Table 3.
Density separation and organic removal for MPs analysis in freshwater sediment.
| No. | Order | Density separation (DS) | Organic removal (OR) | Filtration | Ref. | ||
|---|---|---|---|---|---|---|---|
| Density solution | Procedure | Filter type | Drying conditions | ||||
| 1 | DS only | NaCl (1.20 g/cm3) | 1. Add 200 mL of NaCl solution Stir for 2 min Settle for 2 h 2. Sonicate for 5 min Settle overnight |
N/A | 1.0 μm glass microfiber filter | 50 °C for 48 h | (Wang et al., 2017) |
| 2 | DS → OR | CHKO2 (1.54 g/cm3) | To overflow supernatant into stainless steel tray add solution and settle overnight | Using H2O2 (30%) at 60 °C overnight | 1.2 μm glass microfiber filter | Dry in a desiccator | (Xiong et al., 2018) |
| 3 | DS → OR | 1. NaCl (saturated) 2. NaI (60%) |
Perform a two step density separation 1. Add 1 L of NaCl solution Stir for 2 min Settle for 10 min Sieve using a 48 μm stainless steel sieve Repeat three times 2. Add 375 mL of NaI solution Shake 200 rpm on a shaker for 2 min Settle for 10 min |
WPO (30% H2O2) for 12 h | 0.45 μm glass microfiber filter | 50 °C | (Di and Wang, 2018) |
| 4 | DS → OR | ZnCl2 (1.50 g/cm3) | Add 400 mL of ZnCl2 solution Stir for 30 min Settle for 24 h |
WPO (30% H2O2) | 0.22 μm glass microfiber filter | 60 °C | (Jiang et al., 2018) |
| 5 | DS only | NaCl (1.20 g/cm3) | Add NaCl solution Stir for 2 min Settle for 24 h |
N/A | 1.0 μm glass microfiber filter | Dry to constant weight | (Peng et al., 2018) |
| 6 | DS → OR | ZnCl2 (1.60 g/cm3) | Disaggregate with 400 mL of sodium polyphosphate (5.5 g/L) Stir for 1 h at high rpm Sieve sediments using a 5 mm and 0.055 mm sieve Add 300 mL of ZnCl2 solution and stir Settle for 1 h and transfer supernatant to 0.055 mm sieve and rinse with Milli-Q water |
WPO (30% H2O2 with 0.05 M Fe2+ catalyst) at 75 °C for 5/10 min until it starts boiling and afterwards react at room temperature for 15 h | 0.45 μm membrane filter | 40 °C for 3–5 days | (Rodrigues et al., 2018) |
| 7 | OR → DS | ZnCl2 (1.58 g/cm3) | Add 36 mL of ZnCl2 solution Settle for 24 h |
WPO (30 mL of 30% H2O2) for overnight | 1.2 μm nitrocellulose filter paper |
Air-dry | (Shruti et al., 2019) |
| 8 | OR → DS → OR | ZnCl2 (1.97 g/cm3) | Perform a 2 step density separation 1. Add 1.5 L of ZnCl2 solution Aerate for 1 h Settle for 5 h Drain off solution using a funnel 2. Aerate for 30 min Settle overnight Drain off solution |
1. Pre-oxidation: 50 g of WW subsample was filled with 200 mL Milli-Q water before adding 30 mL of 30% H2O2 (achieving final concentration of 4%) Heat at 50 °C and stir Add 30 mL 30% H2O2 every 24 h (until no foaming) Dry at 50 °C Repeat processing for all of the 3 L sediments 2. Post-oxidation: Fenton reaction by adding 146 mL of 50% H2O2, 63 mL of 0.1 M FeSO4 and 65 mL of 0.1 M NaOH at 15–19 °C Leave for 2 days at room temperature |
500 μm sieve, 10 μm stainless steel filter | 1. Dry particles on a 500 μm sieve at 50 °C 2. Collect the particles on a 10 μm filter into HPLC grade ethanol by ultrasonication and evaporate by nitrogen (N5.0) until dry |
(Liu et al., 2019a) |
| 9 | DS → OR | NaCl (saturated) | Add NaCl solution Stir for 2 min Settle for 24 h |
WPO (30 mL of 30% H2O2) at 100 rpm and 65 °C for 24 h | 0.45 μm membrane filter paper | 50 °C for 24 h | (Ding et al., 2019) |
| 10 | DS only | NaCl (1.20 g/cm3) | Add 40–68 mL of NaCl solution Stir for 1 min Settle for 24 h |
N/A | 11 μm cellulose filter | Room temperature (18–21 °C) | (Blair et al., 2019) |
