Processes

Editorial

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4 pages, 193 KiB

Open AccessEditorial

Emerging Technologies for Biorefining, Food and Environmental Applications

by Roberto Castro-Muñoz

Processes 2021, 9(4), 668; https://doi.org/10.3390/pr9040668 - 10 Apr 2021

Cited by 1 | Viewed by 1472

Abstract

Several emerging technologies, such as membrane technologies, biofermentation, oxidation processes, among others, are currently attracting interest in different areas of biotechnological and chemical engineering [...] Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

Research

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15 pages, 2135 KiB

Open AccessArticle

The Relationship of Moisture and Temperature to the Concentration of O₂ and CO₂ during Biodrying in Semi-Static Piles

by Rosa María Contreras-Cisneros, Carlos Orozco-Álvarez, Ana Belem Piña-Guzmán, Luis Carlos Ballesteros-Vásquez, Liliana Molina-Escobar, Sandra Sharo Alcántara-García and Fabián Robles-Martínez

Processes 2021, 9(3), 520; https://doi.org/10.3390/pr9030520 - 13 Mar 2021

Cited by 12 | Viewed by 2156

Abstract

Biodrying was studied over 46 days in two piles (P1 and P2) composed of orange peel and two structuring materials (mulch: P1; sugarcane bagasse: P2). The oxygen and carbon dioxide levels were recorded at different depths (0.1 to 0.6 m). From the beginning [...] Read more.

Biodrying was studied over 46 days in two piles (P1 and P2) composed of orange peel and two structuring materials (mulch: P1; sugarcane bagasse: P2). The oxygen and carbon dioxide levels were recorded at different depths (0.1 to 0.6 m). From the beginning to days 33–35 the drying was carried out by a combination of microbial heat, convection, and solar irradiance; moisture reached 30%, corresponding to a water activity (a_w) of 0.88–0.9, which was insufficient to maintain microbial activity. Additionally, the O₂ and CO₂ levels (21% and 0%, respectively) evidenced the end of the biological phase of the process. After day 35, the drying occurred only by convection and solar irradiance. At the end, moisture reached 14% (P1) and 12% (P2), showing that the turning frequency, as well as the type and proportion of the structuring materials, were adequate and significantly influenced moisture reduction, allowing the aeration necessary for biodrying. At the end, a material with an average calorific value of 15,500 kJ/kg was obtained, comparable to wood and other fuels obtained from orange peel, making the biodrying process a suitable option for the stabilization and energy recovery of agricultural and agro-industrial waste with high moisture content. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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14 pages, 7360 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Biomass-Derived Nitrogen Functionalized Carbon Nanodots and Their Anti-Biofouling Properties

by Maria K. Rybarczyk, Emilia Gontarek-Castro, Karolina Ollik and Marek Lieder

Processes 2021, 9(1), 61; https://doi.org/10.3390/pr9010061 - 29 Dec 2020

Cited by 14 | Viewed by 4406

Abstract

The prevalence of the antibiotic resistant bacteria remains a global issue. Cheap, sustainable and multifunctional antibacterial membranes are at the forefront of filtrating materials capable of treating multiple flow streams, such as water cleansing treatments. Carbon nanomaterials are particularly interesting objects shown to [...] Read more.

The prevalence of the antibiotic resistant bacteria remains a global issue. Cheap, sustainable and multifunctional antibacterial membranes are at the forefront of filtrating materials capable of treating multiple flow streams, such as water cleansing treatments. Carbon nanomaterials are particularly interesting objects shown to enhance antibacterial properties of composite materials. In this article, amino-functionalized, photoluminescent carbon nanodots (CNDs) were synthesized from chitosan by bottom-up approach via simple and green hydrothermal carbonization. A chemical model for the CNDs formation during hydrothermal treatment of chitosan is proposed. The use of urea as an additional nitrogen source leads to the consumption of hydroxyl groups of chitosan and higher nitrogen doping level as pyridinic and pyrrolic N-bonding configurations in the final carbonaceous composition. These functionalized carbon nanodots that consist of carbon core and various surface functional groups were used to modify the commercially available membranes in order to enhance their anti-biofouling properties and add possible functionalities, including fluorescent labelling. Incorporation of CNDs to membranes increased their hydrophilicity, surface charge without compromising membranes integrity, thereby increasing the factors affecting bacterial wall disruption. Membranes modified with CNDs effectively stopped the growth of two Gram-negative bacterial colonies: Klebsiella oxytoca (K. oxytoca) and Pseudomonas aeruginosa (P. aeruginosa). Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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17 pages, 4324 KiB

