1,720,965 research outputs found
Remediation of Lead-Contaminated Water by Virgin Coniferous Wood Biochar Adsorbent. Batch and Column Application
Full text linkIn this paper, RE-CHAR® biochar, produced by a wood biomass pyrolysis process, which is usually applied as a soil fertilizer, was investigated for a novel use, that was as adsorbent for remediating a lead-contaminated solution. Firstly, a deep physical and chemical characterization of RE-CHAR® biochar was carried out. Then, the adsorption capacity of lead from 50 to 100 mg/L solutions was determined under batch and continuous flow conditions. Kinetics of the batch adsorption process were very rapid and complete removal was achieved within 4-h contact time at both Pb concentrations, using a biochar dosage of 5 g/L. These data were best fitted by the pseudo-second-order model, with the rate constant and the equilibrium capacity equal to ks = 0.0091 g/min and qe = 9.9957 mg/g at 50 mg/L Pb and ks = 0.0128 g/min and qe = 20.1462 mg/g at 100 mg/L Pb, respectively. The Langmuir isotherm model best fitted the equilibrium data at both Pb concentrations, with the Langmuir constant and maximum adsorption capacity equal to b = 11.5804 L/mg and qmax = 4.6116 mg/g at 50 mg/L Pb and b = 2.8933 L/mg and qmax = 9.5895 mg/g at 100 mg/L Pb. Continuous flow column tests showed that adding biochar to the soil of the adsorbent bed significantly extended the breakthrough and exhaustion times, with respect to the column filled with soil only. The Thomas model best fitted the experimental data of the breakthrough curves, with the constant kTH = 5.28 × 10−5 mL/min/mg and the maximum adsorption capacity q0 = 334.57 mg/g which was comparable to the values reported for commercial adsorbents. Based on these results, it can be assessed that RE-CHAR® biochar can be used as an effective adsorbent for lead removal from water solutions even at high concentrations
Biochar as reactive material for heavy metals removal from contaminated water
No full textSeveral studies have recognized that biochar, obtained from pyrolysis of vegetable waste and by-product from agriculture and forestry, can be considered suitable for its adsorbent characteristics to remove different types of contaminants, both organic and inorganic, from soil and water. In fact, nowadays, due to its distinctive characteristics such as microporosity, high specific surface area, high adsorption capacity and ion exchange capacity, research is focusing on many other possible application of this promising material. A further advantage is the fact that biochar can be considered a sustainable alternative to commercial adsorbents because, being a residual product, its use allows to avoid industrial production as well as to reduce the amount of waste to be disposed. Furthermore, the scientific research, concerning the presence and the removal of pollutants from contaminated water, particularly persistent as heavy metals, is still evolving. In this Ph.D. thesis, biochar will be investigated as a potential adsorbent media for heavy metals removal – in particular arsenic and lead – from contaminated water. Compared to commercial adsorbents biochar represents a new valid alternative from an economic and environmental point of view with good application prospects in many fields. As a consequence, the interest in this material has grown enormously, due to its ability to improve the physical, chemical, biological and mechanical properties of the soil. Biochar in Italy has been mainly used, until now, as a soil amendment in agriculture practices. Its capability in playing an adsorbent role can therefore be particularly interesting, focusing on its ability to remove heavy metals from contaminated water. The research was mainly based on experimental activity, after an accurate bibliographic research and acquisition of the literature data, at a multidisciplinary level, in order to understand the emerging research fields of environmental engineering concerning biochar and its multiple use. The first phase of experimental activity will be focused on the determination of the main physical-chemical characteristics of biochar, also carrying out a comparison with a commercial activated carbon. In the successive phases batch and column tests will be used to investigate the performance of biochar, for arsenic and lead removal from aqueous solutions. As regards the batch tests, the data, relating to experimental activities, will be interpreted through the most used models in the case of heavy metals adsorption from contaminated water, for the determination of kinetics and adsorption isotherms. With regard to the experimentation in the column, breakthrough curves will be identified and the characteristic parameters of the system will be used to validate the obtained data. Therefore, starting from the obtained experimental results, biochar may be considered as a useful alternative as adsorbent media for heavy metals removal from contaminated water. Finally, some experimental hypotheses have been suggested in order to continue the research activity, with the aid of further targeted experimental tests
LuckyMera: a modular AI framework for building hybrid NetHack agents
