Showing papers in "Journal of Chemical Technology & Biotechnology in 2020"

Microplastics in soils: a review of possible sources, analytical methods and ecological impacts

Abstract: Microplastics are emerging persistent pollutants that have been extensively detected in aqueous environments. Yet, scientists have little knowledge of microplastic pollution in soils. This study reviewed over 60 articles, with the following objectives: (i) to discuss sources and the global distribution of microplastics in soils; (ii) to evaluate current extraction techniques and analytical methods for microplastics in soils; and (iii) to comprehensively assess their adverse impacts on soils and soil organisms. Moreover, this review highlights the lack of research into microplastic contamination in soils as a significant knowledge gap. Research into the fate, sources and analytical techniques of soil microplastics and the interactions between soil organisms, soils andmicroplastics is essential in order to underpin management decisions aimed at safeguarding the ecological integrity of our soils. © 2020 Society of Chemical Industry

Malic acid production from renewables: A review

Abstract: Malic acid derived from fossil resources is currently applied in the food and beverage industries with a medium global production capacity. However, in the transition from a fossil‐based to a bio‐based economy, biotechnologically produced l‐malic acid may become an important platform chemical with many new applications, especially in the field of biopolymers. In this review, currently used petrochemical production routes to dl‐malic acid are outlined and insights into possible bio‐based alternatives for microbial l‐malic acid production are provided. Besides ecological reasons, the possibility to produce enantiopure l‐malic acid by microbial fermentation is the biggest advantage over chemical synthesis. State‐of‐the‐art and open challenges concerning production host engineering, substrate choice and downstream processing are addressed. With regard to production hosts, a literature overview is given covering the leading natural production strains of Aspergillus, Ustilago and Aureobasidium, as well as Escherichia coli as the most important engineered recombinant host. The utilization of renewable substrates as an alternative to glucose is emphasized in particular as a key aspect for a competitive bio‐based production. Out of the alternative substrates discussed in this review, the industrial side‐streams crude glycerol and molasses seem to be most promising for large‐scale l‐malic acid production. © 2019 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Food wastes and sewage sludge as feedstock for an urban biorefinery producing biofuels and added-value bioproducts

Abstract: The updated Bioeconomy Strategy document “A sustainable bioeconomy for Europe: strengthening the connection between economy, society and the environment”, which was issued by the European Commission in October 2018, encourages the exploitation of organic wastes according to a pyramidal hierarchy in which the extraction of valuable biomolecules, which will be used as they are or as precursors of high‐added‐value compounds, is a priority in biofuel production. This review considers a biorefinery platform in which food waste and sewage sludge are adopted to produce volatile fatty acids (VFAs) through a dark fermentation process. VFA fermentation is optimized by slightly acid pH (6–7), short hydraulic retention time (1–7 days) and high organic load rate (more than 10 gTS L⁻¹ d⁻¹). Attention has been focused on VFA exploitation for polyhydroxyalkanoate (PHA) production via a ‘feast and famine’ strategy performed in sequencing batch reactors. The obtained PHA yields are around 0.4–0.5 gPHA gCOD⁻¹. Moreover, VFAs allow for the production of biofuels, such as hydrogen and methane, through single‐ or double‐staged anaerobic digestion. Innovative bioelectrochemical upgrade strategies for biogas helps producers to obtain biomethane for the automotive sector. Moreover, biogas has recently been tested for the production of polyhydroxybutyrate, a biodegradable and biocompatible thermoplastic made by microorganisms from C1 carbon sources (CO₂ and CH₄). Digestates from anaerobic bioreactors are still rich in nitrogen and phosphorus compounds. These latter compounds have been identified as critical raw materials due to their low availability in the European Union and to increasing demand from the growing global population. Thus, nutrient recovery from digestate allows users to close the loop of the ‘circular economy’ approach. © 2019 Society of Chemical Industry

Phytoextraction technologies for mercury‐ and chromium‐contaminated soil: a review

Abstract: Mercury and chromium represent two important elements of environmental concern and with a strong impact on human health. Several technologies are available to clean up the environment from these kinds of contaminants, but most of them are costly and difficult to use to get optimum results. Currently, phytoextraction is an effective and affordable technological solution used to extract or remove metals from contaminated soil and water by the use of plants as tools. This technology is environment‐friendly and potentially cost‐effective. This paper aims to compile some information about the two metals mercury and chromium, their effects and their possible treatment by phytoextraction, a branch of phytoremediation technologies aimed to confront metal/metalloid pollution. © 2019 Society of Chemical Industry