Open AccessArticle

The Effect of Slurry Wet Mixing Time, Thermal Treatment, and Method of Electrode Preparation on Membrane Capacitive Deionisation Performance

by Ebrahiem Botha, Nafeesah Smith, Bongibethu Hlabano-Moyo and Bernard Bladergroen

Processes 2021, 9(1), 1; https://doi.org/10.3390/pr9010001 - 22 Dec 2020

Cited by 3 | Viewed by 3345

Abstract

Capacitive deionisation (CDI) electrodes with identical composition were prepared using three deposition methods: (1) slurry infiltration by calendering (SIC), (2) ink infiltration dropwise (IID), and (3) ink deposition by spray coating (IDSC). The SIC method clearly showed favourable establishment of an electrode with [...] Read more.

Capacitive deionisation (CDI) electrodes with identical composition were prepared using three deposition methods: (1) slurry infiltration by calendering (SIC), (2) ink infiltration dropwise (IID), and (3) ink deposition by spray coating (IDSC). The SIC method clearly showed favourable establishment of an electrode with superior desalination capacity. Desalination results showed that electrodes produced from slurries mixed longer than 30 min displayed a significant reduction in the maximum salt adsorption capacity, due to the agglomeration of carbon black. The electrodes were then thermally treated at 130, 250, and 350 °C. Polyvinylidene difluoride (PVDF) decomposition was observed when the electrodes were treated at temperatures higher than 180 °C. The electrodes treated at 350 °C showed contact angles of θ = 0°. The optimised electrodes showed a salt adsorption capacity value of 24.8 mg/g (130 °C). All CDI electrodes were analysed using specific surface area by N₂ adsorption, contact angle measurements, conductivity by the four-point probe method and salt adsorption/desorption experiments. Selected reagents and CDI electrodes were characterised using thermogravimetric analysis coupled with mass spectrometry (TGA-MS) and differential scanning calorimetry (DSC), as well as scanning electron microscopy energy dispersive X-ray spectroscopy (SEM-EDS). Electrode structure and the development of the critical balance between ion- and electron- conductive pathways were found to be a function of the electrode slurry mixing procedure, slurry deposition technique and thermal treatment of the electrodes. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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16 pages, 1152 KiB

Open AccessFeature PaperArticle

Effect of Barium Addition on Hydrolytic Enzymatic Activities in Food Waste Degradation under Anaerobic Conditions

by Fuad Ale, Roberto Castro-Muñoz, Blanca Estela Barragán-Huerta and Odín Rodríguez-Nava

Processes 2020, 8(11), 1371; https://doi.org/10.3390/pr8111371 - 29 Oct 2020

Cited by 3 | Viewed by 2384

Abstract

Enzymatic hydrolysis of complex components of residual materials, such as food waste, is a rate-limiting step that conditionates the production rate of biofuels. Research into the anaerobic degradation of cellulose and starch, which are abundant components in organic waste, could contribute to optimize [...] Read more.

Enzymatic hydrolysis of complex components of residual materials, such as food waste, is a rate-limiting step that conditionates the production rate of biofuels. Research into the anaerobic degradation of cellulose and starch, which are abundant components in organic waste, could contribute to optimize biofuels production processes. In this work, a lab-scale anaerobic semi-continuous hydrolytic reactor was operated for 171 days using food waste as feedstock; the effect of Ba²⁺ dosage over the activity of five hydrolytic enzymes was also evaluated. No significant effects were observed on the global performance of the hydrolytic process during the steady-state of the operation of the reactor, nevertheless, it was detected that Ba²⁺ promoted β-amylases activity by 76%, inhibited endoglucanases and α-amylases activity by 39 and 20%, respectively, and had no effect on β-glucosidases and glucoamylases activity. The mechanisms that rule the observed enzymatic activity changes remain unknown; however, the discussion in this paper provides hypothetical explanations for further research. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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19 pages, 3213 KiB

Open AccessArticle

Photochemical Oxidation Process of Copper from Electroplating Wastewater: Process Performance and Kinetic Study

by Aji Prasetyaningrum, Teguh Riyanto, Mohamad Djaeni and Widayat Widayat

Processes 2020, 8(10), 1276; https://doi.org/10.3390/pr8101276 - 12 Oct 2020

Cited by 4 | Viewed by 3730

Abstract

An investigation of the process of ozone combined with ultraviolet radiation has been carried out in order to establish the kinetics for photochemical oxidation of copper (Cu) from electroplating wastewater. The effects of operating parameters, including initial Cu concentration, ozone dosage, UV irradiation [...] Read more.

