Neutralization Degree Of Acrylic Acid Research Articles

Optimization of preparation conditions and performance of a new degradable soil water retaining agent

Using polyaspartic acid (PAsp) and bentonite (BT) as the main raw materials, a new type of degradable soil water retaining agent (PAsp-AA/BT) was synthesized by microwave radiation. The optimum synthesis conditions and comprehensive properties of PAsp-AA/BT were discussed and the structure and surface characteristics of PAspsp-AA/BT were characterized by FTIR, SEM, XRD and TGA in the paper. The results showed that the optimum synthesis conditions of PAsp-AA/BT were as follows: the dosages of polyaspartic acid (PAsp), bentonite (BT), initiator potassium persulfate, crosslinking agent N,N′-methylene bisacrylamide was 5, 3, 0.3, 0.03%, respectively, the neutralization degree of acrylic acid was 75%, and the microwave power was 490W. Under this condition, the absorption ratio of the synthesized PAspsp-AA/BT in deionized water and 0.9% NaCl solution was 953 and 164 g/g, respectively. The synthesized PAsp-AA/BT had a high water absorption rate, good water retention and repeated water absorption, and the degradation rate in soil within 30 days reached 32.75%, with good degradation effect. The analysis of SEM, FT-IR, XRD and TGA showed that: the surface of PAsp-AA/BT was rough and had obvious pore structure, which was conducive to the diffusion of water molecules; polyaspartic acid, bentonite and acrylic acid were polymerized; the cross-linking structure was formed between polyaspartic acid, bentonite and acrylic acid; the product of PASP-AA/BT had good thermal stability. This study provides a new soil water retaining agent, which is helpful for the better development of soil water retaining agent research.

A comprehensive assessment of superabsorbent resin produced using modified quinoa husk and coal fly ash - Preparation, characterization and application

About 200 million tons of coal fly ash (CFA) is not effectively used in China every year. To enhance the utilization of biomass waste quinoa husk (QH) and solid waste CFA and reduce the preparation cost of superabsorbent resin (SAR), a low-cost, biodegradable modified quinoa husk-g-poly (acrylic acid)/coal fly ash superabsorbent resin (MQH-g-PAA/CFA SAR) was synthesized using modified quinoa husk (MQH), acrylic acid and CFA and used to improve the drought resistance and fertilizer conservation ability of soil. The surface morphology and performance of SAR were characterized by Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA), which provided evidence for improving the properties of SAR by grafting MQH and adding CFA. In addition, the synthesis conditions were studied and optimized, together with the contents of initiator, crosslinker, MQH, and CFA to acrylic acid as well as the neutralization degree of acrylic acid. After optimization, the optimum water absorbency of SAR in deionized water, tap water, and physiological saline was 1302, 356, and 91 g/g respectively. The swelling and water-retention mechanisms of SARs were analyzed by a dynamic model and the results were in good agreement with the experimental data. In the soil experiment, the addition of SAR improved the drought resistance ability of soil, and reduced the leaching loss of fertilizer in the soil (from 49.5 % to 36.7 %). Therefore, this material exhibits significant potential in the field of agriculture and offers a novel approach with economic benefit for the utilization of MQH and CFA.

Synthesis, Properties of MIL‐101(Al)‐NH2 Polymers Capable of Absorbing Vapor, Liquid Water Simultaneously

AbstractModified MIL‐101(Al)‐NH2 (MIL‐101(Al)‐NH2‐net) is used as a crosslinking agent and acrylic acid (AA) as a monomer, the MIL‐101(Al)‐NH2‐net grafted polyacrylic acid (MIL‐101(Al)‐NH2‐net‐g‐PAA (MAP)) composite water‐absorbent material is synthesized using the free radical polymerization method to study the application of composite absorbent materials in water collection. The structure and morphology of the composite water‐absorbent material are characterized using Fourier transform infrared spectrometry (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), Brunauer Emmett Teller (BET), and thermogravimetric analysis (TG), and the contents of ammonium persulfate (APS), MIL‐101(Al)‐NH2‐net, and neutralization degree of AA are optimized. Under optimal conditions, the water absorption ratios of the composite materials in distilled water, tap water, and 0.9% NaCl solution are 744, 169.5, and 85.5 g g−1. In addition, the properties of collecting water vapor are investigated. At 25 °C, 50% Relative Humidity (RH), 70% RH, and 90% RH, the MAP water vapor adsorption capacity is 0.0312, 0.5760, and 1.6856 g g−1, respectively. The water vapor adsorption of MIL‐101(Al)‐NH2 and MIL‐101(Al)‐NH2 self‐polymerization products are 0.025 and 0.1278 g g−1, respectively. The result showed that autopolymerization can improve the water vapor adsorption performance.

