A cellulose acetate/Amygdalus pedunculata shell-derived activated carbon composite monolith for phenol adsorption

Construction of attapulgite decorated cetylpyridinium bromide/cellulose acetate composite beads for removal of Cr (VI) ions with emphasis on mechanistic insights

Eco-friendly and renewable composite beads were constructed for efficient adsorptive removal of Cr (VI) ions. Attapulgite (ATP) clay decorated with cetylpyridinium bromide (CPBr) was impregnated into cellulose acetate (CA) beads, which were formulated through a simple and cost-effective solvent-exchange approach. FTIR, XRD, SEM, Zeta potential, and XPS characterization tools verified the successful formation of ATP-CPBr@CA beads. The composite beads displayed a spherical and porous shape with a positively charged surface (26.6 mV) at pH 2. In addition, higher adsorption performance was accomplished by ATP-CPBr@CA composite beads with ease of separation compared to their components. Meanwhile, equilibrium isotherms pointed out that the Langmuir model was optimal for describing the adsorption process of Cr (VI) with a maximal adsorption capacity of 302 mg/g. Moreover, the D-R isotherm model verified the physical adsorption process, while adsorption data obeyed the pseudo-second-order kinetic model. Further, XPS results hypothesized that the removal mechanism involves adsorption via electrostatic interactions, redox reaction, and co-precipitation. Interestingly, the ATP-CPBr@CA composite beads reserved tolerable adsorption characteristics with a maximum removal present exceeding 70% after reuse for seven successive cycles, proposing its feasible applicability as a reusable and easy-separable candidate for removing heavy metals from aquatic bodies.

Pressure Indicator Composite Films via Compressive Deformation of a Translucent Matrix Containing a Contrasting Filler

A neglected mechanism for pressure-responsive color change is demonstrated using cellulose acetate composites prepared by direct (solvent) immersion annealing (DIA), with different loadings of activated charcoal filler. Namely, compressive plastic deformation of the translucent cellulose acetate leads to a decrease in the optical path length and a concomitant increase in the visibility of the opaque contrasting filler. Composites bearing 1-7 wt% activated charcoal exhibited a linear relationship between applied pressure and resulting pressure mark brightness in the range of 12-56 MPa. Comparison of pressure mark patterns with cross-sectional scanning electron microscopy (SEM) supports the importance of the porous morphology arising from DIA for the tuning of the pressure indicator sensitivity. A simple ball drop test is used to illustrate the robustness and utility of these indicators in optical impact assessment.

Complete mitochondrial genome of the endangered Prunus pedunculata (Prunoideae, Rosaceae) in China: characterization and phylogenetic analysis

Introduction

Prunus pedunculata (Prunoideae: Rosaceae), a relic shrub with strong resistance and multiple application values, is endangered in China. Extensive research had been devoted to gene expression, molecular markers, plastid genome analysis, and genetic background investigations of P. pedunculata. However, the mitochondrial genome of this species has not been systematically described, owing to the complexity of the plant mitogenome.

Methods

In the present research, the complete mitochondrial genome of P. pedunculata was assembled, annotated, and characterized. The genomic features, gene content and repetitive sequences were analyzed. The genomic variation and phylogenetic analysis have been extensively enumerated.

Results and discussion

The P. pedunculata mitogenome is a circular molecule with a total length of 405,855 bp and a GC content of 45.63%, which are the smallest size and highest GC content among the known Prunus mitochondrial genomes. The mitogenome of P. pedunculata encodes 62 genes, including 34 unique protein-coding genes (PCGs, excluding three possible pseudogenes), three ribosomal RNA genes, and 19 transfer RNA genes. The mitogenome is rich in repetitive sequences, counting 112 simple sequence repeats, 15 tandem repeats, and 50 interspersed repetitive sequences, with a total repeat length of 11,793 bp, accounting for 2.91% of the complete genome. Leucine (Leu) was a predominant amino acid in PCGs, with a frequency of 10.67%, whereas cysteine (Cys) and tryptophan (Trp) were the least adopted. The most frequently used codon was UUU (Phe), with a relative synonymous codon usage (RSCU) value of 1.12. Selective pressure was calculated based on 20 shared PCGs in the mitogenomes of the 32 species, most of which were subjected to purifying selection (Ka/Ks < 1), whereas ccmC and ccmFn underwent positive selection. A total of 262 potential RNA editing sites in 26 PCGs were identified. Furthermore, 56 chloroplast-derived fragments were ascertained in the mitogenome, ranging from 30 to 858 bp, and were mainly located across IGS (intergenic spacer) regions or rRNA genes. These findings verify the occurrence of intracellular gene transfer events from the chloroplast to the mitochondria. Furthermore, the phylogenetic relationship of P. pedunculata was supported by the mitogenome data of 30 other taxa of the Rosaceae family. Understanding the mitochondrial genome characteristics of P. pedunculata is of great importance to promote comprehension of its genetic background and this study provides a basis for the genetic breeding of Prunus.