Fabrication of TiO2/high‐crystalline g‐C3N4 composite with enhanced visible‐light photocatalytic performance for tetracycline degradation

Abstract: BACKGROUND: The construction of heterojunction between two‐phase semiconductors is a crucial tactic to enhance photocatalytic activity due to its efficient charge separation. RESULT: In this work, a novel TiO₂/high‐crystalline g‐C₃N₄ (HCCN) heterojunction photocatalyst was synthesized successfully via a simply hydrothermal method, which was composed of TiO₂ nanoparticles distributed on the surface of the HCCN nanosheets. The microstructure and morphology of TiO₂/HCCN heterojunction were investigated by various characteristic techniques (such as X‐ray diffraction, transmission electron microscopy and Fourier transform infrared). The photocatalytic performance of as‐prepared photocatalysts was tested though the degradation of tetracycline (10 mg L⁻¹) under visible light irradiation (λ > 420 nm). Significantly, the 50% TiO₂/HCCN composite photocatalyst (mass fraction of TiO₂ is 50%) exhibited the optimum photocatalytic activity (90%, 120 min), and the corresponding reaction rate constant was around 12 times and 54 times higher than those of pristine HCCN and TiO₂, respectively. CONCLUSION: The excellent photocatalytic performance was attributed mainly to the synergistic effect of the TiO₂/HCCN heterojunction as follows: (i) enhanced light absorption capacity; (ii) improved separation and migration of electron–hole pairs; (iii) extended lifetime of photogenerated carriers. This current study extends our knowledge towards constructing other HCCN‐based nanocomposites with extraordinary photocatalytic performance for addressing environmental problems. © 2020 Society of Chemical Industry

A review: applications of ion transport in micro‐nanofluidic systems based on ion concentration polarization

Abstract: Lab‐on‐a‐chip has been used widely in rapid, high‐throughput and low‐consumption analysis of samples in biochemistry. The ion concentration polarization (ICP) produced by ion‐selective transport of nanochannels provides a novel solution for problems in ultra‐low concentration sample detection, systems biology and desalination. This paper reviews the applications of ion transport based on the principle of ICP in micro‐nanofluidic systems. First, the fundamental governing equations of ICP are described. Then, the applications of nano‐electrokinetic ion enrichment and ion current rectification (ICR) are introduced. Nano‐electrokinetic ion enrichment is used mainly in the fields of molecular enrichment, ultra‐low concentration sample detection and seawater desalination. ICR is applied mainly to the sensitive detection of analytical substances such as proteins, nucleic acids and small molecules. The application of ion transport based on ICP principle is summarized and the possible directions worthy of further research are proposed. © 2019 Society of Chemical Industry

Microwave-assisted extraction of cannabinoids and antioxidants from Cannabis sativa aerial parts and process modeling

Abstract: BACKGROUND: Cannabis (Cannabis sativa L.) is one of the most controversial plants. So far, its multiple application in industry for the production of fabrics, paper and construction materials is known. Today, there is increasing interest in its application for medical purposes, as opposed to its opiate activity. In addition to well‐known cannabinoids, the presence of polyphenolic compounds and their antioxidant and reductive abilities are of great importance. Therefore the extraction of both constituents, polyphenolics and cannabinoids (Δ⁹‐tetrahydrocannabinol (THC) and cannabidiol (CBD)), of industrial hemp was carried out using microwave‐assisted extraction (MAE). RESULTS: The effects of different extraction parameters, namely ethanol concentration (30, 50 and 70% v/v), extraction time (10, 20 and 30 min) and solid/liquid ratio (5, 10 and 15 g mL⁻¹), on extraction yield, total phenol content, total flavonoid content, antioxidant activity, reductive capacity, CBD content and THC content were investigated using response surface methodology. For the experimental design, a Box–Behnken design was chosen. In the obtained extracts, the following ranges of targeted compounds were detected: total phenols from 0.8499 to 2.7060 mg gallic acid equivalent mL⁻¹, total flavonoids from 0.4707 to 1.4246 mg catechin equivalent mL⁻¹, THC from 0.0339 to 0.0637 mg mL⁻¹ and CBD from 0.2243 to 1.8415 mg mL⁻¹. Antioxidant activity ranged from 0.0009 to 0.2079 mL mL⁻¹, while reductive capacity ranged from 0.0021 to 0.0066 mL mL⁻¹. CONCLUSION: MAE proved to be a simple, efficient, fast and low environmental impact method for obtaining polyphenols and cannabinoids from C. sativa L. Cannabis herb, which presents a by‐product of fiber and cannabis product, showed to be a promising source of bioactive compounds. © 2019 Society of Chemical Industry

