This work aims to treat paint wastewater from industrial equipment cleaning by electrocoagulation (EC) using aluminum electrodes and reusing residual sludge as a starting material for synthesizing a blue inorganic nano-pigment. An initial pH of the wastewater without adjustment, a current density of 133.33 A/m2, an electrolysis time of 30 min and an inter-electrode distance (IED) of 2 cm were the best operating conditions for EC. The reduction rate of COD and turbidity was about 92% and 99.6%, respectively. At optimum conditions, specific metal consumption and specific electrical energy consumption are about 0.168 kg/m3 and 15 kWh/m3, respectively. The paint wastewater treatment sludge (PWTS) from EC was first characterized and then mixed with cobalt(II) chloride to synthesize an inorganic blue nano-pigment. The effects of Co/Al molar ratios and temperatures were studied. From colorimetric data, the pigment obtained at 1100°C is more bluish than those synthesized at a lower temperature. This study will have beneficial effects on the environment as well as on the economy because it makes it possible to transform PWTS into value-added products. Treated wastewater can be reused for paint equipment cleaning and EC sludge can be completely transformed into pigment. The zero-waste principle can therefore be achieved.

Commercial carbon fibre manufacture is a proprietary process which has resulted in limited information being publicly available in regard to the processing of different materials and their impact on material, environmental and economic characteristics. This study investigates the relationship between different precursor materials and these parameters through an in-depth analysis of process structures, material properties, incurred emissions, energy demand and cost composition. This study compares three important precursor types for carbon fibre manufacture including ecological and economical aspects. Two of the precursors are polyacrylonitrile based, a special carbon fibre and textile grade, while the third is a sustainably derived lignin-cellulose blend. The lower cost textile precursor has significantly higher processing cost than the specialized material while also incurring a higher amount of emissions. Indeed, up to 270% more compared to the special grade precursor. The analysis of the lignin-cellulose blend precursor illustrates its shortcomings, especially with respect to processability and properties, despite its lower environmental impact and up to 25% cost advantage. This study suggests pathways for the industrial processing of alternative precursors outlining their economic and ecological benefits and highlighting areas of necessary improvement such as material properties and energy demand.

The catalytic mechanism of CoFe2O4 nanoparticles (NPs) was investigated in the system of electrochemical enhanced heterogeneous activation of peroxymonosulfate (EC/CoFe2O4/PMS) with moxifloxacin (MOX) as target contaminant. The removal efficiencies of MOX in PMS, CoFe2O4, EC, CoFe2O4/PMS, and EC/CoFe2O4/PMS system were 18.3%, 36.1%, 43.7%, 96.9%, and 98.3%, respectively. Although there was no synergy effect between EC and heterogeneous catalytic oxidation reaction (HCOR) on MOX removal, the value of apparent rate constant (karc) was much higher in EC/CoFe2O4/PMS system (0.24 min−1) compared with CoFe2O4/PMS system (0.13 min−1). Therefore, EC not only kept the structure of CoFe2O4 NPs stable, but also significantly accelerated the reaction rate of HCOR. Meanwhile, according to electrochemical impedance spectra of catalysts synthesized based on ion-substitution strategy and the EC-HCOR experimental results, the decisive role of ≡Co in PMS activation and the electron transfer between ≡Co and ≡Fe were confirmed. The TOC removal efficiency was reached 74.4% as the ratio of PMS to CoFe2O4 NPs being 0.8 mM to 50 mg/L (30 min), and further improved to 87.6% with batch addition (0.25 mM per 30 min) of PMS (120 min, CoFe2O4=100 mg/L). The research results could improve the understanding of catalytic mechanism of spinel oxide in electrochemical system.

