Shi-Chang Hou,Dao-Wei Zhang,Jun Chen,Xiao-Xiao Guo,Abdul Haleem,Wei-Dong He
Because of the increasing scarcity of water resources, the desalination of seawater by photothermal evaporation with harvested solar energy has gradually become a popular research topic. The interconnected macroporous cryogel prepared from polymerization and crosslinking below the freezing temperature of the reactant solution has an excellent performance in photothermal water evaporation after loading photothermal materials. In this study, polyacrylamide (PAM) cryogels were prepared by cryo-polymerization and sulfonated in an alkaline solution containing formaldehyde and Na2SO3. Importantly, the evaporation enthalpy of water in sulfonated PAM cryogel was reduced to 1187 J·g−1due to the introduction of sulfonate groups into PAM, which was beneficial to increase the photothermal evaporation rate and efficiency. The sulfonated PAM cryogels loaded with polypyrrole and the umbrella-shaped melamine foam substrate were combined to form a photothermal evaporation device, and the evaporation rate was as high as 2.50 kg·m−2·h−1under one-sun radiation. Meanwhile, the evaporation rate reached 2.09 kg·m−2·h−1in the 14 wt% high-concentration saline solution, and no salt crystals appeared on the surface of the cryogel after 5 h of photothermal evaporation. Therefore, it was evidenced that the presence of sulfonate groups not only reduced the evaporation enthalpy of water but also prevented salting-out from blocking the water delivery channel during photothermal evaporation, with a sufficiently high evaporation rate, providing a reliable idea of matrix modification for the design of high-efficiency photothermal evaporation materials.Keywords:polymeric cryogel;polyacrylamide;photothermal evaporation;evaporation enthalpy;sulfonating modification
Jianan Guan,Xiao Liu,Guanghong Lai,Qifeng Luo,Shanshan Qian,Jiayu Zhan,Ziming Wang,Suping Cui
A novel polycarboxylate superplasticizer (PCE) was synthesized by graft copolymerization between acrylic acid (AA) and end-functionalized poly (allyl sulfonate) (PALS) to produce comb polymer, i.e. PAA-g-PALS. The molecular structure was confirmed by Infrared Spectroscopy (IR) and 1 H Nuclear Magnetic Resonance ( 1 H NMR), and the molecular properties were characterized by Gel Permeation Chromatography (GPC). The conventional PCE with comb structure using isobutenyl polyethylene glycol (IPEG) as side chains (i.e. PAA-g-IPEG) was also synthesized to explore the effect of the side chain on the PCE performances. The fluidity and its retention, rheological properties, hydrodynamic radii (R h ), adsorption behavior and zeta potential of the cement pastes containing PAA-g-PALS or PAA-g-IPEG were comparatively tested. It was found that this designed “sulfonate modified PCE” exhibited stronger dispersing stability and sulfate tolerance to cement paste and less sensitive to the sulfate competitive adsorption and the increase in ionic strength. Based on the above results, the evaluation method (the sulfate resistance index of PAA-g-PALS was increased by 24% as compared to that of PAA-g-IPEG) was innovatively established and the mechanism of sulfate resistance was clarified in detail. The purpose of this research is to offer an avenue with great potentials to synthesize a novel PCE with excellent workability retention and sulfate tolerance in fresh cement pastes. This sulfonate-modified polycarboxylate superplasticizer has great potentials as a viable alternative to conventional PCE, especially in some harsh cement systems.
Cottonseed protein isolate (CPI) is a valuable agro-industrial waste with potential biotechnological applications. However, inadequate stability in water due to its characteristic hinders its widespread use. Therefore, a new sulfonation modification approach was developed to improve the amphiphilicity and structural flexibility of CPI. Structural characterizations confirmed the successful incorporation of sulfonate groups with structural and conformational changes. This significantly unfolded molecular-chain, and improved amphiphilicity, flexibility, and surface-hydrophobicity while reducing pI (5.1–1.7), and molecular-weight (5745–2089 g/mol). The modified samples exhibited improved emulsification with higher amounts of absorbed proteins on the droplet interface, smaller droplet size, and a higher zeta-potential. Additionally, they possessed good emulsification ability under acidic conditions. The nano-emulsions exhibited long-term stability (≥70 days) under different environmental conditions, with excellent fluidity. This study contributes to understanding sulfonation as a viable approach for improving protein properties, thus, opening up new possibilities for their application and maximizing their economic benefits.
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