The green, ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal ion removal through incorporation of chitosan by various electrospinning ways

The rapid global industrialization worsens the contamination of heavy metals in aquatic ecosystems on the earth. In this study, the green, ultrafine cellulose-based porous nanofibrous membranes for efficient heavy metal removal through incorporation of chitosan by the conventional and core-shell electrospinning ways were firstly obtained. The relations among parameters of electrospun solution, micro-morphology and porosity for nanofibers, the variation of chemical active sites and adsorption performance of biocomposite nanofibrous membranes for conventional and core-shell electrospinning as well as the adsorption effect factors of copper ions including initial concentration, pH of solution and interaction time were comprehensively investigated. The results show that the average diameter for conventional and core-shell ultrafine nanofibers at 50% chitosan and 30% chitosan loading can achieve 56.22 nm and 37.28 nm, respectively. The core-shell cellulose acetate/chitosan (CA/CS) biocomposite nanofibrous membranes induced the surface aggregation of copper ions to impede the further adsorption. The more uniform distribution for chemical adsorption sites can be obtained by the conventional single-nozzle electrospinning than by the core-shell one, which promotes the adsorption performance of copper ions and decreases the surface shrinkage of nanofibrous membranes during adsorption. The 30% CS conventional nanofibrous membranes at the pH=5 aqueous solution showed the optimum adsorption capacity of copper ions (86.4 mg/g). The smart combination of renewable biomass with effective chemical adsorptive sites, the electrospinning technology with interwoven porous structure and the adsorption method with low cost and facile operation shows a promising prospect for water treatment.

Synthesis of hydrated ferric oxide on cation exchange resin for phosphate and hardness removal in water

In this study, a potential adsorbent was synthesized from iron salt and cation exchange resin (FeOOH@CR) and applied for phosphate adsorption in batch experiments. The characteristics of FeOOH@CR materials before and after phosphate adsorption were determined by FTIR, XRD, and SEM. The factors affecting the adsorption process such as reaction time, solution pH, material dosage, concentration, temperature, and competing ions were tested. Kinetic, thermodynamic and isothermal models of the adsorption process were applied to study the nature of the adsorption process. The properties of phosphate adsorption, effect of competitive ions and material reusability were also examined. Results showed that the adsorption time reached equilibrium after 48 h and the suitable adsorption condition was found at solution pH of 6.5, material dosage of 5 g/L. In addition, the durability of the material after 5 times of regeneration was investigated with the remained adsorption ability of about 55% as compared to the original one.

The Adsorption Performance of Polyaniline/ZnO Synthesized through a Two-Step Method

Polyaniline/Zinc oxide (PANI/ZnO) were prepared using a two-step method, and the morphology and the structure of PANI/ZnO composites were characterized through a scanning electron microscope (SEM) and X-ray diffraction (XRD). Factors such as the content of ZnO, the adsorption time and the mass of the adsorbent, and the kinetic equation of PANI/ZnO as adsorbents for the adsorption of methyl orange solution were studied. The results showed that the adsorption efficiency of methyl orange by polyaniline with the increase of adsorbent mass firstly increased and then decreased. Among the composites with the same quality, PANI composites with 8% ZnO have a better adsorption effect for methyl orange, and the maximum adsorption ratio can reach 69% with the increase of adsorption time at 0.033 g; With the increase of adsorbent mass, the adsorption efficiency of PANI composites with 8% ZnO increased continuously. When the mass increased from 0.033 g to 0.132 g, the adsorption rate increased from 69% to 93%, and the adsorption of the methyl orange solution by PANI/ZnO composites was more in line with the quasi-second-order kinetic equation.

Developing Magnetic Material for Remediation of Aquatic Nitrogen Pollution in Water Facilities

