Amino-functionalized cellulose composite for efficient simultaneous adsorption of tetracycline and copper ions: Performance, mechanism and DFT study.

A novel cellulose composite (denoted as PEI@MMA-1) with porous interconnected structure was prepared by adsorbing methyl cellulose (MC) onto microcrystalline cellulose (MCC) and cross-linking polyethyleneimine (PEI) with MCC by the action of epichlorohydrin, which had the excellent adsorption property, wettability and elasticity. The performances of PEI@MMA-1 composite for removing tetracycline (TC), Cu2+ and coexistent pollutant (TC and Cu2+ mixture) were systematically explored. For single TC or Cu2+ contaminant, the maximum adsorption capacities were 75.53 and 562.23 mg/g at 30 °C, respectively, while in the dual contaminant system, they would form complexes and Cu2+ could play a "bridge" role to remarkably promote the adsorption of TC with the maximum adsorption capacities of 281.66 and 253.58 mg/g for TC and Cu2+. In addition, the adsorption kinetics, isotherms and adsorption mechanisms of single-pollutant and dual-pollutant systems have been thoroughly investigated. Theoretical calculations indicated that the amide group of TC molecule with the assistance of Cu2+ interacted with the hydroxyl group of PEI@MMA-1 composite to enhance the TC adsorption capacity. Cycle regeneration and fixed bed column experiments revealed that the PEI@MMA-1 possessed the excellent stability and utility. Current PEI@MMA-1 cellulose composite exhibited a promising application for remediation of heavy metals and antibiotics coexistence wastewater.

Preparation of anisotropic polyimide aerogels for thermal protection with outstanding flexible resilience using the freeze-drying method.

Polyimide aerogels (PIAs) not only possess excellent thermodynamic properties but also have a high porosity structure, making them an exceptional protective and thermal insulation material, and further broadening their application scope in aerospace and other cutting-edge fields. In this work, a series of anisotropic polyimide aerogels (3,3',4,4'-biphenyltetracarboxylic dianhydride (S-BPDA), p-phenylenediamine (PDA), 4,4'-diaminodiphenyl ether (ODA)) with excellent properties were prepared. These PIAs were obtained by unidirectional freeze-drying and thermal amination of two different precursor solutions mixed in proportion. These PIAs possess an irregularly oval tubular structure, exhibiting pronounced anisotropy. (PIA-2 exhibits outstanding flexible resilience in the radial direction. It can still regain its original form after half an hour of compression by a universal testing machine, yet it cannot do so in the axial direction. The thermal diffusivity of PIA-5 in the radial direction at room temperature is as low as 0.067 mm2 s-1, and even at 200 °C, the thermal diffusivity is as low as 0.057 mm2 s-1. Meanwhile, the thermal diffusivity in the axial direction at room temperature is 0.11 mm2 s-1, surpassing the value of 0.106 mm2 s-1 of aerogels prepared from monomeric raw materials and dried under supercritical conditions). PIAs exhibit outstanding thermal stability (the axial strength and modulus retention of PIA-8 at 200 °C are as high as 52.63% and 44.82%), and its weight loss temperature of 5% is as high as 603 °C and it has a glass softening temperature of 387 °C. PIAs also demonstrate exceptional flame retardancy in imitation flame retardant experiments and exhibit outstanding thermal insulation performance when heated on a 150 °C heating plate for 10 minutes (the radial surface temperature of PIA-5 was only 49.9 °C). These anisotropic PIAs materials exhibit outstanding flexible resilience, and thermal protection performance, holding significant importance for their widespread adoption as thermal insulation materials in aerospace, high-precision electronic components, and other domains.

Mn-Co-Ce/biochar based particles electrodes for removal of COD from coking wastewater by 3D/HEFL system: Characteristics, optimization, and mechanism.

