Production of bioplastic through food waste valorization

Tsang, Yiu Fai,Kumar, Vanish,Samadar, Pallabi,Yang, Yi,Lee, Jechan,Ok, Yong Sik,Song, Hocheol,Kim, Ki-Hyun,Kwon, Eilhann E.,Jeon, Young Jae Elsevier 2019 Environment international Vol.127 No.-

<P><B>Abstract</B></P> <P>The tremendous amount of food waste from diverse sources is an environmental burden if disposed of inappropriately. Thus, implementation of a biorefinery platform for food waste is an ideal option to pursue (e.g., production of value-added products while reducing the volume of waste). The adoption of such a process is expected to reduce the production cost of biodegradable plastics (e.g., compared to conventional routes of production using overpriced pure substrates (e.g., glucose)). This review focuses on current technologies for the production of polyhydroxyalkanoates (PHA) from food waste. Technical details were also described to offer clear insights into diverse pretreatments for preparation of raw materials for the actual production of bioplastic (from food wastes). In this respect, particular attention was paid to fermentation technologies based on pure and mixed cultures. A clear description on the chemical modification of starch, cellulose, chitin, and caprolactone is also provided with a number of case studies (covering PHA-based products) along with a discussion on the prospects of food waste valorization approaches and their economic/technical viability.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The tremendous amount of food waste (FW) is produced from diverse sources. </LI> <LI> To resolve FW problems, implementation of a biorefinery platform for FW is essential. </LI> <LI> The adoption of such a process can produce value-added products while reducing the waste. </LI> <LI> This review focuses on current technologies for the production of polyhydroxyalkanoates (PHA). </LI> <LI> Prospects of FW valorization are discussed along with their economic/technical viability. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Recently developed methods to enhance stability of heterogeneous catalysts for conversion of biomass-derived feedstocks

김수산,Yiu Fai Tsang,Eilhann E.Kwon,Kun-Yi Andrew Lin,이제찬 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.1

Many processes for the conversion of biomass and its derivatives into value-added products (e.g., fuels and chemicals) use heterogeneous catalysts. However, the catalysts often suffer from deactivation under harsh reaction conditions, such as liquid phase at high temperatures and pressures. The catalyst deactivation is a big obstacle to developing industrially relevant biomass conversion processes, including leaching, sintering, and poisoning of metals and collapse of catalyst support. Different approaches have been applied to limit the reversible and irreversible deactivation, highly associated with the kind of catalyst, reactants, reaction conditions, etc. This review presents recent advances in strategies to stabilize heterogeneous catalysts against deactivation for biomass conversion reactions.

Elimination of selected personal care products using biological augmentation with biochars

Yi YANG,Yiu Fai TSANG,Jorg RINKLEBE,Yong Sik Ok 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

Energy density enhancement <i>via</i> pyrolysis of paper mill sludge using CO₂

Lee, Jechan,Tsang, Yiu Fai,Kim, Sungpyo,Ok, Yong Sik,Kwon, Eilhann E. Elsevier 2017 Journal of CO<SUB>2</SUB> utilization Vol.17 No.-

<P><B>Abstract</B></P> <P>Paper manufacture is a very energy-intensive industry and generates a large amount of waste such as paper mill sludge (PMS). Given that the current PMS disposal ways (<I>e.g.</I>, incineration and landfilling) are not eco-friendly and costly, establishing an appropriate PMS disposal platform including energy recovery is crucial to making more environmentally benign and economically viable industrial paper manufacturing process. In this respect, this study places a great emphasis on investigating the influence of CO<SUB>2</SUB> on pyrolysis of PMS by systematical analysis of major three-phase pyrolytic products, such as gases and tar, under N<SUB>2</SUB> and CO<SUB>2</SUB> atmospheres. It was validated that using CO<SUB>2</SUB> as a reaction medium in pyrolysis of PMS not only increased the production of CO (a major constituent of syngas) by ∼1000% but also decreased the amount of tar by 23%. The increase in CO production and decrease in tar formation likely resulted from reactions between CO<SUB>2</SUB> and volatile organic compounds (VOCs) generated from thermal decomposition of PMS, which could be expedited by catalytic effects of minerals contained in PMS. The results shown in this paper could be applied to design green paper manufacturing processes efficiently utilizing a potent greenhouse gas, CO<SUB>2</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Paper mill sludge (PMS) disposal <I>via</I> the thermo-chemical process. </LI> <LI> Using CO<SUB>2</SUB> for the energy density enhancement. </LI> <LI> The influence of CO<SUB>2</SUB> was enhanced in the presence of minerals of PMS. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced energy recovery from polyethylene terephthalate via pyrolysis in CO₂ atmosphere while suppressing acidic chemical species