Supercritical fluid extraction for enhancing polyphenolic compounds production from olive waste extracts

Abstract: BACKGROUND: A number of residues are produced during the olive oil extraction process, such as crushed pits, olive leaves, pomace and exhaust olive pomace. In addition, pruning of olive trees results in a huge amount of biomass. All of these lignocellulosic materials constitute a source of energy and chemicals that can be used as raw materials in biorefineries. Among them, antioxidants are of particular interest due to their potential applications in pharmaceutical and food industry. RESULTS: Supercritical fluid extraction (SFE) was applied on three different olive residues – pruning biomass, leaves and exhaust pomace. In this, 60% ethanol was used as cosolvent at three different pressure levels, 200, 250 and 300 bar. The best conditions for each residue were determined and compared with conventional extraction. Results show that 300 bar was the best pressure for SFE in terms of antioxidant activity of the extracts. The main polyphenolic compounds also were identified, among which hydroxytyrosol, chlorogenic acid, caffeic acid and ferulic acid were present. CONCLUSION: SFE at 300 bar proved to be the best option for obtaining a high‐activity antioxidant extract from olive leaves, exhaust pomace and pruning biomass, with hydroxytyrosol the prominent compound detected. This procedure could be integrated in a biorefinery based on olive‐derived biomass. © 2018 Society of Chemical Industry

Reactive oxygen species‐induced heterogeneous photocatalytic degradation of organic pollutant Rhodamine B by copper and zinc aluminate spinels

Abstract: BACKGROUND: The importance of potable water is immeasurable and its contamination by pollutants is a serious environmental problem. Rhodamine B (RhB), one such pollutant, is highly toxic to various organisms and may cause long‐term undesirable effects when improperly disposed of. Thus, development of an efficient treatment technique is necessary. Among the new oxidation methods, heterogeneous photocatalysis is an emerging pollutant destructive technology. RESULTS: The photocatalytic activities of copper (Cu) and zinc (Zn) aluminate spinels (CuAl₂O₄ and ZnAl₂O₄) was evaluated. Chemical and physical properties were considered, and ZnAl₂O₄ showed higher RhB degradation efficiency (73.90% in only 10 min) than CuAl₂O₄ (51.95% in 10 min), reaching up to 100% in 30 min. According to results, a further RhB catalytic degradation pathway by ZnAl₂O₄ was monitored by UV‐visible spectrometry and ultra‐high performance liquid chromatography coupled to diode array detection (UHPLC‐DAD) analysis. When applied to wastewater from gemstone beneficiation, containing elevated RhB concentration, the ZnAl₂O₄ caused 88% color removal in 120 min and its pollutant removal rate was 18 times greater than the commonly used ZnO. CONCLUSION: The superior performance of ZnAl₂O₄ can be attributed to better pore properties, responsible for providing more active sites. These identified reactive oxygen species (ROS)‐induced interactions and the species demonstrated that degradation occurs due to generation of O₂•‐ and h⁺. Thus, ZnAl₂O₄ proved to be an efficient photocatalyst for quick RhB pollutant degradation with promising potential for real wastewater treatment applications. © 2019 Society of Chemical Industry

Valorisation of sugarcane molasses for the production of microbial lipids via fermentation of two Rhodosporidium strains for enzymatic synthesis of polyol esters

Abstract: BACKGROUND: Bioprocess development for microbial oil production using cane sugar and sugarcane molasses via fermentation followed by enzymatic conversion into fatty acid esters is presented in this study. RESULTS: Microbial oil was initially evaluated in shake flask fermentations of Rhodosporidium toruloides NRRL Y‐27012 and R. kratochvilovae Y‐43 using either very high polarity (VHP) cane sugar or sugarcane molasses. Supplementation of phosphate salts, trace elements and nitrogen sources in molasses‐based cultures influenced yeast growth and microbial oil production. R. kratochvilovae had different nutrient requirements than R. toruloides. Fed‐batch bioreactor cultures of R. toruloides in molasses‐based cultures without any phosphate salts and trace element supplementation led to a microbial oil concentration of 25 g L⁻¹ and an intracellular lipid content of 61% (w/w). Nutrient supplementation influenced the fatty acid composition of microbial oils indicating that enrichment in oleic acid could be achieved (up to 65.1%). The microbial oil produced by R. toruloides was enzymatically converted into polyol esters with a conversion yield of more than 85% (w/w). CONCLUSION: This study demonstrates that Rhodosporidium sp. can be cultivated in molasses for the production of oleic acid enriched microbial lipids by adjusting medium composition. The polyol esters derived from microbial lipids could be used as a renewable feedstock for oleochemical production. © 2019 Society of Chemical Industry

