Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

Zwitterionic Nanohydrogel Grafted PVDF Membranes with Comprehensive Antifouling Property and Superior Cycle Stability for Oil‐in‐Water Emulsion Separation

Developing an effective and sustainable solution for cleaning up or separating oily water is highly desired. In this work, we report a completely inorganic mesh membrane made up of cupric phosphate (Cu3(PO4)2) in a special intersected nanosheets-constructed structure. Combing the hierarchical structure with strong hydration ability of Cu3(PO4)2, the nanosheets-wrapped membrane exhibits a superior superhydrophilic and underwater anti-oil-fouling and antibio-fouling property for efficient oil/water separation to various viscous oils such as heavy diesel oil, light crude oil, and even heavy crude oil with underwater oil contact angles (CAs) all above 158° and nearly zero underwater oil adhesive force even when a large preload force of up to 400 μN was applied on the oil droplet. Simultaneously, the membrane exhibits a high chemical and thermal stability and outstanding salt tolerance. Continuous separation operated on a cross-flow filtration apparatus demonstrates a large separation capacity and long-term st...

Cupric Phosphate Nanosheets-Wrapped Inorganic Membranes with Superhydrophilic and Outstanding Anticrude Oil-Fouling Property for Oil/Water Separation

Traditional superhydrophobic coatings prepared from non-degradable materials tend to do harm to the environment throughout the fabrication process as well as after being discarded. Great efforts have been devoted to exploring more environmentally friendly approaches and materials to settle this problem. Here we report an eco-friendly strategy based on aqueous systems to construct superhydrophobic coatings on various fabrics. Fabrics were first coated with polydopamine (PDA) and then modified with the stearic acid emulsion to introduce the desired surface morphology and energy. The as-prepared fabrics achieved robust superhydrophobicity with a contact angle (CA) about 162.0° and sliding angle (SA) about 7.8°. Moreover, due to the UV-absorbing and the photo-thermal conversion ability of PDA, the modified fabrics exhibited excellent UV shielding and solar-induced self-healing properties. The as-prepared fabrics also possessed high efficiency oil–water separation properties. Without the usage of harmful organic solvents and the addition of micro/nano-particles, this biodegradable superhydrophobic fabric exhibited a clear advantage of being environmentally friendly over conventional coatings. Furthermore, the facile and low-cost fabrication process makes its large-scale production easy.

/pdf/a-self-roughened-and-biodegradable-superhydrophobic-coating-doauj66vh7.pdf

A self-roughened and biodegradable superhydrophobic coating with UV shielding, solar-induced self-healing and versatile oil–water separation ability

https://dr.ntu.edu.sg/bitstream/10220/48259/1/Rational%20construction%20of%20highly%20transparent%20superhydrophobic%20coatings%20based%20on%20a%20non-particle%2c%20fluorine-free%20and%20water-rich%20system%20for%20versatile%20oil-water%20separation.pdf

Rational construction of highly transparent superhydrophobic coatings based on a non-particle, fluorine-free and water-rich system for versatile oil-water separation

In spite of the huge research interest, ionic polymers could not have been synthesized in the vapor phase because the monomers of ionic polymers contain nonvolatile ionic salts, preventing the monomers from vaporization. Here, we suggest a new, one-step synthetic pathway to form a series of cross-linked ionic polymers (CIPs) in the vapor phase via initiated chemical vapor deposition (iCVD). 2-(Dimethylamino)ethyl methacrylate (DMAEMA) and 4-vinylbenzyl chloride (VBC) monomers are introduced into the iCVD reactor in the vapor phase to form a copolymer film. Simultaneously in the course of the deposition process, the tertiary amine in DMAEMA and benzylic chloride in VBC undergo a Menshutkin nucleophilic substitution reaction to form an ionic ammonium–chloride complex, forming a highly cross-linked ionic copolymer film of p(DMAEMA-co-VBC). To the best of our knowledge, this is the first report on the synthesis of CIP films in the vapor phase. The newly developed CIP thin film is further applied to the surfac...

One-Step Synthesis of Cross-Linked Ionic Polymer Thin Films in Vapor Phase and Its Application to an Oil/Water Separation Membrane.

Initiated Chemical Vapor Deposition: A Versatile Tool for Various Device Applications

Exquisite surface wettability control of separation system surface is required to achieve separation of liquids with low surface tension difference. Here, we demonstrate a series of surface-energy-controlled homogeneous copolymer films to control the surface wettability of polyester fabric, utilizing a vapor-phase process, termed as initiated chemical vapor deposition (iCVD). The homogeneous copolymer films consist of a hydrophobic polymer, poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane), pV4D4, and a hydrophilic polymer, poly(4-vinylpyridine), p4VP. Because the mixing of two or more components is always favorable in vapor phase, the iCVD process allows the formation of homogeneous copolymers from two immiscible, hydrophilic/hydrophobic monomer pairs, which is highly challenging to achieve in liquid phase. Simply by tuning the flow rate ratio of monomer pairs, a series of homogeneous copolymers with systematically controlled surface energy were formed successfully. The fabricated separation...

Series of Liquid Separation System Made of Homogeneous Copolymer Films with Controlled Surface Wettability

A robust superamphiphobic sponge (SA-sponge) is proposed by using a single initiated chemical vapor deposition (i-CVD) process. Poly(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl methacrylate) (PFDMA) is deposited on a commercial sponge by the polymerization of fluoroalkyl acrylates during the i-CVD process. This PFDMA is conformally coated onto both the exterior and interior of the sponge structure by a single step of the i-CVD process at nearly room temperature. Due to the inherent porous structure of the sponge and the hydrophobic property of the fluorine-based PFDMA, the demonstrated SA-sponge shows not only superhydrophobicity but also superoleophobicity. Furthermore, the fabricated SA-sponge is robust with regard to physical and chemical damage. The fabricated SA-sponge can be utilized for multi-purpose applications such as gas-permeable liquid separators.

/pdf/a-superamphiphobic-sponge-with-mechanical-durability-and-a-39vseo8evk.pdf

A Superamphiphobic Sponge with Mechanical Durability and a Self-Cleaning Effect.

For the efficient separation of lipid extracted from microalgae cells, a novel membrane was devised by introducing a functional polymer coating onto a membrane surface by means of an initiated chemical vapor deposition (iCVD) process. To this end, a steel-use-stainless (SUS) membrane was modified in a way that its surface energy was systemically modified. The surface modification by conformal coating of functional polymer film allowed for selective separation of oil–water mixture, by harnessing the tuned interfacial energy between each liquid phase and the membrane surface. The surface-modified membrane, when used with chloroform-based solvent, exhibited superb permeate flux, breakthrough pressure, and also separation yield: it allowed separation of 95.5 ± 1.2% of converted lipid (FAME) in the chloroform phase from the water/MeOH phase with microalgal debris. This result clearly supported that the membrane-based lipid separation is indeed facilitated by way of membrane being functionalized, enabling us to...

Moo Jin Kwak

Papers

One-Step Synthesis of Cross-Linked Ionic Polymer Thin Films in Vapor Phase and Its Application to an Oil/Water Separation Membrane.

Initiated Chemical Vapor Deposition: A Versatile Tool for Various Device Applications

Series of Liquid Separation System Made of Homogeneous Copolymer Films with Controlled Surface Wettability

A Superamphiphobic Sponge with Mechanical Durability and a Self-Cleaning Effect.

A Simple, Cost-Efficient Method to Separate Microalgal Lipids from Wet Biomass Using Surface Energy-Modified Membranes