An investigation of the process of ozone combined with ultraviolet radiation has been carried out in order to establish the kinetics for photochemical oxidation of copper (Cu) from electroplating wastewater. The effects of operating parameters, including initial Cu concentration, ozone dosage, UV irradiation intensity, and pH value on the photochemical oxidation of Cu have been studied comprehensively. The Cu concentration during the reaction was identified using atomic absorption spectroscopy (AAS) method. The solid product was analyzed using X-ray diffraction (XRD) and scanning electron microscope–energy-dispersive X-ray (SEM–EDX) methods. It was found that the UV-Ozone process has high performance on Cu removal compared to UV and Ozone processes due to the high production rate of HO• radicals. It was also found that the solid product from the UV-Ozone process was CuO monoclinic crystal phase. The initial Cu concentration, ozone dosage, and pH value were significantly affected the Cu removal efficiency. On the other hand, the UV irradiation intensity was not significant; however, it has responsibility in promoting the ozone photolysis. The kinetics model for the photochemical oxidation of Cu was established following the first-order kinetic model. Furthermore, the reaction mechanism was also developed. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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18 pages, 3335 KiB

Open AccessFeature PaperArticle

Integrated Ozonation-Enzymatic Hydrolysis Pretreatment of Sugarcane Bagasse: Enhancement of Sugars Released to Expended Ozone Ratio

by Daryl Rafael Osuna-Laveaga, Octavio García-Depraect, Ramiro Vallejo-Rodríguez, Alberto López-López and Elizabeth León-Becerril

Processes 2020, 8(10), 1274; https://doi.org/10.3390/pr8101274 - 11 Oct 2020

Cited by 17 | Viewed by 3054

Abstract

The combined effects of three key ozonation process parameters on the integrated ozonation-enzymatic hydrolysis pretreatment of sugarcane bagasse (SCB) were investigated, with emphasis on the relationship between sugar release and ozone consumption. A lab-scale fixed bed reactor was employed for ozonation at varying [...] Read more.

The combined effects of three key ozonation process parameters on the integrated ozonation-enzymatic hydrolysis pretreatment of sugarcane bagasse (SCB) were investigated, with emphasis on the relationship between sugar release and ozone consumption. A lab-scale fixed bed reactor was employed for ozonation at varying ozone doses (50, 75 and 100 mg O₃/g SCB), particle sizes (420, 710 and 1000 µm) and moisture contents (30, 45 and 60% w/w) in multifactorial experiments, keeping a residence time of 30 min. The ozonated SCB showed a reduction in the content of acid-insoluble lignin from 26.6 down to 19.1% w/w, while those of cellulose and hemicellulose were retained above 45.5 and 13.6% w/w, with recoveries of 100–89.9 and 83.5–72.7%, respectively. Ozone-assisted enzymatic hydrolysis allowed attaining glucose and xylose yields as high as 45.0 and 37.8%, respectively. The sugars released/ozone expended ratio ranged between 2.3 and 5.7 g sugars/g O₃, being the higher value achieved with an applied ozone input of 50 mg O₃/g SCB and SCB with 420 µm particle size and 60% moisture. Such operating conditions led to efficient ozone utilization (<2% unreacted ozone) with a yield of 0.29 g sugars/g SCB. Overall, the amount of sugars released relative to the ozone consumed was improved, entailing an estimated cost of ozonation of USD 34.7/ton of SCB, which could enhance the profitability of the process. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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25 pages, 6103 KiB

Open AccessArticle

Single and Binary Equilibrium Studies for Ni²⁺ and Zn²⁺ Biosorption onto Lemna gibba from Aqueous Solutions

by Liliana Morales-Barrera, César Mateo Flores-Ortiz and Eliseo Cristiani-Urbina

Processes 2020, 8(9), 1089; https://doi.org/10.3390/pr8091089 - 2 Sep 2020

Cited by 11 | Viewed by 2588

Abstract

The biosorption ability of Lemna gibba for removing Ni²⁺ and Zn²⁺ ions in aqueous batch systems, both individually and simultaneously, was examined. The influences of solution pH and initial single and binary metal concentrations on equilibrium Ni²⁺ and Zn²⁺ [...] Read more.

