Sustainable solvents are a topic of growing interest in both the research community and the chemical industry due to a growing awareness of the impact of solvents on pollution, energy usage, and contributions to air quality and climate change. Solvent losses represent a major portion of organic pollution, and solvent removal represents a large proportion of process energy consumption. To counter these issues, a range of greener or more sustainable solvents have been proposed and developed over the past three decades. Much of the focus has been on the environmental credentials of the solvent itself, although how a substance is deployed is as important to sustainability as what it is made from. In this Review, we consider several aspects of the most prominent sustainable organic solvents in use today, ionic liquids, deep eutectic solvents, supercritical fluids, switchable solvents, liquid polymers, and renewable solvents. We examine not only the performance of each class of solvent within the context of the...

Green and Sustainable Solvents in Chemical Processes

Global warming due to the accumulation of atmospheric CO2 has received widespread attention in recent years. Although various CO2 capture technologies have been proposed, using the captured CO2 from power plants is increasingly popular because of concerns with regard to the safety of underground and ocean CO2 storage. Various techniques related to utilization of CO2 from the exhausted gas of power plants are discussed in this article. The existing and under-development technologies for CO2 utilization in the world are briefly reviewed. Two categories, direct utilization of CO2 and conversion of CO2 to chemicals and energy products, are used to classify different forms of CO2 utilization. Regarding the direct utilization of CO2, in addition to its use in soft drinks, welding, foaming, and propellants, as well as the use of supercritical CO2 as a solvent, CO2 capture via photosynthesis to directly fix carbon into microalgae has also attracted the attention of researchers. The conversion of CO2 into chemicals and energy products via this approach is a promising way to not only reduce the CO2 emissions, but also generate more economic value. Since CO2 is just a source of carbon without hydrogen, a clean, sustainable and cheap source of hydrogen should be developed. This article reviews the literature on the production of biofuel from microalgae cultivated using captured CO2, the conversion of CO2 with hydrogen to chemicals and energy products, and sustainable and clean sources of hydrogen, in order to demonstrate the potential of CO2 utilization.

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A Review: CO2 Utilization

Microalgae has been identified as a potential feedstock for biodiesel production since its cultivation requires less cropland compared to conventional oil crops and the high growth rate of microalgae. Research on microalgae oils often are focused on microalgae oil extraction and biomass harvesting techniques. However, energy intensive and costly lipid extraction methods are the major obstacles hampering microalgae biodiesel commercialisation. Direct biodiesel synthesis avoids such problems as it combines lipid extraction techniques and transesterification into a single step. In this review, the potential of direct biodiesel synthesis from microalgae biomass was comprehensively analysed. The various species of microalgae commonly used as biodiesel feedstock was critically assessed, particularly on high lipid content species. The production of microalgae biodiesel via direct conversion from biomass was systematically discussed, covering major enhancements such as heterogeneous catalysts, the use of ultrasonic and microwave- techniques and supercritical alcohols that focus on the overall improvement of biodiesel production. In addition, this review illustrates the cultivation conditions for biomass growth and lipid productivity improvement, the available harvesting and lipid extraction technologies, as well as the key challenges and future prospect of microalgae biodiesel production. This review serves as a basis for future research on direct biodiesel synthesis from modified microalgae biomass to improve profitability of microalgae biodiesel.

Sustainability of direct biodiesel synthesis from microalgae biomass: a critical review.

Multifaceted roles of microalgae in the application of wastewater biotreatment: A review

https://cyberleninka.org/article/n/1459363.pdf

Solid amine sorbents for CO2 capture by chemical adsorption: A review

Fossil fuels, which are recognized as unsustainable sources of energy, are continuously consumed and decreased with increasing fuel demands. Microalgae have great potential as renewable fuel sources because they possess rapid growth rate and the ability to store high-quality lipids and carbohydrates inside their cells for biofuel production. Microalgae can be cultivated on opened or closed systems and require nutrients and CO_2 that may be supplied from wastewater and fossil fuel combustion. In addition, CO_2 capture via photosynthesis to directly fix carbon into microalgae has also attracted the attention of researchers. The conversion of CO_2 into chemical and fuel (energy) products without pollution via this approach is a promising way to not only reduce CO_2 emissions but also generate more economic value. The harvested microalgal biomass can be converted into biofuel products, such as biohydrogen, biodiesel, biomethanol, bioethanol, biobutanol and biohydrocarbons. Thus, microalgal cultivation can contribute to CO_2 fixation and can be a source of biofuels. This article reviews the literature on microalgae that were cultivated using captured CO_2, technologies related to the production of biofuels from microalgae and the possible commercialization of microalgae-based biofuels to demonstrate the potential of microalgae. In this respect, a number of relevant topics are addressed: the nature of microalgae (e.g., species and composition); CO_2 capture via microalgae; the techniques for microalgal cultivation, harvesting and pretreatment; and the techniques for lipid extraction and biofuel production. The strategies for biofuel commercialization are proposed as well.

/pdf/a-review-microalgae-and-their-applications-in-co-2-capture-1tls10n8kv.pdf

A Review: Microalgae and Their Applications in CO_2 Capture and Renewable Energy

Polyethylenimine-containing mesoporous silica powders (PEI-MSP) were prepared through one-pot synthesis from mixtures of tetraethyl orthosilicate and PEI in water/methanol. This proposed route required only 4% of reaction time and energy and used 50% of chemical reagents used in two-step synthesis of PEI-loaded SBA-15 (PEI/SBA) prepared through impregnation, thereby decreasing the cost of the resulting adsorbents. The PEI component in the one-pot route functioned not only to provide amine active sites for CO2 capture but also as a basic catalyst and a pore-structure-directing agent. The pelletized PEI-MSP using our proposed binder solution possessed high mechanical strength, durability, and CO2 adsorption capacity and recovery, satisfying industrial requirements and reducing the pressure drop in practical use. Dynamic adsorption–desorption cycles of PEI-MSP powders and pellets revealed high thermal stabilities. Therefore, this one-pot synthetic route is promising for preparing PEI-MSP as appropriate adsor...

Worasaung Klinthong

Papers

A Review: Microalgae and Their Applications in CO_2 Capture and Renewable Energy

One-Pot Synthesis and Pelletizing of Polyethylenimine-Containing Mesoporous Silica Powders for CO2 Capture

Continuous extraction of lipids from Schizochytrium sp. by CO2-expanded ethanol.

Polyallylamine and NaOH as a novel binder to pelletize amine-functionalized mesoporous silicas for CO2 capture

Optimization of continuous lipid extraction from Chlorella vulgaris by CO2-expanded methanol for biodiesel production