Low-temperature Pretreatment Research Articles

In-situ N, P co-doped porous carbon derived from biomass waste for supercapacitors

The development of heteroatom-doped porous carbon derived from biomass waste with high-performance electrodes for supercapacitors has been drawn extensive research. Herein, N, P co-doped porous carbon (NPC) was successfully synthesized using Chinese fir sawdust as a carbon source, NaOH as an activator, urea as a nitrogen source, and melamine phosphate as the phosphorus and nitrogen source by pretreatment with low-temperature NaOH/urea system. The low-temperature pretreatment and melamine phosphate greatly promoted the porous structure and uniform distributions of heteroatom about the NPC. The optimized NPC exhibits high specific surface area (1849 m2/g), hierarchical porous structure with high mesoporosity (87.3 %), appropriate heteroatom content (3.32 at% N, 0.36 at% P), and excellent wettability. This unique facilitates improved electrolyte diffusion efficiency and ion transfer rate. In the three-electrode system, the specific capacitance of the NPC electrode is as high as 260 F/g at 0.5 A/g and remains at 235 F/g at 10 A/g, and the charge transfer resistance is very low (0.08 Ω). In addition, the assembled symmetric supercapacitors deliver an energy density of 15.9 Wh/kg at a power density of 246 W/kg, a long cycling life with 90 % capacitance retention after 5000 cycles. The environment-friendly NPC has a broad development prospect for carbon-based high-performance electrodes for supercapacitors.

Unveiling the impact of stabilization pretreatment on sodium storage performance in hard carbon

Stabilization pretreatment coupled with molecular cross-linking is commonly used to modify starch, aiming to obtain starch-based hard carbon materials with appropriate spherical particle sizes. Nevertheless, the impact of the intermediate stabilization process on its sodium storage performance remains unclear. Herein, a hard carbon material with no surface open pores, low specific surface area and abundant internal closed pores with thinner pore walls is successfully synthesized and exhibits significantly improved initial Coulombic efficiency and plateau capacity through a simple low-temperature pretreatment strategy, using renewable and cost-effective soluble starch as the raw material. Additionally, research indicates that an appropriate degree of disorder or defectiveness is conducive to forming a larger quantity of closed pores with thinner pore walls. Both excessively low and high defect levels are detrimental to the formation of closed pores. This work will encourage researchers to further focus on the impact of defectiveness on closed pores, which will promote the development of high-energy practical sodium-ion batteries.

Efficient phosphorus recovery from waste activated sludge: Pretreatment with natural deep eutectic solvent and recovery as vivianite

Recycling phosphorus from waste activated sludge (WAS) is an effective method to address the nonrenewable nature of phosphorus and mitigate environmental pollution. To overcome the challenge of low phosphorus recovery from WAS due to insufficient disintegration, a method using a citric acid-based natural deep eutectic solvent (CA-NADES) assisted with low-temperature pretreatment was proposed to efficiently release and recover phosphorus. The results of 31P nuclear magnetic resonance (NMR) confirmed that low-temperature pretreatment promoted the conversion of organic phosphorus (OP) to inorganic phosphorus (IP) and enhanced the effect of CA-NADES. Changes in the three-dimensional excitation-emission matrix (3D-EEM) and flow cytometry (FCM) indicated that the method of CA-NADES with low-temperature thermal simultaneously release IP and OP by disintegrating sludge flocs, dissolving extracellular polymeric substances (EPS) structure, and cracking cells. When 5 % (v/v) of CA-NADES was added and thermally treated at 60 °C for 30 min, 43 % of total phosphorus (TP) was released from the sludge. The concentrations of proteins and polysaccharides reached 826 and 331 mg/L, respectively, which were 6.30 and 14.43 times higher than those of raw sludge. The dewatering and settling of the sludge were also improved. Metals were either enriched in the solid phase or released into the liquid phase in small quantities (most efficiencies of less than 10 %) for subsequent clean recovery. The released phosphorus was successfully recovered as vivianite with a rate of 90 %. This study develops an efficient, green, and sustainable method for phosphorus recovery from sludge using NADES and provides new insights into the high-value conversion of sludge.