The biosorption ability of Lemna gibba for removing Ni²⁺ and Zn²⁺ ions in aqueous batch systems, both individually and simultaneously, was examined. The influences of solution pH and initial single and binary metal concentrations on equilibrium Ni²⁺ and Zn²⁺ biosorption was explored. The optimal solution pH for Ni²⁺ and Zn²⁺ biosorption was 6.0, for both the single and binary metal systems. Ni²⁺ and Zn²⁺ biosorption capacities increased with increasing initial metal concentrations. The presence of Zn²⁺ ions more adversely affected the biosorption of Ni²⁺ ions in the binary metal systems than vice versa. The single and binary biosorption isotherms of Ni²⁺ and Zn²⁺ revealed that L. gibba’s affinity for Zn²⁺ ions was higher than that for Ni²⁺ ions. The Redlich–Peterson and Freundlich isotherm models fit well to the experimental equilibrium data of Ni²⁺ ions, whereas Redlich–Peterson and Langmuir models better described the equilibrium data of Zn²⁺ ions in single metal systems. The modified Sips isotherm model best fit the competitive biosorption data of Ni²⁺-Zn²⁺ on L. gibba. FTIR analyses suggest the involvement of hemicellulose and cellulose in the biosorption of Ni²⁺ and Zn²⁺. The presence of Ni²⁺ and Zn²⁺ on the L.gibba surface was validated by SEM-EDX. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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25 pages, 9871 KiB

Open AccessArticle

Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Conceptual Study in the Pre-Neogene Basement in the Northern Croatia

by Tomislav Malvić, Maria Alzira Pimenta Dinis, Josipa Velić, Jasenka Sremac, Josip Ivšinović, Marija Bošnjak, Uroš Barudžija, Želimir Veinović and Hélder Fernando Pedrosa e Sousa

Processes 2020, 8(7), 755; https://doi.org/10.3390/pr8070755 - 29 Jun 2020

Cited by 5 | Viewed by 5042

Abstract

The basic principles of geological risk calculation through probability of success (PoS) are mostly applied to numerical estimation of additional hydrocarbon existence in proven reservoirs or potential hydrocarbon discoveries in selected geological regional subsurface volumes. It can be adapted and validated for a [...] Read more.

The basic principles of geological risk calculation through probability of success (PoS) are mostly applied to numerical estimation of additional hydrocarbon existence in proven reservoirs or potential hydrocarbon discoveries in selected geological regional subsurface volumes. It can be adapted and validated for a comprehensive input dataset collected in the selected petroleum province, by dividing up geological events into several probability categories and classes. Such methodology has been widely developed in the last decades in the Croatian subsurface—mostly in the Croatian Pannonian Basin System (CPBS). Through the adaptation of geological categories, it was also applied in hybrid, i.e., stochastic, models developed in the CPBS (Drava Depression), mostly for inclusion of porosity values. As the robustness of this methodology is very high, it was also modified to estimate the influence of water-flooding in increasing oil recovery in some proven Neogene sandstone reservoirs in the CPBS (Sava Depression). This new modification is presented to be applied to geological risk calculation, intending to assess the safety of geological environment storage in deep wells, where spent nuclear fuel (SPN) would be disposed, a subject of great importance. The conceptual study encompassed the magmatic and metamorphic rocks in the pre-Neogene basement of the CPBS, intended to be used for such purpose. Regionally distributed lithologies are considered for nuclear waste disposal purpose, in order to detect the safest ones, considering petrophysical values, water saturation, recent weathering and tectonic activity. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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16 pages, 3347 KiB

Open AccessArticle

Optimization of In Situ Backwashing Frequency for Stable Operation of Anaerobic Ceramic Membrane Bioreactor

by Rathmalgodage Thejani Nilusha, Tuo Wang, Hongyan Wang, Dawei Yu, Junya Zhang and Yuansong Wei

Processes 2020, 8(5), 545; https://doi.org/10.3390/pr8050545 - 7 May 2020

Cited by 11 | Viewed by 2930

Abstract

The cost-effective and stable operation of an anaerobic ceramic membrane bioreactor (AnCMBR) depends on operational strategies to minimize membrane fouling. A novel strategy for backwashing, filtration and relaxation was optimized for stable operation of a side stream tubular AnCMBR treating domestic wastewater at [...] Read more.