Natural organic matter affect water environmental security and posed a potential threat to human health, and thus it has long been considered as a key index to evaluate water treatment performance. Dissolved organic nitrogen is one of the NOM, which produces some disinfection byproducts having more toxic than those carbon-based materials. Coagulation is a key unit of drinking water purification and has received wide attention. However, conventional flocculation technology on removal of DON is so poor that we have to seek more effective improving measurement. The combined use of conventional flocculant and organic polymer can improve treatment efficiency to a certain extent, and enhanced coagulation can also improve the DON removal rate, but their DON removal performance is still not dreamful. At present, there is a lack of systematic research on flocculation to remove DON. Although some achievements have been made, there is still a big gap between the preparation technology of flocculant and the goal of efficient removal of DON in water.For treatment of secondary effluent of industrial wastewater, some studies show that the use of Fe3O4 mainly has the effect of accelerating separation, but the adsorption effect is not good. However, with the synergistic flocculation of amino functionalized Fe3O4 it has a good effect on removing water protein, polysaccharide and humic acid, which can meet the water quality discharge standard and reduce the dosage of flocculant. The above results show that functional nanoparticle materials are of great significance to improve the adsorption and flocculation performance. Therefore, the functional modification of magnetic nanoparticles plays an important role.

Study on the Formation Mechanism of Shale Roof, Floor Sealing, and Shale Self-Sealing: A Case of Member I of the Upper Ordovician Wufeng Formation–Lower Silurian Longmaxi Formation in the Yangtze Region

Similar to North America, China has abundant shale resources. Significant progress has been made in the exploration and exploitation of shale gas in China since 2009. As the geological theory of unconventional oil and gas was proposed, scientists have started researching conditions for shale gas preservation. The shale roof and floor sealing and the shale self-sealing are the critical objects of such research, which, however, are still in the initial stage. This article studies the formation mechanism of shale roof and floor sealing and shale self-sealing by taking marine shales from Member I of the upper Ordovician Wufeng Formation–lower Longmaxi Formation in the upper Yangtze region as the research object. Analyses were performed on the TOC content, mineral composition, and porosity, as well as the FIB-SEM, FIB-HIM, and gas permeability experiments on the core samples collected from the marine shales mentioned above. The conclusions are as follows: for the sealings of shale roof and floor, the regional cap rocks, roof, and floor provide sealing for shales due to physical property differences. For the self-sealing of shales, the second and third sub-members of Member I of the Wufeng Formation–Longmaxi Formation mainly develop clay mineral pores which are dominated by macropores with poor connectivity, while the first sub-member of Member I of the Wufeng Formation–Longmaxi Formation mainly develops organic-matter pores, which are dominated by micropores and mesopores with good connectivity. Owing to the connectivity difference, the second and third sub-members provide sealing for the first sub-member, while the methane adsorption effect of shales can inhibit large-scale shale gas migration as it decreases the gas permeability; thus, the organic-rich shales from the first sub-member of Member I of the Wufeng Formation–Longmaxi Formation provides sealing for itself.

Anti-nonspecific adsorption segments-assisted self-driven surface imprinted fibers for efficient protein separation

At present, the development of high-performance protein imprinted materials is still a research hotspot in the field of protein imprinting. Herein, anti-protein adsorption segment (CBMA)-assisted self-driven BSA surface imprinted fibers MTCFs@SIP@CBMA with high recognition selectivity are pioneered using the strategies of combining magnetic nanomaterial surface imprinting technique with amino-Michael addition. The special structure of the carrier MTCFs endows MTCFs@SIP@CBMA with magnetic performance and self-driven adsorption performance, which simplifies the separation process while improving the adsorption capacity and accelerating the adsorption rate. The adsorption capacity for BSA reached 395.26 mg/g within 30 min. The introduction of CBMA segments on the surface after imprinting by amino-Michael addition makes its polymer chain length and position controllable. Under the strongest anti-nonspecific adsorption effect, MTCFs@SIP@CBMA exhibit excellent specific identification to BSA from mixed proteins. Additionally, MTCFs@SIP@CBMA show considerable reusability. Therefore, MTCFs@SIP@CBMA are expected to be applied in efficient separation of proteins in biological samples.

