Understanding the dependence of biochar properties on different types of biomass.

Owing to the diversity of biomasses and many variables in pyrolysis process, the property of biochar from varied biomass feedstock or even same biomass could differ significantly. Since the property of biochar governs the further application of biochar, this review paid particular attention to the correlation between the nature of biomass feedstock and the specifications of biochar in terms of yield, elemental composition, pH, functionalities, heating value, pore structures, morphologies, etc. The property of the biochar from the pyrolysis of cellulose, hemicellulose, lignin, woody biomass (pine, mallee, poplar, acacia, oak, eucalyptus and beech), bark of woody biomass, leaves of woody biomass, straw, algae, fruit peels, tea waste was compared and summarized. In addition, the differences of the biochar of these varied origins were also analyzed. The remaining questions, about the correlation of biomass nature with biochar characteristics, to be further investigated are analyzed in detail. The deduced information about the relationship of the nature of biochar and biomass feedstock as well as key pyrolysis parameters is of importance for further development of the methods for tailoring or production of the biochar of desirable properties. The results from this study could be interesting technically and commercially for the technology developer using biochar as the source of carbon in different applications.

Activation of waste paper: Influence of varied chemical agents on product properties.

Waste paper (WP) is rich in cellulose, which can be activated to produce porous carbon, bio-oil, and combustible gases. During chemical activation of WP, the use of varied chemical agents not only generates activated carbon of distinct pore structure but also bio-oil/gases of different property. In this study, the activation of WP with varied chemical agents was conducted. The distinct characteristics of activated carbon and also bio-oil/gases were correlated with the different nature of the used chemical agents. The results indicated that H3PO4 and ZnCl2 catalyzed polymerization reactions for producing more bio-oil while less gases owing to their Brønsted and Lewis acidic sites. K2C2O4 showed high activity for cracking/gasification reactions, forming bio-oil with higher abundance of organics with smaller π-conjugated structures. In addition, ZnCl2 could create a very coarse porous structure with abundant macropores via destroying fiber structure in WP and promoting the growth of graphitic crystals. In comparison, K2C2O4 hindered the aromatization and facilitated the formation of amorphous activated carbon. K2C2O4 and ZnCl2 were much more effective than H3PO4 for creating micropores and mesopores from WP, the derived activated carbon showed superior performances as the electrode of supercapacitor and adsorbent for adsorption of oxytetracycline from aqueous solution. In addition, K2C2O4 as activating agent showed lower environmental impact than ZnCl2 in terms of energy consumption, environmental pollution and the greenhouse effect.

Pyrolysis of cellulose: Correlation of hydrophilicity with evolution of functionality of biochar.

Biochar is a carbonaceous material from pyrolysis of biomass, the application of which is governed by its various properties such as the distribution of the functionalities and the associated hydrophilic/hydrophobic nature. This study particularly focused on the correlation of functionalities of biochar with its polarities by conducting the pyrolysis of cellulose from 200 to 700 °C and the characterization of the biochar. The results demonstrated that -OH, instead of CO or C-O-C, played decisive roles in formation of the biochar with hydrophilic surface. The results showed that the maximum of -OH abundance and the aliphatic CH was reached at 440 °C. The significant transition of oxygen-rich functionalities to carbon-rich functionalities occurred in the temperature from 460 to 700 °C. The dominance of aromatization process above this temperature range resulted in the significant increase of hydrophobicity of the biochar. The hydrophilic surface was of importance for the use of biochar as support for promoting the dispersion of Cu in Cu/biochar by generating the bonding sites for chelating with Cu2+.

Determination of nano and microplastic particles in hypersaline lakes by multiple methods.

Microplastics and nanoplastics have a range of impacts on the aquatic environment and present major challenges to their mitigation and management. Their transport and fate depend on their composition, form, and the characteristics of the receiving environment. We explore the spatial and temporal dynamics of plastic particles in the world's second-largest hypersaline lake, combining information from microscopic, thermal gravimetric, and fractional methods. Studies on microplastic and nanoplastic pollution in these important environments are scarce, and there is limited understanding of their dynamics and fate. Our results for Urmia Lake (Iran) in 2016 and 2019 show a discrepancy in the composition and quantity of microplastics measured in river tributaries to the lake and the lake itself, suggesting an active microplastic sink. Potential sink mechanisms in hypersaline lakes are explored. The present study indicates that microplastics have different transport mechanisms and fate in these extreme environments, compared to lake and ocean environments.

Co-hydrothermal carbonization of swine manure and cellulose: Influence of mutual interaction of intermediates on properties of the products.

