Abstract:Types of resins anchored on citric acid were synthesized and identified. The citric acid-modified resins PS-CA, PS-O-CA and PS-N-CA were synthesized by anchoring citric acid on PS-Cl, PS-OH and PS-NH2, respectively. The PS-CA, PS-O-CA and PS-N-CA were used to adsorb Fe3+, Al3+, Cu2+, Pb2+, Cd2+ and Hg2+. The influences of pH, adsorption time and metal ion concentration on the adsorption capacities of the resins were investigated. After optimization, PS-CA was a good adsorbent to Fe3+, Cu2+, Pb2+ and Cd2+ with … Show more
“…The main binding modes of CA on bentonite are as follows: (1) Esterification reaction between bentonite and CA. Abundant -OH groups on the surface of RB can react with CA by forming an ester linkage and thus introduce carboxyl groups in CAB (Figure 9) (El-Sheikh et al, 2018;Liu et al, 2018). (2) Cation exchange reaction between hydrogen ions from CA and the exchange cations (such as Na, Ca, and Mg) in RB interlayer via the following reaction.…”
Raw bentonite (RB) was chemically modified by citric acid (CA) to obtain a low-cost and environment-friendly citric acid incorporated bentonite (CAB) adsorbent, which was applied for the adsorptive removal of Congo Red (CR). The effect of adsorbent dosage, contact time, ionic strength, surfactant, and pH on adsorption was investigated. Adsorption equilibrium data fitted well with Langmuir model while the Langmuir adsorption capacity of CR on CAB reached up to 384 mg•g −1. Furthermore, CR adsorption on CAB followed pseudo-second kinetic model while intra-particle diffusion was not the only rate-limiting step as determined from intra-particle diffusion model investigation. RB and CAB were characterized by XRD, FT-IR, and BET techniques. A proposed mechanism for the adsorption of CR over CAB suggested the chemical adsorption phenomenon is mainly controlled by chelation, hydrogen bonding, and fixing.
“…The main binding modes of CA on bentonite are as follows: (1) Esterification reaction between bentonite and CA. Abundant -OH groups on the surface of RB can react with CA by forming an ester linkage and thus introduce carboxyl groups in CAB (Figure 9) (El-Sheikh et al, 2018;Liu et al, 2018). (2) Cation exchange reaction between hydrogen ions from CA and the exchange cations (such as Na, Ca, and Mg) in RB interlayer via the following reaction.…”
Raw bentonite (RB) was chemically modified by citric acid (CA) to obtain a low-cost and environment-friendly citric acid incorporated bentonite (CAB) adsorbent, which was applied for the adsorptive removal of Congo Red (CR). The effect of adsorbent dosage, contact time, ionic strength, surfactant, and pH on adsorption was investigated. Adsorption equilibrium data fitted well with Langmuir model while the Langmuir adsorption capacity of CR on CAB reached up to 384 mg•g −1. Furthermore, CR adsorption on CAB followed pseudo-second kinetic model while intra-particle diffusion was not the only rate-limiting step as determined from intra-particle diffusion model investigation. RB and CAB were characterized by XRD, FT-IR, and BET techniques. A proposed mechanism for the adsorption of CR over CAB suggested the chemical adsorption phenomenon is mainly controlled by chelation, hydrogen bonding, and fixing.
“…Figure 7 illustrates the effect of contact time on the adsorption of MB and RY using CTSms, TETA-CTSms and PEI-CTSms microspheres. Furthermore, the pseudo-first-order kinetic model and pseudo-second-order kinetic model were adopted to fit the kinetic adsorption data, and the corresponding formulae are as follows [ 24 ]: where Q t and Q e are the adsorption capacities of microspheres for dye at time t and adsorption equilibrium, respectively; k 1 and k 2 are equilibrium adsorption rate constants. Figure 7.…”
Section: Resultsmentioning
confidence: 99%
“…open sci. 6: 182226 pseudo-second-order kinetic model were adopted to fit the kinetic adsorption data, and the corresponding formulae are as follows [24]:…”
Section: Characterization Of Chitosan Microspheresmentioning
Polyamine chelating adsorbents have a good removal effect on dye wastewater. In this study, small molecule triethylenetetramine and macromolecular poly(ethylene imine) were selected as aminated reagent, and two kinds of aminated chitosan microspheres, TETA-CTSms and PEI-CTSms, were obtained by emulsion cross-linking method. The microspheres were fully characterized by FTIR, SEM, XRD, EDS and TGA. EDS results showed that the N content of the PEI-CTSms and TETA-CTSms microspheres increased significantly after the cross-linking reaction and can reach 5.7 wt% and 7.3 wt%, respectively. Adsorption experiments confirmed that TETA-CTSms and PEI-CTSms showed greater adsorption characteristics for anionic dye reactive yellow (RY) in aqueous solutions compared with CTSms, and the adsorption capacity per unit area was increased by 39.11% and 88.56%, respectively. The adsorption capacity of aminated microspheres for RY decreased with the increase of pH. The adsorption kinetics conformed to the pseudo-second-order model, and the adsorption process was in accordance with the Langmuir isotherm model. The negative value of Δ
G
confirmed that the adsorption process was spontaneous, and the dye adsorption was a multiple process dominated by chemical chelating and physical adsorption.
“…Citric acid is recognized as an environmentally friendly compound and resin made from this has demonstrated its ability to replace synthetic resin. When citric acid is combined with another compound it exhibits good resistance against biological attack, dimensional stability, and compression strength [22]. Citric acid can react with a crosslinker that has high adhesion and bonding properties since it has triple carboxyl groups.…”
The escalation of ecological awareness and sustainability has motivated many researchers to foster bio-composite studies and advancement in employing natural fibers and resin. During the last few decades, composites have emerged with various environmental impacts such as degradation, incineration and toxicity. The credence is that bio-composite materials will downsize the need for environmentally and economically synthetic polymers. To enhance the degradability to the maximum extent, natural resin and natural fiber must be acquired from natural resources. A sequence of treatments must be followed throughout the resin synthesis process to obtain a usable and effective form of natural resin. Natural fibers are becoming more and more dominant over synthetic fibres because of their superior strength, stiffness, durability and lack of toxicity. In comparison to synthetic fibres, biocomposites have the potential to diminish material expenses while improving mechanical properties. Many applications of bio-composites have created new opportunities for research and business ventures. Bio-composites are non-abrasive, degradable, and used for various purposes like packaging, medicine, agriculture and automotive industry. The undesirable factors like degradation, incineration, and recycling problem of non-biodegradable composite have induced the research and evolution of bio-composite. This decisive review would manifest a summary concerning the framework of natural resins, natural fibers, and bio-composites, the factors affecting the characteristics of bio-composites and the future prospects for this field.
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