Development and Evaluation of Cellulose/Graphene-Oxide Based Composite for Removing Phenol from Aqueous Solutions

In this study, a graphene oxide/cellulose composite (GO-cellulose) was prepared usingcellulose and graphene oxide (GO) through ultrasonication, followed by the freeze-dried method. The Brunauer-Emmett-Teller (BET) specific surface area of GO-cellulose (~6.042 m²/g) was higher compared to cellulose (1.023 m²/g).The UV-Visible spectraindicated that the prepared GO-cellulose composite removedphenol efficiently from aqueous solutions with high adsorption power. The effectiveness of the composite for phenol adsorption was examinedunder diverse conditions.The results reveal that the composite optimally improved the adsorption at pH 7 with a dose of 0.125 g/30 L in about 40 min. The adsorption process showed that in optimum conditions, 86 ± 2% of phenol was removed in 40 min with an adsorption capacity of 6.192 mg g^-1. The adsorption behavior was well fitted to the pseudo-second-order kinetic model and the Langmuir isotherms at all temperatures.The present study suggests that synthesized GO-cellulose is useful inthe removal of phenol pollutants from aqueous solutions.

Cellulose-based thermosensitive supramolecular hydrogel for phenol removal from polluted water

Pollution of phenolic effluent from spice and plastics factories has become increasingly serious. Thus, developing a green and highly efficient adsorbent to remove phenolic compounds from wastewater is of urgent need. In this study, cellulose graft copolymer was synthesized through grafting 4-vinylpyridine monomer and polyethylene glycol methacrylate to a molecular skeleton of cellulose by free radical polymerization. The supramolecular hydrogel was successfully synthesized by physical cross-linking of cellulose graft copolymer and α-cyclodextrin. These supramolecular hydrogels were thoroughly characterized and the adsorption performance (adsorption isotherms and adsorption kinetics) of phenol on the supramolecular hydrogel were investigated in batch operation. The supramolecular hydrogel not only exhibited excellent adsorption of phenol, but also demonstrated increased mechanical strength due to the introduction of a modified cellulose base material. The adsorption kinetics of phenol on the supramolecular hydrogel followed a quasi-second-order reaction, with a correlation coefficient of 0.9909. The adsorption isotherm conformed to the Langmuir adsorption isotherm, and the maximum adsorption capacity of phenol can reach 80.71 mg g^-1, which was 2-3 times higher than traditional carbon-based materials. The results demonstrate the great promise of the waste-derived supramolecular hydrogel to be used as an efficient adsorbent in wastewater treatment.

Novel reusable amine-functionalized cellulose acetate beads impregnated aminated graphene oxide for adsorptive removal of hexavalent chromium ions

In this study, a multi-featured adsorbent was developed for the adsorptive removal of hexavalent chromium (Cr⁶⁺) ions. Herein, aminated graphene oxide (GO-NH₂) was firstly synthetized and incorporated into cellulose acetate beads (CA) which were followed by surface amine-functionalization process. Varies characterization tools such as FT-IR spectroscopy, SEM, TGA, XRD, BET, XPS and zeta potential were employed to ensure the successful fabrication of GO-NH₂@CA-NH₂ composite beads. An enhancement in the adsorption performance was attained, while the adsorption equilibrium was closely gotten within only 60 min. Therefore, the adsorption capacity was boosted with increasing GO-NH₂ ratio in the beads matrix from 10 to 25%. Furthermore, the adsorption process agreed with Freundlich isotherm model with a supreme adsorption capacity of 410.21 mg/g at pH 2, while data followed the pseudo-second-order kinetic model. Besides, thermodynamic studies denoted that the adsorption process was endothermic, randomness and spontaneous. The composite beads retained better adsorption characteristics for seven sequential cycles with ease of separation. The proposed adsorption of Cr⁶⁺ onto GO-NH₂@CA-NH₂ surface occurred via the electrostatic interactions, reduction process and coordinate-covalent bonds. These findings hypothesize that the fabricated GO-NH₂@CA-NH₂ beads could be act as easy-separable and reusable adsorbent for efficient adsorption of Cr⁶⁺ ions.