Synthesis and Characterization of a Novel Bentonite Composite Superabsorbent Resin Based on Starch

A superabsorbent resin (SAR) is a functional polymer with a high water absorption capacity, which has been widely used in many fields. In this study, a modified aqueous solution polymerization process was adopted to synthesize a SAR. The optimum synthetical mass ratios of starch, bentonite, potassium persulfate (K2S2O8), and N,N′-methylene-bis-acrylamide to acrylic acid (AA) were 7.14%, 3.57%, 0.29%, and 0.057%, respectively, and the neutralization degree of AA was 50%. The molecular structure and the surface morphologies of the SAR were confirmed using Fourier transform infrared spectroscopy and scanning electron microscopy. The SAR had a water absorbency of 1300 mL/g in distilled water and 56 mL/g in 0.9 wt.% NaCl solution. The water absorption rate reached 72.65% of the maximum water absorption in 1 hour and swelled to equilibrium in 4 hours. The water retention rate was 45.86% after heating and evaporation at 150°C for 1 hour. The moisture absorption rate reached 28.2% after 10 days of placement. The modified technology provides a new synthetic method for production of SARs, which is characterized by a lack of nitrogen protection, the direct use of raw AA and potato starch, a simplified synthesis process, substantially improved efficiency, and lower production costs.

Kaolin-Enhanced Superabsorbent Composites: Synthesis, Characterization and Swelling Behaviors

One type of low-cost and eco-friendly organic‒inorganic superabsorbent composite (SAPC) was synthesized by free radical polymerization of acrylic acid (AA), starch (ST), sodium alginate (SA) and kaolin (KL) in aqueous solution. The structure and morphology of the SAPC were characterized by Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The influence of different reaction conditions on water absorption of SAPC, i.e., SA and KL contents, AA neutralization degree (ND), potassium persulfate (KPS) and N, N′-methylenebisacrylamide (MBA) loading were systematically studied. Under the optimal synthesis conditions, very high water absorption of 1200 g/g was achieved. The swelling kinetic mechanism of SAPC was studied by pseudo-second order swelling kinetics model and Ritger‒Peppas model. The performances of SAPC under different environments were tested and results revealed that this new SAPC had excellent swelling capacity, high water retention, good salt tolerance in monovalent salt solution (NaCl solution) and good pH tolerance between 4 and 10.

Preparation and swelling properties of hydrolysis-resistant superabsorbent composite based on acrylic acid and sodium bentonite

A novel hydrolysis-resistant superabsorbent composite was prepared via the solution polymerization based on acrylic acid (AA) and sodium bentonite (SBT) as monomers, tetraallylammonium bromine (TAAB) as crosslinker and ammonium persulfate (APS) as initiator. The mechanism of polymerization and the structure of the superabsorbent polymer (SAP) were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (X-ray), and scanning electron microscopy (SEM). The reaction conditions such as different mass ratios of APS to AA, TAAB to AA, SBT to AA, neutralization degree of AA were optimized by orthogonal experiment, and the influence of each reaction condition on the capacity of water absorption at 150 °C was investigated via single-factor controlled experiment. The hydrolysis resistance and swelling kinetics of the SAP were studied in different solutions at 150 °C. Compared to traditional SAPs, the SAP synthesized with TAAB as crosslinker performed a more excellent hydrolysis resistance and water absorbency capacity at high temperatures. The water absorbency in distilled water or 0.1 mol L−1 NaCl solution could reach 392.6 and 145.2 g g−1at 150 °C, respectively. The SAP maintaining high swelling capacity in the pH range of 5–9 indicated its wide application values in the acidic or alkaline environment at high temperature. In addition, the SAP exhibited good reusability which could still retain about 73% of its initial water absorbency after reswelling six times at 150 °C.

