Enhanced Enzymatic Sugar Recovery of Dilute-Acid-Pretreated Corn Stover by Sodium Carbonate Deacetylation.

The prehydrolysate from dilute acid pretreatment of lignocellulosic feedstocks often contains inhibitory compounds that can seriously inhibit the subsequent enzymatic and fermentation processes. Acetic acid is one of the most representative toxic compounds. In this research, alkaline deacetylation of corn stover was carried out using sodium carbonate under mild conditions to selectively remove the acetyl groups of the biomass and reduce the toxicity of the prehydrolysate. The deacetylation process was optimized by adjusting factors such as temperature, treatment time, and sodium carbonate concentration. Sodium carbonate solutions (2~6 wt%) at 30~50 °C were used for the deacetylation step, followed by dilute acid pretreatment with 1.5% H2SO4 at 121 °C. Results showed that the acetyl content of the treated corn stover could be reduced up to 87%, while the hemicellulose loss remained low. The optimal deacetylation condition was found to be 40 °C, 6 h, and 4 wt% Na2CO3, resulting in a removal of 80.55% of the acetyl group in corn stover and a hemicellulose loss of 4.09%. The acetic acid concentration in the acid prehydrolysate decreased from 1.38 to 0.34 g/L. The enzymatic hydrolysis of solid corn stover and the whole slurry after pretreatment increased by 17% and 16%, respectively.

The solar end game: bibliometric analysis, research and development evolution, and patent activity of hybrid photovoltaic/thermal-phase change material.

Solar photovoltaic-thermal hybrid with phase change material (PVT-PCM) emerges as an intelligent game changer to stimulate the clean, reliable, and affordable renewable energy technology. This PVT-PCM technology can be manipulated into generating both electricity and thermal energy that feature its practicality for residential and industrial applications. Hybridized of PCM into PVT design adds value to existing architecture with its capability to store excess heat that can be used during insufficient solar irradiation. Present work gives overview of the PVT-PCM system on technology innovation toward commercialization (viz, solar end game) subjected to bibliometric analysis, research and development evolution, and patent activity. A consolidation of these review articles was decluttered to focus on the performance and efficiency of PVT-PCM technology based on the fact that commercialization is ready once the technology is completed and qualified (at technology readiness level, TRL: 8). Economic review was conducted to understand the feasibility of the existing solar technologies and how it affects the PVT-PCM market price. Based on the contemporary findings, promising performance of PVT-PCM technology has underpinned its feasibility and technology readiness. China has predominant local and international framework and expected to be the PVT-PCM technology trendsetter in the next years through its strong international collaborative projects and pioneer in PVT-PCM patent filing. This present work underscores the solar end-game strategy and recommendation to create a path forward to achieve clean energy transition. Though, as to the date of submission of this article, no industry  has found to manufacture/sell this hybrid technology in the market.

Prediction model for biochar energy potential based on biomass properties and pyrolysis conditions derived from rough set machine learning.

Biochar is a high-carbon-content organic compound that has potential applications in the field of energy storage and conversion. It can be produced from a variety of biomass feedstocks such as plant-based, animal-based, and municipal waste at different pyrolysis conditions. However, it is difficult to produce biochar on a large scale if the relationship between the type of biomass, operating conditions, and biochar properties is not understood well. Hence, the use of machine learning-based data analysis is necessary to find the relationship between biochar production parameters and feedstock properties with biochar energy properties. In this work, a rough set-based machine learning (RSML) approach has been applied to generate decision rules and classify biochar properties. The conditional attributes were biomass properties (volatile matter, fixed carbon, ash content, carbon, hydrogen, nitrogen, and oxygen) and pyrolysis conditions (operating temperature, heating rate residence time), while the decision attributes considered were yield, carbon content, and higher heating values. The rules generated were tested against a set of validation data and evaluated for their scientific coherency. Based on the decision rules generated, biomass with ash content of 11-14 wt%, volatile matter of 60-62 wt% and carbon content of 42-45.3 wt% can generate biochar with promising yield, carbon content and higher heating value via a pyrolysis process at an operating temperature of 425°C-475°C. This work provided the optimal biomass feedstock properties and pyrolysis conditions for biochar production with high mass and energy yield.

Physicochemical analysis and intermediate pyrolysis of Bambara Groundnut Shell (BGS), Sweet Sorghum Stalk (SSS), and Shea Nutshell (SNS).