One‐step synthesis of a WO3‐CuS nanosheet heterojunction with enhanced photocatalytic performance for methylene blue degradation and Cr(VI) reduction

Abstract: BACKGROUND: The photocatalytic activity of a pristine semiconductor is unsatisfactory due to the rapid recombination of photogenerated electrons and holes. Constructing composite photocatalysts has proven to be an effective method to suppress electron–hole recombination. The composites composed of two materials usually are synthesized through a two‐step process. However, in this work, a simple one‐step solvothermal method employing an homogeneous reaction system was adopted to synthesize a tungsten trioxide (WO₃)‐copper sulfide (CuS) nanosheet heterojunction with enhanced photocatalytic properties. RESULTS: The formation of the WO₃‐CuS heterojunction was confirmed by X‐ray diffraction, transmission electron microscopy, energy‐dispersive X‐ray and X‐ray photoelectron spectroscopy analysis. The composites showed improved visible light harvesting ability, and enhanced photoelectric and photocatalytic properties compared with pure WO₃. The optimized composite displayed a photocurrent almost five‐fold greater than the sum of the photocurrents of WO₃ and CuS, and had superior performance for methylene blue (MB) degradation and hexavalent chromium [Cr(VI)] reduction. The MB degradation and Cr(VI) reduction efficiencies were both improved when they co‐existed in the photocatalytic system. Interferential ions Cl⁻ and NO₃⁻ were much less effective in the degradation of MB than in the reduction of Cr(VI). CONCLUSIONS: Improved photocatalytic activity was achieved after coupling CuS with WO₃, due to the enhanced visible light absorption and efficient electron–hole separation. Photogenerated holes were found to be the dominant reactive species in the MB photodegradation process. A synergistic effect existed between MB degradation and Cr(VI) reduction. Interferential ions Cl⁻ and NO₃⁻ had much greater effect on Cr(VI) reduction than MB degradation. © 2019 Society of Chemical Industry

Dual-functionalized protic ionic liquids for efficient absorption of NH3 through synergistically physicochemical interaction

Abstract: BACKGROUND: Ionic liquids have become promising media for the treatment of tail gases containing ammonia (NH₃), which causes serious environmental problems and threatens human health. RESULTS: In this work, four dual‐functionalized protic ionic liquids (DPILs) [CₙOHim]X (n = 1, 2; X = [NTf₂]⁻, [BF₄]⁻, [SCN]⁻) with both weak acidity proton and hydroxyl group were designed and synthesized for enhanced NH₃ separation. Among them, the maximum NH₃ molar solubility of 3.11 mol NH₃ mol–¹ IL was achieved in [EtOHim][NTf₂] at 40 °C and atmospheric pressure, and the highest mass solubility of NH₃ could be 0.221 g NH₃ g–¹ IL in [EtOHim][SCN]; this is the highest value of any absorbent ever reported under the same conditions. Not only superior NH₃ solubility, along with excellent selectivity of NH₃/CO₂ (65) and NH₃/N₂ (104), but also outstanding recyclability was exhibited in DPILs. CONCLUSIONS: The highly efficient performance of NH₃ absorption by DPILs was ascribed to the synergistically physicochemical interaction between weak acidity proton, hydroxyl group and NH₃, which was confirmed through both spectrum analysis and quantum chemical calculations. This work implied that DPILs have great potentials in NH₃ separation and recovery of NH₃‐containing tail gases. © 2020 Society of Chemical Industry

Chitinous polymers: extraction from fungal sources, characterization and processing towards value‐added applications