A green synthesis route was designed to develop a visible-light-driven thin carbon layered titanium dioxide (CLT) nanocomposite using ascorbic acid as carbon precursor. The presence of a thin layer of carbon (CLT) on the TiO2 surface was observed from HR-TEM. The thickness of CLT is directly proportional to the concentration of carbon precursor, where this CLT acts a photosensitizer for harvesting the broad band of visible light spectrum. CLT nanocomposite (15.485 m2/g) showed an improved surface area of 1.4 times that of a commercial TiO2 (7.461 m2/g). The photocatalytic activity of CLT nanocomposite was investigated for the volatile organic compound destruction using p-xylene pollutant in a standard ISO photocatalytic oxidation reactor under daylight. The mechanism pathway of CLT nanocomposite was followed by the adsorption of chemical contaminants in the pores of CLT that precisely capture the contaminants capture and destruction on its surface. The electron-hole pair recombination rate of CLT nanocomposite was lower than the pristine TiO2 was evident from photoluminescence spectra. The antibacterial activity of CLT was also studied using E. coli as a model pathogen. This environmentally friendly photocatalyst CLT offers a novel route for good industrial utilization because of its low cost and mass production.

Metal based materials are frequently used in electrocatalytic processes for the mitigation of CO2 emissions, increasing the cost of the technology and the toxicity of the material. Metal-free catalysts appear as an interesting alternative. This work focusses on the synthesis of nitrogen and boron doped reduced graphene oxide (rGO) for the electrocatalytic reduction of CO2 in gas phase in continuous operation mode in a PEM type cell. The main reaction products observed have been formic acid and CO, being the first one mainly formed. Results obtained with rGONB have been compared with the undoped rGO and with copper-based catalysts (Cu/rGO and Cu/rGONB). The non-metal doped material (rGONB) is much more active in the CO2 electrocatalytic reduction as compared with the undoped material (rGO). The catalytic activity of rGONB is very similar to those obtained with Cu/rGO and Cu/rGONB catalysts, pointing out rGONB as a very promising material for the electrocatalytic reduction of CO2. This is especially relevant considering that rGONB has been tested in a relatively high geometric area (compared with most works in literature), in gas phase and in continuous operation mode, which is an important step to carry out the further scale-up of the process for industrial applications.

Desalination and removing elements such as calcium from aqueous solutions is very important to improve water quality. In this study, bentonite/nano γ-alumina composites were utilized as a low-cost adsorbent for calcium removal from aqueous solutions. To investigate the adsorption process, several experiments were conducted, including initial calcium concentration, adsorbent dosage, pH, contact time, and the γ-alumina content in the composite. Increasing γ-alumina amounts in the composite by more than 1% had the reverse effect due to agglomeration. The increase in specific surface area for bentonite-1wt% γ-alumina compared to bentonite is mainly due to the addition of γ-alumina. The calcium adsorption capasity increased from 0.5 mg/g to 1.15 mg/g when the initial ion concentration was raised from 60 ppm to 100 ppm. The adsorption capacity of 1.15 mg/g and removal % of 23 with were obtained for optimal initial concentration of 100 ppm, adsorbent dosage of 20 g.l-1, and composite percentage of bentonite/1 wt% γ-alumina. The adsorption mechanism was studied by the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models, and the adsorption data was fitted better by the Freundlich model. The Dubinin-Radushkevich isotherm revealed the physical nature of the adsorption. Conclusively, the bentonite-1wt% γ-alumina nanocomposite had better results than the raw bentonite.

Polyethylene terephthalate (PET) is a widely used polymer in packaging products, leading to the daily disposal of millions of PET bottles as waste. 1.1 to 8.8 million tonnes of plastic waste enter the sea each year. The environmental challenge of non-biodegradable PET waste can be addressed by utilizing it as a thin-layer membrane for gas separation. This study modified the PET membrane by blending it with Pebax polymer and adding zeolite as a filler to enhance its performance. Characterization techniques, including FTIR, SEM, TGA, tensile strength testing, and contact angle measurements, were performed on all modified membranes. The membranes were prepared using phase inversion via immersion precipitation. The results showed that the PET waste membrane had a denser surface pore morphology and asymmetrical cross-sectional pores than other membranes. Adding Pebax and zeolite resulted in a more regular sponge-like pore structure. The PET, PET-Pebax, and PET-Zeolite NaY-Pebax membranes exhibited hydrophilic properties, as indicated by contact angle values ranging from 48-78°. Regarding CO2/CH4 separation, the 9% PET-Pebax membrane had the highest CO2 permeability, a 21% increase from the original PET waste membrane. Adding zeolite to the 9% PET-Pebax membrane increased CO2 permeability to 1044%.

