Environmental and Exergetic Analysis of Large-Scale Production of Citric Acid-Coated Magnetite Nanoparticles via Computer-Aided Process Engineering Tools

Abstract

Considering that functional magnetite (Fe 3 O 4 ) nanoparticles with exceptional physicochemical properties can be highly applicable in different fields, scaling-up strategies are becoming important for their large-scale production. This study reports simulations of scaled-up production of citric acid-coated magnetite nanoparticles (Fe 3 O 4 -cit), aiming to evaluate the potential environmental impacts (PEIs) and the exergetic efficiency. The simulations were performed using the waste reduction algorithm and the Aspen Plus software. PEI and energy/exergy performance are calculated and quantified. The inlet and outlet streams are estimated by expanding the mass and energy flow, setting operating parameters of processing units, and defining a thermodynamic model for properties estimation. The high environmental performance of the production process is attributed to the low outlet rate of PEI compared to the inlet rate. The product streams generate low PEI contribution (−3.2 × 10 3 PEI/y) because of the generation of environmentally friendlier substances. The highest results in human toxicity potential (3.2 × 10 3 PEI/y), terrestrial toxicity potential (3.2 × 10 3 PEI/y), and photochemical oxidation potential (2.6 × 10 4 PEI/y) are attributed to the ethanol within the waste streams. The energy source contribution is considerably low with 27 PEI/y in the acidification potential ascribed to the elevated levels of hydrogen ions into the atmosphere. The global exergy of 1.38% is attributed to the high irreversibilities (1.7 × 10 5 MJ/h) in the separation stage, especially, to the centrifuge CF-2 (5.07%). The sensitivity analysis establishes that the global exergy efficiency increases when the performance of the centrifuge CF-2 is improved, suggesting to address enhancements toward low disposal of ethanol in the wastewater.

Layered double hydroxides: where should research stress on for massive scaling up?

“…The large-scale and sustainable production of LDH requires a quite long list of criteria, depending on the chemical composition. However, for any LDH composition given, one can mention general requirements inspired by the work of Patino-Ruiz et al 28 regarding the composite production of Fe 3 O 4 magnetite nanoparticles: (i) the availability of the precursors, (ii) satisfying production yield by batch, (iii) an excellent control process at any stage of the synthesis, and (iv) eco-friendly design both on the material and the process (possibility of recycling, limited waste, reduced occupational and environmental risks). Regarding these criteria, co-precipitation and mechanosynthesis are relevant candidates for comparison and discussion for large-scale LDH production.…”