Lee, Jechan,Lee, Taewoo,Tsang, Yiu Fai,Oh, Jeong-Ik,Kwon, Eilhann E. Elsevier 2017 Energy conversion and management Vol.148 No.-

<P><B>Abstract</B></P> <P>Herein, CO<SUB>2</SUB> is employed as a pyrolysis medium for thermal treatment (i.e., pyrolysis) of polyethylene terephthalate (PET) waste in an environmentally benign way. The CO<SUB>2</SUB>-assited pyrolysis provides a novel way to not only enhance energy recovery from the PET waste but also reduce acidic byproducts such as benzoic acid. The generation of carbon monoxide (CO) for pyrolysis of the PET waste in CO<SUB>2</SUB> is ∼5 times more than that in N<SUB>2</SUB>. In addition to the enhancement of CO generation, the compositions of benzene derivatives, PAHs, and acidic compounds are lower in pyrolytic products in CO<SUB>2</SUB> than that in N<SUB>2</SUB>. This study suggests that the employment of CO<SUB>2</SUB> in pyrolysis of PET waste would be a more environmentally friendly waste treatment process with enhancing energy recovery.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO<SUB>2</SUB> is used as a pyrolysis medium for treating polyethylene terephthalate (PET) waste. </LI> <LI> The generation of CO for pyrolysis of PET waste is enhanced in CO<SUB>2</SUB> condition. </LI> <LI> CO<SUB>2</SUB> reduces production of acidic byproducts like benzoic acid for pyrolysis of PET. </LI> </UL> </P>

Designer carbon nanotubes for contaminant removal in water and wastewater: A critical review

Sarkar, Binoy,Mandal, Sanchita,Tsang, Yiu Fai,Kumar, Pawan,Kim, Ki-Hyun,Ok, Yong Sik Elsevier BV 2018 Science of the Total Environment Vol.612 No.-

<P><B>Abstract</B></P> <P>The search for effective materials for environmental cleanup is a scientific and technological issue of paramount importance. Among various materials, carbon nanotubes (CNTs) possess unique physicochemical, electrical, and mechanical properties that make them suitable for potential applications as environmental adsorbents, sensors, membranes, and catalysts. Depending on the intended application and the chemical nature of the target contaminants, CNTs can be designed through specific functionalization or modification processes. Designer CNTs can remarkably enhance contaminant removal efficiency and facilitate nanomaterial recovery and regeneration. An increasing number of CNT-based materials have been used to treat diverse organic, inorganic, and biological contaminants. These success stories demonstrate their strong potential in practical applications, including wastewater purification and desalination. However, CNT-based technologies have not been broadly accepted for commercial use due to their prohibitive cost and the complex interactions of CNTs with other abiotic and biotic environmental components. This paper presents a critical review of the existing literature on the interaction of various contaminants with CNTs in water and soil environments. The preparation methods of various designer CNTs (surface functionalized and/or modified) and the functional relationships between their physicochemical characteristics and environmental uses are discussed. This review will also help to identify the research gaps that must be addressed for enhancing the commercial acceptance of CNTs in the environmental remediation industry.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CNTs can be designed through specific functionalization or modification process. </LI> <LI> Designer CNTs can enhance contaminant removal efficiency. </LI> <LI> CNTs can facilitate recovery and regeneration of nanomaterials. </LI> <LI> CNTs hold potential applications in wastewater purification and desalination. </LI> <LI> Further research is needed to enhance commercial acceptance of CNTs. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Employing CO₂ as reaction medium for <i>in-situ</i> suppression of the formation of benzene derivatives and polycyclic aromatic hydrocarbons during pyrolysis of simulated municipal solid waste

Lee, Jechan,Choi, Dongho,Tsang, Yiu Fai,Oh, Jeong-Ik,Kwon, Eilhann E. Elsevier Applied Science Publishers 2017 Environmental pollution Vol.224 No.-

