1,721,109 research outputs found
Adsorption of methyl orange and methylene blue on activated biocarbon derived from birchwood pellets
Full text linkThis study explored the adsorption capacity of a physically activated biocarbon derived from the pyrolysis of
birchwood pellets (ABPB) towards two dyes - methyl orange (MO, anionic) and methylene blue (MB, cationic), at
pH 2, 7 and 11. Compared to mineral commercial activated carbon (CACmineral), ABPB exhibited lower SSA, pores
volume and surface; higher external surface and average pore diameter, similar ash content and aromaticity, and
stronger hydrophilicity and polarity. The maximum adsorption capacity on ABPB was equal to 220 mg/g for MO
and 91 mg/g for MB after 17 h. Batch tests with variable adsorbent amount (0.5–2.5 g/L) showed for both ABPB
and CACmineral better results for lower adsorbent dose. Under all tested conditions, ABPB showed higher or
analogous adsorption capacity compared to CACmineral. Based on the pKa of MB (3.80) and MO (3.46) and on the
pHPZC of ABPB (5.3), the adsorption was favored at pH 2 for MO and at pH 11 for MB. Kinetics analysis and
isotherm modelling revealed that, although many different physicochemical interactions occurred between ABPB
and the dyes molecules, chemisorption is the rate-controlling step and prevalent mechanism. In conclusion, this
study may provide support to further research aimed at exploring the effect of ABPB’s physicochemical properties
on the efficiency and mechanisms of dyes adsorption
A review on the pyrolytic conversion of plastic waste into fuels and chemicals
Full text linkWe reviewed 195 references discussing the pyrolysis of plastic waste, with the aim of analyzing the technical
aspects (feedstocks, process parameters, reactors, products, catalysts, kinetics, and pollutants), the economic
feasibility for the industrial implementation, and the environmental assessment through Life Cycle Analysis
(LCA). In the last decade, the scientific community primarily studied individual virgin polymers (79% of the
references) through batch lab-scale tests, mostly at temperatures around 500◦C (46% of the selected references).
Depending on the polymer (PE, PP, PET, PS), reactor type and operating conditions the relative amounts of gas/
condensable/solid products varied, whereas PVC was considered undesirable due to the formation of corrosive
gases. Liquid products are the most common targets, due to their application as fuels. Several technical issues
(such as the impact of residence time and pressure, and low-cost catalysts) need further attention. Very few LCA
studies explored plastic waste pyrolysis, with insufficient results for a thorough environmental assessment of the
processes. Only seven references investigated the techno-economic feasibility of plastic waste pyrolysis at fullscale,
achieving results that are interesting but too scarce for any conclusive evaluation. This represents the
most significant knowledge gap identified in the review, as the techno-economic sustainability is a fundamental
factor for the technological transfer. Pyrolysis has been proven to be a viable technology to convert plastic waste
into high value-added products that can be utilized as fuels, chemicals and/or building blocks. This review
provides guidance for further research and aims at stimulating the interest of the industrial world regarding the
possible implementation of this technology
Impact of biochar on anaerobic digestion: Meta-analysis and economic evaluation
Full text linkThe growing global energy demand encourages the request for renewable sources, as biomethane from the
anaerobic digestion (AD) of waste biomass. Biochar (BC) can effectively increase methane production when
supplemented to AD, depending on BC physico-chemical properties. This study was developed in two phases.
Firstly, a systematic meta-analysis of current literature was performed to correlate AD performance with BC
properties, aiming to define their optimal range. The obtained results prove that BC enhances and accelerates
biomethane production. Considering 408 experimental conditions of 76 studies in batch mode, biomethane yield
and maximum production rate were significantly increased by BC addition. From the results of the subgroups
meta-analysis, an optimal range of BC physico-chemical properties may be suggested as follows: high ash (≥
20%) and low C contents (< 50%), high O/C molar ratios (≥ 0.3), high contents of O (≥ 20%) and N (≥ 0.6%),
acidic pH (< 7.0), low surface area (< 10 m2 g-1). Secondly, an economic analysis aimed at assessing the
economic profitability of BC addition to an existing AD plant suggest avoiding a dose above 0.45–0.76 gBC gVS -1, independently of the specific AD operating conditions. In conclusion, BC application in full-scale digesters is able to maximize biomethane production and economically feasible
Investigation of innovative and conventional pyrolysis of ligneous and herbaceous biomasses for biochar production
Full text linkPyrolysis is a thermochemical process involving the thermolysis of carbon-based materials in absence of an oxidizing agent. Adjusting the operating conditions, in order to maximize the gaseous, liquid or solid products, may optimize pyrolysis process. This work investigates the performances of three laboratory-scale reactors on the grounds of the quantity and quality of the biochar obtained from different biomasses. Three types of biomass were fed to each reactor: two ligneous (rubberwood and eucalyptus) and one herbaceous (Phragmites australis). A novel reactor developed at ICFAR, the Jiggled Bed Reactor (JBR) was employed in slow pyrolysis mode.
