A portable and washable solar steam evaporator based on graphene and recycled gold for efficient point-of-use water purification

A solar steam evaporator provides a sustainable and efficient alternative water purification solution to address the global freshwater shortage.Previous efforts have made significant advances in maximizing its water evaporation rate,but no single evaporator has all the properties necessary for practical point-of-use application,including a high efficiency for generation of drinkable water,an excellent portability critical for on-site water purification,good washability for mitigating evaporator fouling,and good reusability.We report a strategy to produce a high-performance photothermal material for point-of-use water purification.By simultaneously incorporating graphene and gold particles grown from recycled electronic waste in a mechanically strong sponge,we achieved highly efficient water purification under realistic conditions.In addition to a high evaporation rate(3.55 kg/m^(2)/h under one-sun irradiation)attributed to a control of atomic structure of graphene and the size-dependent surface plasmon resonance of gold nanoparticles,it is portable which can be folded,vacuum compacted,dried and rehydrated without compromising performance.It also allows repeated washing to remove contaminant fouling so that it can be reused.The evaporator transforms various types of contaminated water into drinkable clean water,and can be mounted at any angle to optimize the incident solar irradiation.Furthermore,the assembled steam evaporator device could gain purified water meeting the World Health Organization drinking water standards with a high evaporation rate of 9.36 kg/m^(2)/h under outdoor sunlight.

Phosphorus recovery:a need for an integrated approach

Introduction:Phosphorus(P)is an essential element in food production.P consumption is increasing over the years due to increasing population and increasing demand for agricultural yields.Managing the agricultural P through the understanding of bioav ailability,transport,and runoff will maximize the soil productivity and minimize the environmental effects.Efficient management in agriculture,governance,and lack of integrated international govern-ance need to be addressed to overcome the P scarcity issue.Results and Discussions:This article is focusing one such efficient management of P resource addressing the major portion of phosphorus which is unnoticed in agricultural residues,manures,and other sources.Increasing cost of phosphate fertilizer,a scarcity of high-quality phosphate rock(PR),and increasing surface water pollution are driving a need to accelerate the recovery and reuse of phosphorus(P)from various waste sectors.Options to recover P occur all along the open P cycle from mining to households to oceans.However,P recovery as a regional and global strategy toward P sustainability and future food,bio energy,and water security are in its infancy because of a number of technological,socioeconomic,and institutional constraints.Resolving these constraints requires concerted colla boration between relevant stakeholders and an integrated approach combining successful business models with socioeconomic and institutional changes.