## 1 Introduction  
The magnetic iron oxide nanoparticles are materials with important properties and can be used for different applications. The magnetite (Fe\({}_{3}\)O\({}_{4}\)) are a type of nanoparticles that belong to a special group and they have been drawing expressive technological interests due to their outstanding properties and potential applications in fields as medicine, biotechnology, engineering, among others [1]. Recently, nanosized magnetite particles have received major interest in the manufacturing of magnetic recording devices, protective and sensitive coatings, catalysts, pigments and ferrofluids [2]. The production of this type of nanoparticles can be carried out using different methods, such as thermal decomposition [3; 4], microemulsion and coprecipitation [5]. Chemical coprecipitation is a low-cost and straightforward method for preparing semiconductor materials and it is the most common method due to its non-toxicity, the simplicity in its synthesis and its potential ability to be employed for large scale production [6].  
The coprecipitation technique is widely employed for the generation of M\({}^{2+}\) and Fe\({}^{3+}\) cations using NaOH and NH\({}_{4}\)OH to create alkaline conditions. The nanoparticles after the coprecipitation process are dispersed in aqueous media due to the large surface of hydroxyl groups [7]. The reaction pH value represents a key factor that controls structural morphology (e.g., crystallinity, homogeneity) and particle size of the material [8]. [PERSON] et al. [9] reported several drawbacks in classical coprecipitation, including uncontrollability of the size, size distribution and the phase control of resultant nanoparticles. According to these authors, magnetite production has limited potential on a large scale. For these reasons, the evaluation of the coprecipitation method for synthesizing magnetite nanoparticles is important for industrial scaling-up.  
The environmental assessment features an important tool for guiding the planning process and screening design alternatives [10]. Several methods have been applied to analyze the sustainability of the production systems from an environmental point of view. Life Cycle Assessment (LCA) and Waste Reduction (WAR) algorithm [11] are the most used methodologies to assess the environmental impacts of chemical processes [12]. The WAR methodology estimates potential environmental impacts (PEI) of any chemical process, based on atmospheric and toxicological categories [13]. Some literature contributions have focused on the environmental assessment of emerging and novel chemical processes. [PERSON] et al. [14] performed an environmental evaluation of agar production from the macroalgae feedstock _Gracilaria_ sp. and reported that the value of PEI generated was around 118 PEI/h. [PERSON] et al. [15] studied the synthesis of titanium dioxide (TiO\({}_{2}\)) nanoparticles from titanium isopropoxide (TTIP) via green chemistry and quantified how this process meets sustainability standards through the WAR algorithm.  
In this work, an environmental evaluation is developed for a large scale production of magnetite (Fe\({}_{3}\)O\({}_{4}\)) nanoparticles via coprecipitation with the aim of determining the degree of pollution generated by the process. The WAR algorithm was selected for the environmental analysis of the mentioned process through computer-aided process engineering using the WARGUI software. The novelty of this research is the modeling, simulation and scaling-up of magnetite nanoparticles synthesis process previously performed by authors at a lab scale.