Abstract

Membrane chromatography is mainly used for the separation and purification of proteins and biological macromolecules in the downstream processing process, also applications in sewage disposal. Membrane chromatography is recognized as an effective alternative to column chromatography because it significantly improves chromatography from affinity, hydrophobicity, and ion exchange; the development status of membrane chromatography in membrane matrix and membrane equipment is thoroughly discussed, and the applications of protein capture and intermediate purification, virus, monoclonal antibody purification, water treatment, and others are summarized. This review will provide value for the exploration and potential application of membrane chromatography.

Introduction

Traditional column chromatography has high adsorption capacity and separation accuracy for protein [1, 2]; so far, the downstream processing of biological agents has been highly dependent on the use of packed bed resin columns [3, 4]. However, traditional column chromatography generally suffers from a high-pressure drop; the intraparticle diffusion leads to the accumulation of solute molecules, which made the processing time increases, low ligand utilization, and long treatment time, which limits its productivity [5, 6]; meanwhile, column chromatography is expensive; more than 60% of the cost of the biopharmaceutical production process is concentrated in the downstream process of purification and recovery, in which the downstream purification of virus accounts for 70% of the total production cost [7, 8].

Compared with traditional column chromatography, membrane chromatography is more suitable for large proteins of separation and purification (MR > 250,000); such proteins rarely enter the pores of chromatographic particle matrix [9]. For viruses and macromolecules with obvious diffusion restrictions in conventional chromatographic media, it is particularly important [10]. Although the equilibrium binding capacity is generally low in the membrane, solutes in the membrane pores are mainly transported to the binding sites by convection, reducing the mass transfer resistance of the chromatography process (Fig. 1). Due to the advantage in mass transfer, membrane chromatography is an effective method for extracting trace proteins from large capacity feed, which can maintain their natural conformation by reducing the time in contact with adsorbents, maintaining the biological activity of the required biomolecules while removing impurities [11, 12]. Moenster et al. [13] used the SartobindQ exchange membrane adsorber method to separate and purify penicillin G amidase from cell lysate in one step, compared with previous multiple purification steps, which reduced the operating units and significantly improved the downstream processing efficiency.©

Summary and outlook

As an effective alternative to chromatographic column packing, membrane chromatography has been widely studied in the past to explore the use of virus purification; purified viruses have been used for gene treatment and production of vaccines. Ion-exchange membrane chromatography is currently used for the polishing of monoclonal antibody production processes in the biopharmaceutical industry; hydrophobic interaction chromatography membrane adsorbers are usually in flow mode and are rarely used. At present, the chromatographic process of membrane chromatography combined with column packing or monolithic column has been applied in the field of biological production processes, and has shown good application potential in the treatment of trace harmful matters such as heavy metal ions or dyes in water.

Given the relatively high raw material manufacturing cost of membrane materials, the purification capacity of membrane chromatography must reach a relatively high value, or have a high cycle of reuse to ensure a low commercial cost, to have a relatively high economic value. Predictable and high-precision theoretical models are developing to better clarify the potential mass transfer phenomena and thus improve the separation performance of membranes. Disposable membrane sorbent methods are a small market branch for chromatographic packing at present, from an adoption and evaluation perspective, in the downstream processing technology, which development is more advanced.

Abstract

Compound separation plays a key role in producing and analyzing chemical compounds. Various methods are offered to obtain high-quality separation results. Liquid chromatography is one of the most common tools used in compound separation across length scales, from larger biomacromolecules to smaller organic compounds. Liquid chromatography also allows ease of modification, the ability to combine compatible mobile and stationary phases, the ability to conduct qualitative and quantitative analyses, and the ability to concentrate samples. Notably, the main feature of a liquid chromatography setup is the stationary phase. The stationary phase directly interacts with the samples via various basic mode of interactions based on affinity, size, and electrostatic interactions. Different interactions between compounds and the stationary phase will eventually result in compound separation. Recent years have witnessed the development of stationary phases to increase binding selectivity, tunability, and reusability. To demonstrate the use of liquid chromatography across length scales of target molecules, this review discusses the recent development of stationary phases for separating macromolecule proteins and small organic compounds, such as small chiral molecules and polycyclic aromatic hydrocarbons (PAHs).

