Removal of Pb²⁺ from aqueous solutions using coconut shell carbons produced by KOH activation is performed in this paper. Morphology and pore structure characteristic of coconut shell carbons are analyzed by SEM and nitrogen adsorption techniques. Effects of adsorbent concentration, agitation time and initial ion concentration on the adsorption behavior are investigated, and adsorption isotherm and kinetics on coconut shell carbons are also studied. The results show that high weight ratio of KOH/sample is favorable to produce rich porous structure. The resultant coconut shell carbons with a high specific surface area of 1135 m²/g is obtained and demonstrates good adsorption potential on removal of Pb²⁺ from aqueous solutions. Adsorption data fit well with Freundlich and Halsey isotherms. The kinetic studies indicate that adsorption behavior can be described by pseudo-second-order kinetic model, which also follows external diffusion and intra-particle diffusion in the adsorption process.

The emerging solar-steam generation is recognized as one of the promising pathways to mitigate the global water crisis, but has a major obstacle: the development of sustainable solar-driven water evaporators with favorable evaporation performance. In this work, an all biomass-based hydrogel evaporator was fabricated for efficient solar steam generation, in which squid ink was employed as the photothermal material and starch as the hydrogel matrix. It was found that the hydrogel evaporator achieved a high water evaporation rate of approximately 2.07 kg m⁻² h⁻¹ under 1.0 sun with a corresponding energy efficiency of about 93.7%, arising from its excellent light absorption, light-to-heat conversion, energy confinement, wettability and water replenishment. Additionally, the evaporation performance can be further improved to evaporation rate of 2.62 kg m⁻² h⁻¹ and energy efficiency of 108.1% by capturing the environmental energy through simply increasing the evaporator height from 5 to 50 mm. For seawater desalination, the prepared evaporator exhibited both high salt resistance and good self-regeneration ability that ensure its promise for long-term practical application. The Na⁺ concentration in the collected water was less than 1.0 mg L⁻¹. Thus, this work opens up a fascinating avenue for developing a novel hydrogel evaporator to providing potable and clean water.