Evaluation of Large-Scale Production of Chitosan Microbeads Modified with Nanoparticles Based on Exergy Analysis

Computer-Aided Modeling, Simulation, and Exergy Analysis of Large-Scale Production of Magnetite (Fe3O4) Nanoparticles via Coprecipitation

Magnetite nanoparticles present attractive properties including high magnetization, low toxicity, adsorption capacity, and simple preparation, making them efficient in water purification processes, soil remediation, and biomedical applications. In this sense, there is growing interest in the production of magnetite nanoparticles; therefore, evaluating the performance of this process on a large scale gives relevant information to process designers. In this work, the simulation and exergy analysis of large-scale production of magnetite nanoparticles via coprecipitation were performed using computer-aided tools. The process was modeled for the production of 807 t/year of magnetite nanoparticles; the data for the simulation were obtained from the literature, and experimental results were developed by the authors. The exergy efficiency of the process was estimated at 0.046%. The exergy of waste was estimated to be 105 313 MJ/h, while the unavoidable exergy losses were 2941 MJ/h. Washing 2 and 3 represented the most critical stages of the process, contributing 95.12% of the total irreversibilities due to the waste exergy, which corresponds to the water and ethanol exergy discarded in these stages. These results show that the process must be improved from the energy point of view and require the implementation of process optimization strategies to reach a more sustainable design.

Inherent Safety Assessment of Industrial-Scale Production of Chitosan Microbeads Modified with TiO2 Nanoparticles

In this study, the inherent safety analysis of large-scale production of chitosan microbeads modified with TiO₂ nanoparticles was developed using the Inherent Safety Index (ISI) methodology. This topology was structured based on two main stages: (i) Green-based synthesis of TiO₂ nanoparticles based on lemongrass oil extraction and titanium isopropoxide (TTIP) hydrolysis, and (ii) Chitosan gelation and modification with nanoparticles. Stage (i) is divided into two subprocesses for accomplishing TiO₂ synthesis, lemongrass oil extraction and TiO₂ production. The plant was designed to produce 2033 t/year of chitosan microbeads, taking crude chitosan, lemongrass, and TTIP as the primary raw materials. The process was evaluated through the ISI methodology to identify improvement opportunity areas based on a diagnosis of process risks. This work used industrial-scale process inventory data of the analyzed production process from mass and energy balances and the process operating conditions. The ISI method comprises the Chemical Inherent Safety Index (CSI) and Process Inherent Safety Index (PSI) to assess a whole chemical process from a holistic perspective, and for this process, it reflected a global score of 28. Specifically, CSI and PSI delivered scores of 16 and 12, respectively. The analysis showed that the most significant risks are related to TTIP handling and its physical-chemical properties due to its toxicity and flammability. Insights about this process's safety performance were obtained, indicating higher risks than those from recommended standards.

Gold(III) recovery from aqueous solutions by raw and modified chitosan: A review

Chitosan, a prestigious versatile biopolymer, has recently received considerable attention as a promising biosorbent for recovering gold ions, mainly Au(III), from aqueous solutions, particularly in modified forms. Confirming the assertion, this paper provides an up-to-date overview of Au(III) recovery from aqueous solutions by raw (unmodified) and modified chitosan. A particular emphasis is placed on the raw chitosan and its synthesis from chitin, characteristics of raw chitosan and their effects on metal sorption, modifications of raw chitosan for Au(III) sorption, and characterization of raw chitosan before and after modifications for Au(III) sorption. Comparisons of the sorption (conditions, percentage, capacity, selectivity, isotherms, thermodynamics, kinetics, and mechanisms), desorption (agents and percentage), and reusable properties between raw and modified chitosan in Au(III) recovery from aqueous solutions are also outlined and discussed. The major challenges and future prospects towards the large-scale applications of modified chitosan in Au(III) recovery from aqueous solutions are also addressed.

Inherent Safety Analysis and Sustainability Evaluation of Chitosan Production from Shrimp Exoskeleton in Colombia

Waste valorization strategies are key to achieve more sustainable production within the shrimp industry. The crustacean exoskeletons can be potentially used to obtain value-added products such as chitosan. A comprehensive analysis including both safety and sustainability aspects of chitosan production from shrimp shells is presented in this study. The inherent safety analysis and sustainability evaluation was performed using the Inherent Safety Index (ISI) methodology and the Sustainable Weighted Return on Investment Metric (SWROIM), respectively. The process was designed for a processing capacity of 57,000 t/year. The return on investment (%ROI), potential environmental impact (PEI output), exergy efficiency, and the total inherent safety index (ITI) were used as indicators to evaluate process sustainability. The total inherent safety index was estimated at 25 indicating that the process is inherently unsafe. The main process risks were given by handling of flammable substances, reactivity, and inventory subindices. The overall sustainability evaluation showed a SWROIM of 36.33% indicating that the case study showed higher weighted performance compared to the return on investment metric of 18.08%.

Comparison of Biobutanol Production Pathways via Acetone-Butanol-Ethanol Fermentation Using a Sustainability Exergy-Based Metric

The incorporation of sustainability aspects into the design of chemical processes has been increasing since the last century. Hence, there are several proposed methodologies and indicators to assess chemical facilities through process analysis techniques. A comprehensive assessment involving economic, environmental, safety, and exergy parameters of two alternatives for butanol production from Manihot esculenta Crantz (cassava waste) is presented in this study. The modeling of process topologies involved using Aspen Plus software. Topology 1 generated a product flow rate of 316,477 t/y of butanol, while this value was 367,037 t/y for topology 2. Both processes used a feed flow of 3,131,439 t/y of biomass. This study used seven technical indicators to evaluate both alternatives, which include the return of investment, discounted payback period, global warming potential, renewability material index, inherent safety index, exergy efficiency, and exergy of waste ratio. Otherwise, this study implemented an aggregate index to assess overall sustainability performance. The results revealed that topology 2 presented higher economic normalized scores for evaluated indicators, but the most crucial difference between these designs came from the safety and exergetic indexes. Topology 1 and topology 2 obtained weighted scores equaling to 0.48 and 0.53; therefore, this study found that the second alternative gives a more sustainable design for butanol production under evaluated conditions.