Slow-release fertilizers (SRF) have emerged as a sustainable remedy to the environmental problems caused by conventional water-soluble fertilizers. They have demonstrated their efficacy in reducing fertilizer dosage applications, enhancing fertilizer utilization efficiency, minimizing losses, and ultimately improving crop yield. This study developed biodegradable nanocomposite hydrogels (BHM) as a promising approach by combining cassava starch (Cst), polyacrylamide (PAM), natural rubber (NR), and various montmorillonite (MMT) contents (0-10 wt%) and fabricating via free-radical polymerization and semi-interpenetrating polymer network technology, crosslinked by glutaraldehyde. Notably, the addition of MMT played a crucial role and significantly improved the tensile strength, biodegradability, and N release efficiency of the BHM hydrogels. BHM3 (3 wt% MMT) demonstrated the highest swelling ratio of 7074% and improved N release efficiency, mechanical strength, and biodegradation rate by 39.1%, 260% and 58%, respectively, compared to BHM0. The FWBHM formulations (urea coated with BHM and wax layers) also exhibited good biosafety. Finally, FWBHM3 yielded acceptable growth rates, a greater yield, and a 4-fold lower price than commercial SRF. These findings provide a promising route for developing new nanocomposite hydrogels based on Cst, NR, and MMT components with high swelling and water-retention, high strengths, and excellent biodegradation with greater slow-release duration and sustained environments.

Activated carbon (AC) is one of the typical adsorbents for industrial treatment of VOCs, but AC itself has a high calorific value. When the heat generated by low-temperature oxidation cannot be released, it is easy to store heat and oxidize spontaneously, resulting in immeasurable harm. Therefore, it is important to study and improve the thermal stability of AC. In this study, Mo-doped carbon quantum dots (CQDs) was synthesized to enhance the safety of AC usage. The structure of AC before and after modification was characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD). On the modified Mo-doped CQDs/AC, there are more crystalline structures formed by Mo oxides on the surface, which makes the intermolecular force on the surface of AC increase. At the same time, Mo oxide has strong oxidation resistance, which can inhibit the thermal decomposition process of AC, and has stronger stability. The spontaneous combustion tendency and thermal hazard of AC before and after modification were greatly improved. The heat released in the toluene adsorption by the modified AC at different temperatures was significantly lower than the heat released by the unmodified AC. According to the Langmuir adsorption isotherm, the adsorption performance of Mo-doped CQDs (2.5wt%) was 1.6 times higher than that of AC when the system was 25 °C. The results showed that Na2MoO4 CQDs modified AC could effectively improve the thermal stability and greatly reduce the spontaneous combustion tendency. A relative fire safety performance evaluation model was also established to comprehensively evaluate the fire risk of VOCs treatment by AC.

The aldol condensation reaction, capable of forming new CC bonds from small molecular carbonyl compounds, is gaining attention again for biogenic carbon recovery from discarded aqueous-phase pyrolysis oil of wood to bio-fuels. This comprehensive review describes the aldol condensation reaction based on the literature review and density functional theory studies to efficiently produce biofuel precursors from complex aqueous phase pyrolysis oil and examines the unavoidable effects of water and acid contained in feedstocks on the aldol condensation reaction and catalyst, as key barriers. Additionally, the newly proposed aldol condensation reaction system and recent advances in tandem catalysts are addressed.

