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The adsorption behavior and mechanism of amino-crosslinked hypromellose (AHM) adsorbent crosslinked with epichlorohydrin and modified with diethylenetriamine were studied. This material is unprecedented, and the modification method used to obtain it is relatively simple. The parameters affecting the adsorption of methyl orange (MO) dye by AHM such as pH, adsorbent dosage, contact time, initial concentration, and temperature were investigated. The experimental results show that the optimal adsorption time and dosage were 30 min and 3.6 g L−1, respectively. It was found that the pseudo-second-order kinetic model and the Langmuir isotherm adsorption model provide a good description of the adsorption process, indicating that the adsorption of MO by AHM is mainly controlled by the chemical bonding interactions. Analysis of the thermodynamic parameters showed that the process of MO adsorption on AHM is spontaneous and endothermic. The morphology, surface chemical bonding, crystal structure, specific surface area, and temperature stability of AHM were characterized by SEM, FTIR, XRD, BET, and TGA measurements. The results showed that the AHM materials had large pores, which is favorable for adsorption. AHM may also have an increased content of amino-functional groups that are beneficial for adsorption. The maximum MO adsorption capacities of AHM were 15.56 mg g−1, whereas the maximum adsorption capacity of the unmodified hypromellose was 2.12 mg g−1. It is important to note that the adsorption efficiency of AHM remained above 62% after five adsorption–desorption experiments. Therefore, AHM can be used as an efficient and environmentally friendly adsorbent material for the removal of MO from water. [ABSTRACT FROM AUTHOR]

Novel adsorbent, diethylenetriamine-grafted Spirodela polyrhiza (DSP), was synthesized via modifying natural S. polyrhiza (SP) with diethylenetriamine by cross-linking with epichlorohydrin and applied to adsorb Ni2+ and Pb2+ from water. The effecting parameters on adsorption of Ni2+ and Pb2+ such as adsorbent dosage, pH, contact time, temperature, and initial concentration were studied through equilibrium experiments. The adsorption of Ni2+ and Pb2+ followed the pseudo-second-order model and the Langmuir isotherm adsorption model. The study discusses thermodynamic parameters, including changes in Gibbs free energy, entropy, and enthalpy, for the adsorption of Ni2+ and Pb2+ on DSP, and revealed that the adsorption process was spontaneous and exothermic under natural conditions. The maximum Ni2+ and Pb2+ adsorption capacities of DSP were 33.02 and 36.50 mg/g, respectively. The newly prepared materials were characterized through scanning electron microscopy (SEM), mapping analysis, and zeta potential analysis. Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses indicated that functional groups (-OH and N-H) were involved in Ni2+ and Pb2+ adsorption. Notably, DSP can be easily regenerated and reused for multiple cycles. Therefore, DSP is a promising adsorbent for effective Ni2+ and Pb2+ removal. [ABSTRACT FROM AUTHOR]

By a simple and convenient method of using epichlorohydrin as linkages, a novel Alternanthera philoxeroides (AP) derivative modified with diethylenetriamine (DAP) was synthesized, which can remove copper(II) ions (Cu(II)) in the water environment efficiently. The adsorption capacity of DAP for Cu(II) under various factors was measured using ultraviolet spectrophotometer. The adsorption capacity and removal ratio were 19.33 mg/g and 95.57% at pH 5.5 and 298 K. The kinetic and equilibrium study shows that pseudo-second-order kinetic (R2 = 0.9964) and Langmuir isotherm models (R2 > 0.982) could properly describe DAP adsorption behaviors, and thermodynamic parameters indicate a spontaneous endothermic process (ΔG = − 3.6636 kJ/mol). The combined results of SEM, XRD, FTIR, and XPS analyses reveal that the dominant contribution for enhancement in Cu(II) adsorption is made by the formation of an amino group. And the adsorption mechanism is mainly the complexation reaction. The adsorption efficiency of DAP remained above 72.06% after 6 cycles of adsorption-desorption, which indicated that DAP has good regenerability and stability. All the results suggest that DAP could serve as promising adsorbents for Cu(II) pollution minimization. [ABSTRACT FROM AUTHOR]

Difunctionalization of alkenes has become a powerful tool for quickly increasing molecular complexity in synthesis. Despite significant progress in the area of alkene difunctionalization involving the incorporation of a nitrogen atom across the C-C double bonds, approaches for the direct 1,2-carboamination of alkenes to produce linear N-containing molecules are scarce and remain a formidable challenge. Here we describe a radical-mediated oxidative intermolecular 1,2-alkylamination of alkenes with alkyl nitriles and amines involving C(sp3)-H oxidative functionalization catalysed by a combination of Ag2CO3 with iron Lewis acids. This three-component alkene 1,2-alkylamination method is initiated by the C(sp3)-H oxidative radical functionalization, which enables one-step formation of two new chemical bonds, a C-C bond and a C-N bond, to selectively produce γ-amino alkyl nitriles. [ABSTRACT FROM AUTHOR]