温度敏感聚N-异丙基丙烯酰胺/谷氨酸钠/壳聚糖复合材料制备及吸附性能研究

doi:10.11949/0438-1157.20250598

摘要/Abstract

摘要：

针对传统吸附材料对Ag⁺选择性差、再生效率低的问题，本研究引入谷氨酸钠（MSG）与温敏性聚N-异丙基丙烯酰胺（PNIPAM）协同改性壳聚糖（CS）微球，构建具有动态响应性的智能吸附剂（PNIPAM/MSG/CS）。利用MSG的-NH₂/-COOH双齿配位特性定向螯合Ag⁺，结合PNIPAM的相变行为（LCST=32℃）实现“吸附-解吸”的智能调控；通过一步法交联反应实现功能基团与温敏网络的精准集成。SEM表征分析显示，复合材料表面呈现多孔结构，且XPS证实Ag（I）与-NH₂（399.35 eV）、-OH（531.64 eV）发生配位作用。吸附实验表明：最优pH=5.0，最大吸附容量达90.44 mg/g；动力学符合Elovich模型（R²>0.97），表明吸附过程以化学吸附为主导；热力学拟合Freundlich模型（1/n=0.36），揭示多层非均质吸附特性。材料在竞争离子共存下对Ag⁺具有优异的选择性，且通过升温至40℃（>LCST）触发PNIPAM疏水收缩，实现绿色再生（5次循环后容量保持率82.1%），为重金属污染治理提供了“智能识别-可控释放”新策略。

关键词: 聚N-异丙基丙烯酰胺, 谷氨酸钠, 壳聚糖, 选择性, 吸附, 动力学

Abstract:

In response to the problems of poor selectivity and low regeneration efficiency of traditional adsorbent materials for Ag⁺,this study introduces monosodium glutamate (MSG) and thermosensitive poly (N-isopropylacrylamide) (PNIPAM) synergistically modified chitosan (CS) microspheres to construct an intelligent adsorbent with dynamic responsiveness (PNIPAM/MSG/CS). Utilizing the - NH₂/- COOH bidentate coordination properties of MSG to selectively chelate Ag⁺, combined with the phase transition behavior of PNIPAM (LCST=32 ℃) to achieve intelligent regulation of adsorption desorption; Accurate integration of functional groups and temperature sensitive networks is achieved through a one-step crosslinking reaction. SEM analysis shows that the surface of the composite material exhibits a porous structure, And XPS confirmed that Ag (I) coordinated with -NH₂(399.35 eV) and -OH (531.64 eV). Adsorption experiments demonstrate that the optimal pH is 5.0, with a maximum adsorption capacity of 90.44 mg/g. The kinetic data fit well with the Elovich model (R² > 0.97), indicating that the adsorption process is dominated by chemical adsorption. Thermodynamic analysis shows a good fit to the Freundlich model (1/n = 0.36), revealing the characteristics of multi-layer heterogeneous adsorption. The material exhibits high selectivity for Ag⁺ in the presence of competing ions, and green regeneration can be achieved by heating to 40℃ (> LCST) to trigger the hydrophobic shrinkage of PNIPAM (with a capacity retention rate of 82.1% after 5 cycles). This provides a novel "intelligent recognition-controllable release" strategy for heavy metal pollution control.

Key words: poly(N-isopropylacrylamide), sodium glutamate, chitosan, selectivity, adsorption, kinetics

中图分类号:

TQ 424

吕高颖, 穆超群, 王婷, 何志仙, 徐浩洋, 张志强, 张良. 温度敏感聚N-异丙基丙烯酰胺/谷氨酸钠/壳聚糖复合材料制备及吸附性能研究[J]. 化工学报, DOI: 10.11949/0438-1157.20250598.

Gaoying LV, Chaoqun Mu, Ting Wang, Zhixian He, haoyang Zhang Zhiqiang Xu, Liang Zhang. Preparation and Adsorption Properties of Temperature sensitive poly (N-isopropylacrylamide) / Monosodium glutamate /Chitosan Composites[J]. CIESC Journal, DOI: 10.11949/0438-1157.20250598.

