SMALL-SCALE SEAWATER ELECTRODEIONIZATION

In this work, the performance of electrodeionization (EDI) in seawater desalination was investigated. EDI stack design and operating parameters (applied voltage, recovery, and multi-stage process) were examined during a batch-mode desalination process. The results show that EDI can achieve 99.5% salt removal in a stack with 4 mm spacer thickness (at 20 V applied voltage, 75% recovery, and 2 mL/s circulation flow rate). A thinner spacer thickness can enable a higher desalination rate and lower final solution temperature. Compared to a single-stage process, two-stage desalination can maintain the salt-removal rate, suppress reverse salt diffusion, and shorten the desalination time required to produce similar water quality. The specific energy consumption of EDI is below 12 kWh/m3 or less than 120 Wh for producing 10 L freshwater. Considering its simplicity, EDI can be an attractive alternative for small-scale, decentralized desalination facilities.

Effect of multiple pouring on the accuracy of casts made using 3D-printed custom trays with different spacer thicknesses: A research study

Background . This study aimed to evaluate the effect of different pouring times and spacer thicknesses on the three-dimensional accuracy of casts made of 3D-printed custom trays. Methods. A partial edentulous maxillary model was scanned for fabricating custom acrylic trays. Twenty custom trays were created using a CAD/CAM system and divided into two groups in terms of their spacer thicknesses (2 mm and 4 mm). All the trays were designed with 2-mm thickness, multiple retentive holes measuring 2 mm in diameter, and three interior seating stops (two on the edentulous ridge and one on the incisal edge of the central incisors). Impressions were made using monophasic polyvinyl siloxane and poured in two different times (one hour and 24 hours after removal) with type IV dental stone. All the casts were scanned to measure three distances (inter-buccal cusps, inter-palatal cusps, and inter-fossa distances) between the two first premolars. The data were analyzed with two-way ANOVA and Bonferroni test at a significance level of 0.05. Results. There was no significant difference between the 3D accuracy of casts made using two different spacer thicknesses poured at 1-hour and 24-hour intervals. However, there was a difference between casts made after 1 hour and 24 hours when using custom trays with 2 mm of spacer thickness in terms of inter-buccal distance. Conclusion. There was no significant difference between the accuracy of casts made using custom trays with either 2 or 4 mm of spacer thickness, which were poured 1 hour or 24 hours after tray removal.