ABSTRACTThe current work focused on the intermediate pyrolysis of Bambara Groundnut Shells (BGS-G1), Sweet Sorghum Stalk (SSS), and Shea Nutshells (SNS). These feedstocks are readily available as wastes or by-products from industrial and agricultural activities. The thermo-gravimetric analysis of the biomass samples exhibited decomposition and devolatilization potentials in the temperature range of 110-650°C. The kinetic modelling resulted in the activation energy of BGS G1 being the lowest as 20.43 kJ/mol and SNS as the highest 24.89 kJ/mol among the three biomass samples. Intermediate pyrolysis was conducted in a vertical tube reactor at a temperature of 600°C, with nitrogen flow at 10 ml/min and heating rate ≥ 33.0℃/min. The yield of pyrolysis bio-oil was 38.0 ± 6.4, 44.2 ± 6, and 39.7 ± 5.2 wt.% for BGS-G1, SSS, and SNS, respectively. The HHV of bio-oil varied as 23.7 ± 1.8, 23.8 ± 1.8, to 26.5 ± 2.0 MJ/kg for BGS-G1 SSS and SNS respectively. The biochar recorded the lowest HHV for BGS-G1 as 18.8 ± 1.2 MJ/kg and the highest for SNS as 26.4 ± 1.8 MJ/kg. The FTIR of bio-oil revealed significant functional groups, and GC-MS (Gas Chromatography and Mass Spectrometry) analysis categorized the compounds in bio-oils as ketones, furans, phenolics, acids, phenols and benzene derivatives. The physicochemical analysis of the feedstocks and the products (bio-oil and biochar) showed their potential for bioenergy and biochemical (green chemicals) production.

Synthesis of a highly recoverable 3D MnO2/rGO hybrid aerogel for efficient adsorptive separation of pharmaceutical residue.

Water contamination by non-steroidal anti-inflammatory drugs, such as acetaminophen, is an emerging ecological concern. In this study, a new three-dimensional manganese dioxide-engrafted reduced graphene oxide (3D MnO2/rGO) hybrid aerogel was developed for acetaminophen sequestration. The synthesis involved firstly the self-assembly of GO aerogel, followed by thermal reduction and in-situ MnO2 growth by redox-reaction. The aerogel demonstrated interlinked planes with smooth surfaces deposited with MnO2 nanospheres and pores of 138.4 - 235.3 µm width. The influences of adsorbent dosage, initial pH, acetaminophen concentration, temperature and contact time were investigated. It was determined that the adsorption of acetaminophen occurred on uniform sorption sites in the aerogel, as suggested by the best fit of data to the Langmuir isotherm, yielding a maximum adsorption capacity of 252.87 mg/g. This highest adsorption performance of the 3D MnO2/rGO aerogel was attained at a dosage of 0.6 g/L, initial pH of 6.2 and temperature of 40°C. The process kinetics were in-line with the pseudo-first-order and pseudo-second-order kinetics at 10 and 20 - 500 mg/L concentrations, respectively. Thermodynamic assay showed the spontaneity and endothermicity features of the 3D MnO2/rGO-acetaminophen system. The acetaminophen adsorption mechanisms were mainly hydrogen bonding and pore entrapment. Moreover, the as-synthesised aerogel was effectively regenerated using acetone and re-utilised in four adsorption-desorption cycles. Overall, the results highly recommend the implementation of the 3D MnO2/rGO hybrid aerogel for purification of wastewater polluted by acetaminophen residue.

Utilisation of environmentally friendly okara-based biosorbent for cadmium(II) removal.

Heavy metals released by various industries are among the major pollutants found in water resources. In this research, biosorption technique was employed to remove cadmium (Cd2+) from an aqueous system using a novel biosorbent developed from okara waste (OW), a residue from soya bean-based food and beverage processing. Characterisation results revealed that the OW biosorbent contained functional groups such as hydroxyl-, carboxyl- and sulphur-based functional groups, and the surface of the biosorbent was rough with multiple fissures which might be the binding sites for the pollutant. The effects of dosage, solution pH, initial Cd2+ concentration, temperature and contact time were investigated using batch adsorption mode. The biosorption equilibrium and kinetic were best described by the Langmuir and Elovich models, respectively. The maximum biosorption capacities predicted by the Langmuir model were 10.91-14.80 mg/g at 30-70 °C, and the biosorption process was favourable as evident from 0 < RL < 1. The uptake of Cd2+ by the OW biosorbent was spontaneous and endothermic. The plausible biosorption mechanisms of this study could be ionic exchange, hydrogen bonding and electrostatic interactions. The Cd2+ loaded OW biosorbent could be regenerated using 0.4 M of HCl solution and regeneration was studied for 4 adsorption-desorption cycles. The present investigation supported that OW can be reused as a value-added biosorbent product for the removal of Cd2+ from the contaminated water.