图/表 16

图1 CS凝胶球的制备示意图(a)；聚N-异丙基丙烯酰胺 (PNIPAM)溶液的制备示意图(b)； PNIPAM/MSG/CS复合材料的合成示意图(c)

Fig.1 Schematic diagram of the preparation of CS gel beads (a); Schematic diagram of the preparation of poly(N-isopropylacrylamide) (PNIPAM) solution (b); Schematic diagram for the synthesis of PNIPAM/MSG/CS composite material (c)

图2 CS、PNIPAM/MSG/CS和PNIPAM/MSG/CS-Ag+在不同尺度下的SEM图像(a-c)； CS、PNIPAM/MSG/CS和吸附Ag(I)后的PNIPAM/MSG/CS的XRD图像(d) 吸附前后，PNIPAM/MSG/CS和PNIPAM/MSG/CS-Ag+的EDS-mapping图像(e-h)；

Fig.2 SEM images of CS, PNIPAM/MSG/CS and PNIPAM/MSG/CS-Ag+ at different scales (a- c); XRD images of CS, PNIPAM/MSG/CS, and PNIPAM/MSG/CS after Ag(I) adsorption(d)EDS-mapping images of PNIPAM/MSG/CS before and after Ag(I) adsorption(e-h)

图3 CS、PNIPAM、MSG、PNIPAM/MSG/CS和吸附Ag(I)后的PNIPAM/MSG/CS的FTIR图像(a)；CS、PNIPAM/MSG/CS和吸附Ag(I)后的PNIPAM/MSG/CS的全尺度XPS谱图(b)，高分辨率XPS谱O 1s(c, f)，N 1s(d, g)和Ag 3d(e)

Fig.3 FTIR images of CS, PNIPAM, MSG, PNIPAM/MSG/CS, and PNIPAM/MSG/CS after Ag(I) adsorption(a)；Full-scale XPS spectra of CS, PNIPAM/MSG/CS and PNIPAM/MSG/CS after adsorption of Ag(I) (b), high-resolution XPS spectra of O 1s (c, f), N 1s (d, g) and Ag 3d (e)

图4 (a)不同pH下PNIPAM/MSG/CS的吸附容量(T=303.15K, C0=100mg/L)和(b)不同温度下PNIPAM/MSG/CS和MSG/CS的吸附容量(pH=5, C0=100mg/L)

Fig.4 (a)The adsorption capacity of PNIPAM/MSG/CS under different pH (T=303.15K, C0=100mg/L)and(b) the adsorption capacity of PNIPAM/MSG/CS and MSG/CS at different temperatures (pH=5, C0=100mg/L)

表1 PNIPAM/MSG/CS和MSG/CS在20°C和40°C下的吸水率比较

Table 1 Comparison of water absorption between PNIPAM/MSG/CS and MSG/CS at 20°C and 40°C

Adsorbent	m₀/g	m_20°C/g	m_40°C/g	吸水率(20°C)	吸水率(40°C)
PNIPAM/MSG/CS	0.0996	0.3418	0.2696	2.577	1.707
MSG/CS	0.0995	0.3563	0.3556	2.581	2.574

图5 PNIPAM/MSG/CS的吸附动力学拟合图(a)，颗粒内扩散模型(b)，初始浓度对PNIPAM/MSG/CS吸附容量的影响(c)和PNIPAM/MSG/CS的吸附热力学拟合图(d)(pH=5)

Fig. 5 The adsorption kinetics fitting diagram of PNIPAM/MSG/CS (a), the intraparticle diffusion model (b), the effect of initial concentration on the adsorption capacity of PNIPAM/MSG/CS (c) and the adsorption thermodynamics fitting diagram of PNIPAM/MSG/CS (d) (pH=5)

表2 准一级、准二级和Elovich模型的动力学参数

Table 2 Kinetic parameters for Pseudo-first-order， Pseudo-second-order and Elovich models

Adsorbent	T(°C)	$q e . e x p$	Pseudo-first-order model			Pseudo-second-order model			Elovich kinetic model
			$q e . c a l$	k₁ (min^-1)	R²	$q e . c a l$	k₂	R²	a	b(g/mg)	R²
			(mg/g)	k₁ (min^-1)	R²	(mg/g)	(g/mg min)	R²	(mg/g min)	b(g/mg)	R²
PNIPAM/MSG/CS	20.00	39.13	37.12	0.0122	0.8740	41.90	3.984	0.9496	2.121	0.1306	0.9770
	30.00	36.65	35.28	0.0089	0.9268	41.18	2.629	0.9642	1.262	0.1278	0.9694
	40.00	23.78	21.88	0.0063	0.8459	26.26	2.718	0.9011	0.6429	0.2162	0.9076

表2 准一级、准二级和Elovich模型的动力学参数

Table 2 Kinetic parameters for Pseudo-first-order， Pseudo-second-order and Elovich models