Lignocellulose-Based Superabsorbent Polymer Gel Crosslinked with Magnesium Aluminum Silicate for Highly Removal of Zn (II) from Aqueous Solution

Lignocellulose (LCE) was ultrasonically treated and intercalated into magnesium aluminum silicate (MOT) clay to prepare a nano-lignocellulose magnesium aluminum silicate polymer gel (nano-LCE-MOT) for the removal of Zn (II) from aqueous solution. The product was characterised using nitrogen adsorption/desorption isotherm measurements, Fourier-transform infrared spectroscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The conditions for the adsorption of Zn (II) on nano-LCE-MOT were screened, and adsorption kinetics and isotherm model analysis were carried out to explore the adsorption mechanism and achieve the optimal adsorption of Zn (II). Optimal adsorption was achieved at an initial Zn (II) concentration of 800 mg/L at 60 °C in 160 min at a pH of 4.52. The adsorption kinetics were explored using a pseudo-second-order model, with the isotherm adsorption equilibrium found to conform to the Langmuir model. The maximum adsorption capacity of the nano-LCE-MOT polymer gel toward Zn (II) is 513.48 mg/g. The materials with adsorbed Zn (II) were desorbed using different media, with HCl found to be the most ideal medium to desorb Zn (II). The optimal desorption of Zn (II) was achieved in 0.08 mol/L HCl solution at 65 °C in 60 min. Under these conditions, Zn (II) was almost completely desorbed from the adsorbents, with the adsorption effect after cycling being slightly different from that of the initial adsorption.

Study on Dynamics and Cluster Analysis between Carbon-based Nanoparticles and Amino Acids

We research the interaction between six representative carbon-based nanoparticles (CBNs) and 20 standard amino acids through all-atom molecular dynamics simulations. The six carbon-based nanoparticles are fullerene(C60), CNT55L3, CNT1010L3, CNT1515L3, CNT2020L3, and two-dimensional-graphene(Graphene33). Their curvatures decrease sequentially, and all of CNT are single-walled carbon nanotubes. We have observed that as the curvature of CBNs decreases, the adsorption effect of 20 amino acids with them has an increasing trend. In addition, we also used multi-dimensional clustering to analyze the adsorption effects of 20 amino acids on six carbon-based nanoparticles. We observed that the π-π interaction still plays an extremely important role in the adsorption of amino acids on carbon-based nanoparticles. Individual long-chain amino acids and “Benzene-like” Pro also have a strong adsorption effect with carbon-based nanoparticles.

Improving Oil Recovery Efficiency in Niger Delta Reservoirs Using Corn Starch as a Local Polymer

Polymer flooding is a chemical enhanced oil recovery method that improves the recovery of oil by controlling the mobility of water to oil phase. It uses polymer solutions to increase the viscosity of the displacing water thereby decreasing water/oil mobility ratio (Speight, 2013). The volumetric and displacement sweep efficiencies are positively affected by polymer flooding. The viscosity of the aqueous phase is increased due to the molecular size and structure of the polymer used. The main objective of this research was to study the ability of cornstarch (local polymer) to recover additional oil after conventional water flooding. The objective was successfully achieved by injecting four different unconsolidated samples (sand pack) with cornstarch solution at varying concentration of 500ppm, 1000ppm, 3000ppm, and 9000ppm. From the results of the experiment conducted, it was deduced that Cornstarch has the ability to recover an additional volume of oil about half the volume of oil recovered during conventional water flooding (i.e. if 50% of oil initially in place was recovered during water flooding, cornstarch can recover an additional 25% of the residual oil after water flooding). Also, higher concentrations of cornstarch reduce the recovery factor due to polymer adsorption on the rock surfaces which alters the rock wettability. To reduce the adsorption effect of Cornstarch, it is recommended that the concentration of Cornstarch be measured after the flooding experiments for a better understanding of the adsorption mechanism of cornstarch.

Molecular dynamics study on the mechanical and tribological properties of polyimide reinforced by lanthana

Purpose The purpose of this paper is to investigate the effect of lanthana (La2O3) on the mechanical and tribological properties of polyimide (PI). Design/methodology/approach The mechanical and tribological properties of PI nanocomposites filled with La2O3 were studied by molecular dynamic simulations to explore the deep mechanisms from an atomic or molecular view. Findings The results showed that the hardness of the PI matrix increased after La2O3 modification with a decrease of 72.4% nanoindentation depth. Besides, the friction coefficient of PI decreased by 72.2% after filling La2O3, and the shear deformation was largely reduced under the same conditions. The adsorption effect of La2O3 on the PI molecular, which reduced the atomic relative concentration, velocity, interaction with counterpart Fe layer and the temperature rise in the frictional interface, contributed to the improvement of the mechanical and tribological performance. Originality/value This study reveals the friction and wear mechanism of PI composites filled with rare earth oxide at the nanoscale.