Band 20, Heft 12

In light of the recent COVID-19 pandemic, the demand for hydrogen peroxide has increased significantly due to its widespread use in disinfectant formulations. The present study aims to develop an efficient nanohybrid material as catalyst support for the successful hydrogenation of ethylanthraquinone for the production of hydrogen peroxide. Co-precipitation and wet impregnation methods were used to prepare nanohybrid Zr–Al–La supported Pd catalyst (Pd/Zr–Al–La). The high surface area (146.56 m 2 /g) of Zr–Al–La makes it suitable to use as support and causes to lower the mass transfer resistance and dispersion of active metal. XRF, BET, FTIR, and TGA were used to characterize the developed catalyst. The catalytic activity of the developed catalyst was studied using a high-pressure autoclave reactor to obtain a notable yield of H 2 O 2 as 93.8% at 75 °C, 0.3 MPa, and 0.5 g of catalyst dose, a significant enhancement over the traditional Pd catalyst with Al 2 O 3 support (63%) with the loss of active quinone compound. The mass transfer limitation of the reaction is high using only a Pd catalyst. The calculated mass transfer resistance of the reaction over Pd/Zr–Al–La catalyst was found to be moderate with a diffusion coefficient of the reactant (H 2 ) as 0.0133 × 10 −6  m 2 /s at 75 °C. It was also verified and confirmed with the Thiele modulus (calculated as 0.0314), no mass transfer resistance. The effectiveness factor ( η s ) was found to be 1.0, indicating the negligible mass transfer resistance in the hydrogenation reaction using Pd/Zr–Al–La catalyst.

In this research, the efficiency of advanced oxidation processes (AOPs) including Fenton−Peracetic Acid (PAA) and photo-Fenton− PAA in the removal of the Rodamine B (RhB) dye from aqueous solutions were studied. Investigating the effect of operating parameters such as pH (3–9), contact time (2–30 min), PAA concentration (10–80 mg/L), FeCl 3 .7H 2 O concentration (10–100 mg/L), and dye concentration (25–500 mg/L) on the performance of AOPs in removal of RhB was considered. The results showed that by decreasing pH and dye concentration, RhB removal efficiency increased. The optimal conditions for removal of RhB using Fenton− PAA process were determined to be as follows: dye concentration = 50 mg/L, pH = 3, PAA concentration = 50 mg/L, contact time = 10 min, and FeCl 3  = 50 mg/L; in these conditions, removal efficiency of the RhB was 99.9%. In contrast, the photo-Fenton− PAA process was able to remove this amount of dye in just 5 min. The high performance of the system in a short time is attributed to the synergistic effect of the photo-Fenton− PAA process in the presence of UV. Finally, RhB dye was completely degraded by the photo-Fenton− PAA process and converted into CO 2 and H 2 O products. In general, the photo-Fenton− PAA process compared to other methods can be used as a suitable and reliable method for the treatment of effluents of the dyeing industry and discharge them to the environment.

Distillery industries are the most water-consuming industries discharging a large amount of wastewater that contain a high organic load. Hence it is first treated in biodigester where significant organics reduces (50–60%) and the outcome of biodigester is commonly known as biodigester effluent (BDE). The present study is an attempt to treat BDE in terms of COD and color removal using a batch electrocoagulation reactor (ECR) where stainless steel (SS) is used as an electrode. To optimize the four independent parameters namely initial pH (pH i : 3.5–9.5), current density ( j : 49.5–247 A/m 2 ), electrode gap ( g : 1.2–3.2 cm), and reaction time ( t : 20–100 min) on the color and COD reduction efficiency, a central composite design (CCD) experiment is applied to evaluate the individual and interactive effects of these parameters. The high coefficients of determination for color ( R 2  = 0.9989) and COD ( R 2  = 0.9981) were obtained by analysis of variance (ANOVA) between the experimental data and the predicted data using a second-order regression model. At the optimum condition color and COD removal of 81.4 and 91.9%, respectively, were observed. A material balance of SS has also been incorporated.

