Constructing green, smart wettability-switchable and antibacterial Caragana cellulose filter by cooperative regulation of texture and surface for on-demand purification of emulsions

•Amphiphilic CuSi@CFP can separate water-in-oil and oil-in-water emulsions on demand.•CuSi@CFP has high efficiency (>99.9 %) and flux to purify industrial oil–water emulsion.•CuSi@CFP can remove methylene blue in water and Oil red O dyes in oil.•CuSi@CFP has a broad-spectrum antibacterial property to produce safe clean water.•The spent filter can be regenerated to produce adsorbent with added value.