<P><B>Abstract</B></P> <P>This study proposes a strategic principle to enhance the thermal efficiency of pyrolysis of municipal solid waste (MSW). An environmentally sound energy recovery platform was established by suppressing the formation of harmful organic compounds evolved from pyrolysis of MSW. Using CO<SUB>2</SUB> as reaction medium/feedstock, CO generation was enhanced through the following: 1) expediting the thermal cracking of volatile organic carbons (VOCs) evolved from the thermal degradation of the MSWs and 2) directly reacting VOCs with CO<SUB>2</SUB>. This particular influence of CO<SUB>2</SUB> on pyrolysis of the MSWs also led to the <I>in-situ</I> mitigation of harmful organic compounds (<I>e.g.</I>, benzene derivatives and polycyclic aromatic hydrocarbons (PAHs)) considering that CO<SUB>2</SUB> acted as a carbon scavenger to block reaction pathways toward benzenes and PAHs in pyrolysis. To understand the fundamental influence of CO<SUB>2</SUB>, simulated MSWs (<I>i.e.</I>, various ratios of biomass to polymer) were used to avoid any complexities arising from the heterogeneous matrix of MSW. All experimental findings in this study suggested the foreseeable environmental application of CO<SUB>2</SUB> to energy recovery from MSW together with disposal of MSW.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO<SUB>2</SUB> mitigates the formations of benzene derivatives and PAHs in pyrolysis of MSW. </LI> <LI> CO<SUB>2</SUB> acts as a carbon scavenger to mitigate air pollutants. </LI> <LI> CO<SUB>2</SUB> increases gaseous products from pyrolysis of MSW. </LI> <LI> CO<SUB>2</SUB> enhances the production of CO from pyrolysis of MSW. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Modification of hydrothermal liquefaction products from <i>Arthrospira platensis</i> by using carbon dioxide

Choi, Dongho,Lee, Jechan,Tsang, Yiu Fai,Kim, Ki-Hyun,Rinklebe, Jö,rg,Kwon, Eilhann E. Elsevier Science B.V. Amsterdam 2017 Algal research Vol.24 No.1

<P><B>Abstract</B></P> <P>This study mainly reports that utilizing CO<SUB>2</SUB> as a reaction medium in hydrothermal liquefaction of <I>Arthrospira platensis,</I> as a model feedstock of microalgal biomass, provides a means for modifying the chemical constituents in microalgal bio-oil produced via hydrothermal liquefaction. Prior to hydrothermal liquefaction, the total lipid content of <I>A. platensis</I> was measured as ~3.5wt% (dry basis). Thermal degradation of <I>A. platensis</I> and the major pyrolytic gases from the thermal degradation of <I>A. platensis</I> were characterized to gain an insight into the physico-chemical influences of CO<SUB>2</SUB> in hydrothermal liquefaction. Based on the experiment's findings, hydrothermal liquefaction of <I>A. platensis</I> was conducted to evaluate the influence of CO<SUB>2</SUB>. Hydrothermal liquefaction of <I>A. platensis</I> in CO<SUB>2</SUB> decreased the composition of N-containing species from 63 to 59% and that of O-containing species from 31 to 27% in the bio-oil, significantly suggesting that using CO<SUB>2</SUB> improves the quality of bio-oil as a transportation fuel.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CO<SUB>2</SUB> modifies N & O contents in <I>A. platensis</I>-bio-oil via hydrothermal liquefaction </LI> <LI> Liquefaction in CO<SUB>2</SUB> produces more CO from <I>A. platensis</I> </LI> <LI> Less N & O contained hydrocarbons produced from liquefaction of <I>A. platensis</I> in CO<SUB>2</SUB> </LI> </UL> </P>

Catalytic co-pyrolysis of cellulose and linear low-density polyethylene over MgO-impregnated catalysts with different acid-base properties

Ryu, Hae Won,Tsang, Yiu Fai,Lee, Hyung Won,Jae, Jungho,Jung, Sang-Chul,Lam, Su Shiung,Park, Eun Duck,Park, Young-Kwon Elsevier 2019 Chemical engineering journal Vol.373 No.-