Hierarchical porous MoS2 particles: excellent multi-enzyme-like activities, mechanism and its sensitive phenol sensing based on inhibition of sulfite oxidase mimics

It is important to exploit highly efficient methods for detecting pollutants selectively and sensitively. Artificial enzymes are promising to replace natural enzymes with diverse functions for sustainable developments and various applications. However, it remains the challenge to develop novel mimic enzymes or multi-enzyme mimics for pollutant detection. Herein we report hierarchical porous MoS₂ particles prepared by a simple hydrothermal method, which demonstrated excellent sulfite oxidase (SuO_x)-, nicotinamide adenine dinucleotide (NADH) oxidase- and superoxide dismutase-mimicking activities. In addition, the catalytic conditions for SuO_x-like and NADH oxidase-like activities of MoS₂ were optimized. The catalytic mechanism of the NADH oxidase mimics is that O₂ involves in the oxidation of NADH, to generate O₂^.- intermediate and finally turn to H₂O₂, while SuO_x mimics comes from that MoS₂ particles can effectively catalyze sulfite to reduce [Fe(CN)₆]^3-. Based on the excellent SuO_x-like activity of MoS₂ particles, while phenol can inhibit the oxidation of sulfite, a phenol colorimetric sensor was explored with the dynamic range of 2-1000 μM and the limit of detection of 0.72 μM, applicable to detect phenol in effluents. Therefore, MoS₂ particles with the SuO_x-like, NADH oxidase-like and SOD-like activities has broad application prospects in environmental monitoring and bio-analysis.

Synthesis of high-performance hierarchically porous carbons from rice husk for sorption of phenol in the gas phase

Phenol as a semi-volatile organic compound (SVOC) extensively presents in industrial wastewater. Moreover, it is a main compound of tar existing in the vapor phase from biomass pyrolysis or gasification. So far, most of works on the phenol adsorption by activated carbons have been conducted in the liquid phase. However, the adsorption of phenol in the gas phase has not been reported. This work aims to synthesize the hierarchically porous carbons from the unaltered and pelletized rice husk (RH) via a facile pyrolysis followed by the ball-milling-assisted KOH activation. Herein, the silica nanoparticles in RH acted as a self-template to remarkably increase specific surface areas and pores, thereby giving rise to the formation of hierarchically porous carbons, which showed a relatively high adsorption capacity (maximum value: 1919 mg/g) of phenol in the vapor phase. Generally, the process of phenol adsorption onto porous carbons in the gas phase followed with various interactions, including pore filling, electrostatic interaction, hydrophobic effect, and functional groups effect (e.g., π-π interaction). And the pseudo-second-order model could well describe the adsorption kinetic. It is noted that the pelletized RH was more favorable to develop the porous carbons with the hierarchically meso-microporous structures that could enhance the transfer of the phenol molecules via the outer layer and subsequent uptake by the adsorption sites on the inner layer. Further, the SVOC phenol was hard to volatilize under ambient conditions due to its relatively higher boiling point (181.7 °C), so the thermal desorption was a potential way to regenerate the spent activated biochars.

Activated bio-chars derived from rice husk via one- and two-step KOH-catalyzed pyrolysis for phenol adsorption

The activated bio-chars (AB) were successfully synthesized from rice husk by one- and two-step KOH-catalyzed pyrolysis. The two-step pyrolysis can produce the high yields of AB compared to the one-step pyrolysis. Moreover, the yield of AB decreased with the increase of the mass ratio of KOH and char, which had a significant effect on the development of the surface area and porosity of carbon. In particular, the AB derived from the two-step pyrolysis at 750°C (mass ratio of KOH and char was 3) had the highest specific surface area (S_BET=2138m²/g) with many micro-porous structures, which was favored for the phenol adsorption. The maximum adsorption capacity of AB2-3-750 reached 201mg/g because of its excellent surface porosity property. The phenol can be efficiently removed from water by only several minutes. The Langmuir model defined well the adsorption isotherm with a high correlation coefficient value, indicating a monolayer adsorption behavior. And the adsorption process defined well with the pseudo-second-order model. The phenol molecules passed into the internal surface via the liquid-film controlled diffusion, so the behavior of phenol adsorption onto the AB was predominantly controlled via the chemisorption. Furthermore, the functional groups on the outer surfaces of AB can attract the phenol molecules onto the internal surfaces via "π-π dispersion interaction" and "donor-acceptor effect".

Rice Husk-Derived Activated Carbons for Adsorption of Phenolic Compounds in Water

Activated carbons are synthesized from rice husk by one- and two-step pyrolysis. In general, two-step pyrolysis produces a higher yield of activated carbons. The yield of activated carbon decreases with the increase of mass ratio of KOH and biomass, which has a significant impact on the development of surface area and porosity. The maximum S BET (2138 m2 g-1) is achieved with micro- and mesoporous structures, which is favored for the adsorption process. The activated carbons can efficiently remove phenol from water by a few minutes. In particular, the maximum adsorption capacity (201 mg g-1) is achieved due to the excellent surface textural properties. The Langmuir model can better define the adsorption isotherm. The high correlation coefficient value (R 2 = 0.9991) indicates a monolayer adsorption behavior. The adsorption process can be well-fitted by the pseudo-second-order model. Herein, the phenol molecules pass into the internal surface via liquid-film-controlled diffusion, so the behavior of phenol adsorption onto activated carbons is mainly controlled via chemisorption. In addition, the functional groups on the outer surfaces of activated carbons can attract the phenol molecules onto their internal surface via the "π-π dispersion interaction" and "donor-acceptor effect."