Abstract: Chitin, chitosan and their complexes with β‐glucan (chitin–glucan complex, CGC, and chitosan–glucan complex, ChGC) are value‐added polysaccharides extracted from the cell‐walls of many fungi. Commercial chitin and its deacetylated form, chitosan, are currently obtained from marine waste material, mostly animal sources (crustaceans and marine invertebrates), through harsh chemical procedures that have low reproducibility due to the variability of the composition of the sources and their seasonal character. These disadvantages are overcome by using fungi as sources of chitinous polymers. The extraction of chitin/chitosan from fungi cell‐walls has the great advantage of yielding products with stable composition and properties, using simpler procedures, with the added benefit of also generating CGC and ChGC, two copolymers that combine the proven properties of chitin/chitosan with those of β‐glucans. Over the last decades, fungal chitinous polymers have been the focus of extensive research that included optimization of the cultivation conditions of a wide range of species and the development of optimized extraction, purification and characterization techniques, as well as the demonstration of the biopolymers' biological properties, which include immunomodulatory, anticancer, antioxidant and antimicrobial activity. Given these properties, several attempts were made to develop applications for them in areas ranging from biomedicine and pharmaceuticals to food and agriculture. Despite their wide range of proven functional properties that include the ability to form different polymeric structures, as well as biological activity, fungal chitinous biopolymers are still underexplored. Nevertheless, these biopolymers hold great potential for development into valuable products or applications that are surely worth further investigation. © 2019 Society of Chemical Industry

Adsorption of fluorinated greenhouse gases on activated carbons: evaluation of their potential for gas separation

Abstract: Background: The increasing awareness of the release of fluorinated gases (F-gases) into the atmosphere is instigating the development of techniques to capture them from refrigerants In this work, the adsorption of difluoromethane (R-32), pentafluoroethane (R-125), and 1,1,1,2-tetrafluoroethane (R-134a) on four different activated carbons (ACs) is studied Additionally, the selectivity of the ACs for the components of commercial refrigerants, R-410A and R-407F, is evaluated Results: The estimation of the density of the adsorbed phase as a function of temperature allows the experimental fractional loading of each F-gas on any of the ACs to be correlated as a temperature-independent function of its reduced pressure, which is described by Toth or dual-site Langmuir equations or as an exponential function of the adsorption potential under the framework of the Adsorption Potential theory (APT) It is shown that the APT can be generalized with excellent accuracy to the systems studied if an adsorbate-dependent affinity coefficient is used as a shifting factor to bring the characteristic curves of all F-gases into a single one for each AC R-32 is the F-gas most adsorbed by all adsorbents, followed by R-134a, and by R-125 All ACs are selective for R-125 in R-410A commercial refrigerants, especially at lower pressures Additionally, all ACs are selective for R-125 and R-134a over R-32 in R407-F commercial refrigerant Conclusion: The utilization of ACs for adsorption of the three most used F-gases is promising By selecting ACs with different porous characteristics, it is possible to evaluate their influence on the selectivity for the components of different commercial refrigerants © 2020 Society of Chemical Industry

Surface modification of anti-fouling novel cellulose/graphene oxide (GO) nanosheets (NS) microfiltration membranes for seawater desalination applications

Abstract: BACKGROUND: Reverse osmosis (RO) is becoming the predominant technology for the future of desalinated of seawater Nonetheless, operational challenges such as membrane biofouling in RO desalination plants result in membrane deterioration and high energy costs In this regard, pre-treatment technologies, such as microfiltration (MF) membranes, are proven to reduce the impact of membrane biofouling in RO systems Hence, surface modifications of commercial cellulose MF membranes with graphene oxide nanosheets (GONSs) at different concentrations were carried out in this research study The new membranes were characterized by scanning electron microscopy (SEM) and Raman spectroscopy amongst other methods of analysis A continuous cross-flow MF system was used to investigate the performance of the new cellulose/GONS membranes with regards to total bacteria count (TBC) removal, water flux, and biofouling resistance RESULTS: TBC removal efficiency of 93 6 ± 2 4% and 27 4 ± 12 5% was achieved using the new cellulose/GONS membranes and control pristine cellulose membranes, respectively This higher removal efficiency was achieved at a water flux of 334 7 ± 10 4 L/(m2 h) Furthermore, a dramatic 55% increase in the transmembrane pressure (TMP) of the pristine cellulose membrane was observed after 24 h operation compared to only a 6% increase in the newly fabricated cellulose/GONS membranes, reflecting their strong anti-fouling properties CONCLUSION: Surface modification of MF membranes with anti-fouling nanomaterials such as GONS has the potential to be implemented in the pretreatment of seawater to improve the RO performance and lower the energy consumption © 2020 Society of Chemical Industry