Synthesis and Properties of Cellulose-based Superabsorbent Hydrogel by a New Crosslinker

Cellulose-based superabsorbent hydrogel (SAH) has been successfully prepared by the grafting method with cellulose and sodium acrylate as well as aluminum hydroxide as a novel crosslinker. The factors influencing water absorption such as the neutralization degree of acrylic acid (AA), the amount of initiator ammonium persulfate (APS) and crosslinker, and the proportion of cellulose to AA were investigated. The chemical structure and thermal behavior of the SAH were analyzed by fourier-transform infrared spectrometry, field-emission scanning electron microscopy, and thermal gravimetry, respectively. Results showed that the water absorbency of the SAH in distilled water and 0.9 wt% NaCl solution reached 922 and 118 g/g when the mass ratio of cellulose to AA, APS to AA, Al(OH) to AA, and the neutralization degree of AA was 39 wt%, 0.67 wt%, 0.89 %, and 76 %, respectively. Under the same condition, the hydrogel synthesized by traditional crosslinker N,N-methylenebisacrylamide was only 530 and 84 g/g in distilled water and 0.9 wt% NaCl solution, respectively. The mechanism of polymerization reaction was analyzed. And the cost and feasibility for the mass-producing the hydrogel were analyzed.

A Modified Preparation of Cellulosic‐Absorbent Resin for Cu2+ Removal under Microwave Irradiation

The absorbent resin for Cu2+ removal was prepared under microwave irradiation through grafting acrylamide (AM) and acrylic acid (AA) to cellulose. The initiator is a kind of redox system composed of potassium persulfate/sodium thiosulfate. The crosslinking agent is N,N′‐methylene bisacrylamide. The optimal reaction conditions are as follows: the ratio of AA to cellulose is 10 : 1, initiator to AA is 0.65 wt%, crosslinking agent to AA is 1.0 wt%, neutralization degree of AA is 75%, microwave power level is 320 W, and time is 300 s. The maximum absorption capability of the resin is 65 mg·g−1. Different from previous studies, the reaction was carried out without the protection of nitrogen and troublesome posttreatment. The product was obtained directly by one‐step synthesis without purification and drying of the crude product. The pollution and cost caused by organic solvent are avoided, and the whole preparation period is shortened deeply. Moreover, the time of absorption equilibrium is shorter. In a word, the preparation in this paper has the obvious advantages, such as simple process, short time, no pollution, low‐energy, and low‐cost.

Synthesis and adsorption properties of acrylic acid/styrene binary copolymer resin

In order to improve the adsorption of heavy metals in polyacrylic hydrogels, the experiment uses acrylic acid and styrene as raw materials, potassium per sulfate as initiator, and ethylene glycol as crosslinker to synthesize polyacrylic acid/styrene hydrogel. The effects of monomer ratio, acrylic acid neutralization degree, crosslinker dosage and temperature on product properties were studied by orthogonal test. In addition, the copolymer was characterized by fourier transform infrared spectroscopy. The adsorption of heavy metal performance test found that when the ratio of acrylic acid and styrene is 1:0.2, the degree of neutralization is 65%, the crosslinker accounts for 1.0% of the monomer mass fraction, and the temperature is 65 °C, the polyacrylic acid/styrene copolymer hydrogel is optimal. The adsorption of Pb2 + in the optimal group was 328.25 mg/g.

Synthesis and the Swelling Behavior of Sodium Alginate Graft Poly (Acrylic Acid-co-acrylamide)/Graphite Oxide Super Absorbent Composite

Sodium alginate graft poly(acrylic acid-co-acrylamide)/graphite oxide (P(AA-co-AM)/GO) super absorbent composite was prepared by solution intercalation copolymerization of acrylic acid (AA), acrylamide (AM) and graphite oxide (GO). The composite was characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, transmission electron microscope and differential scanning calorimetry. The effect of reaction conditions, including the mass ratio of monomers, dosages of cross-linker, initiator and GO as well as the neutralization degree of AA, on the absorption capacities of deionized water and 0.9% NaCl was studied. Water retention properties of the composite were also discussed. It was deduced that the interactions between GO and P(AA-co-AM) copolymer were the intermolecular hydrogen bonds. Thermal stabilities of the composite could be improved by the incorporation of GO. Above all, there was a remarkable improvement of absorption capacities owing to the incorporation of GO. Absorption capacities of water and 0.9% NaCl could be improved from 298.6 and 79.2 g/g, respectively, to 870.5 and 183.3 g/g, respectively, as the dosage of GO increased from 0 to 0.1 g. In addition, there was a remarkable improvement of water retention rates. After drying at 25°C for 8 h the water retention rates could be improved up to 17.9% with the incorporation of GO.