In this work, the Mn, Co, Ce co-doped corn cob biochar (MCCBC) as catalytic particle electrodes in a three-dimensional heterogeneous electro-Fenton-like (3D-HEFL) system for the efficient degradation of coking wastewater was investigated. Various characterization methods such as SEM, EDS, XRD, XPS and electrochemical analysis were employed for the prepared materials. The results showed that the MCCBC particle electrodes had excellent electrochemical degradation performances of COD in coking wastewater, and the COD removal and degradation rates of the 3D/HEFL system were 85.35% and 0.0563 min-1 respectively. RSM optimized conditions revealed higher COD removal rate at 89.23% after 31.6 min of electrolysis. The efficient degradability and wide adaptability of the 3D/HEFL system were due to its beneficial coupling mechanism, including the synergistic effect between the system factors (3D and HEFL) as well as the synergistic interactions between the ROS (dominated by •OH and supplemented by O2•-) in the system. Moreover, the COD removal rate of MCCBC could still remain at 81.41% after 5 cycles with a lower ion leaching and a specific energy consumption of 11.28 kWh kg-1 COD. The superior performance of MCCBC, as catalytic particle electrodes showed a great potential for engineering applications for the advanced treatment of coking wastewater.

Preparation of magnetic DTPA-modified chitosan composite microspheres for enhanced adsorption of Pb(II) from aqueous solution.

In this study, magnetic DTPA-modified chitosan composite microspheres (MDCM) were prepared by reverse emulsion-double crosslinking method (carbodiimide followed by glutaraldehyde) for removal of Pb(II) from aqueous solution. The obtained magnetic adsorbents were characterized by FTIR, SEM, XRD, VSM, BET, and 13C NMR. The effects of the pH, contact time, initial concentration, and competitive metal cations (Na(I), Ca(II), or Mg(II)) on Pb(II) adsorption were investigated. The results revealed that MDCM exhibited high removal performance over a wide pH range and in the presence of competitive metal cations. The maximum adsorption capacity of MDCM for Pb(II) is 214.63 mg g-1 at pH 3, which is higher than most recently reported magnetic adsorbents. Adsorption kinetics and isotherms can be described by the pseudo-second-order model and Langmuir model, respectively. In addition, MDCM is easy to regenerate and can be reused five cycles with high adsorption capacity. Finally, the adsorption mechanism was further revealed by FTIR and XPS analysis. Overall, MDCM has practical application potential in removing Pb(II) from contaminated wastewater due to its high adsorption efficiency, good reusability, and convenient magnetic separation.

Dy-Modified Mn/TiO2 Catalyst Used for the Selective Catalytic Reduction of NO in Ammonia at Low Temperatures.

A novel Mn/TiO2 catalyst, prepared through modification with the rare-earth metal Dy, has been employed for low-temperature selective catalytic reduction (SCR) denitrification. Anatase TiO2, with its large specific surface area, serves as the carrier. The active component MnOx on the TiO2 carrier is modified using Dy. DyxMn/TiO2, prepared via the impregnation method, exhibited remarkable catalytic performance in the SCR of NO with NH3 as the reducing agent at low temperatures. Experiments and characterization revealed that the introduction of a suitable amount of the rare-earth metal Dy can effectively enhance the catalyst's specific surface area and the gas-solid contact area in catalytic reactions. It also significantly increases the concentration of Mn4+, chemisorbed oxygen, and weak acid sites on the catalyst surface. This leads to a notable improvement in the reduction performance of the DyMn/TiO2 catalyst, ultimately contributing to the improvement of the NH3-SCR denitrification performance at low temperatures. At 100 °C and a space velocity of 24,000 h-1, the Dy0.1Mn/TiO2 catalyst can achieve a 98% conversion rate of NOx. Furthermore, its active temperature point decreases by 60 °C after the modification, highlighting exceptional catalytic efficacy at low temperatures. By doubling the space velocity, the NOx conversion rate of the catalyst can still reach 96% at 130 °C, indicating significant operational flexibility. The selectivity of N2 remained stable at over 95% before reaching 240 °C.

Preparation of biodegradable composite films based on carboxymethylated holocellulose from wheat straw.

