Environmentally Friendly Polyvinyl Alcohol−Alginate/Bentonite Semi-Interpenetrating Polymer Network Nanocomposite Hydrogel Beads as an Efficient Adsorbent for the Removal of Methylene Blue from Aqueous Solution

Abstract

Hazardous chemicals like toxic organic dyes are very harmful to the environment and their removal is quite challenging. Therefore there is a necessity to develop techniques, which are environment friendly, cost-effective and easily available in nature for water purification and remediation. The present research work is focused on the development` and characterization of the ecofriendly semi-interpenetrating polymer network (semi-IPN) nanocomposite hydrogels composed of polyvinyl alcohol (PVA) and alginate (Alg) hydrogel beads incorporating natural bentonite (Bent) clay as a beneficial adsorbent for the removal of toxic methylene blue (MB) from aqueous solution. PVA−Alg/Bent nanocomposite hydrogel beads with different Bent content (0, 10, 20, and 30 wt%) were synthesized via external ionic gelation method. The designed porous and steady structure beads were characterized by the use of Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM). The performance of the beads as MB adsorbents was investigated by treating aqueous solutions in batch mode. The experimental results indicated that the incorporation of Bent (30 wt%) in the nanocomposite formulation sustained the porous structure, preserved water uptake, and increased MB removal efficiency by 230% compared to empty beads. Designed beads possessed higher affinity to MB at high pH 8, 30 °C, and fitted well to pseudo-second-order kinetic model with a high correlation coefficient. Moreover, the designed beads had good stability and reusability as they exhibited excellent removal efficiency (90%) after six consecutive adsorption-desorption cycles. The adsorption process was found be combination of both monolayer adsorption on homogeneous surface and multilayer adsorption on heterogeneous surface. The maximum adsorption capacity of the designed beads system as calculated by Langmuir isotherm was found to be 51.34 mg/g, which is in good agreement with the reported clay-related adsorbents. The designed semi-IPN PVA−Alg/Bent nanocomposite hydrogel beads demonstrated good adsorbent properties and could be potentially used for MB removal from polluted water.

Development of a Sericin Hydrogel to Deliver Anthocyanins from Purple Waxy Corn Cob (Zea mays L.) Extract and In Vitro Evaluation of Anti-Inflammatory Effects

“…[ 39 ]. In addition, the strong intensity peak at 1180.54 cm −1 (C−OH stretching of secondary alcohol) of PVA was shifted to a low intensity peak at 1080.54 cm −1 in SN2 and 1086.60 cm −1 in SN6, which might indicate the interaction of the −OH of PVA with the C=O of alginate via H-bond ( Figure 11 ) [ 42 ].…”

“…[39]. In addition, the strong intensity peak at 1180.54 cm −1 (C−OH stretching of secondary alcohol) of PVA was shifted to a low intensity peak at 1080.54 cm −1 in SN2 and 1086.60 cm −1 in SN6, which might indicate the interaction of the −OH of PVA with the C=O of alginate via H-bond (Figure 11) [42]. A previous study reported that interactions between alginate and anthocyanin molecules occurred via charge-charge interaction between the negatively charged carboxylic groups of the polymeric backbone of alginate and the flavylium cation of anthocyanin [43].…”

Removal of Methylene Blue from Aqueous Solutions Using a New Natural Lignocellulosic Adsorbent—Raspberry (Rubus idaeus) Leaves Powder

“…It has numerous applications in the textile, tannery, plastics, food, cosmetics, and paper industries. It is also used in the pharmaceutical industry and medical practice (methaemoglobinemia treatment, cyanide poisoning treatment, or as a staining agent) [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 ]. But this dye can also cause various negative effects on human health and the environment.…”

“…In order to remove the dyes (including methylene blue) from aqueous solutions, several different techniques have been applied as follows: coagulation, flocculation, precipitation, membrane processes, chemical oxidation, electrochemical processes, catalytic reduction, photocatalytic degradation, ion exchange, adsorption, microorganism degradation, membrane bioreactors, aerobic, and anaerobic biological treatments [ 1 , 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ].…”

“…Adsorption has proven to be a simple, efficient, and economical method that can use a wide variety of synthetic and natural materials as adsorbents [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 21 , 22 , 23 ]. The adsorbent price is a very important factor when deciding the practical applicability of a new adsorbent material.…”