Effect of Hydrogen Molecule Release on NBTI by Low-Temperature Pre-Treatment in P-Channel Power VDMOS Transistors

Effect of Hydrogen Molecule Release on NBTI by Low-Temperature Pre-Treatment in P-Channel Power VDMOS Transistors

Synergistic effects of low temperature and alkali on the anaerobic digestion of corn stover

Combined with the climatic conditions in cold areas, the effect of the NaOH-pretreatment at low temperature on the methane yield of corn stover was studied by anaerobic digestion at batch mode. For the alkali/freezing pretreatment, the sample reached a maximum specific methane yield of 280.48 ± 21.75 mL/g VS at the conditions of freezing time of 15 days and 2.0 % NaOH. Lower temperature-alkali pretreatment had an obvious effect on the structure of samples, with significant changes in the contents of elemental C, N, cellulose, and lignin, as well as an increase in crystallinity. In addition, a higher energy conversion efficiency (77.9 %) was obtained for the sample pretreated by alkaline/freezing. The results showed that the methane yield after pretreatment followed by alkali/freezing treatment > water/freezing treatment > freezing treatment. Therefore, alkali/freezing pretreatment is an effective method to improve the performance of the anaerobic digestion of corn stover. This study could provide a pathway for developing a low-temperature pretreatment by combining with the climate characteristics of cold areas.

Low temperature coupled with mechanical liquefaction of seaweed for energy and economically efficient anaerobic digestion

This current work was focused on energy and economically efficient biogas production from seaweed (marine macroalgae) using low-temperature coupled mechanical pretreatment (LTMP). Low temperature pretreatment (LTP) was performed at 50–90 °C for varying periods, from 0 to 60 min. Maximum soluble chemical oxygen demand (SCOD) of 1040 mg/L with 13 % liquefaction was obtained at 80 °C in 30 min for the LTP process. Disperser was introduced in the LTP optimum conditions for performing LTMP by varying 6000–14,000 rpm in 30 min. Maximum liquefaction of 17 % was obtained with SCOD release of 1360 mg/L at 15 min in LTMP with energy usage of 21,889 kJ/kg TS. This coupled process promotes biomass liquefaction and reduces the treatment time. The biogas production of 238 mL/g COD was produced from the LTMP substrate, which is high compared to control (untreated) and LTP samples. LTMP was an effective pretreatment with 0.9 and $105.25/ton as energy ratio and net profit, respectively.

Efficiency of Androgenesis In Vitro in the Culture of Isolated Winter Wheat Anthers: 1. The Influence of the Duration of Low-Temperature Pretreatment of Donor Plants on Respiration, Carbohydrate Content, and ROS Levels in Flowers from Different Parts of the Spike

Efficiency of Androgenesis In Vitro in the Culture of Isolated Winter Wheat Anthers: 1. The Influence of the Duration of Low-Temperature Pretreatment of Donor Plants on Respiration, Carbohydrate Content, and ROS Levels in Flowers from Different Parts of the Spike

Efficiency of Androgenesis In Vitro in the Culture of Isolated Winter Wheat Anthers: 2. The Influence of the Duration of Low-Temperature Pretreatment of Donor Plants on the Content of Lipid Peroxidation Products and Fatty Acid Composition in Flowers from Different Parts of the Spike

Efficiency of Androgenesis In Vitro in the Culture of Isolated Winter Wheat Anthers: 2. The Influence of the Duration of Low-Temperature Pretreatment of Donor Plants on the Content of Lipid Peroxidation Products and Fatty Acid Composition in Flowers from Different Parts of the Spike

Combined ultrasound and low temperature pretreatment improve the content of anthocyanins, phenols and volatile substance of Merlot red wine

Ultrasound combined with low temperature treatment is a new food processing technology. In this study, low temperature, three ultrasound power levels, and their combinations were adopted in the must before fermentation to study their effects on Merlot red wine. The results showed that ultrasound combined with low temperature pretreatment increased the total and monomer contents of anthocyanins and phenols, affected the color of the wine, and significantly increased its antioxidant capacity. In particular, 240 W of ultrasound combined with low temperature pretreatment reduced the bad odors (caprylic acid, benzaldehyde, and 1-ethanol content) and improved the flower and fruit aroma (1-octanol and phenethyl acetate), as well as the aftertaste, thus improving the quality of the wine. Ultrasound combined with low temperature pretreatment positively affected the quality of Merlot red wine.