The SFT (swirling flow tundish) is a kind of tundish with SC (swirl chamber) placed in the flow injection zone. The gravity potential energy of the molten steel is converted into rotation kinetic energy as entering into the tundish from the bottom of the SC along the tangential direction. The inclusions tend to collide and aggregate as following the rotating molten steel in the SC. In this work, the collision-coalescence behavior of inclusion was investigated by the mathematical simulation with PBM (population balance model) model, and the removal rate of the inclusion was investigated by the DPM model. The results show that, under the same operating conditions, the average diameter of inclusion at the outlet of the tundish increases from 4.25 μm to 4.35 μm with the introduction of the SC, which means that the SC promotes the collision and aggregation of inclusion. The inclusion removal rate of SFT is 33.09% without considering the collision-coalescence, and it increases into 43.20% as considering the collision-coalescence. The results of considering the collision-coalescence of inclusion is more consistent with the actual movement of inclusion in the tundish.

Polyethylene terephthalate (PET) fabric materials are broadly applied in daily life. However, on one hand, they suffer problem of easy contamination by dust owing to their hydrophilicity, which largely reduce their lifetime. On the other hand, their inflammability will bring many potential safety hazards. Therefore, in this paper, PET fabric material with superior superhydrophobicity and flame retardance through a fluorine-free layer-by-layer (LBL) method was developed, which effectively extended its lifetime and range of applications. The LBL technique was realized through assembly of the mixed polyelectrolytes include chitosan (CS), phytic acid (PA), and ammonium polyphosphate (APP) for only two bilayers (BL), which endowed the fabric superior fire retardance. A final layer consisted of steel slag (SS) particles and octadecylamine (ODA) were further assembled onto the flame-retardant fabric, which successfully gave rise to superior superhydrophobicity with water contact angle (WCA) of 155° and water sliding angle (WSA) of 2°. Compared with the pure fabric, the limited oxygen index (LOI) values of the coated fabric were enhanced from 19.8% to 29.2%. The finally obtained fabric also showed excellent self-cleaning and anti-fouling capabilities. It could be used to highly efficiently separate various oil–water mixtures. It also could endure long-time heating treatment at high temperature of 180 °C without affecting the superhydrophobicity and flame retardance. This method was fluorine-free and made good use of waste SS particles. Such fabric was believed to find vary promising applications in water repellence, self-cleaning, flame retardance, anti-fouling, and liquid separation fields.

In this paper, a set of small stoves was designed which is used for alcohol-based fuel combustion. The research object is the atomization process of alcohol-based fuel in the stove. By combining numerical analysis and experiment, this paper investigated the influence of spray pressure on the atomization characteristics of alcohol-based fuel in the stove under the static environment. The results showed that as the increase of spray pressure, the atomization cone angle increased firstly and then decreased slightly and when the spray pressure was 0.8 MPa, the atomization cone angle reached the maximum value of 79.5°; the SMD (Sauter mean diameter) at the same position of the combustion chamber decreased slowly and the spray height increased slowly and both of the SMD and spray height changed slightly when the spray pressure was not less than 0.8 MPa. The experiment verified the correctness of the numerical analysis method, and the coincidence degree between both was more than 92%. This paper also investigated the influence of swirl structure parameters on the atomization characteristics of fuel in the stove under air distribution condition by using numerical analysis method. The results showed that the air central recirculation zone only generated in the stove combustion chamber when the swirl angle was not less than 30°; the minimum SMD and the maximum average velocity of all central recirculation zones sections were obtained when the combustion chamber with 12 swirl plates and 45° swirl angle, and the atomization characteristics of the fuel in this structure were better. Further research showed that when the combustion chamber with 6 swirl plates and 40° swirl angle, the SMD of all the central recirculation zone sections is the smallest and the average velocity was slightly smaller than the maximum value; and after comprehensive analysis, the atomization characteristics of the fuel in the stove with this structure are the best. These above research results will provide reference value for the design and development of alcohol-based fuel special stoves.

