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Gold is one of the precious metals with multiple uses, whose deposits are much smaller than the global production needs. Therefore, extracting maximum gold quantities from industrial diluted solutions is a must. Am-L-GA is a new material, obtained by an Amberlite XAD7-type commercial resin, functionalized through saturation with L-glutamic acid, whose adsorption capacity has been proved to be higher than those of other materials utilized for gold adsorption. In this context, this article presents the results of a factorial design experiment for optimizing the gold recovery from residual solutions resulting from the electronics industry using Am-L-GA. Firstly, the material was characterized using atomic force microscopy (AFM), to emphasize the material’s characteristics, essential for the adsorption quality. Then, the study showed that among the parameters taken into account in the analysis (pH, temperature, initial gold concentration, and contact time), the initial gold concentration in the solution plays a determinant role in the removal process and the contact time has a slightly positive effect, whereas the pH and temperature do not influence the adsorption capacity. The maximum adsorption capacity of 29.27 mg/L was obtained by optimizing the adsorption process, with the control factors having the following values: contact time ~106 min, initial Au(III) concentration of ~164 mg/L, pH = 4, and temperature of 25 °C. It is highlighted that the factorial design method is an excellent instrument to determine the effects of different factors influencing the adsorption process. The method can be applied for any adsorption process if it is necessary to reduce the number of experiments, to diminish the resources or time consumption, or for expanding the investigation domain above the experimental limits.

Tolerance design plays a very important in any manufacturing process because this activity directly influences products cost and quality. In design activity the designer solve the quality problems selecting tight tolerances for components but this generates cost increasing. The practical problem is to assure the high quality characteristics using the maximum tolerances for components that influence them. The paper’s aim is to find optimal parameters setting which assure the desire value of quality characteristics using the DoE (Design of Experiments), and to find a mathematical model and a respective quality characteristic function of the parameters that it was influenced. Using the mathematical function, by imposing the desired tolerance for quality characteristic, it will be allocated the optimal tolerance for components. This tolerance allocation will be verified using Monte-Carlo method.

The rare metals' potential to pollute air, water, soil, and especially groundwater has received lot of attention recently. One of the most common rare earth group elements, lanthanum, is used in many industrial branches, and due to its toxicity, it needs to be eliminated from all residual aqueous solutions. The goal of this study was to evaluate the control of the adsorption process for lanthanum removal from aqueous solutions, using cellulose, a known biomaterial with high adsorbent properties, cheap, and environment friendly. The cellulose was chemically modified by functionalization with sodium β-glycerophosphate. The experimental results obtained after factorial design indicate optimum adsorption parameters as pH 6, contact time 60 min, and temperature 298 K, when the equilibrium concentration of lanthanum was 250 mg L−1, and the experimental adsorption capacity obtained was 31.58 mg g−1. Further refinement of the optimization of the adsorption process by response surface design indicates that at pH 6 and the initial concentration of 256 mg L−1, the adsorption capacity has maximum values between 30.87 and 36.73 mg g−1.

The present paper investigates the adsorption of Cr(III) ions using the SIR, prepared by impregnation of Amberlite XAD7 with di-(2-ethylhexyl)-phosphoric acid (DEHPA), which has been chosen as an extractant for the purpose of this study. The Amberlite XAD7–DEHPA resin was impregnated with DEHPA and ethylic alcohol as solvent trough dynamic column impregnation method. The influence of different physicochemical parameters (pH, resin dosage, initial concentration of Cr(III) ions, contact time and temperature) upon the adsorption capacity of XAD7–DEHPA, in the Cr(III) ions removal process from aqueous solution, has been investigated. The pH for Cr(III) ions adsorption was found as 3.0 for this material. The results showed that the adsorption equilibrium was reached after 45 min. The adsorption process is best described by the pseudo-second order kinetic model. Langmuir adsorption isotherm gave a satisfactory fit of the equilibrium data. The maximum adsorption capacity is ∼3 mg Cr(III) ions/g SIR. The thermodynamic studies allowed us to determine the thermodynamic parameters Δ G °, Δ H ° and Δ S °. In this paper the factorial design of experiments was used to study the performance of the adsorption process.

