Study on the Bonding Performance of BFRP Bars with Seawater Sand Concrete.

A total of 66 sets of pullout specimens were prepared to investigate the bonding properties of basalt fiber-reinforced polymer reinforcement (hereinafter referred to as BFRP) with seawater sand concrete (hereinafter referred to as SSC). The volume dosages of mono-doped glass fibers and mono-doped polypropylene fibers were 0.1%, 0.2%, and 0.3%; the total volume dosage was set to be constant at 0.3%; and the doping ratios of the hybrid fibers were 1:2, 1:1, and 2:1. The effect on the bonding performance of BFRP reinforcement with SSC was studied on the condition of the diameter D of the BFRP reinforcement being 12 mm; the bond length of SSC being 3D, 5D, and 7D; and the surface characteristics of the reinforcement being sandblasted and threaded. The research showed that due to internal cracks in the matrix, salt crystals in the pores, chloride salts with high brittleness and expansion, as well as sulfate corrosion products such as "Frederick salts" in SSC, the concrete became brittle, resulting in more brittle splitting failures during the pullout test. Doped fibers can increase the ductility effect of concrete, but the bonding effect between the threaded fiber reinforcement and the SSC was not as good as that of the sandblasting group. When the bond length was 5D, the bonding effect between the BFRP reinforcement and SSC was the best, and the bonding performance of the experimental group with doped fibers was better than that of the threaded group. Finally, by combining the ascending segment of the Malvar model with the descending segment of the improved BPE model, a constitutive relationship model suitable for the bond-slip curve between BFRP reinforcement and SSC was fitted, which laid a theoretical foundation for future research on SSC.

High performance, cost-effective and ecofriendly flocculant synthesized by grafting carboxymethyl cellulose and alginate with itaconic acid.

Natural polymer flocculant possesses an exciting prospect in water treatment due to its non-toxicity, wide source, low cost and biodegradability. In this work, we have successfully synthesized the anionic terpolymer of carboxymethyl cellulose-itaconic acid­sodium alginate (CIS) by microwave-assisted copolymerization. By studying the flocculation properties towards cationic dye of crystal violet (CV), the optimum synthesis conditions were determined. The maximum removal rate of 100 mg/L CV simulated wastewater was 92.2 % with CIS concentration of 30 mg/L. The flocculation kinetic results showed the rapid dye removal rate and the dye decolorization ratio of 89.8 % could be obtained at 75 s. Moreover, the CIS flocculant showed excellent flocculation effects in ambient pH of 4-10, flocculation temperature of 10-40 °C, and various inorganic salts. In general, the anionic CIS flocculant shows excellent cost effectiveness, where the predicted operation cost of as-prepared CIS is about 60 % of conventional polyacrylamide flocculant. It also has the advantages of excellent ecofriendliness and rich raw material source, indicative its potential applications of wastewater treatment.

Electrospun molecularly imprinted sodium alginate/polyethylene oxide nanofibrous membranes for selective adsorption of methylene blue.

Molecular imprinting technique is an efficient method to improve the selective adsorption capacity for the target pollutant. In this study, sodium alginate/polyethylene oxide molecularly imprinted nanofibrous membrane (SA/PEO-MINM) with average diameter of 185 ± 20 nm was successfully synthesized by electrospinning for selective adsorption of methylene blue (MB). Benefiting from the molecular imprinted technology, the adsorption amount of SA/PEO-MINM for MB was increased by about 65%, significantly higher than the non-imprinted membrane. Results showed that the adsorption equilibrium could be well fitted with Langmuir isotherm model and the maximum adsorption capacity towards MB was 3186.7 mg/g. Kinetic experiments well complied with the Pseudo second order model. Reusability studies indicated that the removal efficiency of MB could maintain 93% of the original adsorption capacity after four consecutive adsorption/desorption cycles. More importantly, the SA/PEO-MINM with high surface area and specific adsorption recognition sites showed excellent selective adsorption capacity in the adsorption experiment of MB and methylene orange mixed dye solution. In general, the SA/PEO-MINM can be successfully applied for the selective removal of MB from dye wastewater.