Sadhukhan Jhuma, Joshi Nimisha, Shemfe Mobolaji, Lloyd Jonathan R
Centre for Environment and Sustainability, University of Surrey, Guildford, Surrey, GU2 7XH, UK.
School of Earth, Atmospheric and Environmental Science, The University of Manchester, Manchester, M13 9PL, UK.
J Environ Manage. 2017 Sep 1;199:116-125. doi: 10.1016/j.jenvman.2017.05.048. Epub 2017 May 18.
Magnetite nanoparticles (MNPs) have several applications, including use in medical diagnostics, renewable energy production and waste remediation. However, the processes for MNP production from analytical-grade materials are resource intensive and can be environmentally damaging. This work for the first time examines the life cycle assessment (LCA) of four MNP production cases: (i) industrial MNP production system; (ii) a state-of-the-art MNP biosynthesis system; (iii) an optimal MNP biosynthesis system and (iv) an MNP biosynthesis system using raw materials sourced from wastewaters, in order to recommend a sustainable raw material acquisition pathway for MNP synthesis. The industrial production system was used as a benchmark to compare the LCA performances of the bio-based systems (cases ii-iv). A combination of appropriate life cycle impact assessment methods was employed to analyse environmental costs and benefits of the systems comprehensively. The LCA results revealed that the state-of-the-art MNP biosynthesis system, which utilises analytical grade ferric chloride and sodium hydroxide as raw materials, generated environmental costs rather than benefits compared to the industrial MNP production system. Nevertheless, decreases in environmental impacts by six-fold were achieved by reducing sodium hydroxide input from 11.28 to 1.55 in a mass ratio to MNPs and replacing ferric chloride with ferric sulphate (3.02 and 2.59, respectively, in a mass ratio to MNPs) in the optimal biosynthesis system. Thus, the potential adverse environmental impacts of MNP production via the biosynthesis system can be reduced by minimising sodium hydroxide and substituting ferric sulphate for ferric chloride. Moreover, considerable environmental benefits were exhibited in case (iv), where Fe(III) ions were sourced from metal-containing wastewaters and reduced to MNPs by electrons harvested from organic substrates. It was revealed that 14.4 kJ and 3.9 kJ of primary fossil resource savings could be achieved per g MNP and associated electricity recoveries from wastewaters, respectively. The significant environmental benefits exhibited by the wastewater-fed MNP biosynthesis system shows promise for the sustainable production of MNPs.
磁铁矿纳米颗粒（MNPs）有多种应用，包括用于医学诊断、可再生能源生产和废物修复。然而，用分析级材料生产MNPs的过程资源密集，且可能对环境造成破坏。这项工作首次对四个MNPs生产案例进行了生命周期评估（LCA）：（i）工业MNPs生产系统；（ii）先进的MNPs生物合成系统；（iii）优化的MNPs生物合成系统；以及（iv）使用源自废水的原材料的MNPs生物合成系统，以便为MNPs合成推荐一条可持续的原材料获取途径。工业生产系统被用作基准，以比较生物基系统（案例ii - iv）的LCA性能。采用了适当的生命周期影响评估方法组合，以全面分析各系统的环境成本和效益。LCA结果显示，与工业MNPs生产系统相比，使用分析级氯化铁和氢氧化钠作为原材料的先进MNPs生物合成系统产生的是环境成本而非效益。然而，在优化的生物合成系统中，通过将氢氧化钠与MNPs的质量比从11.28降至1.55，并将氯化铁替换为硫酸铁（与MNPs的质量比分别为3.02和2.59），环境影响降低了六倍。因此，通过尽量减少氢氧化钠用量并用硫酸铁替代氯化铁，可以降低通过生物合成系统生产MNPs对环境的潜在不利影响。此外，在案例（iv）中表现出了可观的环境效益，其中Fe(III)离子源自含金属废水，并通过从有机底物中获取的电子还原为MNPs。结果表明，每克MNPs可分别实现14.4千焦的一次化石资源节约和从废水中回收相关电力3.9千焦。以废水为原料的MNPs生物合成系统所展现的显著环境效益为MNPs的可持续生产带来了希望。
