RESUMO
This study presents two modified polymers for Cu2+ ion removal from aqueous media. Shredded maize stalk (MC) and a strong-base anionic resin (SAX) were modified with indigo carmine (IC) in order to obtain two different complexing polymers, i.e., IC-MC and SAX-IC. Initially, the complex reaction between IC and Cu2+ in the solution was studied. Additionally, the complex formation Cu2+-IC in liquid solutions was evaluated at different pH ranges of 1.5, 4.0, 6.0, 8.0, and 10.0, respectively. For Cu2+ ions, adsorption onto the IC-MC and IC-SAX batch experiments were conducted. The contact time for evaluating the optimum adsorption for Cu2+ ions on the complexing materials was established at 1 h. Efficient Cu2+ ion adsorption on the IC-MC and SAX-IC at pH = 10 was achieved. The adsorption of Cu2+ ions depends on the quantity of IC retained on MC and SAX. At 2.63 mg IC/g MC(S4) and 22 mg IC/g SAX(SR2), a high amount of Cu2+ ion adsorption was reported. The highest adsorption capacity (Qe) of IC-MC was obtained at 0.73 mg/g, and for IC-SAX, it was attained at 10.8 mg/g. Reusability experiments were performed using the HCl (0.5 M) solution. High regeneration and reusability studies of IC-MC and IC-SAX were confirmed, suggesting that they can be used many times to remove Cu2+ ions from aqueous matrices. Therefore, the development of complexing materials could be suitable for Cu2+ ion removal from wastewater.
RESUMO
In the present study, two chelating resins were prepared and used for simultaneous adsorption of toxic metal ions, i.e., Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, and Pb2+ (MX+). In the first step, chelating resins were prepared starting with styrene-divinylbenzene resin, a strong basic anion exchanger Amberlite IRA 402(Cl-) with two chelating agents, i.e., tartrazine (TAR) and amido black 10B (AB 10B). Key parameters such as contact time, pH, initial concentration, and stability were evaluated for the obtained chelating resins (IRA 402/TAR and IRA 402/AB 10B). The obtained chelating resins show excellent stability in 2M HCl, 2M NaOH, and also in ethanol (EtOH) medium. The stability of the chelating resins decreased when the combined mixture (2M HCl:EtOH = 2:1) was added. The above-mentioned aspect was more evident for IRA 402/TAR compared to IRA 402/AB 10B. Taking into account the higher stability of the IRA 402/TAR and IRA 402/AB 10B resins, in a second step, adsorption studies were carried out on complex acid effluents polluted with MX+. The adsorption of MX+ from an acidic aqueous medium on the chelating resins was evaluated using the ICP-MS method. The following affinity series under competitive analysis for IRA 402/TAR was obtained: Fe3+(44 µg/g) > Ni2+(39.8 µg/g) > Cd2+(34 µg/g) > Cr3+(33.2 µg/g) > Pb2+(32.7 µg/g) > Cu2+ (32.5 µg/g) > Mn2+(31 µg/g) > Co2+(29 µg/g) > Zn2+ (27.5 µg/g). While for IRA 402/AB 10B, the following behavior was observed: Fe3+(58 µg/g) > Ni2+(43.5 µg/g) > Cd2+(43 µg/g) > Cu2+(38 µg/g) > Cr3+(35 µg/g) > Pb2+(34.5 µg/g) > Co2+(32.8 µg/g) > Mn2+(33 µg/g) > Zn2+(32 µg/g), consistent with the decreasing affinity of MX+ for chelate resin. The chelating resins were characterized using TG, FTIR, and SEM analysis. The obtained results showed that the chelating resins prepared have promising potential for wastewater treatment in the context of the circular economy approach.
RESUMO
In this paper, two chelate resins prepared by a simple procedure were used for the removal of Cd2+, Ni2+, Cu2+, and Pb2+ (M2+) from aqueous solutions. Amberlite IRA 402 strongly basic anion exchange resin in Cl− form (IRA 402 (Cl−) together with Amberlite XAD7HP acrylic ester co-polymer (XAD7HP) were functionalized with chelating agent Direct red 23 (DR 23). The chelate resins (IRA 402-DR 23 and XAD7HP-DR 23) were obtained in batch mode. The influence of interaction time, pH and the initial concentration of DR 23 solution was investigated using UV-Vis spectrometry. The time necessary to reach equilibrium was 90 min for both resins. A negligible effect of adsorption capacity (Qe) was obtained when the DR 23 solution was adjusted at a pH of 2 and 7.9. The Qe of the XAD7HP resin (27 mg DR 23/g) is greater than for IRA 402 (Cl−) (21 mg DR 23/g). The efficiency of chelating resins was checked via M2+ removal determined by the atomic adsorption spectrometry method (AAS). The M2+ removal by the IRA 402-DR 23 and XAD7HP-DR 23 showed that the latter is more efficient for this propose. As a consequence, for divalent ions, the chelated resins followed the selectivity sequence: Cd2+ > Cu2+ > Ni2+ > Pb2+. Additionally, Cd2+, Cu2+ and Ni2+ removal was fitted very well with the Freundlich model in terms of height correlation coefficient (R2), while Pb2+ was best fitted with Langmuir model for IRA 402-DR 23, the Cu2+ removal is described by the Langmuir model, and Cd2+, Ni2+ and Pb2+ removal was found to be in concordance with the Freundlich model for XAD7HP-DR 23. The M2+ elution from the chelate resins was carried out using 2 M HCl. The greater M2+ recovery from chelating resins mass confirmed their sustainability. The chelate resins used before and after M2+ removal by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analysis were evaluated.