The cost-effective and stable operation of an anaerobic ceramic membrane bioreactor (AnCMBR) depends on operational strategies to minimize membrane fouling. A novel strategy for backwashing, filtration and relaxation was optimized for stable operation of a side stream tubular AnCMBR treating domestic wastewater at the ambient temperature. Two in situ backwashing schemes (once a day at 60 s/day, and twice a day at 60 s × 2/day) maintaining 55 min filtration and 5 min relaxation as a constant were compared. A flux level over 70% of the initial membrane flux was stabilized by in situ permeate backwashing irrespective of its frequency. The in situ backwashing by permeate once a day was better for energy saving, stable membrane filtration and less permeate consumption. Ex situ chemical cleaning after 60 days’ operation was carried out using pure water, sodium hypochlorite (NaOCl), and citric acid as the order. The dominant cake layer was effectively reduced by in situ backwashing, and the major organic foulants were fulvic acid-like substances and humic acid-like substances. Proteobacteria, Firmucutes, Epsilonbacteria and Bacteroides were the major microbes attached to the ceramic membrane fouling layer which were effectively removed by NaOCl. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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15 pages, 1131 KiB

Open AccessArticle

Enhancing Astaxanthin Biosynthesis by Rhodosporidium toruloides Mutants and Optimization of Medium Compositions Using Response Surface Methodology

by Tuyet Nhung Tran, Dai-Hung Ngo, Quoc Tuan Tran, Hoang Chinh Nguyen, Chia-Hung Su and Dai-Nghiep Ngo

Processes 2020, 8(4), 497; https://doi.org/10.3390/pr8040497 - 24 Apr 2020

Cited by 12 | Viewed by 4574

Abstract

Astaxanthin is a valuable carotenoid, which has been approved as a food coloring by the US Food and Drug Administration and is considered as a food dye by the European Union (European Commission). This work aimed to attain Rhodosporidium toruloides mutants for enhanced [...] Read more.

Astaxanthin is a valuable carotenoid, which has been approved as a food coloring by the US Food and Drug Administration and is considered as a food dye by the European Union (European Commission). This work aimed to attain Rhodosporidium toruloides mutants for enhanced astaxanthin accumulation using ultraviolet (UV) and gamma irradiation mutagenesis. Gamma irradiation was shown to be more efficient than UV for producing astaxanthin-overproducer. Among the screened mutants, G17, a gamma-induced mutant, exhibited the highest astaxanthin production, which was significantly higher than that of the wild strain. Response surface methodology was then applied to optimize the medium compositions for maximizing astaxanthin production by the mutant G17. The optimal medium compositions for the cultivation of G17 were determined as a peptone concentration of 19.75 g/L, malt extract concentration of 13.56 g/L, and glucose concentration of 19.92 g/L, with the maximum astaxanthin yield of 3021.34 µg/L ± 16.49 µg/L. This study suggests that the R. toruloides mutant (G17) is a potential candidate for astaxanthin production. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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15 pages, 3201 KiB

Open AccessArticle

Monitoring of Fruit and Vegetable Waste Composting Process: Relationship between Microorganisms and Physico-Chemical Parameters

by Cristina Ghinea and Ana Leahu

Processes 2020, 8(3), 302; https://doi.org/10.3390/pr8030302 - 5 Mar 2020

Cited by 32 | Viewed by 8086

Abstract

The aim of this study was to investigate and evaluate the composting potential of fruit and vegetable waste with sawdust in different combinations and to establish the relationship between microorganisms and physico-chemical parameters. Three samples were made with the C/N ratios of 50 [...] Read more.

