Article

Interfacial Solar Evaporation by a 3D Graphene Oxide Stalk for Highly Concentrated Brine Treatment

Casey FinnertyDepartment of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United StatesAkanksha K. MenonEnergy Storage and Distributed Resources Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United StatesKelly M. ConwayDepartment of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United StatesDaryn LeeDepartment of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United StatesMatthew NelsonDepartment of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United StatesJeffrey J. UrbanThe Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United StatesDavid L. SedlakDepartment of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United StatesBaoxia MiDepartment of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United States

2021en

ABI

Abstract

In this work, we demonstrate a 3-dimensional graphene oxide (3D GO) stalk that operates near the capillary wicking limit to achieve an evaporation flux of 34.7 kg m–2 h–1 under 1 sun conditions (1 kW/m2). This flux represents nearly a 100 times enhancement over a conventional solar evaporation pond. Interfacial solar evaporation traditionally uses 2D evaporators to vaporize water using sunlight, but their low evaporative water flux limits their practical applicability for desalination. Some recent studies using 3D evaporators demonstrate potential for more efficient water transfer, but the flux improvement has been marginal because of a low evaporation area index (EAI), which is defined as the ratio of the total evaporative surface area to the projected ground area. By using a 3D GO stalk with an ultrahigh EAI of 70, we achieved nearly a 20-fold enhancement over a 2D GO evaporator. The 3D GO stalk also exhibited additional advantages including omnidirectional sunlight utilization, a high evaporation flux under dark conditions from more efficient utilization of ambient heating, a dramatic increase of the evaporation rate by introducing wind, and scaling resistance in evaporating brines with a salt content of up to 17.5 wt %. This performance makes the 3D GO stalk well suited for the development of a low-cost, reduced footprint technology for zero liquid discharge in brine management applications.

Identifiers

DOI: 10.1021/acs.est.1c04010

Citations and references

Cited by 20 references

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