Liquid Hot Water Research Articles

Comparative Study of Si−O−Al and Si−O−Si Bond Stability in HZSM‐5 Zeolite Under Steam and Hot Liquid Water Environments

AbstractUnderstanding the changes in the zeolite framework and catalytic active sites during zeolite‐based vapor‐phase and aqueous catalytic processes is crucial. Herein, the evolution of framework T atoms (Si and Al) in ammonium hexafluorosilicate (AHFS)‐treated HZSM‐5 zeolite under steam and hot liquid water (HLW) environments was inverstigated using various characterization techniques. In HLW, Si−O−Si bonds exhibit poorer hydrothermal stability than Si−O−Al bonds, in contrast to steam. Significant Si atom leaching occurs regardless of whether the framework tetrahedral Al atoms (Al(IV)‐1) are removed. Similar to steam, Al(IV)‐1 species in HLW sequentially evolve into partially coordinated framework Al species and then into extra‐framework Al (EFAL) species through partial and complete hydrolysis. The generated EFAL species act as Lewis acid sites, but their local structures or chemical environments may differ. These findings reveal the difference in the T−O−T bonds attacked by water molecules: the Si−O−Al bonds are primarily attacked in steam, whereas the Si−O−Si bond are primarily attacked in HLW.

The potential of using liquid hot water pretreated rice straw to produce environment friendly particleboard

The potential of using liquid hot water pretreated rice straw to produce environment friendly particleboard

Turning Data Center Waste Heat into Energy: A Guide to Organic Rankine Cycle System Design and Performance Evaluation

This study delves into the adoption of the organic Rankine cycle (ORC) for recovering waste heat from data centers (DCs). Through a literature review, it examines energy reuse with a focus on electric power generation, the selection of working fluids, and system design principles. The objective is to develop a thorough framework for system design and analysis, beginning with a quantity and quality investigation of waste heat available. Air cooling systems, chosen often for their simplicity, account for about 70% of used cooling methods. Water cooling demonstrates greater effectiveness, albeit less commonly adopted. This study pays close attention to the selection of potential working fluids, meticulously considering the limitations presented by the available sources of heat and cold for vaporization and condensation, respectively. It reviews an ORC-based system setup, incorporating fluid streams for internal processes. The research includes a conceptual case study where the system is designed and simulations are conducted in the DWSIM environment. The simulation model considers hot air or hot liquid water returning from the data center cooling system for ORC working fluid evaporation. Ambient water serves for condensing, with pentane and isopentane identified as suitable organic fluids. Pentane assures ORC net electric efficiencies ranging between 3.1 and 7.1% when operating pressure ratios increase from 2.8 to 6.4. Isopentane systems, meanwhile, achieve efficiencies of 3.6–7.0% across pressure ratios of 2.7–6.0. Furthermore, the investigation provides key performance indicators for a reference data center in terms of power usage effectiveness (PUE), energy reuse factor (ERF), energy reuse effectiveness (ERE), and greenhouse gas (GHG) savings. This study concludes with guidelines for system analysis, including exergy considerations, and details the sizing process for evaporators and condensers.

Enhanced bioethanol production from sugarcane bagasse: combination of liquid hot water and deep eutectic solvent pretreatment for optimized enzymatic saccharification

Enhanced bioethanol production from sugarcane bagasse: combination of liquid hot water and deep eutectic solvent pretreatment for optimized enzymatic saccharification

Thermodynamic analysis of a multiple energy production system based on geothermal energy for commissioning in Canada and optimization by response surface method (RSM)

The thermodynamic analysis of a geothermal-based integrated energy system to produce liquid hydrogen, cooling, hot water, and power was presented in this study. The investigated system consists geothermal subsystems, a modified organic Rankine cycle (ORC), a PEM electrolyzer, and a liquid hydrogen storage source. Different organic fluids including refrigerants R113, R123, and R134a were investigated to increase the system performance. Analysis of organic fluids showed that the best organic fluid is R123 because it helps to increase the performance of the system. The authors employed the Design-Expert software and RSM for optimum results purposes, and the objective functions were chosen to be exergy efficiency (EE) and cost rate (CR). Following introduction of design variables, the mass flow rate of input to the evaporator, the temperature of input to heat recovery vapor generator, turbine efficiency, turbine input temperature, evaporator pinch point temperature, and pump efficiency, their impact on the system's performance were investigated. The optimal values for EE and CR were ultimately found to be 43.91 % and 45.12 $/h, respectively. Also, in this research, seven regions within Canada were investigated for the launch of the proposed system. The studied cities were Victoria, Vancouver, Regina, St. John's, Dawson Creek, Whitehorse, and Port Alberni. Finally, Regina was chosen because of the system's superior performance in electricity production at a reasonable cost in that area. The environmental results showed that the presented energy system in Regina city could help to expand 5 ha of green space by producing electricity at the rate of 4993.03 MWh in one year. The findings indicated that implementing the suggested system in Regina would help prevent 1018.6 tons of CO2/MWh from being emitted into the environment yearly, only by chipping in 24445.9 $/ton of CO2 per year.

