Hollow carbon fiber wrapped by regular rGO wave-like folds for efficient solar driven interfacial water steam generation.

Efficient seawater desalination is an effective way to solve the shortages of fresh water and energy but with limitations of the low fresh water production rate and high cost. Here, a hollow carbon fiber (HCF) wrapped by regular reduced graphene oxide (rGO) wave-like folds (rGO@HCF) is prepared on account of the differences in thermal shrinkage performance between graphene oxide (GO) and willow catkins fiber. Under one sun irradiation (1 kW m-2), the dry and wet surface temperature of the resulting evaporator reached up to 119.1 °C and 61.7 °C, respectively, and the water steam production rate reached 3.42 kg m-2 h-1. Also, for the outdoor experiment, the rGO@HCF exhibits good evaporator performance which reach up 27.8 kg m-2 day-1. Additionally, rGO@HCF also shows good seawater desalination performance and excellent durability for longtime work. DSC results indicate that the evaporation enthalpy of bulk water and adsorbed water decreased from 2503.92 to 1020.54 J g-1. The excellent evaporating performance is mainly attributed to the regular wave-like microstructure surface of the HCF, which can enhance the light absorption, reduced the vaporization enthalpy of the adsorption water. The findings not only introduce a novel approach for agricultural utilization, but also establish a crucial theoretical foundation for the design of regular wave-like microstructures.

Carbon fiber coated by quinoa cellulose nanosheet with outstanding scaled salt self-cleaning performance and purification of organic and antibiotic contaminated water.

To date, various solar driven evaporation technologies have been developed for treatment of seawater and wastewater but with the threat from salt polluted and single treatment of seawater. Herein, we develop a multifunctional evaporator constructed by carbon fiber coated by quinoa cellulose nanosheet (CFQC) with outstanding self-cleaning performance and good purification property for treatment of organic and antibiotic polluted water. The resulting Zn-CFQC exhibits good light to thermal performance which can absorb about 86.95% lights in the range of UV-Vis-NIR (200-2500 nm); therefore, the wet and dry surface temperatures of Zn-CFQC are held at 62.1 and 124.3 °C respectively, and keep a speed of 3.2 kg m-2 h-1 for water evaporating under 1000 W m-2 illumination. Such good light-to-thermal capabilities can be mainly imputed to the unique surface microstructures of the carbon fiber which decorated by two-dimension cellulose and activated by ZnCl2. Additionally, Zn-CFQC shows good salt automatic-cleaning capability at night and corresponding mechanism has been simply elucidated according to the chemical potential theory. The method of treatment of carbon fiber opens a new way for commercial carbon fiber utilization of solar assisted water purification.

The Biochar Derived from Carp for High-Efficiency Solar Steam Generation and Water Purification.

Efficient utilization of solar energy to generate steam is a green and promising technology because of its great potential applications in seawater desalination and industrial wastewater purification. However, the practical application of high-efficiency solar steam generation devices is largely overshadowed due to their complex process, high cost, low life-span, and poor thermal performance. Here, novel meat and bonemeal biochar (MBB) with high solar steam generation efficiency is produced by pyrolyzing dead carp at 300, 400, and 500 °C under anoxic conditions. Attributed to its typical hydrophilic pore structure, the photon trapping ability of MBB500 is up to 97% and 84.1% in the ultraviolet and visible regions and near-infrared light regions, respectively. Meanwhile, hydrophilic pore structural provides a strong capillary force for the rapid transmission of water. As a result, under 1 sun illumination (1 kW m-2), the water evaporation rate and the apparent energy conversion efficiency of MBB500 reach 1.48 kg m-2 h-1 and 131.2%, respectively. In addition, MBB500 also exhibits excellent seawater and heavy metal wastewater evaporation effects, providing a new manufacturing strategy for photo-thermal materials, which greatly benefit their practical application in pure water regeneration.

Qualitative and quantitative adsorption mechanisms of zinc ions from aqueous solutions onto dead carp derived biochar.

The objective of this study is to investigate the qualitative mechanisms of Zn2+ adsorption on carp biochars (CMBx) produced from dead carp at different temperatures (450-650 °C) and their quantitative contribution. The pseudo second order kinetic model and the Langmuir model could fit the kinetic and isothermal adsorption data well, respectively. The intra-particle diffusion was the main rate-limiting step but not the only rate-limiting step. The maximum adsorption capacity obtained from the Langmuir model for CMB650 was 87.7 mg g-1 which was greater than those of other biochars. Precipitation with minerals, ion exchange, and complexation with functional groups (OFGs) were the main adsorption mechanisms. Quantum chemistry calculations confirmed that the functional groups (e.g., hydroxyl, carboxyl and C[double bond, length as m-dash]C) tended to bind with Zn2+ more strongly than with Ca2+ and Mg2+, because the structure of the complex formed by the former was more stable. The contribution of different adsorption mechanisms varied with the pyrolysis temperature to prepare biochar. With increasing pyrolysis temperature, the contribution of the interaction between Zn2+ and the minerals increased from 46.4% to 84.7%, while that of complexation with OFGs decreased from 41.7% to 4.7%. Overall, the mechanism of Zn2+ adsorption on CMB450 was dominated by complexation with OFGs and exchange with cations (accounting for 73.2%), while the mechanisms on CMB650 were dominated by the interaction with minerals. In view of the total adsorption capacity, 650 °C was the optimized pyrolysis temperature for CMBx preparation and adsorption treatment of Zn-contaminated water. These results are useful for screening effective biochars as engineered sorbents to treat Zn-containing wastewater.