A route for large-scale preparation of multifunctional superhydrophobic coating with electrochemically-modified kaolin for efficient corrosion protection of magnesium alloys

Superhydrophobic coating has been widely studied for its great applicational potential, such as for corrosion protection of magnesium alloys while it has been restrained by expensive materials, sophisticated preparation process and infirm rough structures. In this study, the electrochemical method was adopted by using a two-electrode system for rapid hydrophobic modification to obtain superhydrophobic kaolin.By mixing the modified superhydrophobic kaolin with commercial epoxy resin and polydimethylsiloxane glue, a paint can be formed and easily used on various substrates for preparation of superhydrophobic coating via spraying method. The influence factors on wettability of the modified kaolin and the mixing ratio of each component of the coating were explored. Also, the wettability, durability and anticorrosion of the prepared coating were evaluated comprehensively. The coating was able to maintain superhydrophobic after immersed in HCl solution at pH 1, the NaOH solution at pH 14, and 3.5 wt.% NaCl solution for 16, 21, 30 days, respectively. In addition, the coating exhibited 4A grade adhesion, high hydrophobicity after abraded for 200 cycles on a 600-mesh sandpaper with 100 g weight, and 99.86% anticorrosion efficiency after soaked in 3.5 wt.% NaCl solution for 20 days, demonstrating a good robustness and anti-corrosion property. Furthermore, the coating showed good transparency, flexibility and was easy to make in a large scale by the spraying method, which is of great significance to promote the practical application of superhydrophobic coatings and the anticorrosion Mg alloys.

A novel electrolytic-manganese-residues-and-serpentine-based composite(S-EMR) for enhanced Cd(Ⅱ) and Pb(Ⅱ) adsorption in aquatic environment

Electrolytic manganese residue(EMR) is the waste slag generated from the electrolysis manganese industry.As a promising exploitable adsorbent,EMR has become a hot research topic.However,EMR’s low adsorption capacity has limited its applications as an efficient adsorbent.In this study,the EMR was mixed with serpentine and calcined(at 800℃ for 2 h) to prepare a composite adsorbent(S-EMR) with its specific surface area of 11.998 m^(2)·g^(-1)(increased compared to the original EMR) and improved adsorption capacities for Cd^(2+)(98.05 mg·g^(-1)) and Pb^(2+)(565.81 mg·g^(-1)).Kinetic studies have shown that the pseudo-first-order kinetics(PSO)model could best describe the adsorption kinetics of S-EMR for Cd^(2+)/Pb^(2+),implying that the chemisorption process is the rate-limiting step.The effects of different interfering ions on S-EMR’ s adsorption for Cd^(2+)/Pb^(2+)may be due to the difference in their electronegativity.Results of response surface methodology tests showed that pH had the highest influence on adsorption,and the removal efficiency of S-EMR reached 99.92% for Cd(Ⅱ) and 94.00%for Pb(Ⅱ).X-ray photoelectron spectroscopy(XPS) analyses revealed that chemical precipitation was the predominant mechanism for Cd^(2+)/Pb^(2+)removal,and the adsorption mechanisms were associated with ion exchange and electrostatic attraction.The results showed that S-EMR could be used as an effective adsorbent for the removal of Cd(Ⅱ)/Pb(Ⅱ) from water bodies,rendering dual benefits of pollution control and resource recovery.

Nanomaterials for environmental burden reduction,waste treatment,and nonpoint source pollution control:a review

Nanomaterials are applicable in the areas of reduction of environmental burden,reduction/treatment of industrial and agricultural wastes,and nonpoint source(NPS)pollution control.First,environmental burden reduction involves green process and engineering,emissions control,desulfurization/denitrification of nonrenewable energy sources,and improvement of agriculture and food systems.Second,reduction/treatment of industrial and agricultural wastes involves converting wastes into products,groundwater remediation,adsorption,delaying photocatalysis,and nanomembranes.Third,NPS pollution control involves controlling water pollution.Nanomaterials alter physical properties on a nanoscale due to their high specific surface area to volume ratio.They are used as catalysts,adsorbents,membranes,and additives to increase activity and capability due to their high specific surface areas and nano-sized effects.Thus,nanomaterials are more effective at treating environmental wastes because they reduce the amount of material needed.

Binary doping of nitrogen and phosphorus into porous carbon: A novel di-functional material for enhancing CO_(2) capture and super-capacitance

Designing of hetero-atomic doped carbon-based systems through pyrolysis of abundant element organic precursors is a novel approach to construct rational porous carbon materials.Herein,a highly-cross-linked triazine polymer is employed to fabricate N,P co-doped porous carbon(A-TDP-12)with tunable active nitrogen in the carbon framework for simultaneous enhancement of CO_(2) capture capability and Supercapacitance(SC).The synthesized A-TDP-12 possesses a typical hierarchically porous framework(micro-pores and meso-pores)with a large surface area(1332 m^(2) g^(-1))and a rich content of N(7.89 at.%)and P(0.74 at.%).It delivers a CO_(2) adsorption capacity of 1.52 and 5.68 mmol g^(-1) at 1 and 5 bar,respectively,with almost no decay after successive 8 recycles.In 6 M KOH aqueous electrolyte,A-TDP-12 exhibits a superior specific capacitance of 172.7 F g^(-1) at a current density of 1 A g^(-1).Even at a high current density of 10 A g^(-1),80%of its initial capacity still remains.This work not only offers a novel strategy for fabricating promising adsorbents and electrodes for CO_(2) uptake and SCs,but also provides new insights into design of porous carbon material for related applications.