Semiconductor−metal–organic framework (MOF) hybrid photocatalysts become a significant material to treating dyeing wastewater recently. Zinc-based metal–organic framework (ZIF-8) stands out among numerous photocatalysts for its stability and simplicity to prepare. In this work, the gourd-shaped ZIF-8/TiO2 nanocomposites are prepared in situ on anatase TiO2 by precursor method, and then ZIF-8/TiO2 nanocomposites is supported on PVDF electrospinning nanofibers by blending method to form ZIF-8/TiO2 nanofibers (ZIF-8/TiO2 NFs). We compare the degradation ability of Rhodamine B by ZIF-8/TiO2 NFs with different mass ratios and load rates. When the mass ratio of ZIF-8 to TiO2 is 2:1 and the loading rate is 10%, the photocatalytic degradation efficiency of ZIF-8/TiO2 NFs reached 95.4%, and the degradation remained as high as 88.7% after cycling five times. The characterization results showed that ZIF-8 and TiO2 are connected by N − Ti − O chemical bond, which narrows the band gap and rebars the recombination of the electron-hole pairs. The synergistic action of ZIF-8 and TiO2 largely improves the photocatalytic capacity of ZIF-8/TiO2 NFs.

Oxidized cotton linters, TOCell, were used as an adsorbent or derived membrane there from by linters cross-linking with citric acid. The adsorption/desorption study of Pb2+, methylene blue (MB), and crystal violet (CV) removal, was performed. Adsorption data fitting, obtained using the Langmuir model, gave 116 mg g−1 (Pb2+), 179 mg g−1 (MB) and 482 mg g−1 (CV) at 25 ℃ for TOCell linters, while 101 mg g−1 (Pb2+), 165 mg g−1 (MB) and 426 mg g−1 (CV) for TOCell membrane. After desorption dyes were subjected to photocatalytic degradation while lead was transformed into stable lead phthalate (LP), and further used as filler in composites based on unsaturated polyester resins (UPR). UPR was synthesized from waste polyethylene terephthalate (PET). Structural characterization was performed using FTIR, SEM, and NMR methods. Composites loaded with acryloyl modified kraft lignin (A-KfL) and/or LP was tested for tensile strength, Vickers microhardness, and fire resistance (UL-94 V method). The best mechanical and fireproofing properties were obtained at 15 wt.% A-KfL and 40 wt.% Al(OH)3 addition. The results of the toxicity leaching test (TCLP) confirmed the environmentally safe stabilization of desorbed pollutant in the UPR matrix. Application of environmentally friendly membranes, susceptible to easy biodegradation, had low negative effects to the environment.

Nitrogen oxide (NOx) emissions pose major human health and environmental concerns. Gliding arc plasma is a promising technology for reforming various chemicals. To the best of our knowledge, the application of rotating arc plasma for the reforming of diesel fuel as a reductant coupled to selective catalytic reduction (SCR) on the scale of real-world conditions has not been reported yet. This study aimed to investigate the reduction of NOx using hydrocarbons, as reducing agents, supplied through a rotating arc plasma reformer for SCR. Dodecane (C12H26) was selected as hydrocarbon fuel to represent diesel. The effects of the carbon-to-oxygen ratio and its associated products with ozone addition over different catalyst temperatures from room temperature (22±4 °C) to 300 °C were investigated. After investigating fuel-based reductants, NO was supplied to the bench-scale system as a NOx source. Moreover, NOx removal using plasma-derived hydrocarbon species was investigated using in-situ fourier transform infrared spectroscopy. We found that an optimal carbon-to-oxygen ratio (1.4) was critical for NOx removal. Additionally, up to 95% De-NOx could be achieved as the catalyst temperature increased. Besides, additional ozone injection increased the De-NOx performance at a catalyst temperature < 250 °C because of the enhanced oxygenated hydrocarbon species.

Influences of integral multi jet(IMJ), swirling blade nozzle(SBN) and longitudinal vortex generators(LVGs) on uniform mixing behaviors of ternary mixture during water vaporization in spouted beds were simulated from the perspective of temperature and velocity fields. To quantitative evaluate the mechanism of water vaporization, temperature uniformity index(Tu), mixing index(IM) and coefficient of variation(CV) were used. Simulation results: the bubble-like distribution of particles caused by LVGs, IMJ and SBN strengthen the gas-solid radial mixing and improve flow “dead zone”. In the upper of system, the promotion of uniformity and mixing quality is SBN>LVGs>IMJ, and LVGs has the most obvious promoting effect on Tu. Moreover, the influences of operating parameters on Tu, IM and mass fraction of H2O(g)(MFH) were investigated. Vgas=11.2 m/s, Tgas=520 K, and TWater=300 K, the liquid-solid mixing quality is the best. In terms of Tu and MFH, Vgas=11.2 m/s, Tgas=540 K, and Twater=400 K have the most obvious effect.

