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A novel thermochemical conversion route has been developed that yields 5-hydroxymethylfurfural (HMF) from food waste biomass (FWB) in the presence of a heterogeneous catalysts (zirconium phosphate (ZrP)). The ZrP catalyst was prepared by precipitation followed by calcination at 400 (ZrP-400) and 600 °C (ZrP-600) and was characterized by SEM, XRD, XPS, N2 sorption and NH3-TPD. The optimized reaction conditions were identified to maximize HMF yield by varying the type of catalyst, the catalyst loading and the reaction time. The highest HMF yield achieved was 4.3%. On average 33% higher yield for ZrP-600 was obtained compared to that for ZrP-400, which might be due to higher number of acid sites on ZrP-600. The ZrP catalyst was easily regenerated by thermal treatment and showed stable activity upon its reuse. Preliminary calculations of the "minimum selling price" of HMF suggest that it is economically attractive to make this industrially-relevant chemical from FWB., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In this study, thermal characteristics of raw biomass, corresponding pyrolytic biochars and their blends with lignite were investigated. The results showed that pyrolytic biochars had better fuel qualities than their parent biomass. In comparison to raw biomass, the combustion of the biochars shifted towards higher temperature and occurred at continuous temperature zones. The biochar addition in lignite increased the reactivities of the blends. Obvious interactions were observed between biomass/biochar and lignite and resulted in increased total burnout, shortened combustion time and increased maximum weight loss rate, indicating increased combustion efficiencies than that of lignite combustion alone. Regarding ash-related problems, the tendency to form slagging and fouling increased, when pyrolytic biochars were co-combusted with coal. This present study demonstrated that the pyrolytic biochars were more suitable than raw biomass to be co-combusted with lignite for energy generation in existing coal-fired power plants., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

With the awareness of the need for optimal and sustainable use of natural resources, hydrothermal treatment of biomass and biomass waste for energy and resource recovery has received increasing attention. In this context, hydrochars produced by hydrothermal treatment of biomass, which have been traditionally employed as catalyst supports or adsorbents, are now of considerable interest as precursors for activated carbons. Activated carbon produced from hydrochars has been widely used in applications such as energy storage, environmental remediation and resource recovery. Apart from savings in energy and resource conservation, hydrochars are of interest in activated carbon production because they possess unique attributes such as high density of oxygenated functional groups (OFGs) and low degree of condensation which can be tailored to produce activated carbons with specific and desired characteristics. This review aims to integrate the current knowledge on hydrothermal carbonization of biomass waste in the context of resource and energy recovery. Specifically, we bring together recent advances made in this area through a systematic and critical review of the production of activated carbon from hydrochars. Mechanisms involved in the production of hydrochars with different surface characteristics in response to variations in the operating parameters are critically reviewed. The current knowledge gaps and challenges involved in the hydrothermal carbonization of biomass waste are critically evaluated with suggestions for further research. [ABSTRACT FROM AUTHOR]

Recurrent smoke-haze episodes that occur in Southeast Asia (SEA) are of much concern because of their environmental and health impacts. These haze episodes are mainly caused by uncontrolled biomass and peat burning in Indonesia. Airborne particulate matter (PM) samples were collected in the southwest coast of Singapore from 16 August to 9 November in 2009 to assess the impact of smoke-haze episodes on the air quality due to the long-range transport of biomass and peat burning emissions. The physical and chemical characteristics of PM were investigated during pre-haze, smoke-haze, and post-haze periods. Days with PM mass concentrations of ≥35 μg m were considered as smoke-haze events. Using this criterion, out of the total 82 sampling days, nine smoke-haze events were identified. The origin of air masses during smoke-haze episodes was studied on the basis of HYSPLIT backward air trajectory analysis for 4 days. In terms of the physical properties of PM, higher particle surface area concentrations and particle gravimetric mass concentrations were observed during the smoke-haze period, but there was no consistent pattern for particle number concentrations during the haze period as compared to the non-haze period except that there was a significant increase at about 08:00, which could be attributed to the entrainment of PM from aloft after the breakdown of the nocturnal inversion layer. As for the chemical characteristics of PM, among the six key inorganic water-soluble ions (Cl, NO, nss-SO, Na, NH, and nss-K) measured in this study, NO, nss-SO, and NH showed a significant increase in their concentrations during the smoke-haze period together with nss-K. These observations suggest that the increased atmospheric loading of PM with higher surface area and increased concentrations of optically active secondary inorganic aerosols [(NH)SO or NHHSO and NHNO] resulted in the atmospheric visibility reduction in SEA due to the advection of biomass and peat burning emissions. [ABSTRACT FROM AUTHOR]