A series of metal-exchanged phosphotungstate salts, Fe-TPA, Cr-TPA, Cu-TPA, and Ni-TPA were synthesized by sonication and tested for glycerol esterification with acetic acid to obtain biofuel additives. A systematic, chemical, structural, and morphological characterization and determination of acidity were used by various analytical techniques. XRD and FT-IR studies confirmed the Keggin structure of all metal exchanged phosphotungstate salts with no impurities coming from metal nitrate salts. The incorporation of metal cations in phosphotungstic acid leads to decreased crystallite size as seen from XRD diffractograms. N 2 adsorption-desorption analysis showed that the Type II isotherms were obtained for all metal exchanged phophostungstate salts, characteristic of non-porous or macroporous materials. SEM images of metal exchanged phosphotungstate salts displayed well-shaped crystalline particles. SEM-EDX analysis showed that the calculated tungsten metal ratios are in good agreement with the theoretical ratios of those for all the metal exchanged salts, verified by XRF results. The exchange of protons by the metal cations improved the thermal stability observed in the TGA analysis. The acidity strengths, from NH 3 -TPD analysis, were found in the following order; TPA > Fe-TPA > Cr-TPA > Cu-TPA. Additionally, pyridine-FTIR gives that the exchanging of transition metal into the phosphotungstic acid decreased the Brønsted acidity while increasing the Lewis acidity and this mostly affects the efficiency of the esterification reaction. The activity of metal exchanged salts was in the given order; Fe-TPA > Cr-TPA > Cu-TPA > Ni-TPA. Among these Fe-TPA salt, having a good ratio of Brønsted and Lewis acidity, have the selectivity for di- and triacetin (68 and 10%), with the highest conversion (96%). The iron phosphotungstate salts are a promising catalyst with sustainable Bronsted acidity during the reaction, high desired product selectivity at low temperature, easy synthesizability, inexpensive, and environmentally friendly.

Hydro-liquefaction of the thermal extracts (HPC) from lignite was investigated over ZSM-5 and Ni/ZSM-5 with hierarchical pores or not. The thermal extracts dissolved (HPC-S) and deposited (HPC-D) at room temperature were prepared to compare their hydro-liquefaction performances. Combined to the hydrogenation properties of ZSM-5 and Ni/ZSM-5 catalysts for tetralin as a model compound, the roles of the porous structure, acidity and hydrogenation component in Ni/ZSM-5 for hydro-liquefaction of HPC were investigated. A synergy of the porous structures, nickel metal and acidity for hydro-liquefaction of HPC-S over Ni/ZSM-5 catalyst was found. During hydro-liquefaction, it is essential for the presence of nickel in the catalyst, since the parts of the benzene rings in HPC-S are first saturated by hydrogen under the role nickel. Then a certain acidity especially Brønsted acid is required in the catalyst to open the saturated benzene rings. Since there are the macromolecular organic compounds in the HPC-S, the hierarchical porous structures are required in the catalyst to promote the hydro-liquefaction performance due to their improvement on the mass transfer diffusion efficiency.

Integrating and unstable chemical processes showcase instability in open-loop configuration due to the existence of poles at the origin and right-half of the s-plane. They present challenging control requirements due to their non-self-regulating nature. The presence of dead time demands more sophisticated control requirements for the above-mentioned processes. So double-loop control strategies are preferred over PID controllers in single-loop configuration. In this work, a novel IMC-PD double-loop control strategy is proposed for unstable and integrating plants with dead time. The inner-loop consists of PD controller whose initial settings are derived using Routh–Hurwitz stability conditions. The outer-loop consists of an IMC controller whose parameter along with that of the PD controller is optimized using the metaheuristic algorithm called equilibrium optimizer algorithm (EOA). EOA utilizes the range of controller settings from RH criteria for stable operation and provides the optimal settings by minimizing the integral square error (ISE). Merits of the suggested strategy is illustrated with the help of benchmark plant models of unstable/integrating chemical processes and that of a bioreactor. By computing quantitative performance measures, the dynamic responses resulting from the proposed control scheme is found to be more effective than the reported works.