Introduction

Separation is a critical process to isolate a particular compound, whether it is a natural product or a synthetic product. Studies of a compound’s characteristics and elucidation structure provides reliable results for pure compounds because there is no interference from other compounds. The primary source of difficulty in a separation process is the high similarity between two or more compounds, such as racemic and homologous mixtures. Liquid chromatography has proven to be an effective solution to those problems. The key to liquid chromatography separation is a sustainable retention and elution process. Stationary phases essential for separating compounds in liquid chromatography. Various liquid chromatography columns of both preparative and quantitative types have been used and continue to develop. For this reason, multiple studies and publications related to liquid chromatography can be found and accessed easily.

This review will discuss recent developments in liquid chromatography stationary phase technology for compound separation. Analytes that were once inseparable can now be separated and appropriately analyzed. The discussion focuses on the development of column material and separation interactions. This development aims to optimize and overcome the lack of existing columns. This review will discuss three types of analytes to demonstrate the use of liquid chromatography across length scales of target molecules, which are (1) larger biomolecules, particularly the proteins, (2) small chiral molecules, and (3) polycyclic aromatic hydrocarbons (PAHs).

Outlook

As liquid chromatography continues to be one of the main tools in the preparation and analysis of chemical compounds, various developments have been made to improve the binding selectivity and reusability of the columns. The surface chemistry of the stationary phases of silica, polysaccharides, and synthetic polymer matrixes has been adjusted and modified to result in better separation across length scales. The stationary phases can be chemically decorated with desired functional groups to ensure a stable and selective binding to the target molecule. For selective separation of chiral molecules, chiral stationary phases (CSPs) have been prepared using modified polystyrene, cellohydrobiolase, cyclodextrins, chiral metal–organic frameworks (MOF), and ionic liquids as chiral selectors. Hydrophobic surfaces are an essential component of liquid chromatography for PAH binding. Several hydrophobic chemical modifiers have been covalently anchored at silica surfaces to increase their affinities towards PAHs. Moreover, hydrophobic MOF and particle-based acrylics have also been developed as stationary phases to capture PAHs efficiently. In the case of protein capture and purification, affinity chromatography is commonly established through metal–protein complexation as well as ligand–protein complexation. Furthermore, by adjusting the conditions of elution, particularly the pH and ionic strength, hydrophobic charge-induction chromatography (HCIC) and mixed-mode chromatography (MMC) have also been investigated to achieve better protein purification.

Abstract

1. Introduction

2. Experimental section

3. Results and discussion

4. Conclusions

Acknowledgment

References

Abstract

     The addition of graphene as an efficient nano-filler to different polymer matrices lead to a substantial improvement in different physical properties which, as a result, pave the way towards promising applications. In this work, Polystyrene (PS) was reinforced with different low loadings of graphene oxide (GO). The latter was prepared according to the Hummers method. The incorporated weight fractions were (0.01, 0.05, 0.1, 0.25, 1.0) wt. %. Solution blending was the adopted approach to prepare the nanocomposites. The resulted nanocomposites were characterised compared to the neat polymer. Many tools were employed to investigate the structure, morphology, thermal, and thermo-mechanical behaviour of GO, neat polymer, and the nanocomposites. The structural and morphological outcome for GO and PS was confirmed compared to the literature. The outcome confirmed as well the good dispersion of GO nano-sheets in the PS. The thermal and thermo-mechanical properties were enhanced for the nanocomposites compared to the neat polymer. The results emphasised the improvement of nanocomposites’ performance as the inclusion of GO went higher.

Introduction

     Carbon based nano-fillers for a range of applications have recently attracted a considerable attention due to their exceptional mechanical and physical properties such as high strength, high stiffness and high thermal and electrical conductivities. Many of research groups have prepared and study the features of these materials according to their low cost, low weight and ease of processing.[1] Graphite, fullerene, carbon nano-tubes and the recently discovered material, graphene, are derived from this fascinating material, carbon, and they are the most widely studied allotropes of interest to technologists and researchers due to their unique applications in various fields.

     Graphene is a planar honeycomb lattice that is a two dimensional, one atom thick carbon sheet. Its properties include high thermal conductivity, high intrinsic electron mobility, optical transmittance of 98%, large specific surface area and high Young’s modulus.[3] These properties offer graphene the potential for numerous different applications in many disciplines such as sensors, energy conversion, storage devices, solar cells and reinforced composites.[4] To enable the exploitation of these unique properties in applications, graphene and its derivatives have been successfully prepared using different routes such as bottom-up chemical vapour deposition and top down exfoliation of graphite by means of oxidation, intercalation and/or sonication.[5] As a consequence of their high G-G interactions (kind of non-covalent interaction between electron rich G system and another molecule), graphene sheets are not directly mixed with the polymer matrices to produce polymer nanocomposites as the graphene sheets tend to stack into large aggregates. For this reason, graphene oxide is usually incorporated into polymer matrices for making high quality polymer nanocomposites, as it has better compatibility with polymers, forms a uniform dispersion and offers a possibility of mass production.