Holocellulose was extracted from wheat straw and catalytically transformed into carboxymethylated holocellulose (CMHCS) to prepare a biodegradable composite film. By changing the type and amount of catalyst, the carboxymethylation of the holocellulose was optimized with respect to the degree of substitution (DS). A high DS of 2.46 was achieved in the presence of a cocatalyst composed of polyethylene glycol and cetyltrimethylammonium bromide. The effect of DS on the properties of CMHCS-derived biodegradable composite films was further investigated. Compared to pristine holocellulose, the mechanical properties of the composite film were significantly improved and increased with increasing DS. The tensile strength, elongation at break, and Young's modulus increased from 6.58 MPa, 51.4 %, and 26.13 MPa for the unmodified holocellulose-based composite film to 14.81 MPa, 89.36 %, and 81.73 MPa for the film derived from the CMHCS with a DS of 2.46. The biodegradability of the composite film was assessed under soil burial biodisintegration conditions and reached 71.5 % degradation after 45 d. Additionally, a possible degradation process for the composite film was proposed. The results indicated that the CMHCS-derived composite film has good comprehensive performance, and CMHCS is expected to be applied in the field of biodegradable composite materials.

H2O2 modified peanut shell-derived biochar/alginate composite beads as a green adsorbent for removal of Cu(II) from aqueous solution.

In this study, a novel composite bead (MPB-ALG) was prepared by encapsulating H2O2 modified peanut shell-derived biochar (MPB) into alginate matrix through a facile method. The structure and properties of prepared materials were characterized using FTIR, BET, SEM, and XPS. Batch adsorption experiments were performed to compare the Cu(II) adsorption performance of MPB, plain alginate beads (ALG), and MPB-ALG. The effect parameters of the components, solution pH, contact time, initial concentration, and coexisting ions were studied systematically. The results showed that the maximum adsorption capacity of the optimized MPB-ALG-1 (MPB/alginate = 1:1 w/w%) was 117.4 mg g-1 at pH 5, which was much higher than that of MPB (37.4 mg g-1). The adsorption kinetics and isotherms data of Cu(II) on MPB-ALG-1 were well described by Elovich kinetic model and Freundlich adsorption isotherm. Compared with plain ALG beads, MPB-ALG-1 exhibited better reusability and anti-interference of coexisting ions. Finally, the adsorption mechanisms of Cu(II) on MPB-ALG-1 beads were revealed by FTIR and XPS analysis. The experimental results demonstrated that MPB-ALG-1 beads can be used as an environmentally friendly and efficient adsorbent for the removal of Cu(II) from wastewater.

Effective Removal of Fe (III) from Strongly Acidic Wastewater by Pyridine-Modified Chitosan: Synthesis, Efficiency, and Mechanism.

A novel pyridine-modified chitosan (PYCS) adsorbent was prepared in a multistep procedure including the successive grafting of 2-(chloromethyl) pyridine hydrochloride and crosslinking with glutaraldehyde. Then, the as-prepared materials were used as adsorbents for the removal of metal ions from acidic wastewater. Batch adsorption experiments were carried out to study the impact of various factors such as solution pH value, contact time, temperature, and Fe (III) concentration. The results showed that the absorbent exhibited a high capacity of Fe (III) and the maximum adsorption capacity was up to 66.20 mg/g under optimal experimental conditions (the adsorption time = 12 h, pH = 2.5, and T = 303 K). Adsorption kinetics and isotherm data were accurately described by the pseudo-second-order kinetic model and Sips model, respectively. Thermodynamic studies confirmed that the adsorption was a spontaneous endothermic process. Moreover, the adsorption mechanism was investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results revealed the pyridine group forms a stable chelate with iron (III) ions. Therefore, this acid-resistant adsorbent exhibited excellent adsorption performance for heavy metal ions from acidic wastewater compared to the conventional adsorbents, helping realize direct decontamination and secondary utilization.

Adsorption Performance of Methylene Blue by KOH/FeCl3 Modified Biochar/Alginate Composite Beads Derived from Agricultural Waste.

In this study, high-performance modified biochar/alginate composite bead (MCB/ALG) adsorbents were prepared from recycled agricultural waste corncobs by a high-temperature pyrolysis and KOH/FeCl3 activation process. The prepared MCB/ALG beads were tested for the adsorption of methylene blue (MB) dye from wastewater. A variety of analytical methods, such as SEM, BET, FTIR and XRD, were used to investigate the structure and properties of the as-prepared adsorbents. The effects of solution pH, time, initial MB concentration and adsorption temperature on the adsorption performance of MCB/ALG beads were discussed in detail. The results showed that the adsorption equilibrium of MB dye was consistent with the Langmuir isothermal model and the pseudo-second-order kinetic model. The maximum adsorption capacity of MCB/ALG-1 could reach 1373.49 mg/g at 303 K. The thermodynamic studies implied endothermic and spontaneous properties of the adsorption system. This high adsorption performance of MCB/ALG was mainly attributed to pore filling, hydrogen bonding and electrostatic interactions. The regeneration experiments showed that the removal rate of MB could still reach 85% even after five cycles of experiments, indicating that MCB/ALG had good reusability and stability. These results suggested that a win-win strategy of applying agricultural waste to water remediation was feasible.

