Green Chemical Engineering最新文献

Water pollution caused by dye is a serious challenge. Herein, we use a novel discharge process to functionalize carbon nanotube (CNT) by COOH groups to form CNT30 for removing methyl red (MR) from water. By pristine CNT, 75% MR is removed in 60 min, with an adsorption capacity of 68.44 mg g^-1. By CNT30, 85% MR is fast removed in only 5 min, and the removal efficiency reaches to 95% after 30 min, with an adsorption capacity of 80.33 mg g^-1. Thus, a higher MR removal efficiency is achieved in a much shorter time on CNT30. Moreover, CNT30 has an outstanding reusability, with the MR removal efficiency decreasing by only 7% after ten cycles. The COOH groups on CNT30 improve the hydrophilicity of CNT30, thus promoting the interaction of MR in water with CNT30. The hydrogen bonding and electrostatic interaction of MR with the COOH groups on CNT30 could be the force to drive MR adsorption on CNT30. The higher COOH content could be the origin for the better performance of CNT30 in removing dye from water. The discharge process developed herein is operated in O₂, without using harmful substances, and the COOH content on CNT can be efficiently tuned by simply changing discharge time. This is different from the chemical modification widely used to functionalize CNT by strong oxidants, e.g., HNO₃. The present work is of great significance to realize green construction of materials for more efficiently removing dye from water.

Electricity-driven water splitting to convert water into hydrogen (H₂) has been widely regarded as an efficient approach for H₂ production. Nevertheless, the energy conversion efficiency of it is greatly limited due to the disadvantage of the sluggish kinetic of oxidation evolution reaction (OER). To effectively address the issue, a novel concept of hybrid water electrolysis has been developed for energy–saving H₂ production. This strategy aims to replace the sluggish kinetics of OER by utilizing thermodynamically favorable organics oxidation reaction to replace OER. Herein, recent advances in such water splitting system for boosting H₂ evolution under low cell voltage are systematically summarized. Some notable progress of different organics oxidation reactions coupled with hydrogen evolution reaction (HER) are discussed in detail. To facilitate the development of hybrid water electrolysis, the major challenges and perspectives are also proposed.

A novel Ni doped carbon quantum dots (Ni-CQDs) fluorescence probe was synthesized by facile electrolysis of monoatomic Ni dispersed porous carbon (Ni–N–C). The obtained Ni-CQDs showed a high quantum yield of 6.3% with the strongest excitation and emission peaks of 360 nm and 460 nm, and maintained over 90% of the maximum fluorescence intensity in a wide pH range of 3–12. The metal ions detectability of Ni-CQDs was enhanced by Ni doping and functional groups modification, and the rapid and selective detection of Fe³⁺ and Cu²⁺ ions was achieved with Ni-CQDs through dynamic and static quenching mechanism, respectively. On one hand, the energy band gap of Ni-CQDs was regulated by Ni doping, so that excited electrons in Ni-CQDs were able to transfer to Fe³⁺ easily. On the other hand, the abundant functional groups promoted the generation of static quenching complexation between Cu²⁺ and Ni-CQDs. In metal ions detection, the linear quantitation range of Fe³⁺ and Cu²⁺ were 100–1000 μM (R² = 0.9955) and 300–900 μM (R² = 0.9978), respectively. The limits of detection (LOD) were calculated as 10.17 and 7.88 μM, respectively. Moreover, the fluorescence quenched by Cu²⁺ could be recovered by EDTA²⁻ due to the destruction of the static quenching complexation. In this way, Ni-CQDs showed the ability to identify the two metal ions to a certain degree under the condition of Fe³⁺ and Cu²⁺ coexistent. This work paves the way of facile multiple metal ion detection with high sensitivity.

Gasification is a sustainable approach for biomass waste treatment with simultaneous combustible H₂-syngas production. However, this thermochemical process was quite complicated with multi-phase products generated. The product distribution and composition also highly depend on the feedstock information and gasification condition. At present, it is still challenging to fully understand and optimize this process. In this context, four data-driven machine learning (ML) methods were applied to model the biomass waste gasification process for product prediction and process interpretation and optimization. The results indicated that the Gradient Boosting Regression (GBR) model showed good performance for predicting three-phase products and syngas compositions with test R² of 0.82–0.96. The GBR model-based interpretation suggested that both feed and gasification condition (including the contents of feedstock ash, carbon, nitrogen, oxygen, and gasification temperature) were important factors influencing the distribution of char, tar, and syngas. Furthermore, it was found that a feedstock with higher carbon (> 48%), lower nitrogen (< 0.5%), and ash (1%–5%) contents under a temperature over 800 °C could achieve a higher yield of H₂-rich syngas. It was shown that the optimal conditions suggested by the model could achieve an output containing 60%–62% syngas and achieve an H₂ yield of 44.34 mol/kg. These valuable insights provided from the model-based interpretation could aid the understanding and optimization of biomass gasification to guide the production of H₂-rich syngas.