Preparation and Applications of Salt-Resistant Superabsorbent Poly (Acrylic Acid-Acrylamide/Fly Ash) Composite.

Solution polymerization synthesized alt-resistant superabsorbent poly (acrylic acid-acrylamide/fly ash) composites. The mass ratio of acrylic acid (AA) to acrylamide (AM), the concentration of crosslinker, the neutralization degree (ND) of AA, and the polymerization temperature were investigated by single-factor method. Optimized conditions for the synthesis of poly (acrylic acid-acrylamide/fly ash) (PAA-AM/FA) are, as following: m (AA)/m (AM) is 1.5, the content of crosslinker N, N-methylenebisacrylamide. (MBA) is 0.7%, neutralization degree of AA is 70%, polymerization temperature is 70 °C, and fly ash (FA) content is 50%. The prepared PAA-AM/FA demonstrated superior water absorption performance. The absorption capacities of PAA-AM/FA for pure water and 0.9% NaCl solution were found to be 976 g·g−1 and 81 g·g−1, respectively. Furthermore, PAA-AM/FA was found to have excellent adsorption capacity (148 mg·g−1) for Rhodamine B in water. Fourier Transform-Infrared Spectroscopy (FT-IR), Thermogravimetric Analysis (TGA), and Scanning Electron Microscopy (SEM) characterized the prepared materials. Results showed that fly ash was incorporated into the macromolecular polymer matrix and played a key role in improving the performance of the polymer composites.

Synthesis of a starch–acrylic acid–chitosan copolymer as flocculant for dye removal

ABSTRACTFlocculants prepared with modified natural polymers have recently attracted extensive attention in the field of water treatment. In this work, acrylic acid was successfully grafted onto the backbones of starch and chitosan by free radical polymerization. The synthesis parameters of initiator concentration, reaction temperature, and neutralization degree of acrylic acid were optimized as 0.4 wt %, 50 °C, and 70%, respectively, according to the flocculation performance. The ternary copolymer starch–acrylic acid–chitosan (SAAC) could completely remove Acid Blue 113 from 100 mg/L of simulated wastewater (color removal efficiency 99.7%) at the flocculant dosage of 100 mg/L. The SAAC also had effective flocculation capability in a wide range of flocculant dosages and pH values of wastewater. The ternary copolymer based on two natural polymers has enormous potential as flocculant with its advantages of low price, ecofriendliness, and high performance. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47437.

Preparation and absorption properties of poly (acrylic acid‐co‐acrylamide)/graphite oxide superabsorbent composite

AbstractPoly (acrylic acid‐co‐acrylamide)/graphite oxide (P (AA‐co‐AM)/GO) superabsorbent composite was prepared by solution intercalation polymerization of acrylic acid (AA), acrylamide (AM), and graphite oxide (GO). The composite was characterized by Fourier transform infrared spectroscopy, powder X‐ray diffraction, scanning electron microscopy, transmission electron microscope, thermogravimetric analysis , and differential scanning calorimetry. The effect of reaction conditions, including the mass ratio of monomers, dosages of cross‐linker, initiator, and GO as well as the neutralization degree of AA, on water and saline absorption was studied. Water retention properties of the composite were also discussed. It showed that interactions between GO and P (AA‐co‐AM) copolymer were the intermolecular hydrogen bonds. Thermal stabilities of the composite could be improved by the incorporation of GO. Besides, there was a remarkable improvement of absorption capacities owing to the incorporation of GO. Absorption capacities of water and 0.9% NaCl could be improved from 141.7 and 33.6 g/g, respectively, to 809.6 and 131.4 g/g, respectively, as the dosage of GO increased from 0 to 0.1 g. In addition, there was a remarkable improvement of water retention rates. Water retention rates of P(AA‐co‐AM)/GO and P(AA‐co‐AM) were 65.9% and 53.8%, respectively, after drying at 25°C for 8 hr.

Cellulose-Based Absorbent Production from Bacterial Cellulose and Acrylic Acid: Synthesis and Performance.