High-surface area mesoporous activated carbons were prepared from biomass by incorporating H 2 O 2 as an oxidizing agent during hydrothermal pre-treatment of the raw material (coconut shell). Use of H 2 O 2 led to enhanced formation of OFGs in the hydrochar precursor and resulted in activated carbons possessing high mesopore and BET surface areas. A strong interdependence is observed between the extent of formation of oxygenated functional groups (OFGs) in the hydrochars obtained from the hydrothermal pre-treatment and mesopore area in corresponding carbons. The mesoporous carbons showed high adsorption capacity for Rhodamine B up to 714 mg/g. [ABSTRACT FROM AUTHOR]

Simple tuning of hydrothermal pre-treatment parameters is shown to result in significant enhancement in the mesopore area of activated carbon obtained from biomass (coconut shell). ZnCl 2 content and temperature were used as parameters to improve the effectiveness of hydrothermal pre-treatment. With progressive increase in the treatment temperature, the enhancement of ZnCl 2 diffusion was tempered by its reduced solubility. By identifying favorable working ranges for ZnCl 2 content and temperature to promote mesopore formation, up to 80% increase in mesopore area is achieved in comparison to the conventional soaking process for formation of mesoporous activated carbon. The enhancement in mesopore area was substantiated by high adsorption capacities for a mixture of phenol red and phenol up to 351 and 264 mg/g, respectively. [ABSTRACT FROM AUTHOR]

In this manuscript, a dramatic increase in the energy density of , ~ 69 Wh kg-1 and an extraordinary cycleability,∼ 2000 cycles of the Li-ion hybrid electrochemical capacitors (Li-HEC) is achieved by employing tailored activated carbon (AC) of ~ 60% mesoporosity derived from coconut shells (CS). The AC is obtained by both physical and chemical hydrothermal carbonization activation process, and compared to the commercial AC powders (CAC) in terms of the supercapacitance performance in single electrode configuration vs. Li. The Li-HEC is fabricated with commercially available Li4Ti5O12 anode and the coconut shell derived AC as cathode in non-aqueous medium. The present research provides a new routine for the development of high energy density Li-HEC that employs a mesoporous carbonaceous electrode derived from bio-mass precursors. [ABSTRACT FROM AUTHOR]

Air particulate matter (PM) samples were collected in Singapore from 21 to 29 October 2010. During this time period, a severe regional smoke haze episode lasted for a few days (21-23 October). Physicochemical and toxicological characteristics of both haze and non-haze aerosols were evaluated. The average mass concentration of PM (PM with aerodynamic diameter of ≤2.5 μm) increased by a factor of 4 during the smoke haze period (107.2 μg/m) as compared to that during the non-smoke haze period (27.0 μg/m). The PM samples were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) listed by the United States Environmental Protection Agency and 10 transition metals. Out of the seven PAHs known as potential or suspected carcinogens, five were found in significantly higher levels in smoke haze aerosols as compared to those in the background air. Metal concentrations were also found to be higher in haze aerosols. Additionally, the toxicological profile of the PM samples was evaluated using a human epithelial lung cell line (A549). Cell viability and death counts were measured after a direct exposure of PM samples to A459 cells for a period of 48 h. The percentage of metabolically active cells decreased significantly following a direct exposure to PM samples collected during the haze period. To provide further insights into the toxicological characteristics of the aerosol particles, glutathione levels, as an indirect measure of oxidative stress and caspase-3/7 levels as a measure of apoptotic death, were also evaluated. [ABSTRACT FROM AUTHOR]