Conclusions

     In this study, different low loadings of GO were incorporated homogenously into a PS matrix and different structural, thermal properties were studied as well as the nanomechanical behaviour for the polymer, and the nanosheets imaged in the cryogenically fractured surface. The incorporation of low loadings of the GO led to improvement in thermal and thermomechanical performance as the results of TGA, DSC and DMA indicated. As the homogenous dispersion for the nanosheets in the polymer matrix is a prerequisite for a good performance, this kind of dispersion was verified via different microscopic techniques carried out in this study. These techniques included OM, SEM and TEM. According to the very low weight fractions used in this study, no sharp peaks of GO appeared in Raman spectroscopy for the nanocomposites. Weak shoulders appeared in FTIR diagram and tiny humps can be seen in the curves of XRD. These can be attributed to the low loadings of GO in the PS that led to dilution of GO in the polymer matrix. In general, the incorporation of GO in PS using low loadings led to improve thermal and thermomechanical performance for the nanocomposites compared to the neat polymer. Td, Tg, and storage modulus were increased as the weight fraction of GO went higher.

Highlights

Abstract

Keywords

1. Introduction

2. Microfluidic devices in analytical chemistry

3. Separation science

4. Extraction

5. Conclusions and future perspectives

Declaration of competing interest

Acknowledgments

References

Abstract

3D printing has attracted the attention of analytical chemists. 3D printing possesses the merits of fast and low-cost fabrication of geometrically complex 3D structures and has been employed in the fields of microfluidic devices, electrochemical sensors and biosensors, separation sciences, sample pretreatment, and wearable sensors. We focus on the applications and materials of 3D printing in microfluidic devices, separation sciences, and extraction over the last three years and we offer outlook. It is clear that the 3D printing in separation science is here to stay and with new materials development, to develop to on demand fabrication of separation tools.

1. Introduction

Recently, three-dimensional (3D) printing, also called “additive manufacturing,” has become a widely used tool for the construction of different devices in analytical chemistry [1]. 3D models are usually created directly by computer-aided design (CAD) and then printed based on layer-by-layer addition [2]. Compared with traditional manufacturing methods, 3D printing has various merits, including fast, low-cost, and fabrication with minimal waste generated [3,4]. Nowadays, 3D printing is an important tool in manufacturing and prototyping [5-7]. Various technologies for 3D printing have been used consisting of fused filament fabrication (FFF), stereolithography (SLA), selective laser melting (SLS), inkjet and Polyjet printing, and laminated object manufacturing (LOM) [8–11]. The techniques of 3D printing have been well-introduced in several reviews [12–14], thus they will not be covered here in detail.

3D printing was first introduced about 40 years ago [15]. Research in 3D printing has exhibited a rapid growth for printing functional parts, such as biomaterials, nanomaterials, metals, and ceramics as well as polymers [16–18]. 3D printing is has been extensively used in the fields of analytical chemistry, environment sciences, biology, medical devices, and other manufacturing fields [19–22]. In analytical chemistry, the main research fields include microfluidic devices, electrochemical sensors and biosensors, separation sciences, sample pretreatment, wearable sensors, and others [23]. A review of 3D printing applications in sensors and biosensors has been published by our group as well as several reviews published in the special area Journal Pre-proof of analytical chemistry [24–27]. A recent comprehensive review on the broader implications for analytical chemistry was published by Spence et al. in 2017 [12]. This review mainly focuses on using 3D printing in the areas of microfluidic devices, 4 separation sciences, and extraction over the last three years, putting in perspective the application of rapidly developing field of printable materials in connections toanalytical chemistry applications (Fig. 1). We discuss recent developments for past 3 years and we provide outlook and future directions. Future impacts and challenges of 3D printing in these areas will be discussed. We hope that the review will guide analytical scientists to further explore 3D printing techniques in order to realize its potential applications in analytical chemistry

