Response Surface Optimization of Corn Husk Fiber Mercerization Using NaOH

The optimum mercerization parameters for treatment of corn husk using NaOH were analyzed by response surface methodology (RSM). The surface morphology and chemical structures of the raw and NaOH-treated fibers were studied using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) to validate the RSM results. The optimum chemical characteristics of corn husk treated with NaOH obtained when 100g of corn husk biomass was mercerized in 2.5Mol/dm3 NaOH for 8 days were: cellulose -70.51%, hemicellulose -8.99%, lignin -6.54, weight loss – 92.27%, ash content -10.11% and extractive -3.78%. The model summary statistics showed that quadratic model best fitted the optimization analysis. The ANOVA results showed that weight loss, hemicellulose, cellulose and lignin contents of corn husk biomass were affected by retting time, retting concentration and weight of biomass. Cellulose content of corn husk was observed to increase with increment in retting time and retting concentration while the reverse is the case for hemicellulose and lignin contents. The NaOH-treated corn husk has higher cellulose content than the untreated corn husk biomass while the reverse is the case for hemicellulose and lignin. SEM images showed that untreated corn husk biomass has irregular cross-section, non-uniform surface and some impurities while NaOH treated is finely packed together. XRD graphs showed that cellulose is the predominant content of the fiber. The FTIR results also indicated a variation of the peaks of the curves after treatment which favors an increase in the cellulose content.

Post-consumer PET Bottle Recycling: Chemical Dose Optimization

Polyethylene terephthalate (PET) bottles are being used in our daily life and consequently go to the landfills after their use. Additionally, virgin PET resins are produced from nonrenewable resources, such as fossil fuels, whose reserves are depleting continuously. Therefore, to maintain ecological and environmental balances as well as for sustainable development, post-consumer PET (pcrPET) bottles should be recycled. Among many recycling processes, mechanical recycling of pcrPET is attractive due to lower cost involvement. One of the most crucial and important processes of mechanical recycling is hot washing for contaminants removal. Hot washing uses a cleaning solution made of caustic soda (NaOH) and detergent at elevated temperature. In this paper, caustic soda and FORYL LFO (FLO) detergent doses were changed gradually to investigate effective contaminants removal through colorimetric study. Finally, concentration vs. absorbance graphs from colorimetric study suggests that 2% NaOH and 2% FLO detergent is the optimum chemical dose at hot washing for pcrPET recycling.

Phytoremediation of Multi-Metal Contaminated Soil in Iron-Steel Industrial Area with Solanum nigrum L. and Optimized Amendments

The soils in abandoned iron-steel industries contained high concentrations of heavy metals, which adversely affected the environmental quality. In this study, a greenhouse orthogonal (L16) experiment was conducted to investigate the optimal ratio of organic fertilizer, biochar, Maifan stone, attapulgite and phosphate fertilizer assisted with S. nigrum L., aimed to reach the maximum phytoremediation effects. T17 (organic fertilizer:biochar:Maifan stone:attapulgite:phosphate fertilizer = 2:2:2:1:2) was recommended as the optimum chemical proportions of the amendments. The results showed that after the application of amendments, the length and fresh weight of plants increased significantly, the accumulation of heavy metals in plant roots increased, and the transfer to the shoots decreased. The effective fractions of Pb, Zn and Cd were immobilized. The removal rates of heavy metals were the highest after adding the soil amendments in T17, and by the following of Zn (44.0%) > Cd (39.5%) > Pb (36.7%). In conclusion, it was shown that the results of metal phytostabilization can be significantly improved by the synergistic effect of S. nigrum L. and amendments, especially in T17 treatment.

Predictive Modeling of Corrosion in Al/Mg Dissimilar Joint

In the absence of any abnormality (standard conditions), the gradient of any mechanical/thermodynamic stress would be intensified at the dissimilar joint due to an abrupt change in the chemical composition. This paper aims to investigate the effect of delocalizing this stress by imposing an optimum chemical gradient within the dissimilar joint. In this work, we computationally demonstrated that a homogenous distribution of magnesium atoms in the aluminum (100) structure with a specific chemical gradient could potentially reduce the susceptibility of the Mg/Al dissimilar joint towards micro-galvanic corrosion. This is achieved through the minimization of the work function gradient within the dissimilar joint.

