As a potential solution to the crises of energy and resources, forward osmosis(FO) has been limited by the development of draw agents. An ideal draw agent should be able to generate high osmotic pressure and can be ea...As a potential solution to the crises of energy and resources, forward osmosis(FO) has been limited by the development of draw agents. An ideal draw agent should be able to generate high osmotic pressure and can be easily recovered. In this study, a thermo-sensitive polyelectrolyte of poly(N-isopropylacrylamide-co-acrylic acid)(PNA)is developed as an efficient draw agent, and two easy and simple methods are proposed to effectively recover the polyelectrolytes. After adjusting the pH value of polyelectrolyte solutions to around 6.0, the polyelectrolyte can generate relatively high osmotic pressure, and induce average water fluxes of 2.09 and 2.95 L·m^(-2)·h^(-1) during12 h FO processes when the polyelectrolyte concentrations are 0.20 and 0.38 g·ml^(-1) respectively. After acidifying and heating to 70 °C, the PNA-10 polyelectrolyte can aggregate together because of hydrophobic association and separate from water, so it can be easily recovered by either simple centrifugation or gravitational sedimentation. The recovery ratios of PNA-10 polyelectrolyte in both methods are as high as 89%, and the recovered polyelectrolytes can be reused with almost the same FO performance as fresh ones. The results in this study provide valuable guidance for designing efficient and easily recoverable draw agents for FO processes.展开更多
The tribological behavior of 316L stainless steel/CoCrMo alloy contacts under aqueous lubrication was investigated in this work.Three types of microgels including poly(N-isopropylacrylamide)(PNIPAM),polyacrylic acid(P...The tribological behavior of 316L stainless steel/CoCrMo alloy contacts under aqueous lubrication was investigated in this work.Three types of microgels including poly(N-isopropylacrylamide)(PNIPAM),polyacrylic acid(PAA),and poly(N-isopropylacrylamide-co-acrylic acid)(PNIPAM-co-PAA)were prepared and used as lubricant additives in aqueous solutions.Tribological tests were conducted using a ball-on-disk reciprocating tribometer,over a range of temperatures,pH,and concentrations of the microgels.The PNIPAM-co-PAA microgels were proven to have excellent anti-friction and anti-wear properties,depending on the temperature and pH values of the solutions.The maximum friction coefficient coincided with the lower critical solution temperature of the PNIPAM-co-PAA microgels at 32°C.At the same time,the friction coefficient increased with the increase in pH value of the lubricant solution with the PNIPAM-co-PAA microgels.The unique thermal-and pH-sensitive properties of the PNIPAM-co-PAA microgels provided a new strategy for controlling the friction and wear of steel/CoCrMo alloy contacts under aqueous lubrication.展开更多
基金Supported by the National Natural Science Foundation of China(21276162)the Program for Yangtse River Scholars and Innovative Research Team in Universities(IRT1163)
文摘As a potential solution to the crises of energy and resources, forward osmosis(FO) has been limited by the development of draw agents. An ideal draw agent should be able to generate high osmotic pressure and can be easily recovered. In this study, a thermo-sensitive polyelectrolyte of poly(N-isopropylacrylamide-co-acrylic acid)(PNA)is developed as an efficient draw agent, and two easy and simple methods are proposed to effectively recover the polyelectrolytes. After adjusting the pH value of polyelectrolyte solutions to around 6.0, the polyelectrolyte can generate relatively high osmotic pressure, and induce average water fluxes of 2.09 and 2.95 L·m^(-2)·h^(-1) during12 h FO processes when the polyelectrolyte concentrations are 0.20 and 0.38 g·ml^(-1) respectively. After acidifying and heating to 70 °C, the PNA-10 polyelectrolyte can aggregate together because of hydrophobic association and separate from water, so it can be easily recovered by either simple centrifugation or gravitational sedimentation. The recovery ratios of PNA-10 polyelectrolyte in both methods are as high as 89%, and the recovered polyelectrolytes can be reused with almost the same FO performance as fresh ones. The results in this study provide valuable guidance for designing efficient and easily recoverable draw agents for FO processes.
基金supported by the National Natural Science Foundation of China(No.51875155)。
文摘The tribological behavior of 316L stainless steel/CoCrMo alloy contacts under aqueous lubrication was investigated in this work.Three types of microgels including poly(N-isopropylacrylamide)(PNIPAM),polyacrylic acid(PAA),and poly(N-isopropylacrylamide-co-acrylic acid)(PNIPAM-co-PAA)were prepared and used as lubricant additives in aqueous solutions.Tribological tests were conducted using a ball-on-disk reciprocating tribometer,over a range of temperatures,pH,and concentrations of the microgels.The PNIPAM-co-PAA microgels were proven to have excellent anti-friction and anti-wear properties,depending on the temperature and pH values of the solutions.The maximum friction coefficient coincided with the lower critical solution temperature of the PNIPAM-co-PAA microgels at 32°C.At the same time,the friction coefficient increased with the increase in pH value of the lubricant solution with the PNIPAM-co-PAA microgels.The unique thermal-and pH-sensitive properties of the PNIPAM-co-PAA microgels provided a new strategy for controlling the friction and wear of steel/CoCrMo alloy contacts under aqueous lubrication.