Low-cost carbonaceous adsorbents with microporous structures and large specific surface area (up to 2511 m 2 g −1 ) were prepared from a lignocellulosic feedstock by novel hydrothermal carbonization coupled with chemical activation for CO 2 capture. In-depth spectroscopic and microscopic analyses of these adsorbents were performed to gain insights into their structural, morphological and textural characteristics. The microporous carbons have a remarkable CO 2 uptake capacity (3.71 mmol g −1 ) at 25 °C and at a pressure of 1 atm. These materials also feature good selectivity for CO 2 over N 2 gas and are composed of a hydrophobic core making them favorable as adsorbents for CO 2 capture. The Freundlich equilibrium model well correlated with the experimental data obtained from the adsorption isotherms and classical micropore diffusion model described the adsorption kinetics satisfactorily. The Henry’s law constant calculated using Virial model indicates the presence of strong electrostatic interactions and dispersion forces between CO 2 and porous carbons. Furthermore, these carbon-based adsorbents can be used repeatedly up to 10 times for CO 2 adsorption without significant loss of adsorption capacity. Overall, the results suggest that prepared microporous adsorbents provide a feasible option for capturing CO 2 from post-fossil fuel combustion processes due to their potentially low costs, environmentally benign nature, and elevated CO 2 capture capacity. [ABSTRACT FROM AUTHOR]

Abstract: A carbon-rich solid product, denoted as hydrochar, was synthesized by hydrothermal carbonization (HTC) of palm oil empty fruit bunch (EFB), at different pre-treatment temperatures of 150, 250 and 350°C. The conversion of the raw biomass to its hydrochar occurred via dehydration and decarboxylation processes. The hydrochar produced at 350°C had the maximum energy-density (>27MJkg−1) with 68.52% of raw EFB energy retained in the char. To gain a detailed insight into the chemical and structural properties, carbonaceous hydrochar materials were characterized by FE-SEM, FT-IR, XRD and Brunauer–Emmett–Teller (BET) analyses. This work also investigated the influence of hydrothermally treated hydrochars on the co-combustion characteristics of low rank Indonesian coal. Conventional thermal gravimetric analysis (TGA) parameters, kinetics and activation energy of different hydrochar and coal blends were estimated. Our results show that solid hydrochars improve the combustion of low rank coals for energy generation. [Copyright &y& Elsevier]

In this study, activated hydrochar was prepared from orange peel (OP) waste using KOH for the first time for potential environmental applications. The influence of hydrothermal carbonization temperature (180 °C, 200 °C, and 220 °C) on the CO 2 adsorption capacity of OP-derived activated hydrochar (OP-180, OP-200, and OP-220) was investigated. Scanning electron microscope (SEM) images revealed that the activated OP hydrochar has high microporosity, a desired attribute for effective adsorption. The yield and the oxygen content of the hydrochar decreased with the increasing process temperature whereas the carbon content showed an increase. Fourier-transform infrared spectroscopy showed the presence of various functional groups including ketone, aldehydes, esters, and carboxyl in the hydrochar. CO 2 adsorption isotherm was determined for all hydrochar samples. At 25 °C and 1 bar, OP-220 showed the highest CO 2 uptake at 3.045 mmol/g. The use of OP waste for CO 2 adsorption applications contributes to carbon neutrality and a circular economy. [Display omitted] • Novel hydrochar with chemical activation was produced from orange peel waste. • Activated char was characterized using SEM, XRD, FTIR, BET techniques. • Increase in HTC temperature increased the surface area of the hydrochar. • Maximum surface area was obtained for hydrochar produced at 220 °C. • Maximum CO 2 uptake was observed for hydrochar produced at 220 °C. [ABSTRACT FROM AUTHOR]

We report the fabrication of high energy Li-ion capacitor (LIC) using teak wood sawdust derived mesoporous activated carbon (AC-HBP) with electrochemically pre-lithiated graphite (LiC 6 ). Three interesting supercapacitor assemblies are constructed using AC-HBP to realize the high energy density. Amongst, AC-HBP paired with LiC 6 delivered a maximum energy density of ∼111 Wh kg −1 compared to Li 4 Ti 5 O 12 in LIC (∼53 Wh kg −1 ) and AC-HBP (∼37 Wh kg −1 ) in symmetric configurations. This excellent energy density is mainly ascribed to the tailored mesoporous nature (∼67%) of the high surface area activated carbon (2108 m 2 g −1 ) obtained via hydrothermal carbonization process in the presence of processing agent, benzene tetracarboxylic acid followed by physico-chemical activation. [ABSTRACT FROM AUTHOR]