Co-hydrothermal carbonization (HTC) of livestock manure and biomass might improve the fuel properties of the hydrochar due to the high reactivity of the biomass-derived intermediates with the abundant oxygen-containing functionalities. However, the complicated compositions make it difficult to explicit the specific roles of the individual components of biomass played in the co-HTC process. In this study, cellulose was used for co-HTC with swine manure to investigate the influence on the properties of the hydrochar. The yield of hydrochar obtained from co-HTC reduced gradually with the cellulose proportion increased, and the solid yield was lower than the theoretical value. This was because the cellulose-derived intermediates favored the stability of the fragments from hydrolysis of swine manure. The increased temperature resulted in the reduction of the hydrochar yield whereas the prolonged time enhanced the formation of solid product. The interaction of the co-HTC intermediates facilitated the formation of O-containing species, thus making the solid more oxygen- and hydrogen-rich with a higher volatility. In addition, the co-HTC affected the evolution of functionalities like -OH and CO during the thermal treatment of the hydrochar and altered its morphology by stuffing the pores from swine manure-derived solid with the microspheres from HTC of cellulose. The interaction of the varied intermediates also impacted the formation of amines, ketones, carboxylic acids, esters, aromatics and the polymeric products in distinct ways.

Co-hydrothermal carbonization of swine and chicken manure: Influence of cross-interaction on hydrochar and liquid characteristics.

Swine and chicken manures are abundant solid wastes that can be converted into carbonaceous materials through hydrothermal carbonization (HTC). Owing to their unique biochemical compositions, co-HTC of these two types of manures may have significant implications for the generated products. We investigated the co-HTC of swine manure and chicken manure to understand the influence of the interaction between contrasting manures on the properties of the derived products. The results indicated that co-HTC treatment enhanced the formation of solid product and improved the C and N contents, heating value, and energy yield of the resulting hydrochar. Regarding the ignition temperature and comprehensive combustion index, the combustion properties of the hydrochar were enhanced owing to the mutual effect of the HTC intermediates. Additionally, the interaction of the intermediates significantly impacted the transfer of nitrogenous species and generation of organic acids and organic polymers with fused-ring structures. Therefore, co-HTC processing of animal manures could potentially provide a sustainable pathway for the conversion of animal waste into solid products with improved characteristics compared to those produced by treating the two feedstocks separately.

Fates of heavy organics of bio-oil in hydrotreatment: The key challenge in the way from biomass to biofuel.

Heavy organics in bio-oil generally refer to the sugar oligomers and lignin-derivatives. They are important fractions in bio-oil and their effective conversion in hydrotreatment determines carbon yield from biomass or bio-oil to biofuel. Fates of the heavy organics largely determine intrinsic reaction behaviors of bio-oil during hydrotreatment. The heavy organics in bio-oil have high tendency towards polymerization upon thermal treatment, which is one of the main precursors for coke formation and catalyst deactivation. Furthermore, the heavy organics have some other unique characteristics in hydrotreatment such as the steric hindrance for contacting active sites on surface of catalyst. How to effectively convert the heavy organics has been regarded as the bottle-neck issue in hydrotreatment of bio-oil and the key barrier in the roadmap from biomass to biofuels. Thus, this review particularly focuses on the progress in understanding reaction behaviors of the heavy organics in hydrotreatment of bio-oil, a central challenge to be resolved. The results indicated that coke formation from heavy organics in bio-oil remains main obstacle in hydrotreatment and further fundamental studies are required to develop suitable catalyst and process to stabilize the heavy organics in bio-oil. In particular, the mechanism for coke formation from the heavy species of varied chemical family should be clarified and corresponding measures should be developed to tackle high tendency of coking. Techno-economic feasibility should be considered in the first place in development of catalysts or process for tackling the heavy fractions of bio-oil.

Catalytic pyrolysis of tire waste: Impacts of biochar catalyst on product evolution.

Tire scrap is a solid waste that can be potentially used as the feedstock for the production of liquid fuels via the thermochemical process such as catalytic pyrolysis. Nevertheless, it remains challenging to develop the efficient while cost-effective catalyst for the catalytic pyrolysis of tire. In this study, the pyrolysis of tire scrap at 500 °C with the biochar produced from the gasification of poplar wood at 850 °C were conducted. The biochar catalyst significantly affected the evolution of the volatiles and the char properties, while had a slight impact on the yields of the gas, tar and char products. The biochar catalyst catalyzes the cracking of limonene, a major liquid product in tar, to form significantly more propane in gases and alkanes or alkenes in the tar. In addition, the interaction between the biochar with the oxygen-containing organics promoted the re-condensation reaction, which increased the oxygen content in the char, but the biochar catalyst did not influence the evolution of the aromatics. Additionally, the catalytic pyrolysis also makes the biochar catalyst more oxygen-deficient and more resistant towards oxidation. Concluding all the results showed that biochar, which were produced from the gasification of poplar wood can be a potential catalyst for the pyrolysis of tire.

Different reaction behaviours of light or heavy density polyethylene during the pyrolysis with biochar as the catalyst.

Polyethylene is a major contributor of plastic waste, which can be converted into liquid fuel via catalytic pyrolysis. In this study, the pyrolysis of light or heavy density polyethylene (LDPE and HDPE) and their mixture with the biochar produced from gasification of poplar wood as catalyst was investigated. The results showed that, during the co-pyrolysis of LDPE and HDPE in absence or presence of biochar catalyst, cross-interaction of reaction intermediates originated from the degradation of LDPE and HDPE substantially promoted the formation of gaseous products and the evolution of heavy organics with π-conjugated structures in the tar. During the pyrolysis of HDPE, more heavy tar while less wax was produced, while it was contrary during the pyrolysis of LDPE. In the catalytic pyrolysis of LDPE, the volatiles could be effectively cracked over the biochar catalyst, forming more gases, while in the catalytic pyrolysis of HDPE, instead of catalyzing the cracking of the heavy components, the biochar catalyzed the polymerisation reactions. The properties of the biochar catalyst in terms of crystallinity, surface functionality, and internal structures also changed remarkably due to the transfer of oxygen-containing species from the polyethylene to biochar and the interaction of biochar with volatiles in the pyrolysis.

