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Research Project
Laboratory of Separation and Reaction Engineering - Laboratory of Catalysis and Materials
Funder
Authors
Publications
Unveiling Key Parameters: Time Windows and Travel Times in Capacitated Waste Collection
Publication . Silva, Adriano S.; Lima, José; Silva, Adrián; Gomes, Helder; Pereira, Ana I.
Numerous studies in waste management propose solutions
to the Waste Collection Problem, often focusing on constraints such as
time windows and truck capacity. Travel times between points play a vital
role in optimizing waste collection. However, the methods for determin- AQ1
ing them are frequently omitted. Another parameter that has a great
influence on waste collection is the time window. Here, the impact of
time windows and travel times on the capacitated waste collection problem
with time windows solution was assessed for collecting three waste
types. Surprisingly, travel times were found to have minimal influence on
route optimization, while time windows significantly affected the algorithm’s
ability to identify the most efficient collection route. Addressing AQ2
these considerations is crucial for practical application and improving
the performance of waste collection algorithms in real-world contexts.
Separation of CO2/N2 onto Shaped MOF MIL-160(Al) Using the Pressure Swing Adsorption Process for Post-combustion Application
Publication . Karimi, Mohsen; Siqueira, Rafael M.; Rodrigues, Alírio; Nouar, Farid; Silva, José A.C.; Serre, Christian; Ferreira, Alexandre F.P.
Adsorption processes have already been considered as an appealing technology for carbon capture and climate change mitigation. Accordingly, this work investigated the capacity of shaped MIL-160(Al) as a water stable bioderived Al dicarboxylate microporous metal-organic framework for separation of carbon dioxide and nitrogen concerning postcombustion application. First, breakthrough experiments of carbon dioxide and nitrogen were accomplished at 313 K and 4.0 bar. Then, a set of equations/relations were considered to model the dynamic fixed-bed tests, in which the outcomes proved the capacity of the developed model for such a purpose. Next, a pressure swing adsorption (PSA) process with five steps, including pressurization, feed, rinse, blowdown, and purge, was planned and validated using performed experiments in a laboratory-scale PSA setup. In the end, an industrial PSA process was designed to attain a better grasp of the capacity of MIL-160(Al) for postcombustion application. The results indicated an exciting potential of this adsorbent for postcombustion carbon capture, with the purity and recovery of carbon dioxide around 67.3 and 99.1%, respectively.
Beyond batch experiments: unveiling the potential of bimetallic carbon xerogels for catalytic wet peroxide oxidation of hospital wastewater in continuous mode
Publication . Silva, Adriano S.; Roman, Fernanda; Ribeiro, Rui; Garcia, Juan; Gomes, Helder
Single- and bimetallic carbon xerogels were prepared by incorporating iron and iron-cobalt precursors during their synthesis,
respectively, and tested in the catalytic wet peroxide oxidation (CWPO) of ibuprofen spiked into a simulated matrix in
batch mode. The bimetallic catalyst outperformed single and non-metallic catalyst by 25 and 85% after 360 min of reaction,
at mild temperature (30 °C). The best-performing catalyst was further used to treat hospital wastewater in a CWPO system
operating in full continuous mode. Process optimization was carried out considering different catalyst loads, temperatures,
and pH. The results obtained showed that the best conditions are initial pH 3, T = 80 °C, and a catalyst load of 35.4 mg cm−
3.
Having maintained values of chemical oxygen demand (COD) removals as high as 80% after 24 h of continuous operation,
the results herein reported revealed the high potential of the bimetallic carbon xerogel for CWPO of hospital wastewater
beyond conventional applications in batch mode. Despite some catalytic deactivation, the bimetallic carbon xerogel still
delivered a mineralization degree as high as 55% of the initial total organic carbon (TOC) content of the hospital wastewater
in the third 24-h cycle of CWPO in continuous mode of operation with successive catalyst reuse, as opposed to a 73% TOC
removal in the first cycle. Therefore, our results open prospects for the implementation of CWPO for hospital wastewater
treatment in continuous mode of operation.
Selective biphasic oxidation of nitrogenated contaminants with H2O2 using polyolefin-derived carbon nanotubes
Publication . Roman, Fernanda; Piccinin, Larissa; Silva, Adriano S.; Díaz de Tuesta, Jose Luis; Vieira, Admilson L.; Silva, Adrián; Faria, Joaquim; Gomes, Helder
Liquid/liquid biphasic oxidations are extensively employed in the chemical industry to manufacture a variety of
chemicals and for environmental issues, such as the oxidative denitrogenated (ODN) and desulfurization of fuels.
The ubiquitous presence of nitrogenated and sulfonated compounds in petroleum-derived fuels is associated with
environmental and health issues, driving legislation to become stricter regarding the content or related emissions
of those impurities. However, catalysts with high performance, low cost and high activity towards selective
oxidation of targeted contaminants should be developed. This work deals with the oxidative denitrogenation of
quinoline and pyridine, used as model nitrogenated compounds, using carbon nanotubes as catalysts, which were
derived from polyolefins (low-density polyethylene, high-density polyethylene and propylene) representative of
plastic solid waste (PSWs) mixtures found in municipal solid wastes. The carbon precursor used offers not only a
solution to reduce PSWs accumulation in waste management systems but also a cheap feedstock for preparing
CNTs. All PSWs-derived CNTs allowed to remove quinoline completely, pyridine, and both of them in a mixture
under the same conditions (1 h, 80 ◦C, ccat = 2.5 g L^-1, [H2O2]0 = 247 g L^-1, O/W volume ratio = 80:20, [N]0 =
108 mg L^-1). These results were maintained for up to 5 additional reuse cycles for the catalyst prepared with
mixed polyolefins.
Hardwood and softwood lignins from sulfite liquors: structural characterization and valorization through depolymerization
Publication . Casimiro, Filipa M.; Costa, Carina A.E.; Vega-Aguilar, Carlos; Rodrigues, Alírio
This work aims to evaluate the structural characteristics and study the oxidative depolymerization of lignins
obtained from hardwood and softwood sulfite liquors. Lignins were obtained after ultrafiltration and freeze-
drying of the sulfite liquors and characterized based on inorganic content, nitrobenzene oxidation, 13C NMR,
and molecular weight determination. The structural characteristics achieved allow evaluating the potential of
each lignin through oxidative depolymerization to produce added-value phenolic monomers. Hardwood and
softwood lignins were submitted to alkaline oxidation with oxygen and the reaction conditions optimized to
obtain a final oxidation mixture with the maximum yield of phenolic monomers. Through oxidation with O2,
hardwood lignin generates mostly syringaldehyde while lignin from softwood biomass mainly produces vanillin;
moreover, a lower reaction time and the interruption of O2 admission avoid the degradation of the oxidation
products in the final mixture for both lignins, more evidenced to hardwood lignin due to its higher reactivity.
From the results, it is possible to conclude that a phenolic aldehyde-rich oxidation mixture could be obtained,
confirming the viability of lignin as raw material to produce added-value products as vanillin and
syringaldehyde.
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Funders
Funding agency
Fundação para a Ciência e a Tecnologia
Funding programme
6817 - DCRRNI ID
Funding Award Number
UIDP/50020/2020