<P><B>Abstract</B></P> <P>Various MgO impregnated catalysts were used for the catalytic co-pyrolysis (CCP) of cellulose and linear low-density polyethylene (LLDPE) at 600 °C in ambient pressure. Micro reactor-gas chromatography, a semi-batch reactor, was used as a reactor and gas chromatogram/mass spectrometry/flame ionization detector were used for product detection. Three kinds of MgO impregnated catalysts, MgO/Carbon (MgO/C), MgO/Al<SUB>2</SUB>O<SUB>3</SUB>, and MgO/ZrO<SUB>2</SUB>, were prepared by the impregnation of MgO to different s, C, Al<SUB>2</SUB>O<SUB>3</SUB>, and ZrO<SUB>2</SUB>, respectively. Activities of the three MgO-impregnated catalysts were compared with 1:5 of feedstock to catalyst ratio. MgO/C produced the highest quality oil, which consisted of a large amount of aromatic hydrocarbons during the catalytic pyrolysis (CP) of cellulose. When the MgO catalysts were applied to CCP, the selectivity to aromatic hydrocarbons over MgO/C were 13.42%, which were also much higher than those over the other catalysts, including bulk MgO, demonstrating the effectiveness of the MgO/C catalyst on aromatics formation. Importantly, the experimental BTEXs (benzene, toluene, ethylbenzene, xylenes) yields of CCP over MgO/C were also much higher than the theoretical yields, highlighting the effectiveness of hydrogen-rich LLDPE on the CP of cellulose over MgO/C. Further investigation of the cellulose/LLDPE mixing ratio showed that the amount of BTEXs during the CCP of cellulose and LLDPE could be maximized by adjusting the cellulose to LLDPE mixing ratio to 25:75.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co-pyrolysis of cellulose and LLDPE over MgO catalysts was performed. </LI> <LI> MgO catalysts with different surface area and acid/base properties were used. </LI> <LI> MgO/C has largest surface area and adequate acid-base property. </LI> <LI> MgO/C produced the largest amounts of aromatics. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of carbon-slag composite via a pyrolytic platform and its environmental application for arsenic removal as a case study

Lee, Taewoo,Oh, Jeong Ik,Yi, Haakrho,Tsang, Yiu Fai,Kwon, Eilhann E. Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.361 No.-

<P><B>Abstract</B></P> <P>For the valorization of biomass and steel slag, co-pyrolysis of rice straw and steel slag was carried out as a case study. To achieve the more sustainable pyrolytic platform, carbon dioxide (CO<SUB>2</SUB>) was employed as reactive medium. Therefore, this study laid great emphasis on chasing the mechanistic roles of CO<SUB>2</SUB> in the thermolysis of the mixture (rice straw + steel slag) at the fundamental level. This study experimentally validated that CO<SUB>2</SUB> reacted with thermally induced hydrocarbon species from rice straw via the gas phase reactions. Such reactions resulted in CO formation at temperatures ≥ 480 °C, of which the reaction kinetics was catalytically accelerated when steel slag was co-pyrolyzed with rice straw. Note that steel slag contained the significant amount of metals and alkaline compounds. However, co-pyrolysis of rice straw and acid-washed slag revealed that the enhanced reaction kinetics resulting in CO formation at temperatures ≥ 480 °C was imparted from alkaline compounds such as CaCO<SUB>3</SUB>. Also, this study showed that CO<SUB>2</SUB> effectively suppressed dehydrogenation during the thermolysis of rice straw. Such mechanistic roles of CO<SUB>2</SUB> played a pivotal role to shift carbon distribution from pyrolytic oil to pyrolytic gas. The different thermal degradation routes triggered by CO<SUB>2</SUB> led to the morphologic change to carbon-slag composite. In detail, the surface area of carbon-slag composite was enlarged in the CO<SUB>2</SUB> atmosphere. To impart the desirable functionality, the surplus amount of CO formed from CO<SUB>2</SUB> was re-used to transform iron oxides in the composite into zero-valent iron (Fe<SUP>0</SUP>). Porosity and zero-valent iron in carbon-slag composite increased the As(V) sorptive capability, of which the removal efficiency reached up to 99.3% at pH 6.9.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Co-pyrolysis of rice straw and steel slag for waste disposal and energy recovery. </LI> <LI> CO<SUB>2</SUB> co-feed effect was enhanced by catalytic capability imparted from steel slag. </LI> <LI> Carbon-slag composite fabrication was further modified using CO<SUB>2</SUB> and syngas. </LI> <LI> Removal efficiency of As using carbon-slag composite reached up to 99.3%. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>