Facile synthesis of xanthan biopolymer integrated 3D hierarchical graphene oxide/titanium dioxide composite for adsorptive lead removal in wastewater.

Xanthan integrated graphene oxide functionalized by titanium dioxide was successfully prepared through facile, eco-friendly and cost effective ice-templating technique. The three-dimensional (3D) graphene composite demonstrated relatively high temperature stability, chemical functionalities and porous sponge-like structure. The adsorption of lead was favored by high initial concentration and shaking speed at the operational solution pH. The process equilibrium and kinetic adhered to the Langmuir and pseudo-second-order correlations, respectively. The biomass integrated graphene composite showed maximum adsorption capacities ranging from 132.18 to 199.22 mg/g for 30-70 °C. Moreover, it was highly regenerable under mild conditions (0.1 M hydrochloric acid, 30 °C) and used repeatedly while retaining 84.78% of its initial adsorption capacity at the fifth adsorption-regeneration cycle. With comparatively high lead adsorption capacities, adequate recyclability and environmentally friendliness, the as-prepared 3D graphene composite has high application potential in heavy metal-wastewater separation for protection of the environment and human health.

Effect of oxide catalysts on the properties of bio-oil from in-situ catalytic pyrolysis of palm empty fruit bunch fiber.

Fast pyrolysis is a potential technology for converting lignocellulosic biomass into bio-oil. Nevertheless, the high amounts of acid, oxygenated compounds, and water content diminish the energy density of the bio-oil and cause it to be unsuitable for direct usage. Catalytic fast pyrolysis (CFP) is able to improve bio-oil properties so that downstream upgrading processes can be economically feasible. Here, calcium oxide (CaO), magnesium oxide (MgO), and zinc oxide (ZnO) were employed due to their potential in enhancing bio-oil properties. The results showed that overall, all three catalysts positively impacted the empty fruit bunch fibre-derived bio-oil properties. Among the catalysts, CaO showed the most favorable effects in terms of reducing the acidity of the bio-oil and anhydrosugar. Thermal stability of bio-oils produced in the presence of CaO was studied as well.

Environmental application of three-dimensional graphene materials as adsorbents for dyes and heavy metals: Review on ice-templating method and adsorption mechanisms.

The remediation of wastewater requires treatment technologies which are robust, efficient, simple to operate and affordable such as adsorption. Lately, three-dimensional (3D) graphene based materials have attracted significant attention as effective adsorbents for wastewater treatment. The intrinsic properties of 3D graphene structure such as large surface area and interconnected porous structure can facilitate the transport of pollutants into the 3D network and provide abundant active sites for trapping the pollutants. For the synthesis of 3D graphene structure, ice-templating is commonly practiced due to its facile steps, cost effectiveness and high scalability potential. This review covers the ice-templating fabrication technique for 3D graphene based materials and their application as adsorbents in eliminating dyes and heavy metals from aqueous media. The assembly mechanisms of the ice-templating fsynthesis are comprehensively discussed. Further discussion on the fundamental principles, critical process parameters and characteristics of ice-templated 3D graphene structures is also included. A thorough review on the mechanisms for batch adsorption of dyes and heavy metals is presented based on the structures and properties of the 3D graphene materials. The review further evaluates the dynamic adsorption in packed columns and the regeneration of 3D graphene based materials.

Ice-templated graphene oxide/chitosan aerogel as an effective adsorbent for sequestration of metanil yellow dye.

Graphene oxide/chitosan aerogel (GOCA) was prepared by a facile ice-templating technique without using any cross-linking reagent for metanil yellow dye sequestration. The adsorption performance of GOCA was investigated by varying the adsorbent mass, shaking speed, initial pH, contact time, concentration and temperature. The combined effects of adsorption parameters and the optimum conditions for dye removal were determined by response surface methodology. GOCA exhibited large removal efficiencies (91.5-96.4%) over a wide pH range (3-8) and a high adsorption capacity of 430.99 mg/g at 8 mg adsorbent mass, 400 mg/L concentration, 35.19 min contact time and 175 rpm shaking speed. The adsorption equilibrium was best represented by the Langmuir model. GOCA could be easily separated after adsorption and regenerated for re-use in 5 adsorption-desorption cycles thereby maintaining 80% of its adsorption capability. The relatively high adsorption and regeneration capabilities of GOCA render it an attractive adsorbent for treatment of azo dye-polluted water.