The aim of this study was to investigate and evaluate the composting potential of fruit and vegetable waste with sawdust in different combinations and to establish the relationship between microorganisms and physico-chemical parameters. Three samples were made with the C/N ratios of 50 (sample 1), 45 (sample 2), and 30 (sample 3) by adding fruit waste (apple, banana, orange, and kiwi peels) and vegetable waste (cabbage leaves, potato and carrot peels). The total amount of fruit and vegetable waste was approximately 2 kg in each sample to which different quantities of sawdust were added (1.23, 0.14, and 0.203 kg) in order to obtain the C/N ratios proposed and to limit the odor. Composting process was monitored over 70 days, while physico-chemical and microbiological analyses were performed. Results showed that in the first week pH is acidic and electrical conductivity values are high for all three samples, and then the pH values increase during the composting process, while electrical conductivity values decrease. The nitrogen content is low in all samples and will decrease during the first five weeks of the composting process, then begin to increase slightly. Cr, Cu, Ni, and Zn values in the all three compost samples are below threshold values. During the composing process the microbial communities are constantly changing. The compost was successfully obtained and meets the requirement standards for agricultural use. It can be concluded that there is statistically significant association between the microorganisms and physico-chemical indicators. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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11 pages, 1891 KiB

Open AccessArticle

Performance of Smokehouse Designed for Smoking Fish with the Indirect Method

by Muh. Tahir, S. Salengke, Mursalim, Metusalach and Wahyu Caesarendra

Processes 2020, 8(2), 204; https://doi.org/10.3390/pr8020204 - 6 Feb 2020

Cited by 6 | Viewed by 10927

Abstract

Recently, studies about smoked food tend to identify harmful compounds that potentially appear within the smoking process. The process, conducted in a smokehouse, closely corresponds with the design and method. This paper presents a smokehouse designed by integrating a biomass furnace, a heat [...] Read more.

Recently, studies about smoked food tend to identify harmful compounds that potentially appear within the smoking process. The process, conducted in a smokehouse, closely corresponds with the design and method. This paper presents a smokehouse designed by integrating a biomass furnace, a heat exchanger, a cyclone separator, and a smoking chamber. The design target was to obtain a smoking system that produces clean smoked fish. The design and construction phase and the performance tests phase are discussed in this paper. The energy source used was coconut shells, fed into the furnace at predetermined amounts, to achieve the desired temperature. The performance tests were done using skipjack fish, whose weight ranged from 0.7–1.0 kg/head. The results showed that the smoking system was able to complete the smoking process of the fish in 13 h with 20.1% moisture reduction. The temperature of the smoking chamber varied from 70 °C to 108 °C and the internal fish temperature during the cooking phase ranged from 71 °C to 80 °C. The temperature performance was supported by a heat exchanger with an effectiveness of 0.63 and a cyclone separator, which channeled the smoke–heat flow, separated fly ash with particle sizes between 0.2–600 µm and tar. Based on the test results, the indirect smoking system developed and tested in this study is shown to be able to perform the smoking fish process satisfactorily and produce clean smoked fish. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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Review

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24 pages, 2543 KiB

Open AccessReview

Recent Advances in the Synthesis of Nanocellulose Functionalized–Hybrid Membranes and Application in Water Quality Improvement

by Sandrine Mbakop, Lebea N. Nthunya and Maurice S. Onyango

Processes 2021, 9(4), 611; https://doi.org/10.3390/pr9040611 - 31 Mar 2021

Cited by 37 | Viewed by 4247

Abstract

The increasing discharge of voluminous non or partially treated wastewaters characterized by complex contaminants poses significant ecological and health risks. Particularly, this practice impacts negatively on socio-economic, technological, industrial, and agricultural development. Therefore, effective control of water pollution is imperative. Over the past [...] Read more.

The increasing discharge of voluminous non or partially treated wastewaters characterized by complex contaminants poses significant ecological and health risks. Particularly, this practice impacts negatively on socio-economic, technological, industrial, and agricultural development. Therefore, effective control of water pollution is imperative. Over the past decade, membrane filtration has been established as an effective and commercially attractive technology for the separation and purification of water. The performance of membrane-based technologies relies on the intrinsic properties of the membrane barrier itself. As a result, the development of innovative techniques for the preparation of highly efficient membranes has received remarkable attention. Moreover, growing concerns related to cost-effective and greener technologies have induced the need for eco-friendly, renewable, biodegradable, and sustainable source materials for membrane fabrication. Recently, advances in nanotechnology have led to the development of new high-tech nanomaterials from natural polymers (e.g., cellulose) for the preparation of environmentally benign nanocomposite membranes. The synthesis of nanocomposite membranes using nanocelluloses (NCs) has become a prominent research field. This is attributed to the exceptional characteristics of these nanomaterials (NMs) namely; excellent and tuneable surface chemistry, high mechanical strength, low-cost, biodegradability, biocompatibility, and renewability. For this purpose, the current paper opens with a comprehensive yet concise description of the various types of NCs and their most broadly utilized production techniques. This is closely followed by a critical review of how NC substrates and their surface-modified versions affect the performance of the fabricated NC-based membranes in various filtration processes. Finally, the most recent processing technologies for the preparation of functionalized NCs-based composite membranes are discussed in detail and their hybrid characteristics relevant to membrane filtration processes are highlighted. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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21 pages, 3499 KiB

