Synthesis of Mg/Al-LDH nanoflakes decorated magnetic mesoporous MCM-41 and its application in humic acid adsorption

3D-printed solid phase microextraction fiber based on Co-Al layered double hydroxide nanosheets; application in determination of phenolic acids in fruit juice samples

3D printing technology has attracted great attention in various fields of science and technology. Application of this technology in manufacturing analytical tools is developing fast. High precision in manufacturing designed objects, fast production and low cost also green production approach by using biodegradable materials like polylactic acid is promising bright future in scientific researches. The development of new approaches in improving the functional groups of the surface of 3D printed objects in order to make 3D printed parts more functional with conventional 3D printed materials, causes the entry of many advanced materials in this field. In this study, a novel solid phase microextraction fiber was prepared based on Co-Al layered double hydroxide (LDH) nanosheets in-situ growth on 3D-printed aluminum-polylactic acid (PLA) composite and its application for determination of phenolic acids (PAs) including vanillic acid (VA), ferulic acid (FA), p-coumaric acid (p-CA), p-hydroxybenzoic acid (HBA), protocatechuic acid (PCA) and caffeic acid (CA) in fruit juice samples was investigated. The proposed fiber was prepared via a robust one-step hydrothermal synthesis of Co-Al LDH on an anodized 3D-printed Al-PLA fiber. Factors crucial for the extraction, including pH, extraction and desorption time and ionic strength were explored in detail. Under the optimal experimental conditions, for all PAs except PCA, LOD, LOQ and LDR were obtained as 0.03, 0.1 and 0.1-100.0 µgL-1, respectively. For PCA, LOD, LOQ and LDR were obtained as 0.15, 0.50 and 0.5-100.0 µgL-1, respectively.

Effective strategies for reclamation of saline-alkali soil and response mechanisms of the soil-plant system

The combination of amendments has emerged as a potential strategy to efficiently alleviate salt stress in saline-alkali soil. However, knowledge regarding how to optimize the proportion of different amendment materials, comprehensively assess the contribution of each component, and clarify the response mechanisms of the amendment-saline-alkali soil-plant system is incomplete. Based on this, we conducted a pot experiment to evaluate the improvement effect of the combined application of different amendment materials at varying levels and the contribution of the amendment components to alleviating salt stress. Overall, T6 exhibited the most significant improvement effect on the physicochemical and biological properties of the saline-alkali soil and promoted the growth of oilseed rape, with the levels of 2.0 % phosphogypsum, 2.0 % humic acid, 0.25 % bentonite, and 0.03 % sodium carboxymethyl cellulose. Compared with the control group, the EC decreased by 1.51 % to 33.49 %, the soil salt content dropped by 11.40 % to 35.46 %, and the soil soluble Na + concentration significantly declined by 39.47 % to 63.20 %. Additionally, the soil nutrient content and soil microbial community structure were enhanced in treatment groups. Meanwhile, amendments alleviated salt stress in the oilseed rape plant by activating anti-oxidative enzymes and osmoregulatory substances such as soluble sugar and proline, thus improving their ability to remove reactive oxygen species (ROS). The anti-oxidative enzymes such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were significantly increased, with an increase of 10.68 % (SOD, T2) ∼207.31 % (CAT, T6) compared to the control group. The structural equation modeling (SEM) analysis and simulation experiments indicated that the amendment components synergically promoted the amelioration effect on salt stress, and effectively improved soil properties, which affected the response of oilseed rape to soil environment. This research paper provides the relevant reference for the combined application of different amendment materials for soil reclamation.