1- Introduction

2- Materials and methods

3- Results and discussion

4- Conclusion

References

Abstract

In this study, two bacteria strains (Enterobacter sp. SL and Acinetobacter sp. SL-1) and waste molasses (carbon source) were used to remove Zn(II), Cd(II), Cr(VI), and Cr(Total) in the liquid solution (87 mg·L). The results showed the removal efficiencies of Cr(Total) and Cr(VI) could reach over 98.00% after reaction, and the removal efficiencies of Zn(II) and Cd(II) were all about 90.00% by the synergistic actions of microorganisms and waste molasses. In this process, waste molasses provides nutrients for microorganisms and has the characteristics and capability of Cr, Zn, and Cd. Microorganisms mainly use biological adsorption (36.95% and 45.69%) and metabolism (24.37% and 17.05% by producing humic-acid and fulvic-acid like substances) to remove Zn(II) and Cd(II), while waste molasses could to remove Cr(Total) (81.24%) and Cr(VI) (75.90%). This study has potential application value for the treatment of wastewater containing high concentrations of heavy metals.

Introduction

Heavy metal-containing wastewaters are produced in many industries, and their direct discharge has caused serious impacts on human health and environment (Zhu et al., 2018). The popular methods for treatment of heavy metal-containing wastewater include the ion exchange method (Dai et al., 2015), electrochemical method (Kobya et al., 2017), photocatalysis (Luo et al., 2017), and biological method (Wen et al., 2018). Among them, biological method has been widely studied due to the low energy consumption, small secondary pollution, and environmental friendliness. (Zhou et al., 2013). However, applying survivable microbes for biological treatments in toxic environments has become the main challenge (Pradhan et al., 2019) because heavy metal-containing wastewater not only has complex heavy metal compositions but also may contain other toxic substances such as cyanide (a phenolic organic matter) (Wen et al., 2018). In addition, the characteristics of heavy metal-containing wastewater may vary moderately; especially the change of pH can significantly inhibit the bacterial activities (Alexandrino et al., 2014). Moreover, biological treatments of heavy metals normally have been used for low concentration ranges (10–50 mg·L−1) of heavy metals (Guo et al., 2017), and some bacteria can only work with specific single heavy metal [e.g., Zn(II) or Cr(VI)] in the wastewater (Peng et al., 2019; Singh et al., 2011; Wang et al., 2018). Due to the high concentration of heavy metals on microbial stress, it is extremely difficult for microorganisms to remove many kinds of heavy metals simultaneously (Dhal et al., 2013; Guo et al., 2017). Therefore, previous studies have used chemical pretreatment (Mejias Carpio et al., 2016) or the addition of substances such as iron ore (Guo et al., 2017) to reduce heavy metal content or toxicity. Although these methods can improve the activity of microorganisms, they also bring trouble to the subsequent treatment of the final effluent. Alexandrino et al. (2014) and Yan et al. (2018) applied a high concentration of sodium lactate (7.0 g·L−1) as a carbon source to stimulate bacteria growth and heavy metal removal. However, these expensive carbon sources burden wastewater treatment (Li et al., 2019; Wang et al., 2018). In addition, it has been reported that microorganisms need specific nutrient composition to be able to function, and the complex wastewater system (containing heavy metals) will inhibit its activity (Mejias Carpio et al., 2016; Peng et al., 2019; Pradhan et al., 2019). Therefore, biotreatments are usually limited in industrial application due to the multi heavy metals contained wastewater. So, it is important that to develop an economic biotreatment method with multi heavy metals tolerance performance. Moreover, it is critical to differentiate the contributions of biotic (e.g., via microbial metabolisms) and abiotic (the chemical properties of the carbon source) reactions for heavy metals removal in complex wastewater system.

1- Introduction

2- Experimental

3- Results and discussion

4- Conclusions

References

Abstract

For the first time the method DI-SPME/LC-TOFMS was used and developed in order to determine the large antidepressant drugs in real forensic cases. The aim of the study was to optimize the new DI-SPME/LC-TOFMS method for the quantification of the large group of psychotropic drugs such as benzodiazepines, selective serotonin reuptake inhibitors, selective serotonin and noradrenaline reuptake inhibitors, tricyclic antidepressants and sleeping pills “Z”. The volume of the sample, adsorption time, post-adsorption purification and desorption time were precisely optimized. The validation parameters such as limit of detection and quantification, linearity, precision during and between days and the matrix effect were determined. All obtained values are within the acceptable range for toxicological analyses. The usefulness of the method was confirmed by analyzing the post-mortem samples. Drug concentrations were determined in real samples with high precision, which gives perspectives for the DI-SPME/LC-TOFMS routine application in toxicological and forensic analyses in the future.