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ARSENIC REMOVAL FROM DRINKING WATER BY MEANS OF LOW-COST BIOCHARS DERIVED FROM MISCANTHUS AND COCONUT SHELL
Full text linkArsenic is a toxic metalloid highly diffused in groundwater because of natural and anthropogenic factors (mainly deriving from mining activities and pesticides). Inorganic arsenic compounds are classified by the International Agency for Research on Cancer (IARC) in Group I (proven carcinogen). Groundwater concentration of As may vary from 0.5 to 5000 μg/L taking into account more than 70 Countries around the world. The most polluted groundwater of the planet was identified in late 1990s in Bengal delta (Bangladesh and Indian region West Bengal). Inorganic arsenic in natural water (pH 6-8) is mainly found as arsenite (H2AsO3−) and arsenate (HAsO42−), respectively species of As (III) and As (V). Due to the prevailing reducing conditions in deep aquifers of SE Asia, As mainly occurs there as oxyanion of As (III), which is also the most toxic form for humans. Quantitatively the most important human exposure route for As is ingestion. World Health Organization (WHO) set in 2003 a guideline value for maximum As concentration in drinking equal to 10 μg/L, while developing Countries refer to 50 μg/L, mainly because of the prohibitive remediation costs at lower concentrations. The use of biochar as sorbent for water depollution deserved a relevant attention in the recent years. In the specific case of Bangladesh the most critical aspects in order to choose the most efficient depollution method may be the following: high concentration of As (III), presence of numerous dissolved compounds in water and the necessity to find the cheapest and simplest solution considering the lack of instrumentation and technologies. Concerning these features, and also efficiency, cost and management complexity of the possible treatment technologies, adsorption could be considered as the most flexible and promising option for SE Asia. The aim of this work is the investigation of two biochars as low-cost sorbents to remove arsenic from drinking water. The performed laboratory tests involved As (III) and As (V), considering boundary conditions related to Bangladesh. Biochars were synthetized from Miscanthus and coconut shell, then characterized and compared as sorbents with a commercial Granular Activated Carbon (GAC). A novel reactor developed at ICFAR, the Jiggled Bed Reactor (JBR), was employed in slow pyrolysis mode to produce the biochars omitting the activation phase. Biochars deriving from Mischantus and coconut shell exhibited rather different features about surface area (respectively 428 m2/g and 208 m2/g), micro-pores volume (respectively 0.212 cm3/g and 0.098 cm3/g), and pore size (respectively 1.98 nm and 1.89 nm). Taking into account adsorption parameters, contact time, concentration of sorbent and of adsorbate were optimized. Particular attention was given to As (III), because of its higher abundance and toxicity. Isotherm and kinetic parameters in adsorption of As (III) were gathered. The best fitting of adsorption was observed with Freundlich model, while about kinetics with a pseudo-second order model, obtaining better results with Miscanthus biochar. A sensitive interference, due to the presence of sodium in aqueous phase, was quantified in As (III) adsorption (60% decrease). Miscanthus biochar, although un-activated, was found to have an adsorption capacity (0.112 mg/g) comparable to literature data about low-cost biosorbents and biochars already studied about arsenic adsorption. The tested substrates are not suitable for a quantitative removal of arsenic in the evaluated boundary conditions, although they may be considered a reliable option for the pre-treatment of heavily polluted water
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Review of the impact of socio-economic conditions on the development and implementation of biorefineries
Full text linkBiorefineries have been studied, involving technical, economic, and environmental aspects. Substantial research has identified many pathways for producing chemicals and fuels from biomass sources. Nevertheless, the implementation of biorefineries depends not only on biochemistry and technologies. In addition, biorefineries implementation needs to be supported by logistics, existing infrastructure, feedstock supply chains, market uptake opportunities, socio-economic issues, and political context. Therefore, this review paper is addressed to analyze the influence of country conditions on the development of integral biobased industries. For this, a
literature review is done focused on analyzing the possible implementation of biorefineries. Four countries were selected as potential study cases to analyze the integral upgrading of biomass sources in different world regions: Colombia, Canada, Italy, and Greece. Industrialized countries can introduce biorefineries because there are established pathways to support research and development efforts and guarantee economic feasibility combined with existing plants. Nevertheless, emerging industrial and developing countries seem far from implementing
