▎ 摘　　要

NOVELTY - A modified natural plant pith core comprises a natural plant pith core, a zwitterionic hydrogel with a topological structure that forms and interpenetrating network with the natural plant pith core, and a photothermal conversion layer loaded on one end of the natural plant pith core. USE - The modified natural plant pith core is useful as material for desalting seawater, including ordinary seawater, oil stain polluted seawater, or heavy metal polluted seawater, preferably solar seawater, and material for treating heavy metal including nickel, lead, copper, zinc, chromium, and/or cadmium in sewage (all claimed). ADVANTAGE - The modified natural plant pith core uses sunflower stalk core, which has a gradient porous structure, has very low thermal conductivity (sunflower stem thermal conductivity of 0.04 W/mK and wood thermal conductivity of 0.2 W/mK), can efficiently utilize heat to evaporate water, and makes full use of heat after photothermal conversion for water evaporation to improve efficiency. The special structure of the inner surface of the sunflower stalk core provides a special water channel, which accelerates the evaporation of water, thus improving the evaporation efficiency of water, and endows the material with excellent antibacterial and anti-mildew properties to improve the durability and service life of the material. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of the modified natural plant pith core, which involves modifying the natural plant pith core by using the zwitterionic hydrogel, and then compounding the photothermal conversion layer.