Integrated Cr and S poisoning of a La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode for solid oxide fuel cells.

Strontium segregation in a La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) electrode reacts with Cr and S in a solid oxide fuel cell (SOFC), which can cause cell performance deterioration. Integrated Cr and S poisoning for LSCF cathodes of SOFC was studied at 800 °C of 200 mA cm-2 (cathodic) for 20 h. After polarization in Cr and S at 800 °C for 20 h, polarization and ohmic resistances for LSCF were 2.4 Ω cm2 and 3.4 Ω cm2, which were larger than those for LSCF electrodes after Cr deposition only and S deposition only, respectively. The results illustrated that Cr and S deposition occurred on the surface of LSCF, which could form SrCrO4 and SrSO4. Compared to Cr deposition only and S deposition only, integrated Cr and S deposition was unsystematic, and the degradation phenomenon of Cr and S poisoning was more severe. The integrated Cr and S deposition of the LSCF electrodes was induced via interactions among CrO, SO2 and segregated SrO from LSCF.

Cross-interaction during Co-gasification of wood, weed, plastic, tire and carton.

This study investigated the gasification of wood, weed, plastic, tire, carton and their mixtures using zeolite (A4 type) as a catalyst, with the purpose of investigating the potential interactions of the various feedstocks during gasification. The co-gasification of the mixed feedstock led to the occurrences of the cross-interactions, which substantially impacted the distribution of the products in gasification. During the co-gasification, the pyrolysis/gasification of the different feedstocks produced the reaction intermediates with varied structures that interacted with each other and with the char formed from the different feedstock. The interaction could promote the gasification of the tarry compounds into gaseous products, which could also promote the gasification of the char to lower the char yields. Further to this, the cross-polymerisation or cracking of the varied reaction intermediates also took place during the co-gasification, leading to the formation of more coke deposits on catalyst. The co-gasification of the mixed feedstocks significantly impacted the reaction network, impacting the formation of gases, tar, char and the coke on catalysts, originating from the cross-interaction among the reaction intermediates derived from the pyrolysis/gasification of the various feedstocks.

Acid-catalyzed conversion of mono- and poly-sugars into platform chemicals: effects of molecular structure of sugar substrate.

Hydrolysis/pyrolysis of lignocellulosic biomass always produces a mixture of sugars with distinct structures as intermediates or products. This study tried to elucidate the effects of molecular structure of sugars on their acid-catalyzed conversions in ethanol/water. Location of carbonyl group in sugars (fructose versus glucose) and steric configuration of hydroxyl groups (glucose versus galactose) significantly affected yields of levulinic acid/ester (fructose>glucose>galactose). The dehydration of fructose to 5-(hydroxymethyl)furfural produces much less soluble polymer than that from glucose and galactose, which results in high yields of levulinic acid/ester from fructose. Anhydrate sugar such as levoglucosan tends to undergo the undesirable decomposition to form less levulinic acid/ester. Catalytic behaviors of the poly-sugars (sucrose, maltose, raffinose, ß-cyclodextrins) were determined much by their basic units. However, their big molecular sizes create the steric hindrance that significantly affects their followed conversion over solid acid catalyst.

The investigation of ADHD prevalence in kindergarten children in northeast Iran and a determination of the criterion validity of Conners' questionnaire via clinical interview.

In this study, the prevalence of attention-deficit hyperactivity disorder (ADHD) in kindergarten children in northeast Iran was investigated, and the criterion validity of Conners' parent-teacher questionnaire was evaluated through the use of clinical interviews. This study was a cross-sectional descriptive research project with children in kindergartens that was supported by the Behzisti Organization, which included 155 kindergartens and 4143 children. To study the prevalence of ADHD, cluster random sampling was used; 1083 children were chosen as a reference, and random sampling was used to determine the criterion validity. Twenty-two children scoring below a specified cut-off score and 32 children scoring above the cut-off score were interviewed. In the first stage, ADHD was assessed using Conners' parent-teacher questionnaire, and in the second stage, it was assessed with a clinical interview based on DSM-IV-TR criteria. Finally, the prevalence rate was evaluated with descriptive parameters, and the criterion validity was assessed using the tetracoric correlation coefficient. The prevalence of ADHD was estimated at 12.3% ± 2.12%. Moreover, test sensitivity and specificity were evaluated at 90.3% and 81.2%, respectively. Therefore, the criterion validity with α = 0.05 is 90.3%. The prevalence of ADHD among children was high, suggesting a need to screen all children for ADHD before school age. The Conners' questionnaire proved to be a good test for the primary screening of ADHD among kindergarten children.