Application of Techno-economic and Sensitivity Analyses as Decision-Making Tools for Assessing Emerging Large-Scale Technologies for Production of Chitosan-Based Adsorbents

New ways and technologies for synthesizing adsorbent materials have been emerging based on the green chemistry concept for the sustainable use of available resources. In this sense, the chitosan-based products arise as a promising technology alternative for application of several fields that include mitigation, prevention, and control of environmental issues. Nevertheless, there is a lack of information about the development and behavior of these topologies at the industrial scale. This study addressed the techno-economic and sensitivity analyses as decision-making tools to assess promising topologies for production of chitosan-based bio-adsorbents. From the data provided by process inventory, economic analysis of these routes was implemented. The evaluation allowed obtaining a start point market price for chitosan microbeads (64.40 $/t) and chitosan microbeads modified with TiO2 nanoparticles (37 $/t). The economic analysis also showed that there is a vast potential to explore the chitosan market that enables generation of very profitable businesses from the implementation of those processes, considering the obtained economic performance indicators for both topologies. It is crucial to highlight that these indicators were slightly higher for chitosan microbead production. In addition, the sensitivity analysis indicated that the chitosan-TiO2 process could resist higher fluctuations in the operating costs, which might indicate that this topology might be a reliable alternative between evaluated cases.

Environmental and Safety Assessments of Industrial Production of Levulinic Acid via Acid-Catalyzed Dehydration

These days, there is a need to develop novel and emerging processing pathways that permit production of value-added substances and fuels considering sustainability aspects. In this sense, levulinic acid (LA) is one of the most promising biorefinery products. This paper presents environmental and safety assessments of LA production via acid-catalyzed dehydration (ACD) of biomass. The process was modeled by using Aspen Plus process simulation software based on a capacity of 132 000 tons per annum of banana rachis (main raw material). Likewise, environmental and safety assessments were developed. Parameters such as heats of reaction, explosivity, toxicity of substances, and operational conditions along with extended mass and energy balances were used to perform safety and environmental analyses. In this regard, the modeled topology showed an inherent safety index (ISI) score of 24 with an equal contribution of 12 points for both chemical inherent safety index (CIS) and process inherent safety index (PIS). ACD showed a good safety performance, with moderate concerns related to the handling of formic acid. Moreover, the waste reduction algorithm (WAR) was used to assess environmental performance and estimate potential environmental impacts (PEIs) of the simulated topology. It was performed considering four case studies to determine the influence of mass streams (case 1), product streams (case 2), energy streams (case 3), and simultaneous products and energy contribution (case 4). This analysis showed that for this process, the total inletting flow of impacts that enter was less than the amount of these that leave the system according to a generation rate of the PEI for case 1 (-1.89 × 10² PEI/h) and case 3 (-1.83 × 10² PEI/h). From the environmental viewpoint, the major concern is associated with the photochemical oxidation potential category because of the handling of volatile organic compounds through the process.

Computer-aided simulation and exergy analysis of TiO2 nanoparticles production via green chemistry

Background

The production of photocatalytic nanoparticles such as TiO₂ has received increasing interest for biomedical and wastewater treatment applications. However, the conventional synthesis of such materials faces several environmental concerns.

Methods

In this work, green synthesis is addressed to prepare TiO₂ nanoparticles at large scale using Lemongrass (Cymbopogon citratus) and titanium isopropoxide (TTIP). This process was designed and modeled using computer-aided process engineering (CAPE) in order to obtain the extended mass/energy balances, as well as operating parameters. Process simulation was carried out using the commercial software Aspen Plus^®. In addition, energy performance of large-scale nanoparticle production was analyzed to identify alternatives for process improvement from an exergetic point of view.

Results

The production capacity of the plant was estimated as 1,496 t/y of TiO₂ nanoparticles by the conversion of 32,675 t/y lemongrass and 5,724 t/y TTIP. Hence, the overall production yield is 0.26 kg TiO₂/kg TTIP. Exergy analysis reported an overall exergy efficiency of 0.27% and an exergy loss of 159,824.80 MJ/h. These results suggest that such a process requires the implementation of process improvement strategies to reach a more sustainable design from energy and thermodynamic viewpoints.

Towards Efficient and Clean Process Integration: Utilisation of Renewable Resources and Energy-Saving Technologies

The strong demand for sustainable energy supplies had escalated the discovery, and intensive research into cleaner energy sources, as well as efficient energy management practices. In the context of the circular economy, the efforts target not only the optimisation of resource utilisation at various stages, but the products’ eco-design is also emphasized to extend their life spans. Based on the concept of comprehensive circular integration, this review discusses the roles of Process Integration approaches, renewable energy sources utilisation and design modifications in addressing the process of energy and exergy efficiency improvement. The primary focus is to enhance the economic and environmental performance through process analysis, modelling and optimisation. The paper is categorised into sections to show the contribution of each aspect clearly, namely: (a) Design and numerical study for innovative energy-efficient technologies; (b) Process Integration—heat and power; (c) Process energy efficiency or emissions analysis; (d) Optimisation of renewable energy resources supply chain. Each section is assessed based on the latest contribution of this journal’s Special Issue from the 21st conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (PRES 2018). The key results are highlighted and summarised within the broader context of the state of the art development.