Introduction

Due to complicated post-mortem processes that occur in the body after intake of drugs or poisons like redistribution, degradation, and contamination, it is necessary to provide a complex analysis of available body fluids like urine, blood or other alternative materials such as bone marrow. Material which can be helpful in post-mortem investigation is bone marrow aspirate (BMA), which is a semi-liquid form (it can be handled with a pipette) of bone marrow, placed inside the bones [1–3]. However, analysis of alternative materials often carried out with various limitations and compared to that analysis of BMA appears to have few practical advantages. It is a well-preserved post-mortem material, because of the physical barrier provided by cortical bone, which can be easily collected in large amounts and may be used as an alternative material to peripheral venous blood [4–6]. Due to high fat level and blood supply, it is possible to determine psychotropic drugs in bone marrow, which has been confirmed by Snamina et al. [7] with very satisfying results. On the other hand Cartiser et al. [2] provided a comprehensive summary on correlation studies between blood or plasma and bone marrow levels of different xenobiotics. The correlations varied from very low to almost absolute, depending on the drug. The success and application of the method often depend on its capabilities, trueness and also time of whole analysis. Considering extraction of analytes as the most demanding, time-consuming and multistep process it is regarded as a critical process to carry out in the whole analysis. The technique which may facilitate and simplify the extraction of analytes from complex samples like biological materials may be Direct Immersion Solid-Phase Micro Extraction (DI-SPME) [8–10]. It is an extraction technique based on the sorption of analytes on the stationary phase of fused silica, placed on the solid support. The DI-SPME procedure is based on the exposure of the fiber to the sample for sufficient time. This technique integrates extraction, concentration and analyte desorption into a single procedure [11,12]. As the technique is reducing sample handling, solvent use, time and cost it is prosperous for toxicological and forensic analysis. Due to the wide selection of fiber coatings and its sorption capabilities DI-SPME extraction is also used in food and environmental analyses, as well as studies for its in vivo application are carried out. The initial application of the DI-SPME technique in drug analysis was for psychotropic substances. Moreover, in recent years the increase of DI-SPME applications was observed with connection of liquid chromatography and capillary electrophoresis [13,14].

Introduction

Materials and Methods

Results and Discussion

Conclusions

References

ABSTRACT

RNA molecules perform a variety of biological functions for which the correct three-dimensional structure is essential, including as ribozymes where they catalyze chemical reactions. Metal ions, especially Mg2þ, neutralize these negatively charged nucleic acids and specifically stabilize RNA tertiary structures as well as impact the folding landscape of RNAs as they assume their tertiary structures. Specific binding sites of Mg2þ in folded conformations of RNA have been studied extensively; however, the full range of interactions of the ion with compact intermediates and unfolded states of RNA is challenging to investigate, and the atomic details of the mechanism by which the ion facilitates tertiary structure formation is not fully known. Here, umbrella sampling combined with oscillating chemical potential Grand Canonical Monte Carlo/molecular dynamics simulations are used to capture the energetics and atomic-level details of Mg2þ-RNA interactions that occur along an unfolding pathway of the Twister ribozyme. The free energy profiles reveal stabilization of partially unfolded states by Mg2þ, as observed in unfolding experiments, with this stabilization being due to increased sampling of simultaneous interactions of Mg2þ with two or more nonsequential phosphate groups. Notably, these results indicate a push-pull mechanism in which the Mg2þ-RNA interactions actually lead to destabilization of specific nonsequential phosphate-phosphate interactions (i.e., pushed apart), whereas other interactions are stabilized (i.e., pulled together), a balance that stabilizes unfolded states and facilitates the folding of Twister, including the formation of hydrogen bonds associated with the tertiary structure. This study establishes a better understanding of how Mg2þ-ion interactions contribute to RNA structural properties and stability.

INTRODUCTION

RNA molecules have highly diverse structures ranging from simple helices to highly heterogeneous folded conformations that are essential for their wide range of cellular functions (1–3). Specifically, ribozymes, a distinct class of enzymes, exhibit complex tertiary structures and catalyze self-cleavage or the cleavage of phosphodiester bonds of substrate RNA, with metal ions typically playing a central role in the catalytic activity (4–6). To assume their tertiary structures, RNAs must overcome large unfavorable electrostatic interactions associated with their polyanionic phosphodiester backbone (7). To facilitate this, positively charged ions screen the highly negative potential, allowing the RNA secondary structures to collapse into compact tertiary conformations (8–11). Typically divalent ions, most often Mg2þ, facilitate the formation of tertiary interactions required for the full folding of RNA (12–14). However, the inability to visualize the ions during folding represents a key barrier to understanding the role of divalent ions in folding of RNA (15). Studies have used classical molecular dynamics (MD) or other theoretical approaches to investigate Mg2þ-RNA binding, but they were limited to native conformations because of their inability to overcome the issues associated with the Mg2þ exchange rates (16–22). The exchange rate of water complexed to Mg2þ is on the ms timescale (6.7 105 s 1 ), and the exchange rate of Mg2þ with phosphate is on the ms timescale (0.5–2.5 103 s 1 ) (23), which is beyond the timescale of typical atomistic MD simulations (20,24) such that only limited insights into Mg2þ-RNA interactions are accessible (25). Alternatively, simulations using coarse-grained models of nucleic acids provided insights into how Mg2þ can serve to nucleate the folding of key tertiary interactions with the Mg2þ-RNA interactions being dominated by specific interactions even in unfolded states (19,26).

