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Clean Technol., Volume 1, Issue 1 (December 2018)

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Open AccessArticle Preparation and Characterization of Chemically-Modified Biomaterials and Their Application as Adsorbents of Penicillin G
Clean Technol. 2018, 1(1), 114-124; https://doi.org/10.3390/cleantechnol1010008
Received: 22 May 2018 / Revised: 9 August 2018 / Accepted: 30 August 2018 / Published: 5 September 2018
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Abstract
The prevalence of antibiotics in water creates microbial resistance and has a negative impact on the ecosystem. Biomaterials such as spent tea leaves are rich in functional groups and are suitable for chemical modification for diverse applications. This research proposes the use of
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The prevalence of antibiotics in water creates microbial resistance and has a negative impact on the ecosystem. Biomaterials such as spent tea leaves are rich in functional groups and are suitable for chemical modification for diverse applications. This research proposes the use of spent tea leaves of chamomile (CM), green tea (GT), and peppermint (PM) as structural scaffolds for the incorporation of carboxyl, sulfonyl, and thiol groups to improve the adsorption of Penicillin G (Pe). Adsorbents characterization reported a higher number of acidic functional groups, mainly in thiolated products. Scanning electron microscopy (SEM) analysis showed changes on the surfaces of the adsorbents due to reaction conditions, with a stronger effect on thiolated and sulfonated adsorbents. Elemental analysis by Energy dispersive X-ray spectrophotometry (EDS) corroborated the chemical modification by the presence of sulfur atoms and the increase in oxygen/carbon ratios. Batch experiments at different pH shows a strong pH-dependence with a high adsorption at pH 8 for all the adsorbents. The adsorption follows the trend CMs > GTs > PMs. Thiolation and sulfonation reported higher adsorptions, which is most likely due to the sulfur bridge formation, reaching adsorption percentages of 25%. These results create a new mindset in the use of spent tea leaves and their chemical modifications for the bioremediation of antibiotics. Full article
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Open AccessArticle Modeling and Simulation of a Novel Combined Solar Photovoltaic-Thermal Panel and Heat Pump Hybrid System
Clean Technol. 2018, 1(1), 89-113; https://doi.org/10.3390/cleantechnol1010007
Received: 13 July 2018 / Revised: 3 August 2018 / Accepted: 7 August 2018 / Published: 13 August 2018
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Abstract
A numerical simulation model for a novel concept of a hybrid composed of photovoltaic-thermal solar panels and a heat pump is presented. This concept was developed to assess the performance and energy conversion efficiency of the hybrid system used to produce domestic hot
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A numerical simulation model for a novel concept of a hybrid composed of photovoltaic-thermal solar panels and a heat pump is presented. This concept was developed to assess the performance and energy conversion efficiency of the hybrid system used to produce domestic hot water and electricity. A two-dimensional heat transfer and fluid flow dynamic model was developed to describe the behavior of the hybrid system under different solar irradiance, heat pump boundary conditions and different refrigerants. The model is based on dynamic mass and energy equations coupled with the heat transfer coefficients, and the thermodynamic properties of refrigerants as well as material properties. The model compared fairly to experimental data. Full article
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Open AccessReview The Potential Renewable Energy for Sustainable Development in Tanzania: A Review
Clean Technol. 2018, 1(1), 70-88; https://doi.org/10.3390/cleantechnol1010006
Received: 13 June 2018 / Revised: 20 July 2018 / Accepted: 22 July 2018 / Published: 30 July 2018
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Abstract
Currently, renewable energy development is emphasized for sustainable development goals accomplishment and the better realization of sustainable development globally. Tanzania, like other developing countries, is striving to adopt different ways of ensuring affordable and accessible energy supply to its socioeconomic and political sectors
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Currently, renewable energy development is emphasized for sustainable development goals accomplishment and the better realization of sustainable development globally. Tanzania, like other developing countries, is striving to adopt different ways of ensuring affordable and accessible energy supply to its socioeconomic and political sectors to achieve renewable energy development. To secure affordable and accessible energy in the country, renewable energy is termed as an alternative energy source because of it is environmentally friendly. If renewable energy is produced and utilized in a modern and sustainable manner, it will help to eliminate energy problems in Tanzania. Thus, this study aims to review the current potential renewable energy for the achievement of sustainable development in Tanzania. Moreover, challenges of renewable energy development are examined. Full article
(This article belongs to the Special Issue Renewable and Sustainable Energy)
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Open AccessArticle On the Removal and Desorption of Sulfur Compounds from Model Fuels with Modified Clays
Clean Technol. 2018, 1(1), 58-69; https://doi.org/10.3390/cleantechnol1010005
Received: 25 May 2018 / Revised: 21 June 2018 / Accepted: 27 June 2018 / Published: 10 July 2018
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Abstract
The presence of sulfur compounds in fossil fuels has been an important concern in recent decades as an environmental risk due to the increase of greenhouse gases in the atmosphere and accentuation of acid rain. This study evaluates modified clays as low-cost and
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The presence of sulfur compounds in fossil fuels has been an important concern in recent decades as an environmental risk due to the increase of greenhouse gases in the atmosphere and accentuation of acid rain. This study evaluates modified clays as low-cost and efficient adsorbents for the removal of dibenzothiophene (BT) and 4,6-dibenzothiophene (DBT). Adsorption was investigated in a batch system with synthetic fuels (gasoline and diesel) as a function of type of clay modification, adsorbent dosage, initial concentration of the pollutants, desorption, and isotherm modeling. Maximum adsorption was observed with clays modified with benzyltrimethylammonium ion (BM), achieving a maximum adsorption capacity (qmax) of BT of 11.3 mg/g in gasoline and 31.3 mg/g in diesel. The formation of Van der Waals interaction as well as aromatic forces as the main mechanism is proposed based on the results. A 40% desorption was accomplished in 0.1 N HCl. Adsorbents were characterized by scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR), indicating their optimum properties as adsorbents in fuels. This work highlights the potential use of reverse polarity clays in the elimination of sulfur compounds from model fuels as a low-cost and environmentally friendly purification technique. Full article