A significant improvement of up to 94% in mesopore area of hydrochar-derived activated carbons (ACs) has been achieved using optimal concentrations of biomass (coconut shell) and chemical activating agent (ZnCl 2 ) during hydrothermal pre-treatment. For the first time, we have demonstrated that stoichiometry can influence hydrochar properties and availability of ZnCl 2 for activation which has significant impact on the textural properties of mesoporous activated carbons. Tuning of key process parameters and hydrothermal treatment conditions (ZnCl 2 :biomass ratios and biomass & ZnCl 2 concentrations), together with hydrothermal pre-treatment with H 2 O 2 , resulted in BET and mesopore areas up to 2440 m 2 g −1 and 1121 m 2 g −1 , respectively. When the mesoporous carbon was employed as an electrode material in supercapacitors, stable energy density at 7.6 W h kg −1 was observed (90% of 8.5 W h kg −1 @ 0.22 kW kg −1 ) at a high power density of ∼4.5 kW kg −1 , which is one the best performance observed thus far in biomass-derived activated carbons. [ABSTRACT FROM AUTHOR]

Hydrothermally upgraded chars with improved density and friable characteristics were produced from oil-palm empty fruit bunch (EFB) at three temperatures (150, 250, and 350°C—denoted as H-150, H-250 and H-350). These chars were co-combusted with low rank Indonesian coal and with hydrothermally upgraded coal (HT-coal). The composition of major gaseous pollutants released from the co-combustion process with specific reference to CO, CO2, CH4, NO, and SO2 was studied in real-time using a thermogravimetric analyzer coupled with a Fourier transform infrared spectrometry. Combustion characteristic factor (CCF) was determined for a systematic analysis of the thermal decomposition process. In the co-combustion of hydrothermally treated biomass with coal and HT-coal, H-250 (50%)/HT-coal (50%) (CCF =4.1×10−7) fuel blend showed the highest CCF values i.e. the most efficient co-combustion process. Further analysis of the emission profiles of gaseous pollutants revealed that the co-combustion of 50% H-350 with 50% HT-coal by mass produced the lowest levels of gaseous pollutant emissions. Overall, a systematic combustion carried out in this study showed that co-combustion of hydrothermally upgraded EFB biochar with coal and HT-coal leads to environmental benefits, specifically reduced emissions of toxic (CO), acidic (NO and SO2) and greenhouse (CH4 and CO2) gases. [ABSTRACT FROM AUTHOR]

Smoke haze episodes , resulting from uncontrolled biomass burning (BB) including forest and peat fires, continue to occur in Southeast Asia (SEA), affecting air quality, atmospheric visibility, climate, ecosystems, hydrologic cycle and human health. The pollutant of major concern in smoke haze is airborne particulate matter (PM). A number of fundamental laboratory, field and modeling studies have been conducted in SEA from 2010 to 2020 to investigate potential environmental and health impacts of BB-induced PM. The goal of this review is to bring together the most recent developments in our understanding of various aspects of BB-derived PM based on 127 research articles published from 2010 to 2020, which have not been conveyed in previous reviews. Specifically, this paper discusses the physical, chemical, toxicological and radiative properties of BB-derived PM. It also provides insights into the environmental and health impacts of BB-derived PM, summarizes the approaches taken to do the source apportionment of PM during BB events and discusses the mitigation of exposure to BB-derived PM. Suggestions for future research priorities are outlined. Policies needed to prevent future BB events in the SEA region are highlighted. ga1 • Emission of biomass burning-derived particulate matter in Southeast Asia. • Physicochemical properties and health impacts of BB-derived PM. • Environmental impacts of BB-derived PM. • Source identification and source apportionment of BB-derived PM. • Future research directions for BB-related environmental and health issues. [ABSTRACT FROM AUTHOR]