of budesonide gel at 0.1mg/kg in rats showed relative bioavailability of 230% with significant increase in rectum uptake.