Adsorptive decontamination of diclofenac by three-dimensional graphene-based adsorbent: Response surface methodology, adsorption equilibrium, kinetic and thermodynamic studies.

Pharmaceutical residues are emerging pollutants in the aquatic environment and their removal by conventional wastewater treatment methods has proven to be ineffective. This research aimed to develop a three-dimensional reduced graphene oxide aerogel (rGOA) for the removal of diclofenac in aqueous solution. The preparation of rGOA involved facile self-assembly of graphene oxide under a reductive environment of L-ascorbic acid. Characterisation of rGOA was performed by Fourier transform infrared, scanning electron microscope, transmission electron microscopy, nitrogen adsorption-desorption, Raman spectroscopy and X-ray diffraction. The developed rGOA had a measured density of 20.39 ±â€¯5.28 mg/cm3, specific surface area of 132.19 m2/g, cumulative pore volume of 0.5388 cm3/g and point of zero charge of 6.3. A study on the simultaneous interactions of independent factors by response surface methodology suggested dosage and initial concentration as the dominant parameters influencing the adsorption of diclofenac. The highest diclofenac adsorption capacity (596.71 mg/g) was achieved at the optimum conditions of 0.25 g/L dosage, 325 mg/L initial concentration, 200 rpm shaking speed and 30 °C temperature. The adsorption equilibrium data were best fitted to the Freundlich model with correlation coefficient (R2) varying from 0.9500 to 0.9802. The adsorption kinetic data were best correlated to the pseudo-first-order model with R2 ranging from 0.8467 to 0.9621. Thermodynamic analysis showed that the process was spontaneous (∆G = - 7.19 to - 0.48 kJ/mol) and exothermic (∆H = - 12.82 to - 2.17 kJ/mol). This research concluded that rGOA is a very promising adsorbent for the remediation of water polluted by diclofenac.

Multistage optimizations of slow pyrolysis synthesis of biochar from palm oil sludge for adsorption of lead.

This research investigated the removal of lead (Pb2+) by a novel biochar derived from palm oil sludge (POS-char) by slow pyrolysis. Multistage optimizations with central composite design were carried out to firstly optimize pyrolysis parameters to produce the best POS-char for Pb2+ removal and secondly to optimize adsorption conditions for the highest removal of Pb2+. The optimum pyrolysis parameters were nitrogen flowrateof30mLmin-1, heating rateof10°Cmin-1, temperatureof500°C and timeof30min. The optimum Pb2+ adsorption conditions were concentrationof200mgL-1, timeof60min, dosageof0.3g and pH of 3.02. The various functional groups within POS-char played a vital role in Pb2+ uptake. Regeneration was demonstrated to be feasible using hydrochloric acid. Adsorption equilibrium was best described by Freundlich model. At low concentration range, adsorption kinetic obeyed pseudo-first-order model, but at high concentration range, it followed pseudo-second-order model. Overall, the results highlighted that POS-char is an effective adsorbent for Pb2+ removal.

Assessment of fish scales waste as a low cost and eco-friendly adsorbent for removal of an azo dye: Equilibrium, kinetic and thermodynamic studies.

In this study, AB113 dye was successfully sequestered using a novel adsorbent made of mixed fish scales (MFS). The influence of adsorbent dosage, initial pH, temperature, initial concentration and contact time on the adsorption performance was investigated. The surface chemistry and morphology of the adsorbent were examined by FTIR, TGA and SEM. Amides, phosphate and carbonate groups were evidently responsible for the high affinity of MFS towards the dye. The adsorption equilibrium and kinetic were well described by Langmuir and pseudo-second-order models, respectively. The maximum adsorption capacities of MFS were 145.3-157.3mg/g at 30-50°C. The adsorption of AB113 dye onto the adsorbent was exothermic and spontaneous as reflected by the negative enthalpy and Gibbs energy changes. The results support MFS asa potential adsorbent for AB113 dye removal.

Biochar potential evaluation of palm oil wastes through slow pyrolysis: Thermochemical characterization and pyrolytic kinetic studies.