Reverse Engineering is a technique that is based on creating virtual models from existing products, is used to enhance or reproduce the look/function/role of the original part. It is used for shape design applications in different domains: aerospace, automotive, manufacturing, civil engineering, architecture, medicine, etc. For many years were used contact acquisition devices because of their ability to collect data with high accuracy, but this devices are slow during the acquisition process and constrained in digitization of small size objects. Thanks to the computer industry development and improvements in laser technology, in recent years have appeared scanning devices and scanning machine which have a smaller data acquisition time, and are able to scan a large variety of objects, whatever the size, shape or material. The advantages and disadvantages using scanning devices will be presented in the paper. In this paper we present an experiment conducted on Roland Laser Scanning Machine LPX-600, in which we want to determine factors influencing the surface quality of virtual models, obtained after scanning. For this experiment we used plastic and aluminum parts, cylindrical and prismatic shapes, both rotary scanning and plane scanning strategies and different scanning resolution. The results were processed and analyzed using Minitab.

The reaction of phenylphosphonic dichloride with 4,4′-cyclohexylidenebisphenol by a gas–liquid interfacial polycondensation was investigated. The design of experiments (DoE) method is used for determination of the best reaction conditions. The correlation of simultaneous influence of the parameters (reaction time, reaction temperature, alkaline medium, reagents molar ratio) on yield and inherent viscosity was studied.

Processable conducting materials for large-scale utilization were prepared by mechanical mixing of polyaniline (PANI) paste and commercially acrylic resin. Doped PANI with organic phosphorus acid was synthesized. These blends can be used for the production of semiconductive paints with good corrosion resistance. By mixing doped PANI with commercially acrylic acid (SMP 63 AZUR SA) hard semiconducting and low elastic films are obtain. The effect of four variables was simultaneously studied: PANI (concentration), stirring speed (ST), mixing time (MT), dispersing agent (DA). Due to the number of variables, a factorial-design was chosen in order to reduce the number of experiments required in order to obtain coatings with high hardness and elasticity and semiconductive behavior. The results indicated that the influences of control factors decrease in order: PANI (concentration), mixing time (MT), dispersing agent (DA) and stirring speed (ST). From the studied variables, the resistance is significantly influenced by the two control factors PANI and MT.

The reaction of phenylphosphonic dichloride with bisphenol A (BA) by inverse phase transfer catalysis method was investigated. The design of experiments method was applied to establish the correlation between the simultaneous influence of the parameters (alkaline medium, reaction temperature, reagents molar ratio, and stirring speed) on yield and inherent viscosity, as well as for identifying the best reaction conditions. This method allows the simultaneous variation of control factors, thus decreasing the number of experiments in the polyphosphate synthesis. The process control factors used in this study were reagents' molar ratio, base concentration, and reaction temperature. The experimental results using 20 and 14 process runs, lead to an optimal synthesis procedure. The optimal values for yield and viscosity were obtained at molar ratio = 1, base concentration = 1.1 M, and reaction temperature = −12°C and have been experimentally verified with a series of four runs. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

One of the main aims for a process is to find the optimum values of the parameters which assure the desired values of the process responses. This activity must be made in the minimum of the time and with the minimum use of consumable resources. The design of the experiments (DoE) assisted by the computer assures that this happens. In this paper, DoE was used to study the adsorption performance of Fe-XAD8-DEHPA in the removal process of As(V) ions from aqueous solutions. It was observed that the Adsorption Capacity and the Efficiency in the removal process of As(V) from the aqueous solution was significantly influenced by concentration and pH. The mathematical model of the process is very good. It includes the experimental data of over 99% in the case of adsorption capacity and over 97% in the case of efficiency. From the contour plots of adsorption capacity and efficiency can be seen that the chemical process is nonlinear. The DOE helped us to find the optimum values of the control factors (pH, contact time and arsenic initial concentrations from solutions) in order to obtain maximum values of Adsorption Capacity and Efficiency.