Chemical Engineering & Technology最新文献

This study investigates the potential of a salt bridge-mediated microbial fuel cell (MFC) for power generation and wastewater sludge treatment in breweries. Unlike traditional “one-parameter-at-a-time” methodologies, this study uses a three-variable Box–Behnken design response surface methodology to optimize critical MFC operational parameters. The effects of parameters such as solution pH, salt bridge molarity, and temperature were studied in the range of 4 to 10, 1 to 5 M, and 20 to 45 g L⁻¹. The optimum operating parameters were found to be solution pH of 5.853, salt bridge molarity of 3.343 M, and temperature of 32.5 °C for chemical oxygen demand and biological oxygen demand removal efficiencies of 92.485 % and 88.51 %, respectively. Temperature was found to be the most significant factor affecting the reactor's performance.

An internal thermally coupled air separation column (ITCASC) process is an effective energy-saving technology in the air separation process. However, a large economic investment is a crucial factor for the widespread use of this technology in practical applications. In this article, an alternative configuration design, namely, top-integrated (T-ITCASC), bottom-integrated (B-ITCASC), and top-bottom-integrated ITCASC (T-B-ITCASC) with a focus on energy savings and economic feasibility are studied. A rigorous optimization based on a nonlinear interior-point algorithm was developed by integrating the dynamic model into the optimization formulation. In the context of ITCASC process design and optimization, numerical simulations demonstrated that T-ITCASC, B-ITCASC, and T-B-ITCASC configurations improved energy-saving potential and reduced capital investment, compared to the F-ITCASC and conventional air separation column (CASC) configurations. Among these optimized configurations, the T-B-ITCASC configuration is preferred.

In the pursuit of mitigating CO₂ emissions, this study investigates the optimization of CO₂ purification within a negative CO₂ emission power plant using a spray ejector condenser (SEC) coupled with a separator. The approach involves direct-contact condensation of vapor, primarily composed of an inert gas (CO₂), facilitated by a subcooled liquid spray. A comprehensive analysis is presented, employing a numerical model to simulate a cyclone separator under various SEC outlet conditions. Methodologically, the simulation, conducted in Fluent, encompasses three-dimensional, transient, and turbulent characteristics using the Reynolds stress model turbulent model and mixture model to replicate the turbulent two-phase flow within a gas–liquid separator. Structural considerations are delved into, evaluating the efficacy of single- and dual-inlet separators to enhance CO₂ purification efficiency. The study reveals significant insights into the optimization process, highlighting a notable enhancement in separation efficiency within the dual-inlet cyclone, compared to its single inlet counterpart. Specifically, a 90.7 % separation efficiency is observed in the former, characterized by symmetrical flow patterns devoid of wavering CO₂ cores, whereas the latter exhibits less desirable velocity vectors. Furthermore, the investigation explores the influence of key parameters, such as liquid volume fraction (LVF) and water droplet diameter, on separation efficiency. It is ascertained that a 10 % LVF with a water droplet diameter of 10 µm yields the highest separation efficiency at 90.7 %, whereas a 20 % LVF with a water droplet diameter of 1 µm results in a reduced efficiency of 50.79 %. Moreover, the impact of structural modifications, such as the addition of vanes, on separation efficiency and pressure drop is explored. Remarkably, the incorporation of vanes leads to a 9.2 % improvement in separation efficiency and a 16.8 % reduction in pressure drop at a 10 % LVF. The findings underscore the significance of structural considerations and parameter optimization in advancing CO₂ capture technologies, with implications for sustainable energy production and environmental conservation.

In this work, cellulose was effectively produced from corn husks by a simple and eco-friendly method. Major influencing variables for cellulose extraction were examined, and the highest yield of lignin and hemicellulose cleavage was achieved after corn husks were treated in 12.5 wt % NaOH solution at solid/liquid ratio (S/L) of 1:10 g mL⁻¹, 70 °C for 90 min. Subsequent bleaching conducted in 10 wt % H₂O₂ solution at 80 °C for 90 min produced cellulose with a lightness value (L^*) of ∼87, chromaticity indexes a^* = −1.85, b^* = 2.94 with high purity, 90.86 %, and crystallinity, 64.94 %. Fourier transform infrared, scanning electron microscopy, and x-ray diffraction analysis showed a clear transition in morphology, structure modification, and crystallinity consistent with the alteration of the chemical composition from raw material to delignified residue and the bleached one. To synthesize microcrystalline cellulose (MCC), the hydrolysis was investigated in H₂SO₄ solutions of different concentrations and durations via monitoring particle size distribution by laser diffraction spectroscopy. At the most efficient conditions (30 wt % H₂SO₄, 18 h, 45 °C, 1:10 S/L ratio), the obtained MCC reached an average particle size of 42.68 µm, crystallinity degree of 61.6 %, and cellulose purity of 92.5 %. Meanwhile, similar parameters with 4 N HCl solution produced MCC with the same purity but higher crystallinity (65.6 %), higher mean size, 67.62 µm, and higher aspect ratio. SEM images showed that 4 N HCl caused less detrimental and erosive action, and less fragmentation on cellulose microfibrils compared to 30 wt % H₂SO₄. The study's outcome supports the feasibility of corn husks to produce cellulose and MCC for further applications.

