1,720,958 research outputs found
A review on the removal of carbamazepine from aqueous solution by using activated carbon and biochar
Full text linkCarbamazepine (CBZ), one of the most used pharmaceuticals worldwide and a Contaminant of Emerging Concern, represents a potential risk for the environment and human health. Wastewater treatment plants (WWTPs) are a significant source of CBZ to the environment, polluting the whole water cycle. In this review, the CBZ presence and fate in the urban water cycle are ad-dressed, with a focus on adsorption as a possible solution for its removal. Specifically, the scientific literature on CBZ removal by activated carbon and its possible substitute Biochar, is comprehensively scanned and summed up, in view of increasing the circularity in water treatments. CBZ adsorption onto activated carbon and biochar is analyzed considering several aspects, such as physicochemical characteristics of the adsorbents, operational conditions of the adsorption processes and adsorption kinetics and isotherms models. WWTPs usually show almost no removal of CBZ (even negative), whereas removal is witnessed in drinking water treatment plants through advanced treatments (even >90%). Among these, adsorption is considered one of the preferable methods, being economical and easier to operate. Adsorption capacity of CBZ is influenced by the characteristics of the adsorbent precursors, pyrolysis temperature and modification or activation processes. Among operational con-ditions, pH shows low influence on the process, as CBZ has no charge in most pH ranges. Differently, increasing temperature and rotational speed favor the adsorption of CBZ. The presence of other micro-contaminants and organic matter decreases the CBZ adsorption due to competition effects. These results, however, concern mainly laboratory-scale studies, hence, full-scale investigations are recommended to take into account the complexity of the real conditions
A novel treatment for Cd-contaminated solution through adsorption on beech charcoal: the effect of bioactivation
No full textIn this paper, biochar produced by pyrolysis of beech has been investigated as a potential adsorbent
for remediation of cadmium-contaminated groundwater. The experimental activity included
determination of the main physical–chemical characteristics of charcoal and the study of the
adsorption kinetics and isotherms through batch tests. Adsorption column tests were also carried out
and breakthrough curves determined. The same tests were repeated using the beech charcoal after the
addition of specific bacterial strains able to produce a reactive monolayer biofilm. The results showed
that both charcoal and bioactivated charcoal (biocharcoal) are effective adsorbents for Cd at initial concentration of 25 mg/L, with the latter providing slightly better performance. The pseudo-secondorder model provided the best fitting of the kinetic data of both media, with the following values of the constants: qe = 0.600 mg/g and ks = 0.395 g/mg min for charcoal, and qe = 1.409 mg/g and ks = 0.061 g/mg min for biocharcoal, where qe and ks stand for the equilibrium adsorption capacity and the constant rate, respectively. Among the isotherm models, the Langmuir equation provided the best fitting of the experimental data for both charcoal and biocharcoal. The maximum adsorption capacity of biocharcoal
was found to be about four times higher than that of charcoal (3.2 and 0.8 mg/g, respectively)
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
An Eco-Balanced and Integrated Approach for a More-Sustainable MSW Management
No full textAbstract: Strategies for Municipal Solid Waste (MSW) management can be sustainable only because of site-specific analyses and choices that take into account not only financial but also environmental costs. Generally, a correct approach should use different scenarios based on the environmental, social, economic and technological conditions of the specific area and on its expected potential. The aim of this paper is to presents an innovative model for the implementation of integrated MSW management approach which can result extremely useful where the MSW systems have to be refined or even designed such in the case of low-income countries. The proposed approach provides the best solid waste (SW) allocation/distribution among the available treatments and disposal options minimizing at the same time the total cost by means of an optimization procedure. The environmental impacts of potential scenarios are simultaneously estimated by means of a tailored Life Cycle Assessment procedure. The LCA tool in the model focus on the specific impacts from a SW management scenario that makes the model more explicit with respect to traditional LCA application. Additional tools allow, through site-specific numerical models, to provide also a preliminary evaluation of local impacts when required (e.g. atmospheric emissions). Such a model can be useful as a supporting tool in decision making for both governmental and non-governmental institutions involved in the planning of more sustainable eco-friendly strategies for MSW management. Graphic Abstract: [Figure not available: see fulltext.]
