Efficient Removal of Co2+ from Aqueous Solution by 3-Aminopropyltriethoxysilane Functionalized Montmorillonite with Enhanced Adsorption Capacity

Abstract

To achieve a satisfactory removal efficiency of heavy metal ions from wastewater, silane-functionalized montmorillonite with abundant ligand-binding sites (-NH2) was synthesized as an efficient adsorbent. Ca-montmorillonite (Ca-Mt) was functionalized with 3-aminopropyl triethoxysilane (APTES) to obtain the APTES-Mt products (APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt, APTES4.0CEC-Mt) with enhanced adsorption capacity for Co2+. The physico-chemical properties of the synthesized adsorbents were characterized by spectroscopic and microscopic methods, and the results demonstrated that APTES was successfully intercalated into the gallery of Ca-Mt or grafted onto the surface of Ca-Mt through Si-O bonds. The effect of solution pH, ionic strength, temperature, initial concentrations and contact time on adsorption of Co2+ by APTES-Mt was evaluated. The results indicated that adsorption of Co2+ onto Ca-Mt, APTES1.0CEC-Mt and APTES2.0CEC-Mt can be considered to be a pseudo-second-order process. In contrast, adsorption of Co2+ onto APTES3.0CEC-Mt and APTES4.0CEC-Mt fitted well with the pseudo-first-order kinetics. The adsorption isotherms were described by the Langmuir model, and the maximum adsorption capacities of APTES1.0CEC-Mt, APTES2.0CEC-Mt, APTES3.0CEC-Mt and APTES4.0CEC-Mt were 25.1, 33.8, 61.6, and 61.9 mg·g-1, respectively. In addition, reaction temperature had no impact on the adsorption capacity, while both the pH and ionic strength significantly affected the adsorption process. A synergistic effect of ion exchange and coordination interactions on adsorption was observed, thereby leading to a significant enhancement of Co2+ adsorption by the composites. Thus, APTES-Mt could be a cost-effective and environmental-friendly adsorbent, with potential for treating Co2+-rich wastewater.

Functionalization of Porous Clay Heterostructures with Silane Coupling Agents

“…The modification of PCH with silane coupling agents (APTES and GPTMS) was highlighted by the apearance of new peaks at 2927 cm -1 (APTES) and 2951 cm -1 (GPTMS) attributed to the streaching vibrations of C-H from CH 2 groups of the coupling agents. Similar results were reported for various inorganic clays (halloysite, montmorillonite, kaolinite, MCM) modified with silane coupling agents [9,[14][15][16].…”

“…The BET results indicated that the modified samples are charaterized by lower values of specific surface area (S BET =381-91 m 2 /g) and total pore volume (V t =0.2-0.3 cm 3 /g) than unmodified PCH (S BET = 628 m 2 /g and Vt= 0.8 cm 3 /g). According to these results it can be concluded that silane coupling agents are located inside the pores and also on the surface of PCHs.Similar results were obtained for mesoporous silica modified with different silane couplig agents [15,[18][19][20].…”

“…For example, modified MSN with APTES exhibited a high drug encapsulation efficiency, controlled drug delivery profile and an enhanced uptake ability for cancer cells [16]. Modified montmorillonite (MMT) with APTES presented an improve adsorption capacity, and therefore may be considered a potential material for treating wastewater [15]. Modified halloysite (HNT) showed an improved capacity for enzyme immobilization and controlled release and modified SBA-15 presented enhanced catalytic properties [7].…”

Core–Shell Interface-Oriented Synthesis of Bowl-Structured Hollow Silica Nanospheres Using Self-Assembled ABC Triblock Copolymeric Micelles

“…The formation of an N-H bond was also confirmed from the band vibrational peak observed at 2324 cm -1 (Figure 3b inset). In their study, Huang et al 50 around this wavenumber, which was confirmed from the FTIR spectrum of the calcined polymer@silica composite sample. In the calcined polymer@silica composite sample, the peak intensity was drastically reduced with further shifting in peak position from 1078 cm -1 to 1074 cm -stretching at 1074 cm -1 in the polymer@silica composite.…”

Three-dimensional, printed water-filtration system for economical, on-site arsenic removal

“…A batch experiment was conducted to investigate the kinetics of adsorption and the adsorption capacity for a small amount of solute in the solution. Normally, batch experiments are conducted through agitation at a constant rate and temperature [44]. However, for our 3D, printed filtration system, such batch studies cannot be applied because the adsorbent is immobilized on the filter's surface and can be neither separated nor agitated in the solution.…”