An application of integrated EPC–SPC methodology for simultaneously monitoring multiple output characteristics

Purpose The purpose of this paper is to develop an integrated engineering process control (EPC)–statistical process control (SPC) methodology for simultaneously monitoring and controlling autocorrelated multiple responses, namely, brightness and viscosity of the pulp bleaching process. Design/methodology/approach The pulp bleaching is a process of separating cellulose from impurities present in cooked wood chips through chemical treatment. More chemical dosage or process adjustments may result in better brightness but adversely affect viscosity. Hence, the optimum chemical dosage that would simultaneously minimize the deviation of pulp brightness and viscosity from their respective targets needs to be determined. Since the responses are autocorrelated, dynamic regression is used to model the responses. Then, the optimum chemical dosage that would simultaneously optimize the pulp brightness and viscosity is determined by fuzzy optimization methodology. Findings The suggested methodology is validated in 12 cases. The validation results showed that the optimum dosage simultaneously minimized the variation in brightness and viscosity around their respective targets. Moreover, suggested solution has been found to be superior to the one obtained by optimizing the responses independently. Practical implications This study provides valuable information on how to identify the optimum process adjustments to simultaneously ensure autocorrelated multiple responses on or close to their respective targets. Originality/value To the best of the authors’ knowledge, this paper is the first to provide application of the integrated EPC–SPC methodology for simultaneously monitoring multiple responses. The study also demonstrates the application of dynamic regression to model autocorrelated responses.

Modeling the influence of chemical composition on compressive strength behavior of alkali-activated phosphorus slag cement using statistical design

In this study, a statistical experimental design based on response surface methodology (RSM) has been applied to predict and optimize the compressive strength of alkali-activated phosphorus slag in different ages (3, 7, and 28 days). For this purpose, the binder samples were prepared with different molar ratios of SiO2/Na2O (S/N), Na2O/Al2O3(Na/Al), and H2O/Al2O3(H/Al) as alkali activator. Results showed that S/N molar ratio plays its role in early ages of curing and Na/Al molar ratio, and showed its significant effect on 7 and 28 days of compressive strength. H/Al molar ratio had the most significant effect on compressive strength compared to the other parameters. The derived RSM models were statistically adequate and could be used to predict the compressive strength. The optimum chemical composition of activator to obtain the highest compressive strength was achieved as 0.39, 1.34, and 30 for S/N, Na/Al, and H/Al molar ratios, respectively, with compressive strength of 30, 65, and 100 MPa at 3, 7, and 28 days of curing.

COD Removal of Edible Oil Content in Wastewater by Advanced Oxidation Process

Different Advanced Oxidation Processes (Photo Fenton process, Fenton process and H₂O₂/UV) were studied in order to reduce COD from oily compounds aqueous solution using batch system. To get the optimum condition, different variables were studied for each of these processes; such as pH, time, concentration of H₂O₂, concentration of oil, concentration of FeSO₄·7H₂O and temperature as parameters. It was found that the optimal pH value for the three processes was 3 and the optimal temperature was 30^oC for Photo-Fenton and UV/H₂O₂ system and 20^oC for Fenton process. Photo-Fenton process gave a maximum COD reduction of 80.59 % (COD from 2684 to 521 mg/l), Fenton gave 53.22 % (COD from 2587-1130) and the combination of UV/H₂O₂ gave a COD reduction of 22.69 % (COD from 2450 to 1894). The percentage of removal found was after the total reaction time (180 min.). The optimum chemical reagents for Photo-Fenton, Fenton and UV/H₂O₂ were as the following H₂O₂ = 800 mg/l, 1500 mg/l and 2000 mg/l, Fe₂SO₄·7H₂O = 60 mg/l, 100 mg/l.