No full textIn the last few decades we have witnessed a significant development in Artificial Intelligence (AI) thanks to the availability of a variety of testbeds, mostly based on simulated environments and video games. Among those, roguelike games offer a very good trade-off in terms of complexity of the environment and computational costs, which makes them perfectly suited to test AI agents generalization capabilities. In this work, we present LuckyMera, a flexible, modular, extensible and configurable AI framework built around NetHack, a popular terminal-based, single-player roguelike video game. This library is aimed at simplifying and speeding up the development of AI agents capable of successfully playing the game and offering a high-level interface for designing game strategies. LuckyMera comes with a set of off-the-shelf symbolic and neural modules (called "skills"): these modules can be either hard-coded behaviors, or neural Reinforcement Learning approaches, with the possibility of creating compositional hybrid solutions. Additionally, LuckyMera comes with a set of utility features to save its experiences in the form of trajectories for further analysis and to use them as datasets to train neural modules, with a direct interface to the NetHack Learning Environment and MiniHack. Through an empirical evaluation we validate our skills implementation and propose a strong baseline agent that can reach state-of-the-art performances in the complete NetHack game. LuckyMera is open-source and available at https://github.com/Pervasive-AI-Lab/LuckyMera
Application of biochar to the remediation of Pb-contaminated solutions
Full text linkBIOTON® biochar, produced by a wood biomass pyrolysis process, which is usually applied as soil amendment, was investigated for a novel application, i.e., the adsorption of lead from contaminated solutions. The experimental activity included physical and chemical characterization of BIOTON®; and Scanning Electron Microscope (SEM) images to highlight its internal structure. The adsorption process was investigated through batch and column experiments. Adsorption kinetics showed very rapid achievement of equilibrium conditions, i.e., 50 mg/L and 100 mg/L initial Pb concentration at 2 h and 4 h, respectively. Complete removal also occurred within the same time. The Brunauer–Emmett–Teller model was a better fit for the equilibrium data of both Pb concentrations, whereas the kinetics were best represented by the pseudo second-order model. Column tests showed that the addition of biochar as an adsorbent media within the bed significantly extended the time of breakthrough and exhaustion, with respect to the column filled with soil only. The values found for the adsorption capacity of BIOTON®- versus lead-containing solutions were comparable to those reported for commercial adsorbents. Therefore, BIOTON® can be considered a valid option: It also offers the additional benefit of allowing the recovery of a residue, which alternately would need to be disposed of
Remediation of Water Contaminated by Pb(II) Using Virgin Coniferous Wood Biochar as Adsorbent
No full textCharcoal from vegetable wastes showed good adsorbent properties for lead-contaminated water. Adsorption capacity at equilibrium was about 10 and 20 mg/g at 50 and 100 mg/L Pb, respectively. Breakthrough curves highlighted longer operation times of column plant filled with charcoal mixed sand than with sand only
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
LCA Sensitivity Analysis of an Energy-Biochar Chain from an Italian Gasification Plant: Environmental Trade-offs Assessment
Full text linkDue to its potential applications in bioenergy production, coproducts (bio-oil and syngas), mitigation of global warming, sustainable agriculture, pollutant removal, and other uses, biochar has drawn interest from all over the world. Producing and using soil-based biochar as a method of carbon sequestration could help reduce emissions while benefiting the soil and opening up possibilities for bioenergy production. However, to characterize the production cycle’s environmental and energy loads and confirm all of the advantages of biochar, Life Cycle Assessment (LCA) represents a reliable tool for evaluation. This work is based on continuing the study of Marzeddu and Cappelli (Marzeddu, Cappelli, et al., 2021) to understand the environmental impact of an energy-biochar chain involving a gasification plant in Italy. In the LCA carried out in the previous paper for the characterization of biochar, which is used as a soil conditioner, soil carbon sequestration, nitrous oxide emissions, fertilizer use, and water use for irrigation were considered. The results showed that the use of gasification for energy and biochar is an attractive strategy for mitigating the environmental impact analysis, especially climate change, with a net decrease of about ‒8.3·103 kg CO2, eq. The previous study was lacking a sensitivity analysis. For this reason, a sensitivity analysis is proposed in this study to consistently assess the environmental trade-offs of the biochar and the amended soil. In specific for the upstream processes the sensitivity is addressed to the selection of a different type of woodchips, for the core process in terms of selection of different packing material, and to the entire cradle-to-grave perspective by improving the logistics of the transportation, the distances within the supply chain and the choice of BAT technology for the transportation vehicles. This study highlights strategic research developments that combine to find potential environmental trade-offs and thresholds towards using biochar and its final use as a soil conditioner
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