Use of scrap particleboard to produce recycled particleboard

Recycling is presently the most environmentally friendly approach that deals with wood waste. Each year a huge amount of particleboard completes its service life and needs to be disposed of or recycled. Scrap particleboard has the potential to be reused as raw material for particleboard production. A crucial step for producing particleboards using scrap particleboards is to break down urea-formaldehyde (UF) resins in the scrap particleboards to obtain separated particles. In this study, liquid hot water (LHW) pretreatment was employed to decompose the UF resins to detach and recover wood particles from the scrap particleboards. The recovered wood particles and fresh industrial wood particles in different proportions were used as the raw material for the particleboard. The physical and mechanical properties of the recycled particleboards were evaluated. The modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond (IB) of the recycled particleboards were lower than those of the particleboards made with fresh wood particles. However, the 2 h thickness swelling (TS) of the recycled particleboards was better than that of the fresh particleboards, indicating that the recycled particleboards were more dimensionally stable. The mechanical properties of the particleboards containing up to 40% recycled wood particles met the minimum Chinese National Standard requirements for general-purpose particleboards. Conclusively, scrap wood particleboards could be utilized as raw material in particleboard production.

Liquid Hot Water (LHW) and Hydrothermal Carbonization (HTC) of Coffee Berry Waste: Kinetics, Catalysis, and Optimization for the Synthesis of Platform Chemicals

Colombia is the world’s leading producer of mildly washed arabica coffee and produces 12.6 million bags of green coffee, but at the same time, 784,000 tons of waste biomass are dumped in open fields, of which only 5% is recovered or used. The objective of this project was to evaluate the production of platform chemicals from these coffee wastes for sustainable resource management. To achieve this, biomass characterization was carried out using proximate analysis, ultimate analysis, and structural analysis. Hydrothermal valorization was carried out at a temperature range of 120–180 °C (LHW) and 180–260 °C (HTC) for one hour. The platform chemicals obtained were quantified by HPLC-RI and monitored by pH and conductivity, and the solid fraction was characterized by monitoring the functional groups in IR spectroscopy and elemental analysis. Hydrolysis processes were obtained at 150 °C, production of platform chemicals at 180 °C, and maximum concentration at 180 °C-4 h; over 200 °C, degradation of the products in the liquid fraction starts to take place. Homogeneous basic and acid catalysts were used to improve the yields of the reaction. The kinetics of the hydrolysis of lignocellulosic structures to sugars were also analyzed and described, and reaction orders of 1 (LHW), 3 (HTC), and their respective reaction rate equations were reported.

Hydrothermal Valorization via Liquid Hot Water and Hydrothermal Carbonization of Pea Pod Waste: Characterization of the Biochar and Quantification of Platform Molecules

Pea pod cultivation spans various regions and climates, with a global production of around 20 million tons. The pea peel wastes, which make up 30–40% of the total weight of the peas, are freely available in large quantities. The biomass used was characterized via ultimate, proximate, and structural analysis, obtaining 20.2%w of cellulose and 17.4%w of hemicellulose, which, via valorization processes, can be transformed into platform chemicals. Hydrothermal valorization presents itself as a clean form of treatment for these wastes, ranging from 120 to 180 °C (LHW) and from 180 to 260 °C (HTC). The use of LHW can lead to the production of sugars (up to 70%w yield) and levulinic acid (4%w yield), while the use of HTC leads to formic acid (40%w yield) and levulinic acid (4%w yield). The use of LHW for longer periods favors the production of HMF and furfural. The use of homogeneous catalysts (H2SO4, CH3COOH, KOH, and NaHCO3) was implemented, and their selectivity was described. Solid fractions of LHW and HTC were characterized via FTIR and elemental analysis, and the change in their structure was described as they shifted from biomass to biochar. Optimal conditions for each platform chemical were reported to best utilize the pea pod waste.

