ACS Sustainable Chemistry & Engineering
pubs.acs.org/journal/ascecg
Research Article
hydro, 3% natural gas, and 1% biogas. 68 To estimate the energy required in the drying stage (heating), the following equation was used = × Q m C T ( )d T T i P i , 1 2 (2) Here, Q represents the energy required, while T 1 and T 2 denote the initial and final temperatures, respectively. The terms m i and C P , i refer to the mass and heat capacity of compound i , respectively. The heat capacity of EFB fibers and pulp used was 1.48 and 1.4 J g − 1 K − 1 , respectively. 69,70 A polyester-based air filter served as the benchmark in the LCA model, with its lifecycle inventory being obtained from Ecoinvent. Both the EFB/hairy cellulose fiber nonwoven and the polyester air filter are assumed to have the same durability. The functional unit (f.u.) for this study was defined as a performance indicator for particulate filtration efficiency of ∼ 98% for PM 1 over an area of 1 m 2 . To meet this performance requirement, the EFB/hairy cellulose fiber nonwoven contain- ing 10 wt % hairy cellulose fibers refined for 30 min was modeled with a grammage of 1000 g m − 2 . In comparison, the polyester air filter achieved the same filtration efficiency at a grammage of 550 g m − 2 . 48,71 Detailed lifecycle inventory can be found in the Supporting Information. Figure 7B represents the ReCiPe 2016 LCA results, comparing the production of EFB/hairy cellulose fiber nonwovens to polyester-based air filters across global warming potential (GWP) and three end point categories including HH, ecosystem quality (EQ), and resource scarcity (RS). The production of the polyester air filter exhibits net GWP, HH, EQ, and RS values of 6 kgCO 2 e, 1.3 × 10 − 5 DALY, 2.7 × 10 − 8 species.yr, and 0.5 USD 2013 per functional unit, respectively. In contrast, the EFB/hairy cellulose fiber nonwoven consistently shows significantly lower values in GWP and all end point categories, with net values of − 1.21 kg CO 2 e for GWP, 0.7 × 10 − 5 DALY for HH, 0.6 × 10 − 8 species.yr for EQ, and 0.08 USD 2013 for RS per functional unit. These lower environmental impacts are driven by (i) the use of renewable biomass resources as the primary materials (EFB and hairy cellulose fibers), which offer lower environmental burdens compared to fossil-derived materials, (ii) biogenic CO 2 uptake from EFB and hairy cellulose fibers, as the biomass contains 50% carbon by dry weight, 72 providing the environmental credits by storing atmospheric carbon within the material, 73 and (iii) the avoidance of open disposal of EFB (avoided burden), thus preventing the release of ∼ 27 kg of methane per ton of EFB via anaerobic digestion, as estimated in our prior work. 29 Altogether, these factors establish the EFB/hairy cellulose fiber nonwoven as a sustainable alternative to polyester-based air filters, offering significantly lower environmental impacts. 3. CONCLUDING REMARKS Conventional air filters predominantly rely on fossil-derived polymers, raising environmental concerns related to sustain- ability and end-of-life disposal. In this study, nonwoven air filters made from EFB fibers and cellulose fibers as the binder were produced by mimicking the papermaking technique. Mechanical refinement was carried out on the cellulose fibers to introduce “hairy” microfibrils on its surface, enhancing the particle capture of EFB/hairy cellulose fiber non wovens. The increase in the refining time and the loading of hairy cellulose fibers as the binder were shown to significantly improve the
further, we characterized the performance differences of the rigid EFB/hairy cellulose fiber nonwoven as-molded and remolded using the steam-rewetting approach, particularly at a 10 wt % binder loading (significant warpage was observed for 20 and 30 wt % binder samples; see Figure 5C,D). We first investigated the tensile properties of as-molded EFB/(hairy) cellulose fiber nonwovens containing 10 wt % binder, as well as their remolded counterparts (Figure 6A for modulus and Figure 6B for strength). As expected, both the tensile modulus and strength of the resulting nonwovens improved with (hairy) cellulose fibers with longer refining time were used as the binder. However, all remolded nonwovens exhibited lower tensile modulus and strength compared to their pristine as- molded counterparts, regardless of binder content and refining time. The deterioration in mechanical performance is particularly severe when unrefined cellulose fibers were used as the binder. A ∼ 29% decrease in tensile modulus and a ∼ 35% decrease in tensile strength was observed for remolded nonwoven containing unrefined cellulose fibers as the binder compared to pristine as-molded nonwoven counterpart, although the use of hairy cellulose fibers as the binder reduced this deterioration in mechanical performance by ca. 12% and 16% for tensile modulus and strength, respectively, across all cellulose fiber refining time. This can be attributed to the stronger hornification of the hairy cellulose pulp fibers used as the binder, maintaining a better structural stability 64 during the steam-rewetting cycle. A similar effect was reported in hand sheets subjected to multiple drying-and-rewetting cycles, where a more hornified network preserved strength more effec- tively. 65 The changes in PM 1 aerosolized particulate filtration efficiency between the as-molded and remolded samples is shown in Figure 6C. The largest decrease in filtration efficiency was observed for nonwovens containing unrefined cellulose fiber as the binder; ca. 7%pt decrease compared to pristine as- molded counterpart. In contrast, nonwovens with hairy cellulose fibers as the binder showed a smaller decrease in aerosolized particulate filtration efficiency of <1.5% pt across all refining times. 2.7. Lifecycle Assessment (LCA) of EFB/Hairy Cellu- lose Fiber Nonwovens. To evaluate the environmental sustainability of producing EFB/hairy cellulose fiber non- wovens, a cradle-to-gate lifecycle analysis was conducted. This assessment covered the entire process, from the collection of EFB at the palm oil mill (Figure 7A) to the production of EFB/hairy cellulose fiber nonwoven with considering the business-as-usual scenario of EFB, open disposal, as the avoided environmental burden. The lifecycle inventory incorporated data from the manufacturing process of EFB/ hairy cellulose fiber nonwovens generated in this work as foreground data, while background data were sourced from Ecoinvent V3.9. The LCA was conducted in accordance with the guidelines established in the literature 66 utilizing lifecycle engineering software (SimaPro V9.5, PRé Sustainability, Amersfoort, Netherlands) and ReCiPe 2016 framework. 67 The production of EFB/hairy cellulose fiber nonwovens was located in Riau Province, Indonesia. This location was selected based on our previous findings, 29 which identified Riau as an optimal site for the production of EFB/hairy cellulose fiber nonwovens due to the extensive oil palm plantations and the more sustainable electricity source than other provinces in Indonesia. The regional electricity grid is composed of 48% biomass, 23% combined cycle gas, 14% lignite, 6% oil, 4%
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https://doi.org/10.1021/acssuschemeng.5c00041 ACS Sustainable Chem. Eng. 2025, 13, 6209 − 6221
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