Keywords

1. Introduction

2. Graphene Oxide

3. Aerogels

4. Supercapacitor and Energy Storage

5. Supercapacitor applications of graphene and graphene oxide based aerogels

6. Conclusion

References

Abstract

Graphene and graphene-based materials have a high potential, especially in energy storage technology. Thanks to the three-dimensional (3D) structures developed with this material, their importance in the production and application of energy storage devices has increased. Studies on supercapacitor applications of graphene-based aerogels have begun to arouse interest in recent years. In this study, recent studies on aerogel supercapacitors, in which researchers have shown great interest, have been compiled and collected. In this study, production methods and properties of graphene oxide, properties and production of aerogels, production and applications of graphene/graphene oxide aerogels are discussed. In this way, the data is presented and discussed in an organized way for the researchers who study or who want to study in this field.

Introduction

Today’s rapidly depleted energy resources and the deteriorating ecological balance prioritized the need for energy storage systems. Moreover, the growing popularity of telecommunications equipment, backup storage devices, portable electronic devices, cardiac pacemakers and hybrid electric vehicles has aroused great interest towards energy storage devices. In this context, supercapacitors, which are mostly preferred among various energy storage devices, are electrochemical energy storage devices that cover the gap between batteries and dielectric capacitors with their high-power density, high specific energy and long life (>100,000 cycles) [1]. Furthermore, flexible solidstate supercapacitors are important for wearable electronic devices [[2], [3]].

Graphene, which come into prominence with wide specific surface area (SSA) (2630 m2 g−1 ), high electrical conductivity and chemical stability, as well as excellent mechanical, thermal and optical properties, has become popular especially for supercapacitors. However, a serious loss in surface area is observed due to the re-stacking of graphene layers during chemical reduction. The conversion of graphene nanotubes to graphene aerogel having a stable three-dimensional network solves this problem. The re-stacking problem resulting from π-π interactions between graphene layers and the Van der Waals forces are solved and the layers are chemically bonded together. Thus, the structure is intended to provide better performance in supercapacitors with much higher electronic conductivity, rapid charge transport between the layers and the resulting high surface area. The most interesting feature of GOs is that they are well protected by a hexagonal structure having functional groups such as hydroxyl, epoxide, carboxyl and some randomly distributed alkyl groups in the plane, together with a clear AB stacking order. Hydroxyl and epoxide functional groups are located close to each other in the basal planes, whereas carboxyl and alkyl groups are located at the edges of GO flakes. With longer oxidation times, hydroxyl groups are converted to more epoxide groups in the basal plane.

Abbreviations

1. Introduction

2. Method and analysis section

3. Petrochemical wastewater pretreatment and advanced treatment

4. Future perspectives

Acknowledgements

Appendix A. Supplementary data

References

Abstract

Petrochemical wastewater is a major industrial source of pollution that produces a variety of refractory and toxic organic pollutants that are detrimental to animals and plants in natural water bodies; it is especially harmful to biological treatment systems. Regardless of these threats, studies on these specific organic pollutants are limited at present. Consequently, it is extremely essential to promote relevant problem solving efficiently. Currently, only limited processes are available for pretreatment of high-concentration wastewater, and advanced treatment of secondary effluent as compared to the conventional treatment are introduced by current studies. Therefore, in this review, we have systematically generalized the characteristics of petrochemical wastewater; we have particularly summarized and compared different methods (recent developments, influencing factors, etc.) which are applied in pretreatment and advancement of current methods. Additionally, the interaction mechanisms of microbes under a wide range of concentrations of specific organic pollutants and associated degradation pathways have been described comprehensively. Moreover, we have analyzed bioenergy recovery from the degradation/removal of specific organic pollutants with environmental-friendly and economically methods because it can help realize the goal of circular resource utilization during the process of detoxification and minimization.