biorefineries as brownfield processes since context variables do not support this change (e.g., logistics performance, industrial competitiveness). In conclusion, international cooperation and biomass trading could be feasible to make a faster economic transition in all world regions (i.e., bioeconomy instead of oil-based economy)
Biochar as biofertilizer
No full textBiochar application as biofertilizer in agriculture provides multiple advantages, such as enhancing soil quality, boosting crop productivity, and mitigating climate change. Biochar is rich in stable carbon and essential nutrients, and improves soil features as water retention, aeration, and nutrients’ availability. This reduces the need for chemical fertilizers and helps sequester carbon in the soil. When made from agricultural waste, biochar reduces waste and supports the circular economy by transforming waste materials into valuable resources, promoting a more sustainable agriculture.
In this study, the effect of biochar on the growth and development of strawberry plants was evaluated. Strawberry plants sprouts were rooted in commercial garden soil supplemented with biochar produced via pyrolysis of soft wood at 550°C. Biochar was dosed according to literature (2-12 tons/ha) involving 12 pots supplemented with biochar and 3 control (i.e. no biochar) pots placed in a lab-scale greenhouse. Biochar was applied unaltered and after physical activation with CO2 at 900°C. The growth and productivity of the plants was monitored for 3 months, recording plant height, number of flowers, and number of ripe fruits twice per week, and through continuous remote sensing. Specifically, a low-cost automated proximal sensor system was installed in the greenhouse to monitor the micro-climate and plant development. The system includes a MAPIR Survey 3W multispectral camera, a DHT22 temperature and humidity sensor, and five capacitive soil moisture sensors. The sensors were integrated using a Raspberry Pi 4 for data collection and storage. The 12 MP camera captured three spectral bands (550nm, 660nm, 850nm) with an 87° field of view and was positioned to capture all plants in one nadir image. Images were taken hourly, recording red, green, and near-infrared (RGN) spectral data, which allows for the calculation of vegetation indices (VIs) like the Normalized Difference Vegetation Index (NDVI) to estimate plant health. The correlation between NDVI and the biochar dose was investigated.
The average height of the plants supplemented with biochar was 16.35 ± 2.05 cm, with activated biochar was 16.3 ± 1.75 cm, and for the control group was 11.1 ± 1.30 cm. During the first month +17% net plant height was observed in the pots supplemented with biochar, but no significant difference was noticed between activated biochar and unaltered biochar (Figure 1). In terms of number of flowers and ripe fruits, the plants treated with biochar were 15 days beforehand when compared to control plants. Again, no evident difference was visible between activated and unaltered biochar.
This study was carried out within the Agritech National Research Center and received funding from the European Union Next-GenerationEU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4 – D.D. 1032 17/06/2022, CN00000022)
A CFD study of biomass pyrolysis in a downer reactor equipped with a novel gas-solid separator - I:Hydrodynamic performance
Full text linkThis study presents the first part of a CFD study on the performance of a downer reactor for biomass pyrolysis. The reactor was equipped with a novel gas-solid separation method, developed by the co-authors from the ICFAR (Canada). The separator, which was designed to allow for fast separation of clean pyrolysis gas, consisted of a cone deflector and a gas exit pipe installed inside the downer reactor. A multi-fluid model (Eulerian-Eulerian) with constitutive relations adopted from the kinetic theory of granular flow was used to simulate the multiphase flow. The effects of the various parameters including operation conditions, separator geometry and particle properties on the overall hydrodynamics and separation efficiency were investigated. The model prediction of the separator efficiency was compared with experimental measurements. The results revealed distinct hydrodynamic features around the cone separator, allowing for up to 100% separation efficiency. The developed model provided a platform for the second part of the study, where the biomass pyrolysis is simulated and the product quality as a function of operating conditions is analyzed. Crown</p
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