Photocatalysis is the most viable and significant approach for treating wastewater for several reasons, including its simplicity, low cost, reproducibility, manageability, and efficiency. Photocatalysis is considered a green technology and utilizes less energy, and is safe for humans as well as animals. Due to the non-toxic behavior of several semiconductor materials, such as TiO2, ZnO, SnO2, CeO2, and other carbon-based catalysts, they are used efficiently for pollutant degradation. Phenolic derivatives are produced from natural and artificial processes, thus causing threats to human health as well as the environment. High concentrations of phenolic effluent will be created during industrial manufacturing operations, notably those involving petroleum processing. In this review, (1) photocatalytic treatment of phenolic compounds using various metal oxide and carbon-based catalyst, (2) influence of various reaction parameters, and (3) the mechanism and kinetics of the photodegradation of phenolic compounds, are discussed. It was noticeable that low-cost photocatalysts illustrated remarkable photocatalytic degradation efficiency for phenolic compounds.

In this study, we explore how the covalent bonds linking individual building block molecules can substantially alter the suprastructure of molecular self-assembly. We focus on the role of covalent bonding within the self-assembled structures of a cysteinyl bolaamphiphile which consists of two cysteinyl motifs connected by a central hydrophobic heptyl chain spacer. The cysteinyl bolaamphiphile molecules self-assemble into a nanobelt structure with the creation of disulfide bonds during assembly, which prompts anisotropic molecular ordering and subsequent bending of the nanobelts. A series of control experiments revealed the twofold contribution of disulfide bonds: they facilitate the bending of the nanobelt assembly and the formation of longer assembled structures. Molecular dynamics simulation study confirms that the anisotropic distribution of disulfide bonds causes the bending of a nanobelt assembly. Moreover, the simulation and experimental studies demonstrated an increase in the nanobelt curvature as more disulfide bonds are generated. These results highlight the previously unappreciated influence of covalent bonds in causing macroscopic deformation of self-assembled structures.

To obtain a green, low-cost and efficient adsorbent, polydopamine (PDA) and β-cyclodextrin (β-CD) were adopted to modify coal fly ash (CFA) to prepare polydopamine/β-cyclodextrin/coal fly ash composite (PDA/β-CD/CFA). The successful introduction of PDA and β-CD was proved by FT-IR, XRD and XPS. The uranium extraction efficiency on PDA/β-CD/CFA reached 95.6% (pH = 5.0, T = 298 K, C0 = 10 mg/L and m/V = 0.2 g/L) and the whole adsorption process was perfectly fitted by the Pseudo-second-order model (R2 = 0.999), illustrating that uranium was extracted via chemisorption. The correlation coefficient R2 of Langmuir model was 0.999, which was higher than other models, meaning that uranium extraction behavior on PDA/β-CD/CFA was uniform monolayer adsorption. The maximum extraction capacity of uranium on PDA/β-CD/CFA calculated by Langmuir model was 537.6 mg/g, which was larger than most of reported adsorbents, indicating that PDA/β-CD/CFA was a potential candidate for uranium extraction from water environment. Moreover, PDA/β-CD/CFA performed excellent uranium extraction properties with the existence of coexisting ions and the desorption efficiency of uranium by PDA/β-CD/CFA was higher to 95.8% at the fifth cycles, fully suggesting that PDA/β-CD/CFA possessed good selectivity and cycle stability. Characterization results demonstrated that uranium was immobilized on PDA/β-CD/CFA through chelation, complexing action, electrostatic interaction and hydrogen bonding.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus has become a dangerous human pathogen and caused severe illness that can lead to death. Yet, the standard practical diagnostic tools for detecting the SARS-CoV-2 virus require multi-step assay, including extraction and labeling steps. Thus, a simple and accurate detection tool is incredibly desirable to support on-site screening, preventing its spread. In this work, we develop a portable surface plasmon resonance (SPR) sensor chip modified with metal-organic frameworks (MOF) UiO-66 that serves as an immobilization matrix of single-chain variable fragment (scFv) receptors. Large surface area and good adsorption of UiO-66/scFv-modified surface lead to an improvement of binding capacity towards the protein target of the SARS-CoV-2 receptor binding domain (RBD). We further successfully demonstrate the use of this portable SPR to detect the SARS-CoV-2 virus from patients' nasopharyngeal swab samples. Interestingly, the SPR sensors can directly distinguish the positive and negative patients within 15 minutes on six samples, simultaneously, without the need for labeling, and the results are in line with the gold standard PCR tests. In addition, the detection limit of the sensors is 10.085 x 105 virus/mL, which follows the standard of practical screening tools. Therefore, these UiO-66 modified SPR chip sensors offer a rapid, label-free, and low-cost detection of the SARS-CoV-2 virus that can be potentially developed for other infectious diseases.