Improving performance of bamboo fluff pulp by liquid hot water pretreatment and combination with longer fibers

Bamboo has several disadvantages as a raw material for the preparation of fluff pulp, including short fiber length, a high proportion of hemicellulose and high levels of fines and non-fibrous cells. Here, the proportion of hemicellulose was reduced by liquid hot water (LHW) pretreatment. The bamboo was then kraft cooked, screened through a 100 mesh screen plate to remove fines and non-fibrous cells, and bleached to prepare bamboo pulp fibers. Changes in the functional groups and crystallinity after LHW pretreatment were investigated by Fourier-transform infrared spectroscopy and X-ray diffraction. Analysis of the cross-sectional and surface morphology of the bamboo before and after pretreatment and of the surface morphology of the fluff pulp by field emission scanning electron microscopy showed that LHW pretreatment effectively removes hemicellulose from the bamboo. Combination of the bamboo pulp fibers with softwood fiber or cotton linter fiber produced a fluff pulp fiber with improved strength and water absorption. The new bamboo-cotton and bamboo-wood mixed fiber fluff pulps outperformed a branded commercial fluff pulp.

Bioconversion of spray corn husks into L-lactic acid with liquid hot water pretreatment

Agricultural by-products like rice husk, bran, and spray corn husks, often utilized as feed, are considered less desirable. This study aims to enhance the utilization rate of these materials by subjecting then to liquid hot water (LHW) pretreatment, followed by enzymatic hydrolysis to produce fermentable sugars. We investigated the production of L-lactic acid using two methods: simultaneous saccharification fermentation (SSF) and separate hydrolysis fermentation (SHF), following varying intensities of LHW pretreatment. The results showed that the optimal enzymatic hydrolysis efficiency was achieved from spray corn husks under the pretreatment conditions of 155 °C and 15 min. SHF was generally more effective than SSF. The glucose L-lactic acid conversion rate in SHF using spray corn husks can reach more than 90 %. Overall, this work proposed a novel, environmental-friendly strategy for efficient and for L- lactic acid production from spray corn husks.

Enhancement of Liquid Hot Water Pretreatment on Corn Stover with Ball Milling to Improve Total Sugar Yields

Conversion of the lignocellulosic biomass to bioethanol contributes to the reduction of greenhouse gas emissions, enhancement of energy security, utilization of waste materials, and the promotion of sustainable agricultural practices. In this study, we report the effect of combining ball milling followed by liquid hot water (LHW) pretreatment of corn stover to lower the amount of enzyme required while also greatly increasing the recovery of xylose in fermentable form compared to either pretreatment alone. Short-duration ball milling for 60 min reduces the particle size of corn stover to 37.3 μm; however, the glucose only increased to 47% compared to 32% for unpretreated corn stover. In contrast, liquid hot water pretreatment alone can achieve increasing enzyme hydrolysis yields of cellulose from 49% to 93% as the pretreatment severity factor is increased from 3.24 to 4.41. However, the xylose yield decreased to 36% due to the fact that a considerable part of the xylose was degraded into furfural and humins. Surprisingly, the combination of mild ball milling (30 min) followed by mild liquid hot water pretreatment (190 °C, 15 min) could achieve both high glucose (83%) and xylose (72%) yields for a total sugar yield of 79%, theoretically. Thus, combining ball milling with liquid hot water pretreatment allows for milder conditions for both processes that lead to enhanced cellulose conversion without sacrificing xylose to degradation, which hinders enzymatic hydrolysis.

Sustainable biorefinery development for valorizing all wastes from date palm agroindustry

This study examined how various residues from date palm agroindustrial can be utilized in a biorefinery platform to produce ethanol, methane, and lignin. Liquid hot water, ethanol organosolv, and catalyzed ethanol organosolv (CEO) pretreatments were applied to trunk, leaves, leaf sheath, pedicels, date cake, and seeds. The process included extracting lignin from the liquid fraction, followed by converting the pretreated solid material into ethanol. The fermentation residues were also utilized to produce biomethane through anaerobic digestion. Two different scenarios were employed for the biorefining, i.e., (Ⅰ) maximum lignin production and (Ⅱ) maximum biofuel production. The best results for the first scenario were obtained when CEO was employed in the pretreatment of date palm wastes, where 806.9 mL ethanol, 902.8 L methane, and 528.0 g lignin were produced from each kg of each residue. In energetic terms, the biofuel products (i.e., ethanol and methane) were determined to have a combined energy content equivalent to 1553.1 mL of gasoline. Likewise, the most favorable outcomes of the second scenario were obtained by incorporating CEO pretreatment of trunk, leaf sheath, leaves, and pedicels in the valorization of untreated date cake and seeds. Furthermore, for the second scenario, the resulting products were 967.5 mL ethanol, 1605.3 L methane, and 341.0 g lignin, with the biofuel products having a combined energetic content equivalent to 2452.0 mL of gasoline. These findings indicate that the biorefining of date palm agroindustrial wastes has significant potential for bioenergy production.