Introduction

The petrochemical industry is a fundamental industry that plays an essential role 4 in any country’s national economy and provides support to many other sectors, such as agriculture, energy, transportation, etc. (Fig. 1) (Clews, 2016c; Jafarinejad 2017).  Petrochemical wastewater is generated via several routes from this industry, including effluent from raw materials, factory rainwater, cooling water, and domestic sewage. It has been reported that global petroleum production has reached 4.40 billion tons based on related industrial statistics (https://www.sohu.com/a/119515720_122917). Moreover, relevant studies have revealed that 3.00-3.50 m3 10 of petrochemical wastewater is generated per ton of petroleum refinery process (Zhang and Fan, 2016; 12 Siddique et al., 2017). For instance, China’s annual industrial wastewater discharge is 2.10 × 1010 13 t, of which the proportion of petrochemical wastewater was 3.00-5.00% in 14 2016. A report derived from China’s oil and chemical industry has shown that 2.00 15 billion tons of petrochemical wastewater were produced only in 2016, and the total 16 emission increased up to 4.00 billion during the 13th 5-year plan period (CMEP, 17 2015). Moreover, massive petrochemical wastewater was produced all over the world 18 during the same period that needed to be treated properly and urgently.

1. Data

2. Experimental design, materials, and methods

Acknowledgments

References

Abstract

The data presented in this article relate to the scientific article “Pyrolysis of a mixture of monosilane and alkanes in a compression reactor to produce nanodispersed silicon carbide” [1]. In the above article, a method is proposed for producing nanosized silicon carbide powder by compression in a cyclic process of a chemical reactor. Pyrolysis is initiated in mixtures of monosilane and hydrocarbon with argon. The article also presents the analysis data of the obtained product by X-ray diffraction and electron microscopy.

Data

The data set of this article contains information on the characteristics of silicon carbide nanopowders, obtained by the method of adiabatic compression in a chemical reactor [2]. Data on parameters inside the compression chamber, pressure and temperature are given. In papers [3e5], the importance of knowing the law of variation of these quantities during the compression-rarefaction cycle is indicated. The experimental data on the change in pressure inside the chamber during a period of three cycles of compression – rarefaction shows in Fig. 1. The black line is the experimental value obtained. The green line is the calculated dependence obtained in the approximation of the adiabatic ideal gas process, without taking into account the pressure drop during the opening of the exhaust valve. The experiment was performed using a crank mechanism. The calculation of the periodicity of cycles was obtained in the approximation of the harmonic law of motion of a piston with a frequency of 10 Hz. The temperature in the graph in Fig. 1 is marked with a blue line. The calculation was performed in the adiabatic compression approximation of a monatomic ideal gas according to T$Vg ¼ const and p$Vg ¼ const for initial data p ¼ 0.45 MPa, T ¼ 300 K

1. Introduction

2. Experimental

3. Results and discussion

4. Conclusions

Acknowldgement

Appendix A. Supplementary data

References

Abstract

Handling of petrochemical waste oil (PWO) is costly, tedious, and risky to human health and environment. Hence, upcycling of PWO for biomass conversion to platform chemicals would be very advantageous. Herein, a highly porous sheet-like structure of sulfonated graphene oxide (sGO) catalyst was synthesized from PWO. The synthesized sGO possessed high surface area (246.2 m2 g1) due to its mesoporosity and high content of sulfonic groups (2.4 mmol g−1) grafted onto its surface. As its application, the synthesized sGO was employed to convert fructose to levulinic acid (LA) within deionized water. The high yield (61.2 mol %) of LA was obtained under a condition of 160 °C, 1 h, and 6 g g−1 fructose to sGO weight ratio. It can be reused several times (5 runs) with no severe degradation of catalytic activity. Therefore, the sGO derived from petrochemical waste oil would be considered as an environmentally benign catalyst for producing platform chemicals, i.e. LA from fructose and other biomass derivatives.

