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Sustainable Biochar Derived from Agricultural Wastes for Removal of Methylene Green 5 from Aqueous Solution: Adsorption Kinetics, Isotherms, Thermodynamics, and Mechanism Analysis
Published in Tushar Kanti Sen, Air, Gas, and Water Pollution Control Using Industrial and Agricultural Solid Wastes Adsorbents, 2017
Hai Nguyen Tran, Sheng-Jie You, Huan-Ping Chao, Ya-Fen Wang
Methylene green 5 (MG5) is a cationic phenothiazine dye and heterocyclic aromatic chemical compound that can be considered as a nitro derivative of methylene blue. MG5 can be classed as a nitro-aromatic contaminant because it contains polar nitro-functional groups. In addition, MG5—commonly used in various industries—shows considerable solubility in both polar organic media and water. The investigation of MG5 adsorption onto various kinds of adsorbents has been published in the literature. These adsorbents were comprised of (1) pristine biosorbents derived from coconut shell (CC), orange peel (OP), and golden shower pod (GS) (Tran et al., 2017f); (2) hydrochars prepared from CC, OP, GS, and commercial glucose through hydrothermal carbonization (Tran et al., 2017a, 2017e); (3) activated carbons synthesized from OP, GS, and commercial saccharide precursors (i.e., glucose, xylose, and sucrose) (Huang et al., 2014; Tran et al., 2017d); (4) commercial activated carbons (Huang et al., 2014; Tran et al., 2017b); (5) hydrochar and activated carbon functionalized with triethylenetetramine (Tran et al., 2017a); and (6) others (i.e., silver and zinc oxide nanostructures loaded on activated carbons, mesoporous zeolite, and collagen-g-poly(acrylamide-co-maleic anhydride) hydrogel nanocomposite) (Lee et al., 2007; Marandi et al., 2013; Ghaedi et al., 2014). However, the capacity and mechanism of MG5 adsorption onto agricultural waste-derived biochar have not yet been investigated or presented in the scientific literature.
Elemental Ferromagnetic Nanomaterials
Published in Sam Zhang, Dongliang Zhao, Advances in Magnetic Materials, 2017
Suneel Kumar Srivastava, Samarpita Senapati
Chemical contaminants are divided into organic and inorganic contaminants. Water is also polluted by organic contaminants, such as nitrophenols, dyes, pesticides, industrial solvents, fuels, etc. Their toxicity, stability to natural decomposition, and persistence in the environment is the cause of much concern to societies and regulation authorities around the world. Therefore, the removal of organic pollutants from water is very important in environmental protection. Among the processes developed for the destruction of organic contaminants, biodegradation has received the greatest attention. However, many organic chemicals, especially those that are toxic or refractory, are not amenable to microbial degradation. Therefore, in recent years considerable attention has been focused on advanced oxidation processes, which are considered as the alternative green techniques to replace existing conventional methods for the degradation of dyes and pesticides. In this regard, maximum interest has been focused on semiconductor-based photocatalysis [11]. However, the difficulty in removing suspended nanosized photocatalysts from the water medium is a serious drawback. On the other hand, the recyclability of the catalyst is also important for its multiple usage and cost effectiveness. Commonly used separation steps, such as filtration or centrifugation are tedious. Fortunately, the problem has been overcome by selecting magnetically separable photocatalysts consisting of ferromagnetic nanoparticles and a semiconductor oxide, either in the core–shell structure or in the form of a composite. Therefore, the removal of aromatic compounds, methylene green, arsenazo (III) dye, congo red, and gaseous pollutants has been investigated using hierarchical Co [59], Ni nanoparticles functionalized graphene sheets, carbon–cobalt nanocomposites, nickel nanoparticles loaded on activated carbon, and nickel and Ni impregnated activated carbon fibers as adsorbents [59,417–421], respectively. Alternatively, the photodegradation of organic pollutants in the presence of stepped hexagon-shaped Ni/ZnO [11], Fe nanoparticles [44], Fe/TiO2 [422] Si-doped iron–iron oxide [423], Pd-doped Co nanofibers [339], and TiO2-coated Ni nanoparticles [26,340] have also been successfully used to purify contaminated water. It has been noted that Ni/ZnO nano-structures exhibit better photocatalytic activity compared to pure ZnO. This may be due to interfacial charge transfer between the metal semiconductor interface which prevents electron–hole recombination and improves photocatalytic activity. Room-temperature degradation of nitrophenols has also been reported in the presence of Co [12], pure Ni [13,373–375], Ni/Ag [13], and Ni/Au [232] nanostructures acting as the catalysts. Interestingly, inorganic pollutants, for example, heavy metals, metalloids, and nonmetal pollutants can also be removed by these ferromagnetic nanomaterials and their core–shell nanostructures [33,276,341–363,424,425] as referred to in Table 2.5.
Removal of various contaminants from water by renewable lignocellulose-derived biosorbents: a comprehensive and critical review
Published in Critical Reviews in Environmental Science and Technology, 2019
Hai Nguyen Tran, Hoang Chinh Nguyen, Seung Han Woo, Tien Vinh Nguyen, Saravanamuthu Vigneswaran, Ahmad Hosseini-Bandegharaei, Jörg Rinklebe, Ajit Kumar Sarmah, Andrei Ivanets, Guilherme Luiz Dotto, Tho Truong Bui, Ruey-Shin Juang, Huan-Ping Chao
Figure 11 indicates the typical interactions contributing to the adsorption of cationic methylene green 5 dye onto biosorbent. Similarly, the functional groups can determine the adsorption capacities of dyes on the biosorbent. Dissimilar to the adsorption of potentially toxic metals, the adsorption mechanism of organic compounds onto the adsorbent can be determined by comparing the FTIR spectra of the adsorbent before and after adsorption. For example, Tran, You, Nguyen, et al. (2017) studied the adsorption mechanism of cationic methylene green 5 onto various biosorbents. Based on the studies of adsorption (the effects of pH, NaCl salt, temperature, and initial dye concentration) and desorption and the FTIR analysis, they proposed that the primary involved adsorption mechanisms are electrostatic attraction, dipole–dipole and Yoshida hydrogen bonding formations, and n–π interaction. Their FTIR spectra verified that the –OH, C=O, and C–O peaks shift and decrease in intensity after dye adsorption.
Saccharide-derived microporous spherical biochar prepared from hydrothermal carbonization and different pyrolysis temperatures: synthesis, characterization, and application in water treatment
Published in Environmental Technology, 2018
Hai Nguyen Tran, Chung-Kung Lee, Tien Vinh Nguyen, Huan-Ping Chao
In this study, three pure saccharide precursors (glucose, sucrose, and xylose) were used to synthesize a newer spherical biochar compared to non-spherical biochar derived from lignocellulose materials or non-conventional materials. The spherical biochar was synthesized through a two-stage process as follows: (1) a hydrothermal carbonization at 190°C under an autogenous pressure to produce spherical hydrochar; and (2) pyrolysis of the hydrochar at different temperatures in a laboratory scale reactor for obtaining spherical biochar. The effects of pyrolysis temperatures from 300°C to 1100°C on the spherical biochar’s properties (i.e. textural, morphological, crystal, electrical, and adsorptive) were examined using various techniques. The spherical biochar was then applied to remove various potentially toxic pollutants from aqueous solutions. The target adsorbates in the study of adsorption isotherms comprised two heavy metals (copper and lead), phenol, one cationic dye (methylene green 5), and one anionic dye (acid red 1).