Feasible synthesis of coal fly ash based porous composites with multiscale pore structure and its application in Congo red adsorption

Facing the great challenge that the increasing solid waste fly ash is difficult to treat and utilize properly, this paper reports a class of novel low-cost fly ash porous materials with high interconnected porosity fabricated by a facile foaming process. On this basis, composites with multiscale pore structures from the nanometer to macroscopic scale were designed and constructed by decorating layered double hydroxide (LDH) onto the inner channel surface. Such porous materials with 3D through-hole structures showed high interconnected porosity (up to 77.61%), suitable compressive strength (up to 23.79 MPa) and significant water permeation flux (549.86 m³∙m^-2∙h^-1 at 0.1 MPa). Moreover, the adsorption effect of dosage, initial concentration, pH, temperature and contact time on Congo red (CR) from simulated wastewater was investigated. The composites exhibited a good adsorption efficiency of ∼100% and adsorption capacities of 45.79 mg/g. The adsorption kinetic can be explained well by the pseudosecond-order kinetic equation and isotherm adsorption followed Langmuir isotherm model. This suggests that low-cost and eco-friendly fly ash composites have potential applications in industrial-scale wastewater treatment. This work also provides a general strategy to design and utilize fly ash porous materials for filtration and adsorption.

Layered Double Hydroxide Catalysts Preparation, Characterization and Applications for Process Development: An Environmentally Green Approach

The adage of new generation of fine chemicals process is the best process applied in the absence of conventional methods. However, many methods use different reaction parameters, such as basic and acidic catalysts, for example oxidation, reduction, bromination, water splitting, cyanohydrin, ethoxylation, syngas, aldol condensation, Michael addition, asymmetric ring opening of epoxides, epoxidation, Wittig and Heck reaction, asymmetric ester epoxidation of fatty acids, combustion of methane, NOx reduction, biodiesel synthesis, propylene oxide polymerization. Layered Double Hydroxides (LDHs) have received considerable attention due their potential applications in flame retardant and has excellent medicinal property for reducing acidity. These catalysts are characterized using analytical techniques, such as: X-ray diffraction (XRD), Fourier-transform infrared (FT-IR), Raman spectroscopy, Thermogravimetric-Differential Thermal Analyzer (TG-DTA), Scanning electron microscope (SEM), Transmission electron microscopes (TEM), Brunauer-Emmett-Teller (BET) surface area, N2 Adsorption-desorption, Temperature programmed reduction (TPR), X-ray photoelectrons spectroscopy (XPS), which gives its overall picture of its structure, porosity, morphology, thermal stability, reusability, and activity of catalysts. LDHs catalysts have proven to be economic and environmentally friendly. The above discussed applications make these catalysts unique from Green Chemistry point of view since they are reusable, and eco-friendly catalysts. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

Controllable synthesis of bifunctional corn stalk cellulose as a novel adsorbent for efficient removal of Cu2+ and Pb2+ from wastewater

A corn stalk cellulose-based adsorbent with bifunctional groups of -NH-/-NH₂ and C-S/C=S for efficient removal of Cu²⁺ and Pb²⁺ was successfully synthesized. Under specific alkali and reaction conditions, 4.58 mmol/g of C-S/C=S groups were further introduced on surface of aminated cellulose with 6.99 mmol/g of amino groups. The introduced CS₂ would only participate in the esterification with -NH₂ groups to form special dithiocarbamate (DTC) structures containing -NH- groups (-NHCS₂^-). The synthesized DTC structures would not reduce total amount of -NH-/-NH₂ groups on aminated cellulose to keep its excellent adsorption performance for Cu²⁺, and the introduced appropriate number of C-S/C=S groups could ensure the efficient removal of Pb²⁺. It was suitable for removal of coexisting Cu²⁺ and Pb²⁺ with low initial concentration in real wastewater, and the removal rates were both close to 100%. The application of the bifunctional cellulose offered a novel way for purpose of 'waste treatment by waste'.

Adsorption of nitrate from water by quaternized chitosan wrinkled microspheres@MgFe-LDHs core-shell composite

In recent years, nitrate pollution in water became one of the global ecological problems. In this study, a new core-shell composite (GCS@CTA@MgFe-LDHs) was prepared by in-situ growth of MgFe-Cl--LDHs plates...