Low-temperature pretreatment by AlCl3-catalyzed 1,4-butanediol solution for producing ‘ideal’ lignin with super-high content of β-O-4 linkages

High contents of internal β-O-4 linkages in lignin are critical for high-yield production of high-value aromatic monomers by depolymerization. However, it remains great challenge due to lack of suitable protection strategy. In this work, a very effective lignin-first strategy was developed to produce ideal lignin with a super high content of β-O-4 linkages (up to 72 %) from poplar, in which the pretreatment was undertaken at low temperatures of 90–130 °C with the use of AlCl3-catalyzed 1, 4-butanediol solution. 2D-HSQC NMR spectra revealed that lignin β-O-4 linkages were protected from etherification of the OH group by 1, 4-butanediol at the α position of lignin aliphatic chains. Besides, the OH groups at the γ position of lignin was also etherified, leading the formation of a structure of Ph-CH=CHCH2O(CH2)4OH. Interestingly, structure protection facilitated the formation of lignin nanoparticles via self-assembly (<100 nm). In addition, it was observed from pyrolysis results that addition of 1, 4-butanediol remarkably protected the structure of lignin by avoiding condensation, promoting the production of aromatics. The cellulose-rich fraction possessed a high cellulose digestibility of 91.64 % by enzymatic hydrolysis at a cellulase dosage of 15 FPU/g cellulose, approximately 6-fold untreated poplar (15.91 %). This low-temperature lignin-first strategy was of great importance for multi-products biorefining lignocellulose because it leads to the production of both lignin with super high content of β-O-4 linkages for depolymerization and highly digestible cellulose for sugar production.

Reinvestigating the concurring reactions in early-stage cellulose pyrolysis by solution state NMR spectroscopy

Low temperature pre-treatments increase the char yield during cellulose carbonization. Although this effect is mostly understood on a kinetic basis, the formed chemical structures leave room for scrutiny. In ongoing ambitions to enhance the char yield of bioderived precursors, the thereby occurring chemistry was reinvestigated. A set of isothermal heating protocols ranging from 150° to 250°C was applied to man-made Ioncell® cellulose fibers and to Avicel® PH-101 microcrystalline cellulose. The prepared cellulosic samples were examined by solution state NMR using a tetra-n-butyl phosphonium acetate ([P4444][OAc]): DMSO-d6 (1:4 wt%) electrolyte as dissolving medium. Complementary, IR spectroscopy, size-exclusion chromatography (SEC) and thermogravimetric analysis coupled with mass spectroscopy (TGA-MS) measurements were performed. The NMR spectra evidenced the formation of levoglucosan end capped moieties as being the first and major occurring reaction during low temperature pre-treatments. In contrast to other mechanistic proposals, no signs for carbonyl or alkene functionalities were discernible in the cellulosic material soluble in the NMR electrolyte, even after treatment at 250 °C for several hours. Thermal cross-linking was observed in SEC already at temperatures not known to significantly influence the overall char yield. In the solution state analytics only partial solubility was observed, owing to the formation of a reluctant fraction previously described as “thermostable condensed phase”. This resulted in analytical blind spots and led to discrepancies between NMR results and FTIR spectra in which carbonyl and alkene vibrations were clearly discernible. Those discrepancies might also imply the co-existence of different fractions in the early stages of cellulose pyrolysis.

Biochemical assays of intensified methane content in biogas from low-temperature processing of waste activated sludge

Anaerobic digestion (AD) is implemented as an important ‘waste to energy’ approach for converting organic-rich byproducts such as sewage sludge into biogas and nutrient-rich digestate. Sewage sludge consists of primary sludge and waste activated sludge (WAS), and low biodegradability of WAS limits methane production. This study presents the influence of the low-temperature pretreatment (LT-PT) of WAS on the efficiency of AD. Different conditions of LT-PT process were tested in terms of temperature (45 °C/50 °C/55 °C/60 °C) and exposure time (24h/48h). LT-PT caused the increase of biomethane potential, which was even 43% higher if compared with the untreated WAS; 90% of all methane production was reached between 6 and 12 day of the LT-PT process. The highest improvements were observed in samples pretreated at 55 °C and 60 °C for 48 h (198.8 ± 5.5 NmL CH4/g VS and 194.3 ± 4.2 NmL CH4/g VS, respectively). Changes in the microbial community during LT-PT of WAS showed an oxygen-driven decrease among the predominant phyla except for Firmicutes. Taxonomic diversity and numerous rare taxa with the potential for functional compensation were observed. It was also proved that AD of pretreated WAS, combined with the heat recovery, achieved a positive net energy balance (improved by over 40%) and better energy performance, than AD without LT-PT.

