Revealing the brick-laying process of foulants layer in membrane distillation for desulfurization wastewater treatment: Insight into the mineral scaling

Zheng, Liping; Liu, Mengmeng; Li, Chenlu; Kang, Shenghong; Chen, Meixue; Zhong, Hui; Jun, Wang; Wei, Yuansong

doi:10.1016/j.desal.2020.114888

Cited by 20 publications

(4 citation statements)

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“…Naidu et al (2017) demonstrated that LMW organics possess hydrophilic propensities causing a substantial reduction in membrane hydrophobicity, causing a significant deposition of hydrophilic LMW organics. Moreover, Zheng et al (2021) demonstrated the hydrophobic-hydrophilic interaction as 'brick-layering' process, where hydrophobic foulants acts as concrete and hydrophilic foulants act as bricks. Thus, it can be concluded that model organics (such as HA and SA) do not accurately replicate real humic compounds and polysaccharides.…”

Section: Characterisation Of Organic Foulants By Lc-ocdmentioning

confidence: 99%

Membrane distillation of wastewater: comparison of model and real organics

Habib,

Phuong Do,

Asif

et al. 2024

Water Science &Amp; Technology

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Fouling behaviour in membrane distillation (MD) processes plays a crucial role in determining their widespread acceptability. Most studies have primarily focused on model organic foulants, such as humic acid (HA) and sodium alginate (SA). This study investigates the fouling of a polytetrafluoroethylene membrane in a direct contact MD (DCMD) using model organics (i.e., HA and SA) and real wastewater. The results indicated that the flux decline (5–60%) was only observed during the initial phase of the operation with model organic foulants. In contrast, real wastewater caused a gradual decline in flux throughout the experiment in both the concentrate (40%) and continuous (90%) modes. The study also found significant differences in the fouling layer morphology, composition, and hydrophobicity between the model organic foulants and real wastewater. Fourier transform infrared spectroscopy findings demonstrated that the fouling layer formed by real wastewater varied significantly from model organics, which primarily comprised of protein-like and polysaccharide-like functional groups. Finally, liquid chromatography–organic carbon detection revealed that the fouling layer of the MD membrane with real wastewater was composed of 40.7% hydrophobic and 59.3% hydrophilic organics. This study suggests that model organics may not accurately reflect real wastewater fouling.

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Section: Characterisation Of Organic Foulants By Lc-ocdmentioning

confidence: 99%

Membrane distillation of wastewater: comparison of model and real organics

Habib,

Phuong Do,

Asif

et al. 2024

Water Science &Amp; Technology

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“…Once solutes or crystals penetrate into the membrane pores, it is difficult to clean the membrane and the MD process fails. The formation of a scale layer involves two pathways: (i) heterogeneous crystallization on the membrane surface and (ii) homogeneous crystallization in the bulk feedwater with crystals eventually depositing on the membrane surface. ,, Compared with homogeneous crystallization, heterogeneous crystallization readily induces the intrusion of crystals into the inner pores of the membrane because of the larger contact area and stronger crystal–polymer interactions. , Therefore, heterogeneous crystallization is more likely to cause membrane pore deformation and wetting (i.e., scale-induced wetting) than homogeneous crystallization.…”

Section: Introductionmentioning

confidence: 99%

“…However, studies on the contributions of heterogeneous and homogeneous crystallization to membrane scaling and wetting are still very limited, and the results of previous investigations have generally been contradictory. Several studies have proposed that membrane scaling is mainly caused by heterogeneous crystallization on the membrane surface, ,, whereas other researchers have suggested that the deposition of crystals originating from homogeneous crystallization accounts for the water flux decline. − In addition, solutes in the feedwater, such as natural organic matter (NOM), also affect scaling during pressure- or osmosis-driven membrane filtration. , Membrane scaling for RO, nanofiltration (NF), and forward osmosis (FO) can be accelerated by the formation of an organic fouling layer on the membrane surface, − which can be attributed to an increase in concentration polarization. In addition, the functional groups of NOM (e.g., the carboxyl groups) can promote the heterogeneous crystallization of gypsum on the membrane surface. , Different from the above membrane processes, MD is driven by the vapor pressure difference and uses hydrophobic membranes.…”

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

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Membrane Scaling and Wetting in Membrane Distillation: Mitigation Roles Played by Humic Substances

Wang

Cheng

Zhang

et al. 2022

Environ. Sci. Technol.

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Membrane scaling and wetting severely hinder practical applications of membrane distillation (MD) for hypersaline water/wastewater treatment. In this regard, the effects of feedwater constituents are still not well understood. Herein, we investigated how humic acid (HA) influenced gypsum-induced membrane scaling and wetting during MD desalination. At low concentrations (5–20 mg L–1), HA notably mitigated membrane scaling and wetting. The morphological characterization of scaled membranes revealed that the antiwetting behavior could be ascribed to the formation of a compact and protective gypsum/HA scale layer, which blocked the flow channel of scaling ions and suppressed the intrusion of scale particles into membrane pores. Based on the comprehensive analysis of the scaling process, the formation of the scale layer was related to the heterogeneous crystallization of gypsum on the membrane surface. Moreover, deprotonated HA interfered with the heterogeneous crystallization process by inhibiting the formation of gypsum nuclei and altering the orientation of crystal growth, thus delaying membrane scaling and altering the morphology of the scale layer. Thermodynamic and kinetic analyses further demonstrated the mitigation mechanism of HA. Furthermore, improved fouling reversibility and antiwetting ability in synthetic seawater treatment endowed by HA were observed. This study provides new insight into the roles played by the organic constituents of water/wastewater during membrane desalination, providing a valuable reference for developing novel strategies to improve the performance of MD.

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