Amirkabir University of Technology

About: Amirkabir University of Technology is a education organization based out in Tehran, Iran. It is known for research contribution in the topics: Nonlinear system & Finite element method. The organization has 15254 authors who have published 31165 publications receiving 487551 citations. The organization is also known as: Tehran Polytechnic & Tehran Polytechnic University.

Super-hydrophilic/oleophobic chitosan/acrylamide hydrogel: an efficient water/oil separation filter

Abstract: Oil spills are one of the most serious problems which have a negative effect on our environment especially on the marine ecosystem. Thus, water/oil separation is considered as an important process to eliminate the oily pollutants. In the current study, a super-hydrophilic and super-oleophobic filter was prepared by in situ synthesis of chitosan/acrylamide hydrogel on the cotton fabric as a substrate. Different concentrations of chitosan and acrylamide monomers, cross-linking agent (MBA), and thermal initiator (APS) were tested by the Design Expert 7.0.0 Central Composite (CCD) software and the water absorption capacity of hydrogels were evaluated by a tea-bag method. The optimum concentration of MBA and APS was measured 0.03 g and 0.1 g, respectively. The optimal hydrogel-based filter was characterized by FTIR and SEM tests. The results confirm the successful synthesis of chitosan/acrylamide hydrogel with a porous structure on the cotton fabric. In addition, according to the results of the swelling study, the optimal synthesized hydrogel has high water retention capacity with a great stability in the seawater-simulated medium. Moreover, contact angle measurement and water/oil separation test demonstrate the super-hydrophilic/oleophobic behavior and high efficiency and durability of filter for water/oil separation.

Measurement of Activity of Water in Aqueous Poly(ethylene glycol) Solutions (Effect of Excess Volume on the Flory−Huggins χ-Parameter)

Abstract: Activities of water are reported for aqueous solutions of poly(ethylene glycol) (PEG) with number average molecular weights of 300, 400, 4000, and 6000 are measured at 35, 45, 55, and 65 °C and at various concentrations from 0 to 40 wt % of PEG using vapor-pressure osmometery. A cubic equation in terms of PEG concentrations is sufficient for correlation of activities. Using measured activities, the Flory−Huggins interaction parameters have been calculated. The effect of temperature, molecular weight of PEG and its concentration, and volume change upon mixing on interaction parameter have been considered. Ignoring the volume change of mixing can lead to an average error of 2.5% with a maximum error of 5.3%.