Aligned Millineedle Arrays for Solar Power Seawater Desalination with Site‐Specific Salt Formation

Abstract

With the global environment worsening, water purification technologies for clean water collection especially from seawater or wastewater have drawn huge research enthusiasms in the past few decades. [6][7][8][9][10] Compared with traditional water purification methods, solar-driven water evaporation is considered to be a promising technology and can realize practical seawater desalination, brine purification, or polluted water remediation. [11][12][13][14][15][16] In a typical solar evaporation, high efficiency solar-thermal conversion, good heat confinement, and salt blockage is three major requirements for achieving efficient solar water evaporation. [17][18][19] Although many efforts have been devoted onto development of solar evaporators to improve the evaporation efficiency, salt from seawater would unavoidably accumulate on the interface of evaporator in the process of seawater desalination. [20][21][22][23][24][25] This resulted salt crystal will severely reduce solar absorption and also block the water supply, leading inefficient solar energy conversion and water transport. [26][27][28][29][30] Therefore, anti-salt accumulation of solar evaporation is a critical issue but remains challenging.To address the issue of salt accumulation, recent efforts have been closely paid to receive high-efficient and continuable solar still. Hu and co-works designed an anti-salt solar evaporator by vertically installing large-caliber channel array into the evaporator, and by which the high-concentration salt water on the evaporation interface could availably transport into the nearby channel via osmotic pressure mechanism. [31][32][33][34] On the other hand, "Janus" solar stills with a upper hydrophobic layer and lower hydrophilic layer have also been developed to confine salt crystallization in hydrophilic layer and then dissolute the salt crystal along the water pumping. [35][36][37] Many other strategies, such as self-clean nanoarchitecture, ion-pumping layer, and vertically aligned vessel, have been well developed for resolving salt blockage issue. [38][39][40][41][42] Although all these methods do control salt formation for some extents, water evaporation efficiency is often compromised. [43] Notably, recent reports found that salt crystallization on the edge of evaporator could effectively refrain the salt interference and maintain the efficiency of water evaporation. [44][45][46] Thus, confining salt crystallization at customized sites offers a viable approach for simultaneously realize highperformance water evaporation and precise salt harvesting.In this work, we demonstrate rational design of a millineedle array-patterned 3D solar still for site-specific salt crystallization As a sustainable and clean water production technology, solar thermal water evaporation has been extensively studied in the past few years. One challenge is that upon operation, salt would form on surface of the solar absorbers leading to inefficient water supply and light absorption and thus much reduced water vaporization rate. To address t...

A vasculatural hydrogel combined with Prussian blue for solar-driven vapor generation

“…5b, when the floating PVA/PB was exposed to simulated sunlight of 1 kW m −2 , the surface temperature of PVA/PB rapidly increased from 18.8 to 28.6 °C within 10 min, and gradually increased further to 31.4 °C within 60 min, similar to that of reported SVGs. 14,35,36 In contrast, there are no obvious changes in the temperature of the bulk water even for 60 min (from 18.8 to 20.2 °C).…”

Recent developments of hydrogel based solar water purification technology

“…What's more, imitating the water absorption and release cycle of pufferfish, the inherent lower critical temperature of poly(N-isopropyl acrylamide) (PNIPAm) hydrogel was used for hydrophilic (in dark conditions) and hydrophobic (under sunlight) conversion. 154 Additionally, surface biomimetic morphology is also common in studies to enhance light acquisition, 69,89 anti-fouling, 155 and additional water collection capacity. 146 In addition to seawater desalination and wastewater purification, there are still some other particular application scenarios for solar water purification.…”

“…In the next year, the same group reported a PPy/chitosan/PVA hydrogel platform that exhibited an enhanced solar vapor generation capacity of 3.6 kg m −2 h −1 . 137 Recent research on conjugated polymer solar absorbers has been extended to polyaniline (PANI), 149,150 poly(3,4-ethylene dioxythiophene) (PEDOT), 151,152 polydopamine (PDA), 66,153–156 perovskite hole layer material DPP-2T, 157 and covalent organic frameworks (COFs). 122,158 Furthermore, conjugated copolymer materials such as poly(aniline- co -pyrrole) 34 have also shown up in recent research, proving a novel approach for solar water purification by combining the advantages of two polymers.…”

“…43,112 Guo et al 184 recently attached catechol groups to the CTS hydrogel for hydrogen peroxide (a broad-acting antibacterial agent) generation, combining with the synergistic effect of quinone-modified AC, to enhance the anti-fouling properties and guarantee 3 months of performance maintenance. There are numerous methods to improve the anti-crystalline fouling ability, including the construction of the Janus structure 130,165 and the umbrella-shaped platform, 91 the use of ions rejection polymer, 85,152,169 the introduction of bubbles in the middle section, 140 the weight imbalance sensitive spherical platform capable of rotating and renewing the evaporation surface, 163 the millineedle array on the surface for site-specific salt crystallization without salt clogging 155 and so on. In addition, the self-floating hydrogel platform is out of the external support substrate, which is not conducive to water transport, usually by adding low-density materials ( i.e.…”

Fabrication of Monopile Polymer Foams via Rotating Gas Foaming: Hybrid Applications in Solar‐Powered Interfacial Evaporation and Water Remediation

“…Associated with clean water production, several hybrid applications (i.e., decontamination, environmental stimuli response, waste energy conversion, and zero liquid discharge) have been integrated with SGs, delivering other promising functions beyond clean water production and scaling up solar conversion efficiencies. [35][36][37][38][39][40][41][42] Despite the promising advantages of closed-cell 3D foams over aerogels and hydrogels, fabrication of shape-controlled 3D polymer foams and the specific use in SGs is still in a nascent stage. [43][44][45][46][47][48][49][50][51][52][53] System-level design of 3D polymer foams…”