Cellulose-based superabsorbent was synthesized by bacterial cellulose (BC) grafting acrylic acid (AA) in the presence of N,N′-methylenebisacrylamide (NMBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The influence of different factors on composite synthesis, including the weight ratio of the monomer to BC, initiator content, crosslinker content, AA neutralization degree, reaction temperature, and reaction time on the water absorbency of the composite, were systematically learned. Under the optimized conditions, the maximum water absorbency of the composite was 322 ± 23 g/g distilled water. However, the water absorbency was much less for the different salt solutions and the absorption capacity of the composite decreased as the concentration of the salt solutions increased. The pH value had a significant influence on water absorption performance, and with the increase of temperature, the water retention rate of the composite decreased. Additionally, the structure of this composite was characterized with nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results of NMR and FT-IR provided evidence that the composite was synthesized by BC and AA, and the microstructure showed that it had good performance for water absorption. In addition, the composite possessed suitable thermal stability, and that it could be used in a few high-temperature environments. Overall, this composite is promising for application in water absorption.

Recycling waste polyethylene film for amphoteric superabsorbent resin synthesis

Amphoteric superabsorbent resin (SAR) is excellent in both cation and anion adsorption. In the present study, typical waste polyethylene film was employed to develop a novel amphoteric SAR through polymerization with acrylic acid (AA) and dimethyl diallyl ammonium chloride (DMDAAC). The maximum water absorbing capacities of the obtained amphoteric SARs for distilled water and rainwater reached 286.3 and 213.5g/g, respectively. A determination of the structure and morphology of the amphoteric SAR confirmed that monomers were successfully grafted onto the plastic film. The water absorbing capacity of SAR was greatly affected by the monomer to waste polyethylene ratio, the amount of initiator and cross-linker, the neutralization degree of acrylic acid and external solution. Meanwhile, the swelling kinetic, pH sensitivity, water retention and reswelling ability of the prepared polymer were also systematically investigated. This study provides a novel process for value-added recycling of waste polyethylene film.

Construction and water absorption capacity of a 3D network‐structure starch‐g‐poly(sodium acrylate)/PVP Semi‐Interpenetrating‐Network superabsorbent resin

A new semi‐interpenetrating network superabsorbent resin (semi‐IPN SAR), starch‐g‐poly (sodium acrylate)/PVP, with a three‐dimensional (3D) network structure constructed from a starch‐g‐poly(sodium acrylate) (starch‐g‐PNaA) network and linear poly(vinylpyrrololidone) (PVP) was synthesized by a free‐radical solution polymerization method in the presence of initiator ammonium persulfate (APS) and crosslinker N,N′‐methylene‐bis‐acrylamide (MBA). The synthesis conditions were systematically investigated. The optimum synthesis mass ratio of PVP, starch, APS, and MBA to AA was 20, 30, 1.25, and 0.15%, respectively, the neutralization degree of acrylic acid was 80%, and the reaction temperature was 60°C. Furthermore, the semi‐IPN SAR was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and three‐dimensional X‐ray diffraction microscopy (3D‐XRDM). FTIR and TGA results agreed that PNaA had been grafted onto the starch macromolecular chains and the starch‐g‐PNaA network was penetrated by linear PVP polymers by a hydrogen binding action. Moreover, the surface morphology of the resin exhibited apparent wrinkling due to the introduction of PVP. The 3D‐XRDM result further proved that the resin was provided with a three‐dimensional network structure. The introduction of PVP and the formation of the semi‐IPN structure greatly enhanced the water absorbency of the resin. The water and saline absorbency of the optimized material was improved to 2017.8 g/g distilled water and 89.7 g/g NaCl aqueous solution (0.9 wt%), respectively. Furthermore, kinetic analysis agreed that the pseudo‐second‐order kinetic model was fitted to describe a whole adsorption process, which indicated the adsorption process was not controlled by diffusion steps.

Preparation of low cost superabsorbent hydrogel by urea and acrylic acid

We describe a method for the synthesis of low cost superabsorbent hydrogel (LCSH) via solution polymerization with urea, acrylic acid (AA) and N,N'-methylenebisacrylamide (MBA). The various factors influencing the water absorbency of LCSH material were studied, including the mole ratio of urea to AA, weight ratio of MBA to AA (wt%) and neutralization degree of AA. The optimal conditions were found as follows: n(urea):m(AA)=1.6:1, the weight ratio of MBA to AA (wt%) and the neutralization degree of AA was 0.005% and 85%, respectively. The maximum absorbency in distilled water was 835g/g. The characteristics of LCSH material were investigated by Fourier Transform Infra Red (FTIR), scanning electron microscope (SEM) and precision electronic balance (FEB). The results indicated that LCSH material was successfully developed and it’s broad network structure offers the hydrogels excellent water absorbency.