In this study, chitosan (CS) from fish waste was used to prepare bio-based environmentally friendly flame retardants. After the hydroxyl group (−OH) of CS and the ammonium group (NH4+) of ammonium polyphosphate (APP) underwent reactions, they were filtered and dried to obtain CS-APP. The amino group of CS-APP then reacted with the epoxy group of 4,4′-methylenebis(N,N-diglycidylaniline) (NDY) to form CS-APP-NDY. Isophorone diisocyanate, polyol, and 3-aminopropyltriethoxysilane reacted to form silicon polyurethane. CS-APP-NDY was then mixed with Si-PU to prepare polymer composites. To determine the structure, thermal properties, flame retardancy, and mechanical properties of the composites, Fourier-transform infrared spectroscopy, thermogravimetric analysis, limiting oxygen index (LOI), cone calorimetry, UL-94, thermal analysis-FTIR (TA-FTIR) spectroscopy, universal machine testing, scanning electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy were performed. The TGA results revealed that, after the addition of CS-APP-NDY, char yield increased from 0.5 wt% to 25.8 wt%, and the thermal stability of pristine PU also improved. In addition, the LOI and UL-94 results indicated that, after the addition of CS-APP-NDY, the LOI increased from 18.2% to 26.3%, and the UL-94 level improved from “Fail” to V-1. Overall, these results indicated that the addition of CS-APP-NDY to pristine PU increased its flame-retarding performance.

Nowadays, layer-structured two-dimensional (2D) Ti3C2 MXenes have been created a platform as promising candidates for developing next-generation photodetectors. Scalable spatial organization of Ti3C2 MXenes enables responsive template at the interface of various semiconductors for significant improvement in the photodetector performance. In this review, we provide prospective discussion on geometrical potentiality of 2D Ti3C2 MXenes to advance the current photodetector device performance. Specifically, we guide the versatility of Ti3C2 MXenes such as a metal electrode, flexible material, transparent nature, and self-power behavior during UV, visible, and broadband photodetector performance. By the excellence of 2D Ti3C2, we begin to comprehend the Schottky barrier, built-in electric field, and van der Walls heterojunction formation. It is imperative to understand the vast opportunities of Ti3C2 MXene-based photodetectors even under flexible conditions, which is higher than conventional gold and graphene. Owing to the desirable properties, Ti3C2 garnered significant progress in (i) large-size flexible photodetector formation without altering the structural and charge carrier properties, (ii) replacing conventional metal electrodes by electrically conductive Ti3C2 in Ti3C2-semiconductor-Ti3C2 (MX-S-MX) photodetector, and (iii) Schottky junction formation at the interface of various semiconductors. Finally, we conclude the status of 2D Ti3C2 MXene applicability, challenges, and possible viewpoints for advancement in next-generation photodetectors.