Open AccessFeature PaperReview

A Review of Zein as a Potential Biopolymer for Tissue Engineering and Nanotechnological Applications

by Carlos Joaquín Pérez-Guzmán and Roberto Castro-Muñoz

Processes 2020, 8(11), 1376; https://doi.org/10.3390/pr8111376 - 29 Oct 2020

Cited by 67 | Viewed by 7221

Abstract

Tissue engineering (TE) is one of the most challenging fields of research since it provides current alternative protocols and materials for the regeneration of damaged tissue. The success of TE has been mainly related to the right selection of nano-sized biocompatible materials for [...] Read more.

Tissue engineering (TE) is one of the most challenging fields of research since it provides current alternative protocols and materials for the regeneration of damaged tissue. The success of TE has been mainly related to the right selection of nano-sized biocompatible materials for the development of matrixes, which can display excellent anatomical structure, functionality, mechanical properties, and histocompatibility. Today, the research community has paid particular attention to zein as a potential biomaterial for TE applications and nanotechnological approaches. Considering the properties of zein and the advances in the field, there is a need to reviewing the current state of the art of using this natural origin material for TE and nanotechnological applications. Therefore, the goal of this review paper is to elucidate the latest (over the last five years) applications and development works in the field, including TE, encapsulations of drugs, food, pesticides and bandaging for external wounds. In particular, attention has been focused on studies proving new breakthroughs and findings. Also, a complete background of zein’s properties and features are addressed. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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27 pages, 1016 KiB

Open AccessReview

Plant Extracts as Green Corrosion Inhibitors for Different Metal Surfaces and Corrosive Media: A Review

by Alan Miralrio and Araceli Espinoza Vázquez

Processes 2020, 8(8), 942; https://doi.org/10.3390/pr8080942 - 6 Aug 2020

Cited by 235 | Viewed by 25000

Abstract

Natural extracts have been widely used to protect metal materials from corrosion. The efficiency of these extracts as corrosion inhibitors is commonly evaluated through electrochemical tests, which include techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurement. The inhibition efficiency [...] Read more.

Natural extracts have been widely used to protect metal materials from corrosion. The efficiency of these extracts as corrosion inhibitors is commonly evaluated through electrochemical tests, which include techniques such as potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss measurement. The inhibition efficiency of different extract concentrations is a valuable indicator to obtain a clear outlook to choose an extract for a particular purpose. A complementary vision of the effectiveness of green extracts to inhibit the corrosion of metals is obtained by means of surface characterizations; atomic force microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy analysis are experimental techniques widely used for this purpose. Moreover, theoretical studies are usually addressed to elucidate the nature of the corrosion inhibitor—metal surface interactions. In addition, calculations have been employed to predict how other organic substances behave on metal surfaces and to provide experimental work with fresh proposals. This work reports a broad overview of the current state of the art research on the study of new extracts as corrosion inhibitors on metal surfaces in corrosive media. Most constituents obtained from plant extracts are adsorbed on the metal, following the Langmuir adsorption model. Electron-rich regions and heteroatoms have been found to be responsible for chemisorption on the metal surface, whereas physisorption is due to the polar regions of the inhibitor molecules. The plant extracts compiled in this work obtained corrosion inhibition efficiencies above 60%, most of them around 80–90%. The effect of concentration, extraction solvent, temperature, and immersion time were studied as well. Additional studies regarding plant extracts as corrosion inhibitors on metals are needed to produce solutions for industrial purposes. Full article

(This article belongs to the Special Issue Emerging Technologies for Biorefining, Food and Environmental Applications)

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