Experimental and numerical study of biochar fixed bed column for the adsorption of arsenic from aqueous solutions
Full text linkTwo laboratory tests were carried out to verify the suitability of an Italian commercial biochar as an adsorbing material. The chosen contaminant, considered dissolved in groundwater, was As. The circular economic concept demands the use of such waste material. Its use has been studied in recent years on several contaminants. The possibility of using an efficient material at low cost could help the use of low-impact technologies like permeable reactive barriers (PRBs). A numerical model was used to derive the kinetic constant for two of the most used isotherms. The results are aligned with others derived from the literature, but they also indicate that the use of a large amount of biochar does not improve the efficiency of the removal. The particular origin of the biochar, together with its grain size, causes a decrease in contact time required for the adsorption. Furthermore, it is possible that a strong local decrease in the hydraulic conductibility does not allow for a correct dispersion of the flow, thereby limiting its efficiency
A life cycle assessment of an energy-biochar chain involving a gasification plant in Italy
Full text linkLife cycle assessment (LCA) is a fundamental tool for evaluating the environmental and energy load of a production cycle. Its application to renewable energy production systems offers the possibility of identifying the environmental benefits of such processes—especially those related to the by-products of production processes (i.e., digestion or biochar). Biochar has received worldwide interest because of its potential uses in bioenergy production, due to its coproducts (bio-oil and syngas), as well as in global warming mitigation, sustainable agriculture, pollutant removal, and other uses. Biochar production and use of soil is a strategy for carbon sequestration that could contribute to the reduction of emissions, providing simultaneous benefits to soil and opportunities for bioenergy generation. However, to confirm all of biochar’s benefits, it is necessary to characterize the environmental and energy loads of the production cycle. In this work, soil carbon sequestration, nitrous oxide emissions, use of fertilizers, and use of water for irrigation have been considered in the biochar’s LCA, where the latter is used as a soil conditioner. Primary data taken from experiments and prior studies, as well as open-source available databases, were combined to evaluate the environmental impacts of energy production from biomass, as well as the biochar life cycle, including pre-and post-conversion processes. From the found results, it can be deduced that the use of gasification production of energy and biochar is an attractive strategy for mitigating the environmental impacts analyzed here—especially climate change, with a net decrease of about −8.3 × 103 kg CO2 eq. Finally, this study highlighted strategic research developments that combine the specific characteristics of biochar and soil that need to be amended
Cd-contaminated solution treatment by activated and non-activated beech charcoal
No full textBiochar obtained from pyrolysis of vegetable waste has been recognized to possess adsorbent capacity. Furthermore, it represents an economic and environmentally sustainable alternative to commercial adsorbents because, being a waste product, its use allows to avoid industrial activities for adsorbent production as well as to reduce the amount of waste to be disposed of.
In this paper, the biochar produced by pyrolysis of beech has been investigated as a potential adsorbent for remediation of cadmium-contaminated groundwater.
So far, beech charcoal has been mainly used as a soil amendment and only few experiences have been reported about its use as an adsorbent medium. The present experimental activity started with a series of analyses to obtain the main physical-chemical characteristics of charcoal. Adsorption kinetics and isotherms through batch experiments were then determined. Furthermore, breakthrough curves were obtained through column experiments. The same tests were repeated using the beech charcoal after modification through the addition of specific bacterial strains able to produce a reactive monolayer biofilm. The results showed that bio-activated charcoal has enhanced adsorption capacity for cadmium-contaminated solution.
Therefore, charcoal and bio-activated charcoal may be considered valid options as adsorbents for the remediation of solution contaminated by cadmium
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
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