چكيده به لاتين
the unique characteristics of hydrogels made them an appropriate choice to use in various
applications such as water treatment. According to the high amount of different contaminants
such as dyes, heavy metals, pharmaceutical pollutants, etc in the ground and underground
water, and their harmful effect on human health and the environment, water and wastewater
treatment is essential. In this research, the effective parameters such as additives and their
percentage in the PVA hydrogel composites to achieve hydrogel with open pores and the ability
to absorb water pollutant by the freeze-thawing method was investigated. Raw bentonite,
purified bentonite (by two different approaches; ultrasonication, and sedimentation),
organoclay, and zeolite was applied as an additive. The freeze-thawing procedure contains
three cycles, 12 h of freezing and 2 h of thawing. In addition to the formulas of water
absorption, porosity, density, and gel fraction; X-ray diffraction (XRD), Fourier-Transform
infrared (FT-IR) Spectroscopy, Ultraviolet-Visible Spectroscopy (UV-Vis), Atomic
Absorption Spectroscopy (AAS), energy dispersive X-ray spectroscopy (EDS), Scanning
Electron Microscopy (SEM) analysis and compressive strength were used for phase bonding,
adsorption, microstructure, and strength studies. Porosity percentage, compressive strength,
and water absorption capacity in PVA composite are 285%±50%, 1.8±0.1 MPa, and 10±3 (g/g),
respectively. Porosity percentage, compressive strength, and water absorption capacity in
PVA/additive composites are in the range of 300%-1350%, 1.7-2.7 MPa, and 11-24 (g/g),
respectively. PVA/zeolite hydrogel (5 wt.% PVA, 1 wt.% zeolite) has the maximum porosity
percentage and compressive strength, which are 7337%±120% and 2.7±0.1 MPa respectively.
The PVA/purified bentonite (5 wt.% PVA, 1 wt.% purified bentonite) has the maximum water
absorption (24±1 g/g). Optimum efficiency of methylene blue and Pb2+ absorption are
99%±4% and 84%±4%, which are achieved by 0.1 g PVA/purified bentonite (5 wt.% PVA, 1
wt.% purified bentonite) composite in 50 ppm initial solution after one week. The
PVA/organoclay (5 wt.% PVA, 1 wt.% organoclay) has the maximum efficiency
(14.5%±0.1%) in paracetamol removal.