Immobilization CoOOH nanosheets on biochar for peroxymonosulfate activation: Built-in electric field mediated radical and non-radical pathways.

The strong electron interaction between metal oxide-carbon-based catalyst components plays a vital role in the peroxymonosulfate (PMS) activation for pollutant degradation. Herein, a novel CoOOH nanosheets anchored on rape straw-derived biochar (BC) surface (labeled as CoOOH/BC) as an efficient PMS activator toward degrading sulfamethoxazole (SMX) was synthesized. Experimental results indicated that integrating CoOOH nanosheets on the BC surface could inhibit CoOOH aggregation to increase the specific surface areas, exert a component synergistic effect to enhance activation degradation activity, and improve the catalyst stability. As a result, a 96 % degradation efficiency of SMX was achieved within 20 min over 20 wt% CoOOH/BC composite catalyst under the optimal conditions. Density functional theory (DFT) calculations disclosed that a built-in electric field (BIEF) pointing from BC to CoOOH was constructed at their interface, which could mediate PMS activation for reactive oxygen species (ROS) generation and induce direct electron transfer from SMX to PMS, resulting in efficient SMX degradation via both radical and non-radical pathways. Moreover, quenching experiments and electron paramagnetic resonance (EPR) measurements confirmed that single oxide (1O2) and superoxide radical (O2·-) are the dominant active species in the current system. Additionally, the possible SMX degradation routes were reasonably proposed based on liquid chromatography-mass spectrometry (LC-MS) results. This work provides an in-depth understanding of the role of BIEF in PMS activation, and expands the application of biochar-based materials in the field of environmental remediation.

Anaerobic digestion of sulphate wastewater mediated by biochar.

In this paper, the influences of biochar on the anaerobic digestion of sulphate wastewater, including the COD removal rate, methane yield, intermediate products and the change of microbial community structure, were investigated. The results showed that sulphate could promote the anaerobic digestion with the SO42-/COD ratio increasing from 0 to 0.1, while the activity of MPB was inhibited, which led to the decrease of COD removal rate and methane yield with the SO42-/COD ratio increasing from 0.1 to 2. At 1 g biochar loading, 344.97 mL CH4/gCODremoval was obtained compared with the control group (220.70 CH4/gCODremoval) at 2 of SO42-/COD. Biochar could also reduce the secondary accumulation of NH4+-N and TVFA. Meanwhile, methanogenic microorganisms were selectively enriched especially for methanobacterium, methanosaeta and methanolinea, while the growth of SRB was inhibited with biochar addition.

Enhancing anaerobic digestion of sulphate wastewater by adding nano-zero valent iron.

In this paper, the effects of nano-zero valent iron (nZVI) on anaerobic digestion of sulphate wastewater with different SO42-/COD ratios, including the COD removal rate, methane yield, intermediate products and the change of microbial community structure, were investigated. The results showed that nZVI could effectively enhance the treatment efficiency and methane yield. Compared with the control group without nZVI, the methane yield increased from 348.6833 to 1007.05 mL CH4/gCODremoval with 4 g nZVI loading at SO42-/COD = 0.1. nZVI could make electron flow from sulphate reduction to methane production, which increased methane yield even at high sulphate concentration. The microbial community analysis showed that adding nZVI could increase the abundance of acetoclastic methanogens, which accelerated hydrolysis acidification.

Unleashing the power within short-read RNA-seq for plant research: Beyond differential expression analysis and toward regulomics.