Introduction

Heavy reliance on depleting fossil resources to produce platform chemicals and fuels contributes to the economic dilemma and rising emission of greenhouse gases [1-3]. Hence, alternative ways including utilization of biomass in integrated biorefineries have been explored to compete with fossil-based refineries [4]. Biomass is a renewable resource that can be exploited to produce many high value-added products, i.e. alcohol, 5- hydroxymethylfurfural (5-HMF), furfural, formic acid (FA) and levulinic acid (LA) [5, 6]. LA is considered as top ten platform chemicals, which could be further utilized to produce succinic acid, resins, polymers, herbicides, pharmaceuticals, flavoring agents, solvents, plasticizers, anti-freeze agents and biofuels/oxygenated fuel additives [3, 7]. Generally, conversion of biomass into LA involves multiple steps, which are (1) hydrolysis of cellulose to glucose, (2) isomerization of glucose to fructose, (3) dehydration of fructose to HMF, and (4) further hydrolysis to form equimolar LA and FA [2, 8]. These processes are often realized through chemical or enzymatic routes. Nevertheless, the chemical route has been recognized as high potential for commercially viable LA production [9, 10].

In the past, homogeneous acid catalysts (e.g. H2SO4, HCl, H3PO4) were used to ensure a high conversion of reactants because of lower mass transfer resistance [11]. However, those acidic catalysts are corrosive, detrimental to the environment, and non-recyclable [8, 10, 12]. Hence, heterogeneous solid acid catalysts, such as ion-exchange resins, sulfated metal oxides, modified mesoporous silica, zeolites, and natural clays have been developed to overcome the disadvantages of those homogeneous acid catalysts [13, 14]. Recently, several of these types of catalysts have been used for conversion of fructose to LA from actual biomass [15-17].

Though p-xylene derived from naphtha reformate is in high demand as a raw material in the production of polyesters and polyethylene terephthalates, its separation from the FCC reformate is not easy due to close boiling points among the components in the reformate. When a proper solvent for the p-xylene separation is available, an extractive distillation can be applied in the separation. Currently the separation utilizes an adsorption process requiring a large amount of costly adsorbent and a desorption process followed by distillation. In the proposed extractive distillation here, p-dinitrobenzene has been utilized to improve the separation of p-xylene from its ethylbenzene mixture. The VLE data of the ternary mixture estimated with the UNIFAC were compared to those computed from molecular simulation to show their reliability. An extractive distillation and solvent recovery were applied to obtain 99.6% purity p-xylene with 99.1% recovery. The economics of the proposed process demonstrates its comparability to the existing Parex process.

Introduction

Xylene isomers and ethylbenzene are coexisting components in naphtha reformate, and they are separated by distillation as a group. Before the separation, the C8 compounds are in the aromatic compounds mixture, including benzene and toluene, contained in the extracts of extractive distillation using sulfolane [1]. Further distillation splits the C8 components of close boiling points from others. Among the mixture p-xylene has high demand to produce terephthalic acid, a raw material in the production of polyesters and polyethylene terephthalates (PETs). The separation processes of p-xylene based on solvent extraction [2] or crystallization [3,4] were not efficient with only 60–65% recovery rate. The extractive distillation of ethylbenzene and p-xylene has been studied for many years [2,5,6–9], but no commercial process was developed due to no effective extractant found. Recently searching effective extractants extended to ionic liquid solvents in many extractive distillation processes [10–12]. In 1971, the Universal Oil Products (UOP) commercialized a new separation method of p-xylene, an adsorption process, called the Parex process with a 95% recovery rate [13,14]. Though the adsorption process is largely effective and efficient in the separation of a specific component from a mixture with high recovery and high purity, it requires a large volume of high-cost adsorbents. Moreover the next stage of the adsorption includes a desorption process to recover the adsorbate from the adsorbent using a desorbent [15]. The recovery and recycling of the desorbent accommodate a distillation column separating the targeted p-xylene. A continuous processing has been desired for a large throughput of chemical production, and distillation and extraction are suitable for the processes. On the other hand, because the adsorption was a batch process, a simulated moving bed (SMB) operation [16], a quasi-continuous process, requiring multiple beds of adsorbents was introduced to the Parex process [13,17]. While one of the beds releases the adsorbate, the product, other three beds are preparing for the next production in sequence. Consequently, the SMB operation necessitates a large volume of high-cost adsorbents [18]. In this study, an efficient solvent, p-dinitrobenzene, for the separation of p-xylene from the mixture of ethylbenzene and p-xylene, two main components in the naphtha reformate, is suggested, and the separation process of p-xylene is designed for 99.1% recovery and 99.6% purity of p-xylene using an extractive distillation. The design procedure is explained to present the performance of the proposed separation process. The estimated VLE data of ternary mixture of ethylbenzene, pxylene and p-dinitrobenzene used in the process design are probed by comparing to the computed ones with molecular simulation. The separation performance and economics of the proposed process are measured to the Parex process.