RESUMO
In this research, eco-friendly material represented by maize stalk (MS) obtained after acid treatment was employed for simultaneous removal of Cu2+, Pb2+, Ni2+, Cd2+, Cr3+ and Fe3+ (MX+) from simulated textile aqueous matrix and tannery wastewater produced by the leather industry. The acid treatment of MS was done with 4 M HCl. The influence of experimental parameters was evaluated in order to optimize the adsorption process for simulated textile matrix. The contact time 10-60 min and initial concentration of 0.5-1 mg/L MX+ influence were studied by batch method. Additionally, the adsorption data of MX+ onto MS was fitting by kinetic and isotherm models. The results obtained showed that the 60 min was necessary to reach adsorption equilibrium of the MS. The adsorption capacity of MS was 0.052 mg Cu2+/g of MS, 0.024 mg Pb2+/g of MS, 0.042 mg Ni2+/g of MS, 0.050 mg Cd2+/g of MS, 0.056 mg Fe3+/g of MS and 0.063 mg Cr3+/g of MS at pH = 4.2. The Langmuir model described the adsorption process very well. The MS showed huge selectivity for Cr3+ and Fe3+ in the presence of Cu2+, Pb2+, Ni2+ and Cd2+. The adsorption of MX+ from liquid phases were analyzed by spectrometric adsorption method (AAS). The solid phases of MS before and after adsorption by TG and SEM analysis were characterized. When MS was used for removal of MX+ from tannery wastewater, two major issues were investigated: First, the decrease of MX+ content from highly polluted and difficult to treat tannery wastewaters by improve its quality and in the second part, specific recovery of MX+ from MS mass increasing the economic efficiency of metals production based on green technology.
RESUMO
This research had two stages of development: during the first stage, the purpose of the research was to evaluate the adsorption properties of the natural polymer represented by shredded maize stalk (MS) and by Amberlite XAD7HP (XAD7HP) acrylic resin for removal of toxic diazo Acid Blue 113 (AB 113) dye from aqueous solutions. The AB 113 concentration was evaluated spectrometrically at 565 nm. In the second stage, the stability of MS loaded with AB 113 (MS-AB 113) and of XAD7HP loaded with AB 113 (XAD7HP-AB 113) in acidic medium suggests that impregnated materials can be used for selective removal of metal ions (Cr3+, Zn2+ and Mn2+). The metal ions using atomic absorption spectroscopy method (AAS) were determined. The use of MS-AB 113 ensures a high selectivity of divalent ions while the XAD7HP-AB 113 had excellent affinity for Cr3+ in the presence of Zn2+ and Mn2+. As a consequence, two advanced polymers, i.e., MS-AB 113 and XAD7HP-AB 113 that provide huge capacity for removal of Zn2+, Mn2+ and Cr3+ from acid polluted wastewater were obtained.
RESUMO
Despite Acid Blue 113 (AB 113)'s extensive use and negative environmental impact, very few studies have focused on its efficient and environmentally friendly removal. This research aims the removal of AB 113 from environmental aqueous media and its consequent enzymatic biodegradation. A strongly basic anion exchange resin in Cl- form, Amberlite IRA 402 (IRA 402(Cl-)) was used for AB 113 adsorption and a laccase was used to further biodegrade it. For the first time, two novel, efficient and environmentally friendly physical-chemical and biological assays for AB 113 wastewater removal and subsequent biodegradation were combined. The adsorption of AB 113 onto IRA 402(Cl-) was tested in batch and continuous flux modes. Influence of contact time, concentration and desorption in acidic media were evaluated. The kinetic data were best modulated by the Lagergren model with R2 = 0.9275. The Langmuir isotherm model best fitted the experimental data, and the maximum adsorption capacity was 130 mg/g. Dye, resin and AB113 loaded resin were characterized by thermogravimetry and FTIR to evaluate their physical chemical properties modification. Based on the performed studies, a consecutive methodology is proposed, incorporating the ion exchange process in the first stage and the biodegradation process in the second. Thus, in the second stage the residual concentration of AB 113 is reduced by an efficient bio-degradation process produced by the laccase at pH = 4.
RESUMO
New research applications involving the use of cellulosic material derived from maize stalk for on-site treatment of leachate were evaluated for specific removal of Cu(II) and Fe(III) from real, highly polluted tailing pond and mine wastewater samples. Two major issues generated by anthropic mining activities were also tackled: wastewater metal content decrease to improve water quality and subsequently metal specific recovery, increasing the economic efficiency of metal production by using a green technology for residual management. Rapid saturation of the maize stalk mass determined in batch studies and the mine pilot experiment led to diminished metal concentrations in the second pilot experiment, where Cu(II) and Pb(II) from synthetic solutions were monitored in order to test biomaterial performances. In addition, in the second pilot experiment, maize stalk removed Pb(II) in the first 36 h, below the determination limit of the analytical method. The biomaterial bed in the column was saturated after 252 h of inflow solution. FTIR-ATR, TG and SEM techniques probed the interaction between maize stalk polar groups C=O, -OH, C-O and tailing water metallic ions by large FTIR band displacements, intensity decrease and shape changes, modification of thermal stability and by changes in the appearance of adsorbent microstructure images owing mainly to ion exchange mechanism.