Investigation of property of biochar in staged pyrolysis of cellulose

Pyrolysis involves heating of a feedstock from room temperature in an oxygen-deficient atmosphere, during which the heating at low temperature could potentially change the structure of feedstock and impacted the subsequent pyrolysis. In this study, the initial torrefaction of cellulose at 170, 260 and 350 °C and the subsequent pyrolysis at 600 °C was conducted, aiming to probe effect of the low-temperature pretreatment on evolution of the pyrolysis products, especially biochar. The results showed that the cellulose crystals could be partially destroyed at 260 °C and completely removed at 350 °C, and meanwhile aromatization reactions took place. This favored the formation of gases through further aromatization in the pyrolysis at 600 °C, but generated less light organics, especially for the pretreatment at 350 °C. The pretreatment at 260 °C, however, facilitated formation of anhydrate sugars and organics with π-conjugated structures. In addition, the torrefaction also enhanced the graphitization degree of biochar obtained at 600 °C through promoting the deoxygenation reactions, generating the biochar with higher C/O ratio, higher heating value, higher thermal stability and hydrophobicity. Besides, the torrefaction also significantly reduced formation of the reaction intermediates with aliphatic structures and the oxygen-containing functionalities such as -OH, CO and C-O-C in/on the biochar.

Integrated biorefinery of Mucor circinelloides biomass and sugarcane bagasse for application of high-value biopolymers

The replacement of expensive components in microbial growth media with pretreated lignocellulosic waste component to increase the product spectrum and add value to the bioproducts has been encouraged to achieve sustainable and feasible utilization of waste biomass as per the biorefinery approach. This study demonstrates an integrated biorefinery approach towards utilization of sugarcane bagasse and biomass of Mucor circinelloides ZSKP. A maximum reducing sugar recovery of 80.67 g/l was achieved after combining pretreatment with saccharification. A low temperature, glycerol, and ammonium phosphate pretreatment method was established, where glycerol pretreatment conditions were reduced from 250 to 150 °C and from 120 to 45 min. The ammonium phosphate-containing hydrolysate yielded 12.89 g/l of fungal biomass after fermentation to add to 20.8 g lignin from the delignification step. The biomass production was further improved to 17.69 g/l after supplementation with corn steep solids and mineral salts. The fermentation process also yielded 2.36 g/l chitosan and 4.9 g/l of lipids after extraction from the oleaginous fungus. The lignin infused glycerol plasticized chitosan biocomposite plastic had a 100% improvement in thermogravimetric properties with almost 50% more energy needed to increase the temperature of the material when compared to glycerol only plasticized biocomposite. The fungal chitosan showed antimicrobial properties and was effective as a preservative spray for fresh tomatoes and apples extending their shelf life to at least 14 and 18 days, respectively. This study therefore demonstrated that a novel two-step pretreatment process could be environmentally beneficial and yielded multiple products for biotechnological applications.

Agricultural residue lignin from novel low-temperature pretreatment as potential raw material for LPF resins

Agricultural residue lignin from novel low-temperature pretreatment as potential raw material for LPF resins

Modulation of stress factors for cryopreservation of Paracentrotus lividus (Lamarck 1816) larvae

In the present work we modulated two stress factors salinity and temperature, whose ranges have been previously determined by bioassays using six pre-treatments (18 °C-29.5‰; 18 °C-35‰; 18 °C-39‰ and 20 °C-29.5‰; 20 °C-35‰; 20 °C-39‰), in order to obtain a successful cryopreservation protocol for pluteus larvae of the sea urchin P. lividus (Lamarck 1816). Toxicity tests were performed with different cryoprotectants in a range of 0.5–3 M. Best results pointed out to METH and Me2SO as those more suitable for cryopreservation. First an exploratory cryopreservation experiment with Me2SO supplemented with 0.04 M trehalose (TRE) was tested following the protocol for cryopreservation of embryos (8-h blastula) of Bellas and Paredes, 2011, which did not give satisfactory results. A cryopreservation experiment was performed with both cryoprotectants supplemented with 0.04 M trehalose on 4-arm pluteus larvae (48 h-old) developed in these pre-treatment conditions, followed by a simpler and shorter protocol with a cooling rate of 1 °C/min to −35 °C, achieving for the first time the successful cryopreservation of P. lividus larvae. When larvae were incubated in low salinity or low temperature pre-treatments, they showed delayed larval development and abnormalities. In contrast, pretreatments with high temperature and salinity showed good results. Dimethyl sulfoxide with trehalose proved to be the only effective cryoprotectant for successful cryopreservation of P. lividus larvae. The success of dimethyl sulfoxide is consistent with that described for other cases in previous literature, where dimethyl sulfoxide, although not the least toxic compound, gave the best cryopreservation result.