RNA-seq has become a state-of-the-art technique for transcriptomic studies. Advances in both RNA-seq techniques and the corresponding analysis tools and pipelines have unprecedently shaped our understanding in almost every aspects of plant sciences. Notably, the integration of huge amount of RNA-seq with other omic data sets in the model plants and major crop species have facilitated plant regulomics, while the RNA-seq analysis has still been primarily used for differential expression analysis in many less-studied plant species. To unleash the analytical power of RNA-seq in plant species, especially less-studied species and biomass crops, we summarize recent achievements of RNA-seq analysis in the major plant species and representative tools in the four types of application: (1) transcriptome assembly, (2) construction of expression atlas, (3) network analysis, and (4) structural alteration. We emphasize the importance of expression atlas, coexpression networks and predictions of gene regulatory relationships in moving plant transcriptomes toward regulomics, an omic view of genome-wide transcription regulation. We highlight what can be achieved in plant research with RNA-seq by introducing a list of representative RNA-seq analysis tools and resources that are developed for certain minor species or suitable for the analysis without species limitation. In summary, we provide an updated digest on RNA-seq tools, resources and the diverse applications for plant research, and our perspective on the power and challenges of short-read RNA-seq analysis from a regulomic point view. A full utilization of these fruitful RNA-seq resources will promote plant omic research to a higher level, especially in those less studied species.

Investigation on the Preparation of Rice Straw-Derived Cellulose Acetate and Its Spinnability for Electrospinning.

Rice straw-derived cellulose (RSC) with purity of 92 wt.% was successfully extracted from rice straw by a novel and facile strategy, which integrated the C2H5OH/H2O autocatalytic process, dilute alkali treatment and H2O2 bleaching process. Influencing factors of the cellulose extraction were systematically examined, such as ethanol concentration, alkali concentration, H2O2 bleaching process and so on; the optimal extraction conditions of cellulose was determined. A series of rice straw-derived cellulose acetate (RSCA) with different degree of substitution (DS) were prepared by the acetylation reaction; the effects of Ac2O/cellulose ratio, reaction temperature and reaction time on the acetylation reaction were investigated. Results of FTIR and XRD analysis demonstrated that highly purified RSC and RSCA were prepared comparing with the commercial cellulose and cellulose acetate. Solubility analysis of RSCA with different DS indicated as-prepared RSCA with DS of 2.82 possessed the best solubleness, which was suitable for electrospinning. Moreover, the flexible RSCA fibrous membrane was easily fabricated by a facile electrospinning method. Our proposed method provided a strategy for realizing the high-value utilization of waste rice straw resource, as prepared RSC and RSCA can be used as chemical raw material, and electrospun RSCA fibrous membrane has various applications in medical materials, food packaging, water purification and so on.

Influence of surfactant on CO2 adsorption of amine-functionalized MCM-41.

Concerning the increasing greenhouse effect, the development of efficient CO2 adsorbents is very important. In this study, the influence of surfactant on the adsorption performance of amine-functionalized MCM-41 was analysed. The results showed that the residual amount of surfactant in MCM-41 was gradually decreased with the increase of calcination temperature which improved the pore structure. The maximum adsorption capacity (5.495 mmol/g) appeared at PEI-MCM-41-100°C indicated that the adsorption capacity could be improved under the function of surfactant. By calculating the diffusion coefficient of CO2 adsorption process in PEI-MCM-41-100/200/300/400/550°C, the diffusion resistance of CO2 was the lowest in PEI-MCM-41-100°C, which directly proved that the synergism of surfactant and organic amine could reduce the diffusion resistance of CO2 in the pore.

Oxidative conversion of lignin isolated from wheat straw into aromatic compound catalyzed by NaOH/NaAlO2.

Lignin was isolated from wheat straw via organosolv process and further transferred to monophenolic compounds via oxidative conversion. Wheat straw lignin (WSL) with purity at 91.4 wt% was acquired in the presence of heterogeneous and recyclable catalyst of Amberlyst-45. WSL was characterized by infrared spectrometer (IR), nuclear magnetic resonance spectroscopy (NMR) including 1H NMR and 13C NMR spectra. The results showed that WSL possesses typical syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, and it is mainly composed of S and G units. The product distribution was dependent on the composition of WSL. Derivatives from S and G units were found to be the main products. The oxidative conversion of WSL was performed by varying oxidant and catalyst. Both the formation of monophenolic compounds and aromatic aldehydes were enhanced by combining oxidants and catalysts. The composite catalyst composed of NaOH/NaAlO2 was effective for the oxidation of WSL in the presence of nitrobenzene and atmospheric pressure air. The total yield of monophenolic compounds reached up 18.1%, and yields at 6.3 and 5.7% for syringaldehyde and vanillin were achieved, respectively.

