A stably cross-linked ink on filter paper with 1D transport for efficient photothermal water treatment

Abstract

Photothermal water evaporation using natural solar energy has been attracted more attentions due to wide applications such as water purification, sterilization, power generation and energy conservation. This article reports a low-cost and stable material for efficient generation of water vapor as well as saline and pollution water treatment. The hierarchically porous material consisting of nanoporous carbon and microporous paper is prepared by simply depositing and chemically cross-linking colloidal ink onto a filter paper. A stably homogeneous nanocarbon deposition is formed over microfibers in the paper. The nanocarbon particles greatly increase the surface area of pristine paper (from negligible to 12 m2 g−1) and light absorption. The carbon modified paper allows high water evaporation rate of 1.34 kg h−1 m−2 from a nanoporous carbon film, continuous capillary water transport in the micropores of paper, as well as minimal convective loss to bulk water due to 1D low contact area with water. The pore sizes of filter papers on the water evaporation together with the controlling of surface temperature and evaporating rate are also performed. Finally, this water solar evaporation system is applied for desalination and wastewater purifying (including heavy metal ion and organic pollutions). A safe freshwater is obtained after treatment. This study demonstrates the potential application of chemical modification of inked filter paper to achieve high evaporation rate and efficiency by rational design. A low-cost and stable material for efficient generation of water vapor and wastewater treatment was brought out, which is prepared by simply depositing and cross-linking colloidal ink onto a filter paper. The carbon modified paper allows efficient light absorption, high water evaporation rate from a nanoporous carbon film, continuous capillary water transport in the micropores of paper, as well as minimal energy loss.