'Green-to-Green': Iron oxides embedded in lignin-based carbon scaffolds for water remediation via oxidation excluding free-radical pathways.

Advanced oxidation processes (AOP) are a common tool to remove organic compounds from the water cycle. The process is mostly relied on free radicals (i.e., SO4•- and HO•) with high oxidation power in solution. Surface-mediated mechanism could improve this process to prevent undesired quenching of aqueous radicals that widely exists in free radical pathways and alleviate metal leaching through direct electron transfer. In this work, a facile low-temperature pre-treatment combined with pyrolytic strategy was employed to construct a green catalyst with iron oxides embedded in Kraft-lignin derived bio-char (γ-Fe2O3 @KC), upon which radicals stay surface mediated and the activity-stability trade-off is achieved for pollutant degradation. The γ-Fe2O3 @KC is capable of activating PMS to generate non-radical species which are more stable (1O2 and Fe(V)=O) and of enhancing electron transfer efficiency. A surface-bound reactive complex (Catalyst-PMS*) was identified by electrochemical characterization and was discussed with primary surface-bound radical pairs to explain the contradictions between quenching and EPR detection results. We analyzed the γ-Fe2O3 @KC as a PMS-activating catalyst for a wider range of oxidation targets, such as Rhodamine B (∼100%), p-nitrophenol (∼85%), and Ciprofloxacin (∼63%), and found competitive removal efficiencies. The system also shows an encouraging reusability for at least 5 times and high stability at pH 3-9, and the low concentration of iron in γ-Fe2O3 @KC/PMS system implies the carbon scaffold of biochar alleviate the leakage process. The combined findings highlight the applicability in 'green (source) to green (application)' processes using cost-effective and bio-friendly iron@carbon catalysts, where alternative oxidation pathways are activated to play a dominant role for water purification.

Long-lasting low temperature pretreatment of soybean seeds enhance plant field performance and content of free metabolites

Long-lasting low temperature pretreatment of soybean seeds enhance plant field performance and content of free metabolites

Bulb development in garlic – a review

ABSTRACT Many factors including cold conditioning, temperature, photoperiod, plant population, clove weight, soil nutrients, irrigation, plant growth regulators, and genetic responses influence bulb development in garlic. Garlic produces poor bulbs in warm and short-day conditions but cool and long-days induce flowering. Bulbs exposed before planting from 0° to 10°C for 8 weeks accelerate growth as the low temperatures modify the hormonal balance. Large cloves (>2–4 g) yield heavier bulbs than small (1–2 g) cloves. Plant population has an impact on bulb size: the higher the plant population, the smaller the bulb size. Garlic is sensitive to moisture stress especially during bulb initiation and development. Depending upon cultivar, soil type, and fertility status, NPK fertilisation for enhancement of bulb yield varies from 60–200, 20–75, and 40–166 kg ha−1, respectively. Low-temperature pre-treatment (4°C) increases salicylic acid (SA) concentration in the leaf sheath and enhances bulbing. Injecting garlic plants with gibberellin (GA3) solution increases clove number per bulb. Like onion, flowering and bulb formation in garlic are controlled by different (Flowering Locus T) FT genes. Two antagonistic FT-like genes regulate bulb formation. AsFT1 enhances bulb formation, while AsFT4 prevents AsFT1 up-regulation and inhibits bulbing.

Low-Temperature Pretreatment of Biomass for Enhancing Biogas Production: A Review

Low-temperature pretreatment (LTPT, Temp. &lt; 100 °C or 140 °C) has the advantages of low input, simplicity, and energy saving, which makes engineering easy to use for improving biogas production. However, compared with high-temperature pretreatment (&gt;150 °C) that can destroy recalcitrant polymerized matter in biomass, the action mechanism of heat treatment of biomass is unclear. Improving LTPT on biogas yield is often influenced by feedstock type, treatment temperature, exposure time, and fermentation conditions. Such as, even when belonging to the same algal biomass, the response to LTPT varies between species. Therefore, forming a unified method for LTPT to be applied in practice is difficult. This review focuses on the LTPT used in different biomass materials to improve anaerobic digestion performance, including food waste, sludge, animal manure, algae, straw, etc. It also discusses the challenge and cost issues faced during LTPT application according to the energy balance and proposes some proposals for economically promoting the implementation of LTPT.