A thermally coupled distillation technology can bring energy-saving benefits, but it poses challenges to process control. This article explores dynamic control of different side-stream quaternary extractive distillation configurations. One the one hand, the open-loop controllability of these processes is analyzed in terms of various criteria by the control design interface technology of Aspen Plus Dynamics. On the other hand, their control structures are established and examined by introducing large feed flow and composition perturbations. The results show that the triple-side-stream distillation still performs the best state and input–output controllability in spite of the strongest nonlinearity, and is also well resistant to large feed perturbations using a simple control structure.

ZnO nanorods (NRs) were synthesized hydrothermally on a pre-seeded graphene/nickel foam (NF) substrate. The effects of concentration on the photoelectrochemical (PEC) cell performance and hydrothermal reaction were studied. The field emission scanning electron microscopy images revealed that the precursor concentrations influenced the shape of the ZnO NRs on graphene/NF (ZGN). The X-ray diffraction pattern for hexagonal wurtzite demonstrated strong orientation along the (002) direction. Notably, compared with the other concentrations, 0.04 M ZGN exhibited the highest photocurrent density, which was attributed to the optimal diameter and length of the rods for efficient light absorption. This research showed enhanced PEC performance, compared with existing literature, emphasizing the exceptional quality of the produced ZGN.

The present study aims to remove chromium (Cr) from a synthetic solution using Ziziphus jujube seed (ZJS)-activated biochar (ZJSAB) as an adsorbent. Physicochemical characterization was carried out to understand the properties of ZJSAB samples. Adsorption characteristics of ZJSAB were determined using batch experiments for various temperatures, pH, dosage, concentration, and duration. The study reveals ZJSAB has 93 % efficiency in the removal of Cr for an initial concentration of 60 mg L⁻¹ at 30 °C and 2 pH with 0.6 g L⁻¹ dosage and 120 min duration. Freundlich isotherm and pseudo-second-order models were best fit with maximum removal efficiency for ZJSAB. When 0.3 N hydrochloric acid was introduced to a desorption study, Cr desorption was 93.47 %. The study reveals that activated biochar from ZJS was efficient for Cr removal from aqueous solutions.

The advanced gasification technology of coal is mainly based on oxidation reaction and high temperature but is not suitable for biomass conversion. High tar and CO₂ content are the two main issues that affect the efficiency of biomass gasification. In order to deeply convert hydrocarbons/tar and CO₂ simultaneously, and enhance syngas yield, the cracking/partial oxidation/reforming reactions and their integrated reaction routes are investigated from an interrelated view. The effects of each reaction on the distribution of C/H elements in hydrocarbons/tar and syngas are illustrated. By cracking and oxidation reaction, the syngas yield can only reach 0.93 Nm³ kg⁻¹, about 58 % of the theoretical maximum value; a large proportion of residual C/H atoms existing in stable hydrocarbons/tar/CO₂/H₂O are not converted. Based on the concept of lattice O oxidation combined with dry reforming, it realizes syngas yield (CO+H₂) 1.56 Nm³ kg⁻¹ with 91.6 % concentration, demonstrating that tar/hydrocarbons and CO₂/H₂O are converted to syngas efficiently. The effects of [O]/C ratio on gas yield represent a synergistic coordination between lattice Os oxidation and catalytic reforming reaction. Oxidation-reforming is the optimum route for biomass conversion to high-quality syngas.

The reactor is very critical to intensify the reaction rate controlled by mass transfer. Solid magnesium hydride (MgH₂) shows great advantages in hydrogen storage; however, poor liquid–solid hydrolysis kinetics limit its application. Various chemical reactors were explored and are used to improve the hydrolysis efficiency. Results show that the mixing style could affect the surface coating behavior. Specifically, the higher temperature and mixing strength could promote the MgH₂ hydrolysis. Furthermore, induced crystallization could effectively relieve coating and strengthen the hydrolysis, especially at the high mixing level. The result indicated that the mass transfer distance between crystal seed and formed MgH₂ particles played an important role in MgH₂ hydrolysis.