Liquid–Liquid membrane contactors incorporating surface skin asymmetric hollow fibres of poly(4-methyl-1-pentene) for ammonium recovery as liquid fertilisers

Two novel hollow-fibre liquid–liquid membrane contactor (HF-LLMC) modules, containing S-type (skin layer with low porosity) and Q-type higher fibres, have been evaluated. Both asymmetric, porous, hydrophobic membranes, made from poly(4-methyl-1-pentene) (PMP), were used as efficient technology for ammonia recovery to produce liquid fertilisers. The ammonia-rich stream was fed into the shell side of PMP-HF-LLMC, while nitric acid or phosphoric separately lumen N-type (NO3–-NH4+) N-P-type (NH4+-P2O5) fertilisers, respectively. maximum NH3 (>95%) achieved in a closed-loop configuration fibres showed better performance terms production more concentrated fertiliser. With highest values fertilisers (8.0 % N (NH4+) 20.3% P2O5 (w/w)) using acid, value water flux across PMP < 0.01 kg m–2h?1. overall mass transfer coefficient (Km), measured solutions 5.0 gNH3 L–1 feed/stripping volume ratio 60:1, (2.9 ± 0.2) × 10?7 m s?1. Additionally, ultraviolet–visible spectroscopy two-dimensional excitation-emission matrix fluorescence employed monitor absence pore-wetting events stability PMP-HF-LLMC under strongly acidic basic conditions.