Ocimum Gratissimum essential oil: A review of extraction methods, phytochemical constituents, pharmacological uses and formulation approaches

Ocimum gratissimum is a plant native to Africa. Its leaves have been used in local dishes over the years, with documented evidence of varying pharmacological uses of its essential oil. This review focuses on the extraction methods, phytochemical constituents, pharmacological uses and formulation approaches of Ocimum gratissimum essential oil. The traditional extraction methods that have been widely used include the solvent, cold press and hydrodistillation methods. However, newer methods such as steam distillation, ultrasound and microwave assisted hydrodistillation, supercritical fluid extraction, pressurized liquid extraction and pressurized hot water extraction methods have not been fully reported. These methods provide more yield of the essential oil compared with the traditional methods and their processes are less laborious. Furthermore, they are often limited to analytical applications as they cannot handle large quantities of samples. The phytochemical constituents of Ocimum gratissimum essential oil vary, based on location of the plant and the time of the season the plant parts were harvested for extraction. The African species have more thymol than eugenol. Other notable constituents are saponins, terpenes and flavonoids in both African species and others. The essential oil of Ocimum gratissimum bears the scent of the plant and other important properties such as protection of the plant from pests and to attract insects for cross-pollination. The essential oil of this plant has been noted to possess various pharmacological properties which explains its use in inflammatory conditions and the treatment of diarrhoeal disease, wound healing and cerebrovascular disorder, amongst others. The essential oil of Ocimum gratissimum has been embedded in gels, cream, silver nanoparticles and nanoemulsion to improve its pharmacological activity and bioavailability. This review article highlights the potentials of the essential oil of this ubiquitous plant as a therapeutic source for the treatment of different tropical diseases.

Geospatial environmental techno-economic assessment of pretreatment technologies for bioethanol production

Second-generation biofuels, starting from lignocellulosic biomass, are considered as a renewable alternative for fossil fuels with lower environmental impact and potentially higher supply and energy security. The economic and environmental performance of second-generation bioethanol production from corn stover in the European Union (EU) is studied, starting in Belgium as base case. A comparative environmental techno-economic assessment has been conducted, with process simulations in Aspen Plus and corn stover availability data in thirteen EU countries to calculate minimum ethanol selling prices (MESP) and Greenhouse gas emissions (GHGe). In this analysis, the emphasis is on the comparison of different pretreatment technologies, namely (i) dilute acid, (ii) alkaline, (iii) steam explosion and (iv) liquid hot water. Dilute acid showed the best economic and environmental performance for the base case scenario. Within the EU, Hungary and Romania presented the lowest MESP for the steam explosion model at 0.39 and 0.43 EUR/L respectively. Poland showed the lowest GHGe, at 0.46 kg CO2eq/L for the alkaline model, mainly due to the avoided product allocation on electricity and its high carbon intensity in the electricity generation sector. The second lowest GHGe were obtained in France for the dilute acid model and are attributed to its low agricultural emissions intensity. This study identifies a location-dependence of the economic and environmental performance of pretreatment technologies, which can be extrapolated from the EU to other large regions around the world and should be taken into consideration by decision-makers.

Bioconversion of cellulose and hemicellulose in corn cob into L-lactic acid and xylo-oligosaccharides

With the banning of antibiotic chemical feed additives, multi-functional bioactive feed additives have been extensively sought after by the feed industry. In this study, low-cost and renewable corn cobs were treated with liquid hot water and converted into bioactive xylo-oligosaccharides and L-lactic acid after enzymatic hydrolysis, strain activation, and fermentation under mild conditions, which achieved a full utilization of cellulose and hemicellulose in corn cobs. Simultaneous saccharification fermentation after strain activation with enzymatic hydrolysate delivered the highest conversion rate of glucose to L-lactic acid (93.00 %) and yielded 17.38 g/L L-lactic acid and 2.68 g/L xylo-oligosaccharides. On this basis, batch-feeding fermentation resulted in a 78.03 % conversion rate of glucose to L-lactic acid, 18.99 g/L L-lactic acid, and 2.84 g/L xylo-oligosaccharides. This work not only provided a green and clean bioconversion strategy to produce multi-functional feed additives but can also boost the full utilization of renewable and cheap biomass resources.