Synthesis of the poly(acrylic acid‐acrylic sodium) bentonite composite and its adsorption of Cd(II)

AbstractIn order to improve the adsorptive properties of bentonite, a new poly(acrylic acid‐acrylic sodium) bentonite composite was prepared by copolymerization reaction. The properties of the bentonite composites were investigated. Based on the amount of acrylic monomers dissolution and Cd2+ ions adsorption as objective functions, the optimal conditions which were determined with single‐factor experiments are as follows: the neutralization degree of acrylic acid, the polymerization temperature, the polymerization time, and the mass ratio of bentonite to acrylic acid monomer unneutralized were 20%, 80 °C, 3 h and 8 : 2, respectively. The bentonite composite was characterized by XRD, IR, and SEM. It was indicated the basic structure of bentonite had not been destroyed when the monomers were intercalated into the bentonite interlayers. The synthetic products had excellent adsorption properties to Cd2+ ions, such as the removal rate of Cd2+ ions reached 99.9% for 100 mL solution with initial Cd2+ ions concentration of 50.0 mg/L by adding 0.5 g sample of the bentonite composite, whose removal rate was significantly superior to calcium bentonite and other modified bentonite reported in literatures. The adsorption process to Cd2+ ions was corresponding with the Lagergren secondary adsorption kinetics equation and the Langmuir isotherm equation. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

Fast‐swelling oxidized starch phosphate–poly(acrylate/acrylamide/2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid) superabsorbent composite

A fast‐swelling superabsorbent composite was prepared by solution polymerization of acrylate, acrylamide, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid and oxidized starch phosphate. Ethanol, propyl alcohol, butyl alcohol, and sodium bicarbonate were used as foaming agents to produce fast‐swelling characteristics. The structure of the superabsorbent composite was characterized using Fourier transform infrared spectroscopy (FTIR). The influences of the amount of water, acrylamide, 2‐acryloylamino‐2‐methyl‐1‐propanesulfonic acid, oxidized starch phosphate, initiator, and trihydroxymethyl propane glycidol ether, as well as the neutralization degree of acrylic acid on the equilibrium swelling degree and swelling rate of the superabsorbent composite, were investigated. The equilibrium swelling degree of the superabsorbent composite prepared in a 0.9 wt% NaCl aqueous solution was 52 g g−1, and the swelling rate reached 0.86 mL g−1 s−1. The swelling kinetics was also investigated, and the results indicate that swelling of the superabsorbent composites obeys Schott's pseudo second‐order kinetics model. POLYM. ENG. SCI., 56:1267–1274, 2016. © 2016 Society of Plastics Engineers

A novel Enteromorpha based hydrogel optimized with Box–Behnken response surface method: Synthesis, characterization and swelling behaviors

A novel hydrogel consisted of Enteromorpha (EP) and acrylic acid (AA) was prepared by solution polymerization using a response surface methodology. This methodology was based on a three-level, three-variable Box–Behnken design (BBD) that was used to optimize the synthesis parameters. Influences of the three variables, (i.e. the mass ratio of AA to EP (AA/EP), neutralization degree (ND) of AA, and the mass ratio of crosslink agent methylene-bis-acrylamide (MBA) to AA (MBA/AA)) on water swelling capacity of the hydrogel were evaluated. The swelling properties, kinetics and mechanisms of the hydrogel achieved at different grain sizes, salt concentrations, pH values and temperature conditions were intensively investigated. The results indicated that optimal preparation parameters for the hydrogel were predicted as AA/EP of 8.4, ND of AA of 54.3% and MBA/AA of 0.33; under these conditions, a hydrogel was prepared and used to conduct water swelling experiments. The Schott’s pseudo second order model was effective in evaluating the swelling kinetics of hydrogel. In addition, hydrogel with the highest and fastest water swelling capacity was obtained at a condition of small grain size (40–60 mesh), low salt concentration (0%), weak acidity condition (pH=5–6) and low temperature (20°C).