Chemical Engineering & Technology最新文献

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.

Poly(lactic acid) (PLA) is a biodegradable polymer with limited application because of its intrinsic brittleness, low toughness, and low elongation at break. Melt blends were prepared by mixing a natural rubber (NR, poly(1,4-cis-isoprene) in the form of liquid NR (LNR), liquid-epoxidized NR (LENR), and polypropylene (PP) in the PLA matrix. Four blend systems were designed and prepared, i.e., PLA–PP, PLA–PP–LNR, and PLA–LNR or PLA–LENR. The composition of PP in the blend was fixed at 10 % PLAPP (90/10). Results showed that PLA–PP mixed with LNR improved impact and elongation at break. The binary blend of PLA–LNR (90/10) significantly enhanced impact strength and elongation at break properties. In contrast, the binary blends of PLA–LENR (90/10) showed a lower value of elongation at break (9.5 % vs. 37.3%) and impact strength (4.56 kJ m⁻² vs. 6.44 kJ m⁻²). The melting temperature (T_m) and the glass transition temperature (T_g) were measured by differential scanning calorimetry, which recorded slight changes in the glass temperatures and melting temperatures. Scanning electron microscopy images of the tensile fracture of the PLA–LNR (90/10) blend showed the presence of large fibrils associated with the ductile failure related to neat PLA. Finally, the fracture toughness (K_IC) of PLA–LNR (90/10) showed an increase of 39 % over neat PLA (2.94 MPa.m^1/2 vs. 4.08 MPa.m^1/2).

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.

Air separation processes are time-consuming and energy-intensive. Most of the energy used in air separation unit (ASU) is used for air compression. During the air compression process, some energy is lost, which is converted into waste heat. This wasted energy is used to warm liquefied natural gas (LNG). At some point, LNG ships will dock at an LNG regasification facility. Here, LNG is converted back to gas and supplied to the distribution and transmission systems. During the regasification process, cryogenic LNG has a huge opportunity for cold energy recovery. An innovative air separation process that is integrated with the cold utilization of LNG is presented in this study along with a thorough conceptual design and analysis. The results of this study show that producing high-purity oxygen and nitrogen, respectively, requires 0.28 kWh kg⁻¹ and 0.06 kWh kg⁻¹ of specific energies. Prior to integration with cold utilization of natural gas, 25 141.6 kW is needed for air compression. However, following integration, 10 554.6 kW of energy is needed, resulting in a 58.01 % energy savings. Exergy destruction as well as efficiency have been calculated for the primary components of the system. Sensitivity analysis is carried out to examine the effects of LNG streams on important parameters. In conclusion, a cryogenic ASU is integrated with an LNG-direct expansion cycle-organic Rankine cycle power cycle to supply the necessary power for operation and reduce extraneous power inputs. Overall, this integrated approach increases efficiency, lowers costs, benefits the environment, allows for flexibility and adaptability, and raises system dependability.

Copyright: © Crystal Kwok @ Unsplash

A Box-Behnken design was used for the analysis using a gray wolf optimizer (GWO)-coupled artificial neural network (ANN) model and response surface methodology (RSM) to analyze the effect of three operating parameters (volumetric exchange ratio [VER], aeration rate [AR], and cycle time [CT]) manipulated during an aerobic granular sludge process (AGS) sequencing batch reactor on modeling the removal of chemical oxygen demand (COD) in mixed wastewater. The most efficient architecture for COD showed the highest efficiency for modeling the AGS. The RSM model and plot results indicate that the CT and AR were the most influential on COD removal efficiency. When compared with models with statistical indices, GWO-ANN demonstrated higher performance compared to RSM.