| 11 | DS → OR | ZnCl2 (1.70 g/cm3) | Leave a 1.5 cm margin, fill ZnCl2 solution into a 100 mL flask Sonicate at 160 W/35 kHz for 15 min Stir at 250 rpm for 1 h Settle for 30 min Add 20 mL of ZnCl2, allow the excess fluid to overflow Store supernatants at 4 °C |
1. Sieve using 500 μm sieve Filter using 10 μm stainless steel disk 2. <500 μm particles: oxidation by adding Fenton reagent (10 mL of FeSO4 (7.2 mM, pH 5)) in a 20 °C water bath Add 20 mL 30% H2O2 after 15 min and sonicate at 215 W/35 kHz for 5 min 3. >500 μm particles: retain for subsequent analysis |
1. 0.2 μm anodisc (<500 μm) 2. 0.45 μm mixed cellulose ester (500 μm-2 |
50 °C for least 2 days | (Mani et al., 2019) |
| 12 | DS → OR | 1. NaCl (saturated) 2. NaI (60%) |
1. Add 1 L of NaCl solution Settle for 2 h Sieve using 50 μm stainless steel sieve and rinse with distilled water Repeat three times 2. Add 500 mL of NaI solution and perform the same way and repeat three times |
WPO (30 mL of 30% H2O2) | 0.7 μm glass microfiber filter | N/A | (Yuan et al., 2019) |
| 13 | DS only | NaCl (30%) | Add 400 mL of NaCl solution Stir for 2 min using spoon Leave until no more visible material floats |
N/A | 1.2 μm glass microfiber filter | 105 °C for 30 min | (Alam et al., 2019) |
| 14 | DS → OR | LMT (1.60 g/cm3) | Shake with 300 mL of LMT solution for 1 min Settle for 10 min Transfer supernatant Repeat twice with 200 mL of LMT |
WPO (20 mL of 35% H2O2 with Fe2+ solution) at 75 °C at 180 rpm for 30 min Add H2O2 every 30 min |
5 μm polycarbonate filter paper | Room temperature | (Eo et al., 2019) |
| 15 | DS → OR | ZnCl2 (1.80 g/cm3) | Mix with ZnCl2 (1:10(w/v)) Stir for 15–20 min Settle overnight Collect on filter paper (0.7 μm glass microfiber filter) |
WPO (30% H2O2) for 3 h | 0.7 μm glass microfiber filter | Dry in a desiccator for 36 h | (Sarkar et al., 2019) |
| 16 | DS only | 1. DI water (1.0 g/cm3) 2. NaI (1.60 g/cm3) |
1. Elutriation step with water for 20 min Mix sediments by air stone Collect overflow materials on a 63 μm sieve by adding water (250 L/h flow rate) Transfer into a 50 mL centrifuge tube 2. Add 30 mL of 3.3 M NaI solution Centrifuge for 5 min at 3500 G Settle for 1 h Repeat once again |
N/A | 1.2 μm glass microfiber filter | 60 °C | (Dikareva and Simon, 2019) |
| 17 | DS, OR simultaneously | NaCl (1.20 g/cm3) | Use 200 mL of NaCl +20 mL of 30% H2O2 solution Heat at 50 °C Stir for 20 min at 200 rpm Settle at 50 °C for 1 h and afterwards settle at room temperature for 1 h Transfer foam from reaction and mix with 50 mL of NaCl + 20 mL of H2O2 and then heat, mix, settle, and filter supernatant Meantime, add 20 mL of H2O2 to WPO solution and sediments, heat, mix and settle the mixture again and then collect and filter supernatant |
0.7 μm glass microfiber filter | 40 °C overnight | (Simon-Sánchez et al., 2019) | |
| 18 | DS → OR | ZnCl2 (1.60–1.80 g/cm3) | Fill with ZnCl2 solution Settle for 24 h |
WPO (30% H2O2 and 10% H2SO4) at 55 °C for 5 days After filtration, repeat the washing process at least twice (until the washing water pH is 7) Finally, transfer the suspended powder on the filter to the new filter |
2.7 μm glass microfiber filter | 55 °C for 7 days (For pyr-GC–MS analysis) | (Scherer et al., 2020) |
| 19 | OR → DS | NaCl (1.20 g/cm3) | Add NaCl solution Stir for 2 min Settle for 24 h |
WPO (30% H2O2) | 1.0 μm glass microfiber filter | 40 °C for 24 h | (Peng et al., 2017) |
| 20 | DS → OR | NaI - NaCl (1.50 g/cm3) | Add 250 mL of NaI - NaCl solution Air floatation for 40 s Settle for 5 min |
WPO (30 mL of 35% H2O2) at room temperature for 7 | 0.45 μm membrane filter | N/A | (Han et al., 2019b) |