This research investigated the potential of palm kernel shell (PKS), empty fruit bunch (EFB) and palm oil sludge (POS), abundantly available agricultural wastes, as feedstock for biochar production by slow pyrolysis (50mLmin-1 N2 at 500°C). Various characterization tests were performed to establish the thermochemical properties of the feedstocks and obtained biochars. PKS and EFB had higher lignin, volatiles, carbon and HHV, and lower ash than POS. The thermochemical conversion had enhanced the biofuel quality of PKS-char and EFB-char exhibiting increased HHV (26.18-27.50MJkg-1) and fixed carbon (53.78-59.92%), and decreased moisture (1.03-2.26%). The kinetics of pyrolysis were evaluated by thermogravimetry at different heating rates (10-40°C). The activation energies determined by Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models were similar, and comparable with literature data. The findings implied that PKS and EFB are very promising sources for biochars synthesis, and the obtained chars possessed significant biofuel potential.

Utilization of palm oil sludge through pyrolysis for bio-oil and bio-char production.

In this study, pyrolysis technique was utilized for converting palm oil sludge to value added materials: bio-oil (liquid fuel) and bio-char (soil amendment). The bio-oil yield obtained was 27.4±1.7 wt.% having a heating value of 22.2±3.7 MJ/kg and a negligible ash content of 0.23±0.01 wt.%. The pH of bio-oil was in alkaline region. The bio-char yielded 49.9±0.3 wt.%, which was further investigated for sorption efficiency by adsorbing metal (Cd(2+) ions) from water. The removal efficiency of Cd(2+) was 89.4±2%, which was almost similar to the removal efficiency of a commercial activated carbon. The adsorption isotherm was well described by Langmuir model. Therefore, pyrolysis is proved as an efficient tool for palm oil sludge management, where the waste was converted into valuable products.

Catalytic pyrolysis of green algae for hydrocarbon production using H+ZSM-5 catalyst.

Microalgae are considered as an intriguing candidate for biofuel production due to their high biomass yield. Studies on bio-oil production through fast pyrolysis and upgrading to hydrocarbon fuels using algal biomass are limited as compared to other terrestrial biomass. Therefore, in this study, a fresh water green alga, Chlorella vulgaris, was taken for pyrolysis study. The average activation energy for pyrolysis zone was found to be 109.1 kJ/mol. Fixed-bed pyrolysis of algae gave a bio-oil yield of 52.7 wt.%, which accounts for 60.7 wt.% carbon yield. In addition, analytical pyrolysis of C. vulgaris was carried out in a Py/GC-MS to identify major compounds present in bio-oil with and without catalyst (H(+)ZSM-5). The study found that in catalytic-pyrolysis, as the catalyst loading increased from zero to nine times of the biomass, the carbon yield of aromatic hydrocarbons increased from 0.9 to 25.8 wt.%.

Production of hydrocarbon fuels from biomass using catalytic pyrolysis under helium and hydrogen environments.

This study is focused on hydrocarbon production through changing carrier gas and using zeolite catalysts during pyrolysis. A large reduction in high molecular weight, oxygenated compounds was noticed when the carrier gas was changed from helium to hydrogen during pyrolysis. A catalytic pyrolysis was conducted using two different methods based on how the biomass and catalysts were contacted together. For both methods, there was no significant change in the carbon yield with the change in pyrolysis environment. However, the mixing-method produced higher aromatic hydrocarbons than the bed-method. In addition, two methods were also tested using two ratios of biomass to catalyst. Nonetheless, there was no significant increase in hydrocarbon yield as the catalyst loading was increased from two to five times of biomass in the catalyst-bed method. In contrast to this, a significant increase was noticed for the catalytic-mixing method when the biomass to catalyst loading was increased from 1:4 to 1:9.

Physiochemical properties of bio-oil produced at various temperatures from pine wood using an auger reactor.

A fast pyrolysis process produces a high yield of liquid (a.k.a. bio-oil) and has gained a lot of interest among various stakeholders. Nonetheless, some of the properties inherent by the bio-oil create significant challenges for its wider applications. Quality of the bio-oil and its yield are highly dependent on process parameters, such as temperature, feedstock, moisture content and residence time. In this study, the effect of temperature on bio-oil quality and its yield were examined using pine wood, an abundant biomass source in the southeastern part of the United States. Physical properties of bio-oil such as pH, water content, higher heating value, solid content and ash were analyzed and compared with a recently published ASTM standard. Bio-oil produced from pine wood using an auger reactor met specifications suggested by the ASTM standard. Thirty-two chemical compounds were analyzed. The study found that the concentration of phenol and its derivatives increased with the increase in pyrolysis temperature whereas the concentration of guaiacol and its derivatives decreased as the temperature increased. Concentration of acetic and other acids remained almost constant or increased with the increase in temperature although the pH value of the bio-oil decreased with the increase in temperature.