Adsorption of Malachite Green Dye from Liquid Phase Using Hydrophilic Thiourea-Modified Poly(acrylonitrile-co-acrylic acid): Kinetic and Isotherm Studies

Abstract

Thiourea-modified poly(acrylonitrile-co-acrylic acid) (TU-poly(AN-co-AA)) adsorbent was a surface modification of poly(acrylonitrile-co-acrylic acid) synthesized by facile redox polymerization. Surface functionalization with thiourea was carried out to provide hydrophilicity on the surface of a polymeric adsorbent. Fourier transform infrared (FTIR) spectrometer, scanning electron microscope (SEM), and Zetasizer characterized the morphology and structures of TU-poly(AN-co-AA). Copolymerization of poly(acrylonitrile-co-acrylic acid) and its successful incorporation of the thioamide group was confirmed by the FTIR spectra. The SEM micrographs depicted uniform and porous surface morphologies of polymeric particles. The average diameter of modified and unmodified poly(acrylonitrile-co-acrylic acid) was 289 nm and 279 nm, respectively. Zeta potentials of TU-poly(AN-co-AA) revealed the negatively charged surface of the prepared polymer. Adsorption capacities of hydrophilic TU-poly(AN-co-AA) were investigated using malachite green (MG) as an adsorbate by varying experimental conditions (pH, initial concentration, and temperature). Results showed that the pseudo-second-order reaction model best described the adsorption process with chemisorption being the rate-limiting step. Furthermore, Elovich and intraparticle diffusions play a significant role in adsorption kinetics. The equilibrium isotherm has its fitness in the following order: Freundlich model > Temkin model > Langmuir model. Thermodynamic analysis indicates that the sorption process is spontaneous and exothermic in nature. The reusability results suggested potential applications of the TU-poly(AN-co-AA) polymer in adsorption and separation of cationic malachite green dye from wastewater.

Adsorptive Removal of Methylene Blue from Aquatic Environments Using Thiourea-Modified Poly(Acrylonitrile-co-Acrylic Acid)

“…Poly(AN- co -AA) were synthesized by redox polymerization as proposed in the scheme of Figure 1 as presented in our previous work [25]. Subscripts p and q are the minimal molar concentrations of AN and AA in the reactor, to maintain a 100 percent molar basis.…”

“…The thioamide incorporation conditions of poly(AN- co -AA) were selected according to our previous work [25]. Briefly, 6 g of thiourea was stirred with deionized water/ethanol mixture at 200 rpm, 70 °C for 0.5 h. Thereafter, 5 g of the synthesized poly(AN- co -AA) was introduced to the solution and the surface functionalization reaction allowed for 5 h. The solid formed denoted as TA-poly(AN- co -AA) soaked in ethanol/deionized water, filtered and dried overnight at 50 °C.…”

“…The TA-poly(AN- co -AA) was used as a high capacity adsorbent for methylene blue (MB) uptake from aqueous environment. MB is selected as a linear molecular structure cationic dye compare to malachite green (MG) with triangular molecular structure reported in our previous work [25]. This is to ascertain whether molecular structure directly affects their adsorption isotherm using the same modified poly(AN- co -AA) adsorbent.…”

The synthesis and characterisation of porous and monodisperse, chemically modified hypercrosslinked poly(acrylonitrile)-based terpolymer as a sorbent for the adsorption of acidic pharmaceuticals

“…As expected from the BET surface area analysis, the HXL poly(AN-co-DVB-80-co-VBC) with the highest surface area achieved the highest percentage removal of drugs (DCF, 87%; MA, 85%; MNZ, 87%). After the modification with ethylenediamine, the EDA-modified HXL poly(AN-co-DVB-80-co-VBC) possessed more positively charged species due to the present of pendant diamine groups on the terpolymer surface, which enhanced the selectivity toward the polar analytes (34). The adsorption capacity was increased significantly by 38%, 36%, and 20% for the sorption of DCF, MA and MNZ, respectively compared with the adsorption capacity of the unmodified hypercrosslinked sample.…”

Dye separation using a semi-batch foaming process: Process optimization using Taguchi methodology and Grey relational analysis

“…The heat of desorption (λ) was also evaluated to establish the equilibrium relationship between the dye concentration in the bulk phase and the foam phase [64]. There is a direct analogy between the batch distillation and the batch foaming process.…”