The worldwide application of organophosphorus pesticides (OPs) has promoted agricultural development, but their gradual accumulation in soil and water can seriously affect the central nervous system of humans and other mammals. Organophosphorus hydrolase (OPH) is an effective enzyme that can catalyze the degradation of the residual OPs. However, the degradation products such as p-nitrophenol (p-NP) is still toxic. Thus, it is of great significance to develop a multi-functional support that can be simultaneously used for the immobilization of OPH and the further degradation of p-NP. Herein, a visible light assisted enzyme-photocatalytic integrated catalyst was constructed by immobilizing OPH on hollow structured Au-TiO₂ (named OPH@H-Au-TiO₂) for the degradation of OPs. The obtained OPH@H-Au-TiO₂ can degrade methyl parathion to p-NP by OPH and then degrade p-NP to hydroquinone with low toxicity by using H-Au-TiO₂ under visible light. OPH molecules were immobilized on H-Au-TiO₂ through adsorption method to prepare OPH@H-Au-TiO₂. After 2.5 h of reaction, methyl parathion is completely degraded, and about 82.64% of the generated p-NP is further degraded into hydroquinone. After reused for 4 times, the OPH@H-Au-TiO₂ retains more than 80% of the initial degradation activity. This research presents a new insight in designing and constructing multi-functional biocatalyst, which greatly expands the application scenarios and industrial value of enzyme catalysis.

Modular bioreactors can provide a flexible platform for constructing complex multi-step pathways, which may be a solution for maximizing reactions and overcoming the complexity of multi-enzyme systems. Here, we selected wood-derived cellulose scaffold as a support for enzyme immobilization and constructed the modular bioreactor. Cellulose scaffold was prepared after removing lignin from wood, followed by citric acid functionalization and the addition of glutaraldehyde finally allowed the cross-linking of enzymes. Three enzymes, horseradish peroxidase (HRP), glucose oxidase (GOD), and catalase (CAT), were separately immobilized, resulting in the immobilized enzyme amount to over 40 mg/g. The introduction of carboxyl groups from citric acid facilitated the rapid enzyme adsorption on the support surface and immobilized enzymes possess ∼65% expressed activity. Modular bioreactors were constructed by using the immobilized enzymes. With the immobilized HRP module, reactor showed desired catalytic performance with the phenol degradation rate of > 90%. Also, a pH regulation can occur in the bioreactors for preserving enzyme activities and neutralizing acid products. In the GOD/CAT modular bioreactor, the cascade reaction with adjusting pH values can achieve a 95% yield of sodium gluconate and exhibit a favorable reusability of 5 operation cycles.

The construction of rapid prototyping for structured ceramics has a promoting effect on potential applications. In this work, engineering slurry with different formulations were used to develop aqueous colloidal ceramic slurry for direct ink writing (DIW). Optimized slurry of Formulation 5 possessed good printing effect for DIW with stable mechanical properties. Related characteristics, including shrinkage, compressive strength, rheological behavior, and chemical property, were also examined. DIW ceramics prepared from optimized slurry can be preliminarily applied to adsorption of Rhodamine B and chlortetracycline, and possessed the advantages of easy separation and operation compared with powder adsorbents. This work provides a strategy for the design of 3D-printed kaolin ceramic slurry, and also extends to potential application in adsorption.

Membrane separation technology provides an effective alternative to mitigate the massive carbon emission with high carbon capture productivity and efficiency. In the context of operating membranes under high CO₂ pressures allows increased separation productivity and reduced gas compression cost, which, however, often leads to CO₂ induced plasticization, a key hurdle for current gas separation membranes. In this review, we reviewed the latest development of membranes with anti-plasticization resistance, potentially suited for operation under high CO₂ feed streams. Specifically, the separation performance of polymeric membranes, inorganic membranes, and mixed matrix membranes under high CO₂ feed pressures are discussed. Approaches to enhance CO₂ induced plasticization of those membranes are also summarized. We conclude the recent progress of membranes for high CO₂ pressures with perspectives and an outlook for future development.