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Open AccessArticle Biogas Cleaning: Activated Carbon Regeneration for H2S Removal
Clean Technol. 2018, 1(1), 40-57; https://doi.org/10.3390/cleantechnol1010004
Received: 5 March 2018 / Revised: 25 May 2018 / Accepted: 4 June 2018 / Published: 13 June 2018
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Abstract
The coupling of fuel cell technology with wastewater treatment plants (WWTPs) is within the sustainable development imperative for the integration of energy production purposes and recovery of materials, even if research is still under development in this field. The anaerobic digestion process can
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The coupling of fuel cell technology with wastewater treatment plants (WWTPs) is within the sustainable development imperative for the integration of energy production purposes and recovery of materials, even if research is still under development in this field. The anaerobic digestion process can be used for fuel cell feeding, only if trace contaminants are removed continuously. The most harmful and frequent contaminant is H2S. This article shows the results of H2S adsorption on activated carbon fixed-beds (dry process), since it is one of the best solutions from both the complexity and costs perspectives. Inside the wide range of commercial activated carbons, a specific commercial carbon has been used in test campaigns, since it is also used in the Società Metropolitana Acque Torino (SMAT) real plant. Thermal regeneration of spent carbons was exploited, using different conditions of temperature, treatment time and atmosphere, since it is a better cost-effective and environmentally sound option than immediate carbon disposal after adsorption. Regeneration with CO2 showed the best regeneration ratio values. In particular, the best conditions achieved were 300 °C and 75 min of thermal treatment time, with a regeneration ratio of 30%. Full article
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Open AccessReview The Drivers and Barriers of Renewable Energy Applications and Development in Uganda: A Review
Clean Technol. 2018, 1(1), 9-39; https://doi.org/10.3390/cleantechnol1010003
Received: 9 March 2018 / Revised: 23 April 2018 / Accepted: 27 April 2018 / Published: 6 May 2018
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Abstract
Following the increasing global awareness of the dangers posed by the present state of climate change, many countries such as Uganda have adapted long-term plans for a transition to decarbonised economies. A major strategy for decarbonisation is to replace fossil fuels with renewable
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Following the increasing global awareness of the dangers posed by the present state of climate change, many countries such as Uganda have adapted long-term plans for a transition to decarbonised economies. A major strategy for decarbonisation is to replace fossil fuels with renewable energy (RE) sources as the fundamental energy source. Uganda has substantial RE resources for the provision of energy services and production, yet these resources remain untapped. It is therefore crucial that the use of these abundant resources should be heightened. This paper examines and discusses the potential and current RE utilization and development in Uganda from the perspective of sustainable development. The status of the different RE resources and their application/utilization, including details of existing projects in the country, are carefully explored and discussed. The possible drivers for a huge advancement of RE applications and development in Uganda are also discussed before elucidating the major barriers and challenges faced by the energy sector as regards RE. Measures and policies required to facilitate the utilization of RE in Uganda are proposed. These evidence-based policies could guide the delivery of affordable and sustainable energy solutions for all by 2030 in Uganda. Full article
(This article belongs to the Special Issue Renewable and Sustainable Energy)
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Open AccessShort Note Membrane-Assisted Condenser
Clean Technol. 2018, 1(1), 2-8; https://doi.org/10.3390/cleantechnol1010002
Received: 5 March 2018 / Revised: 3 April 2018 / Accepted: 20 April 2018 / Published: 25 April 2018
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Abstract
In industrial processes, recycling and reusing of process streams—and of water, in particular—is necessary for minimizing fresh water requirements. Water supply issues are increasing in importance for new and existing industrial plants because the freshwater supply is limited and the forecast are that
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In industrial processes, recycling and reusing of process streams—and of water, in particular—is necessary for minimizing fresh water requirements. Water supply issues are increasing in importance for new and existing industrial plants because the freshwater supply is limited and the forecast are that by 2025 two-thirds of people will live in regions with water scarcity. In this short note, the potentialities of a membrane-assisted condenser for the recovery of evaporated waste water from industrial gases are presented. The modelling of the process was carried out for predicting the membrane-based process performance. The experimental data were compared with the results achieved through the simulations. The comparison showed good agreement confirming the validity of the realized model and its suitability for a screening of the operative conditions to be utilized. Full article
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Open AccessEditorial Introduction to a New Open Access Journal by MDPI: Clean Technologies
Clean Technol. 2018, 1(1), 1; https://doi.org/10.3390/cleantechnol1010001
Received: 14 February 2018 / Accepted: 14 February 2018 / Published: 14 February 2018
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Abstract
Nowadays, we are experiencing rapid economic and technological development all over the world[...] Full article
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