Turning waste into value: eco‐efficient recovery of by‐products from biomass pretreatment in lignocellulosic biorefineries

AbstractThis original research contributes to enhancing the viability of biorefineries through recovering valuable by‐products from the liquid remaining after the biomass pretreatment by hot liquid water. A novel downstream processing method is developed for the recovery of acetic acid, formic acid, furfural and 5‐hydroxymethylfurfural (HMF) by enhanced distillation. The major challenge in this research is the processing of the highly diluted initial solution (>96 wt% water) and the thermodynamic limitations owing to possible formation of several azeotropes. This new process recovers 78.7% of the acetic acid (99.8 wt%), while the rest of it is recycled back to the biomass pretreatment step together with most of the separated water from the initial solution. Over 99.5% of formic acid, furfural and HMF is also recovered, at purities of 74.7, 98.0 and 100 wt%, respectively. Vapor recompression and heat integration are implemented to decrease the energy use. The results demonstrate a 77.4% decrease in total annual costs (from $3.44 to 0.78/kgproduct), a 75.0% reduction in minimum average selling price (from $3.50 to 0.87/kgproduct), an 81.1% reduction in energy requirements (from 77.41 to 14.66 kWthh/kgproduct) and an up to 99.7% decrease in CO2 emissions (from 11.17 to 0.03 kgCO2/kgproduct).

Integrating surfactants with low enzyme loading to increase the glucan conversion and ethanol concentration of reed after combined pretreatment

In this study, in order to obtain high concentration bioethanol, reed pretreated with liquid hot water and ammonia oxygen (LHW-NH3·H2O/O2) was used as the substrate for fermentation. Enzymatic hydrolysis becomes difficult by the ineffective lignin adsorption and the decline in cellulase activity. It is worth noting that even under low enzyme loading (9 FPU/g pretreated solid), this study was able to maintain a higher glucan conversion rate (97.60%). In addition, under high solid loading conditions, the combined effect of PEG 6000 and rhamnolipids increased ethanol yield (78.40%) and ethanol concentration (71.5 g/L). The combined LHW-NH3·H2O/O2 pretreatment with fed-batch semi-simultaneous saccharification and fermentation technique may be utilized to industrialize the production of bioethanol from reed since we concentrated on the maximum exploitation of biomass resources and reduction in energy consumption.

Optimizing monosaccharide production from liquid hot water pretreatment and enzymatic hydrolysis of grass-clover press cake

In the present study, clover-grass press cake was treated by liquid hot water at temperatures of 180–200 °C for a reaction time of 5–10 min. Evaluation of pretreatments was based on the monosaccharide yield after enzymatic hydrolysis of the pretreated slurry and solid fraction, respectively. Extraction of up to 48% hemicellulose and 4% cellulose was observed during pretreatment. The optimal pretreatment conditions were identified as 190 °C and 10 min resulting in monosaccharide yields of 90% and 73% of the theoretical maximum by slurry and solid conversion, respectively. At optimal conditions, the C6 monosaccharide yield (83–90%) was fairly equal compared to the C5 monosaccharide yield (56–89%), which increased by slurry conversion due to near-complete monomerization of soluble xylo-oligosaccharides. In this study, we showed that clover-grass press cake possesses considerable potential as feedstock for production of fermentable sugars in a biorefinery context.

The potential of walnut shells for production of oligosaccharides by liquid hot water treatment

The potential of walnut shells for production of oligosaccharides by liquid hot water treatment

Detoxification of high solid-liquid hydrothermal pretreated sugar cane bagasse by chromatographic adsorption for cellulosic ethanol production

The conversion of sugar cane bagasse (SCB) into cellulosic ethanol by microorganism becomes challenging at high solid liquid ratio (SLR) due to high concentration of inhibitors in the liquid hot water pretreatment. Therefore, this study aims to produce cellulosic ethanol by detoxifying the high SLR hydrolysate (1:6, w/v) using SY-01 resin. The detoxification effects of SY-01 resin dosage and adsorption modes were systematically investigated. The resulting detoxified hydrolysate was successfully fermented, and the highest ethanol concentration achieved was 30.94 ± 0.13 g/L. Additionally, the ethanol yield was 102.51 ± 0.94%, and the ethanol production from SCB was 210 ± 1 mg/g SCB. Our findings confirm that SY-01 resin is effective in detoxifying lignocellulosic enzymatic hydrolysate, providing an economical and feasible method for the high-value utilization of biomass resources.