Preparing high purity white carbon black from rice husk.

In this paper, rice husk (RH) was used as raw material to prepare white carbon black, and the key technological parameters of preparing white carbon black from RH were studied through single-factor test, orthogonal experiment, and response surface analysis. Meanwhile, the characteristic of white carbon black was also analyzed. Through orthogonal experiment analysis, it was confirmed that the order of factors affecting the purity of white carbon black was calcination temperature > alkali treatment time > final pH > surfactant. Based on the response surface optimization analysis, the optimum parameters for preparation of white carbon black were as follows: calcination temperature 610°C, alkali treatment time of 2.3 hr, final pH of 10, CTMAB was used as the surfactant. Under this condition, the purity of silica prepared could be reached to 99.39%, and the particle size was uniform, spherical, and well dispersed, which satisfied the requirements of GB/T 34698-2017 standard.

Synthesis of 5-hydroxymethyl furfural from cellulose via a two-step process in polar aprotic solvent.

The synthesis of 5-hydroxymethyl furfural (HMF) from cellulose via a two-step process was investigated. To optimize reaction conditions, the separate conversion of cellulose and glucose was first performed in tetrahydrofuran (THF) and N, N-dimethylformamide (DMF) via a one-step process using hosphotungstic acid (PHA) as catalyst. The direct conversion of cellulose to HMF was then performed via the two-step process. The first step and the second step were carried out in THF and the mixture solvent composed of THF/DMF, respectively. Cellulose was converted to HMF and glucose in the first step in THF. Both of cellulose and the as-formed glucose were then converted to HMF in the second step. The conversion of cellulose to HMF and glucose were significantly improved by the two-step process, and the total yield of HMF and glucose was elevated from 52.1 to 97.0%. A possible mechanism for the formation of HMF from cellulose via the two-step process was also proposed.

Amberlyst 15 as a new and reusable catalyst for the conversion of cellulose into cellulose acetate.

The acetylation of cellulose using sulfonated Amberlyst 15 as a new and reusable catalyst was investigated. Optimization of the acetylation process was carried out by variation in the amount of added catalyst, acetic acid, and acetic anhydride as well as the reaction conditions, which includes reaction time and reaction medium. Cellulose acetate, with a degree of substitution (DS) value of 2.38 and yield of 54.1%, was obtained under the optimized conditions and characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), and differential scanning calorimetry (DSC). The sulfonated polymer catalyst could be easily recovered by centrifugation after acetylation. Both the fresh and recovered catalysts were characterized by means of FTIR, TGA-DTG, DSC, and scanning electron microscopy (SEM), and the recovered catalyst could be successfully reused without further treatment. It was found that Amberlyst 15 possessed excellent catalytic stability, no significant changes in the DS values, and consistent yields of cellulose acetate observed over four reaction cycles.

Isolation of cellulose from rice straw and its conversion into cellulose acetate catalyzed by phosphotungstic acid.

Cellulose was isolated from rice straw by pretreatment with dilute alkaline and acid solutions successively, and it was further transferred into cellulose acetate in the presence of acetic anhydride and phosphotungstic acid (H3PW12O40·6H2O). The removal of hemicellulose and lignin was affected by the concentration of KOH and the immersion time in acetic acid solution, and 83wt.% content of cellulose in the treated rice straw was obtained after pretreatment with 4% KOH and immersion in acetic acid for 5h. Phosphotungstic acid was found to be an effective catalyst for the acetylation of the cellulose derived from rice straw. The degree of substitution (DS) values revealed a significant effect for the solubility of cellulose acetate, and the acetone-soluble cellulose acetate with DS values around 2.2 can be obtained by changing the amount of phosphotungstic acid and the time of acetylation. Both the structure of cellulose separated from rice straw and cellulose acetate were confirmed by FTIR and XRD.