Fabrication of an oil–water separation copper filter using laser beam machining

Abstract

In this study, oil and water are successfully separated using a copper filter that is fabricated using only laser beam machining. Even though copper is hydrophilic and recast copper material, which inevitably results during laser beam machining, is super-hydrophilic, the filter can prevent the water from penetrating and allow oil to flow based on surface tension of the liquids at the hole exit. For practical uses of the filter, both the pressure differences at which the filter is able to retain its ability to separate and the oil penetration rate of the filter are revealed. The fabrication process is simple and time-saving, and the filter has high durability because of lack of surface coating or surface chemical modification.

Microengineered Membranes for Sustainable Production of Hydrophobic Deep Eutectic Solvent-Based Nanoemulsions by Membrane Emulsification for Enhanced Antimicrobial Activity

“…Hence, in a subsequent stage where the membranes were cleaned to remove the excess of the metallic redeposited material around the pores, a 100 μm pitch was selected. Three different cleaning strategies reported in the literature were used that included immersion of the circular membrane in piranha solution for 4 min, or in a concentrated nitric acid solution for 30 s, or using a sonication method . Among these, sonication for 30 min was a friendly and successful procedure to remove the entire excess redeposited (recast) material.…”

Expedited Transition in the Wettability Response of Metal Meshes Structured by Femtosecond Laser Pulses for Oil-Water Separation

“…Copper filters were created by drilling micron-sized holes in copper sheets followed by raster scanning to produce underwater-superoleophobic and underoil-superhydrophobic wetting states (Zhou et al, 2018 ). Additionally, copper filters fabricated by nanosecond lasers showing a superhydrophilic underwater-superoleophobic state were also reported to separate oil-water mixtures (Ha and Chu, 2016 ). Micro-through holes were also drilled in titanium (Ye et al, 2016 ) and aluminum (Li G. et al, 2016 ; Zhang et al, 2017 ) to produce superhydrophilic underwater-superoleophobic wetting states, whereas polytetrafluoroethylene (Yong et al, 2016 ) structured with femtosecond lasers led to a superhydrophobic-superoleophilic wetting state that has been employed for oil-water separation.…”

Review: Porous Metal Filters and Membranes for Oil–Water Separation

“…Oxidation refers to the formation of a metal oxide layer with high surface energy on a metal surface through an oxidation reaction, endowing the filter membrane surface with superhydrophilicity. At present, direct oxidation [ 13 , 65 , 67 ], electrochemical oxidation [ 47 , 55 , 66 , 68 ] and laser surface oxidation [ 8 , 69 ] can be used for the fabrication of superhydrophilic–underwater superoleophobic filter membranes.…”

“…Ho et al [ 69 ] fabricated copper micronpore-array filter membranes using femtosecond laser drilling and created a superhydrophilic filter membrane. The entrance location and the exit location of the hole created using laser beam machining are shown in Fig.…”

“…b The exit location. (The laser beam conditions are 500 μJ per pulse, 20 kHz and 10 shots) [ 69 ]. c The location of the water contact line on a hole with recast material at an equilibrium state [ 69 ] …”