Farm waste-derived recyclable photothermal evaporator
A carbonized manure photothermal evaporator derived from naturally abundant farm waste has high solar absorptance, effective water transportation, and rapid salt dissipation. It achieves high evaporation under 1-sun irradiance and is recyclable, durable, and cost-effective for use in energy-efficient solar-driven interfacial desalination.
1 . A photothermal evaporator for a water desalination system, comprising:
a planar carbonized manure (CM) body having a first side, a second side opposing the first side, a thickness therebetween, and an interconnected channel structure formed by black carbon fibers of the CM body;
wherein the first side is positionable in contact with a body of water and the second side is exposed to air and incident sunlight above the body of water;
wherein the interconnected channel structure transports water from the first side to the second side via capillary action, thereby generating an ion concentration gradient between the first side and second side, allowing salt to diffuse back toward the body of water; and
wherein the CM body converts the incident sunlight to heat at the second side for evaporating the transported water.
2 . The photothermal evaporator of claim 1 , wherein the CM body includes randomly arranged black carbon fibers defining water transport and salt-rejection channels.
3 . The photothermal evaporator of claim 1 , wherein the CM body includes randomly arranged black carbon fibers forming a macropore structure configured to trap and scatter the incident sunlight inside the CM evaporator.
4 . The photothermal evaporator of claim 1 , wherein the CM body comprises manure that has been pressed, dried, and carbonized.
5 . The photothermal evaporator of claim 1 , wherein the manure comprises farm animal manure.
6 . The photothermal evaporator of claim 1 , wherein the CM body is recyclable.
7 . The photothermal evaporator of claim 1 , wherein the CM body has a solar absorptance of about 0.98.
8 . The photothermal evaporator of claim 1 , wherein the CM body has an evaporation rate of about 2.8 kg m −2 h −1 under 1 sun irradiance.
9 . The photothermal evaporator of claim 1 , wherein the CM body is capable of stable operation in water comprising at least 15 wt % NaCl solution without salt accumulation.
10 . A method of manufacturing a photothermal evaporator for a water desalination system, comprising the steps of:
(a) crushing manure into pieces;
(b) molding the pieces of manure into a bulk form;
(c) drying the manure in the bulk form to form dried manure; and
(d) carbonizing the dried manure to form a carbonized manure (CM) evaporator having a first side, a second side opposing the first side, a thickness therebetween, and an interconnected channel structure formed by black carbon fibers of the CM evaporator.
11 . The method of claim 10 , wherein step (a) is performed using a blender.
12 . The method of claim 10 , wherein step (b) comprises molding the pieces of manure into a planar slab.
13 . The method of claim 10 , wherein step (c) is performed by heating the manure at about 180° C.
14 . The method of claim 10 , wherein step (d) is performed in an inert gas or vacuum environment.
15 . The method of claim 10 , further comprising recycling the CM evaporator by mixing the CM evaporator with fresh manure to form a mixed manure, molding the mixed manure into a bulk form, drying the manure in the bulk form to form a dried manure, and carbonizing the dried manure to form a recycled CM evaporator.
16 . The method of claim 10 , wherein the CM evaporator is configured to have one side positioned in a body of water and an opposite side positioned in air above the body of water and exposed to incident sunlight, and said CM evaporator is configured to draw water from the body of water through capillary action, convert the incident sunlight to heat for evaporating the water, and reject salt to the body of water.
17 . The method of claim 10 , wherein the CM evaporator includes randomly arranged black carbon fibers defining water transport and salt-rejection channels.
18 . The method of claim 10 , wherein the CM evaporator includes randomly arranged black carbon fibers forming a macropore structure configured to trap and scatter incident sunlight inside the CM evaporator.