Adsorbent	T(°C)	$q e . e x p$	Pseudo-first-order model			Pseudo-second-order model			Elovich kinetic model
			$q e . c a l$	k₁ (min^-1)	R²	$q e . c a l$	k₂	R²	a	b(g/mg)	R²
			(mg/g)	k₁ (min^-1)	R²	(mg/g)	(g/mg min)	R²	(mg/g min)	b(g/mg)	R²
PNIPAM/MSG/CS	20.00	39.13	37.12	0.0122	0.8740	41.90	3.984	0.9496	2.121	0.1306	0.9770
	30.00	36.65	35.28	0.0089	0.9268	41.18	2.629	0.9642	1.262	0.1278	0.9694
	40.00	23.78	21.88	0.0063	0.8459	26.26	2.718	0.9011	0.6429	0.2162	0.9076

表3 颗粒内扩散模型的动力学参数

Table 3 Kinetic parameters for intra-particle diffusion model

Adsorbent	T(°C)	intra-particle diffusion model
		ki.1	c (mg/g)	R²	ki.2	c (mg/g)	R²
		(mg/g min1/2)	c (mg/g)	R²	(mg/g min1/2)	c (mg/g)	R²
PNIPAM/MSG/CS	20.00	1.790	5.967	0.9855	0.440	27.88	0.7838
	30.00	1.670	3.039	0.9986	0.550	22.62	0.8761
	40.00	0.750	3.024	0.9776	0.750	3.715	0.9932

表4 PNIPAM/MSG/CS上Ag（I）吸附的Langmuir和Freundlich等温模型常数

Table 4 Langmuir and Freundlich isotherm models for Ag （Ⅰ） adsorption on PNIPAM/MSG/CS

Adsorbent	T(°C)	Langmuir models			Freundlich models
Adsorbent	T(°C)	q_m(mg/g)	K_L (L/mg)	R²	K_F (mg/g)	1/n	R²
PNIPAM/MSG/CS	20.00	90.44	0.0077	0.9933	1.612	0.6975	0.9947
	30.00	79.38	0.0078	0.9881	1.440	0.6948	0.9887
	40.00	73.88	0.0058	0.9387	0.9551	0.7281	0.9585

图6 (a) PNIPAM/MSG/CS在七元金属离子溶液中的吸附选择性，(b) PNIPAM/MSG/CS的吸附再生性(在5个吸附-解吸循中的吸附容量变化)(pH=5, T=303.15K, C0=100mg/L)

Fig.6 (a) adsorption selectivity of PNIPAM/MSG/CS in seven-membered metal ion solutions, (b) adsorption regeneration of PNIPAM/MSG/CS (change in adsorption capacity over five adsorption-desorption cycles) (pH=5, T=303.15K, C0=100mg/L)

表5 PNIPAM/MSG/CS吸附不同金属离子的选择性参数

Table 5 Selectivity parameters for adsorption of different metal ions by PNIPAM/MSG/CS

Adsorbent	Substrate	C(mg/L)	pH	q_e(mg/g)	K_d (mL/g)	k
PNIPAM/MSG/CS	Zn(II)	100.0	5.000	0.2800	0.0024	181.2
	Mg(II)	100.0	5.000	0.9500	0.0089	49.26
	Ni(II)	100.0	5.000	1.050	0.0093	47.14
	Cd(II)	100.0	5.000	1.700	0.0129	33.98
	Pb(II)	100.0	5.000	2.880	0.0220	19.93
	Cu(II)	100.0	5.000	4.280	0.0398	11.02
	Ag(I)	100.0	5.000	30.70	0.4384	—

表6 PNIPAM/MSG/CS 与其他吸附剂的性能比较

Table 6 Comparison of properties between PNIPAM/MSG/CS and other adsorbents.

吸附剂	吸附容量(mg/g)	循环稳定性	k（相对异离子的选择性系数）	材料结构变化（吸附/解析时）
壳聚糖/聚多巴胺@ C @磁性粉煤灰^[13]	57.02	95.70%（5次循环）	Cu(II) 8.660 Zn(II) 14.15 Ni(II) 37.66	否
多硫基聚合物(PDMTD)^[29]	127.9	52.00%（5次循环）	Zn(II) 28.80 Pb(II) 24.50 Ni(II) 26.00 Mn(II) 192.7	否
丙烯酸接枝羧甲基壳聚糖/双醛淀粉^[30]	404.8	91.29%（5次循环）	Co(II) 3.200 Cr(III) 1.540 Ni(II) 4.95	否
[n-BBIM]9PW9O34^[31]	141.6	52.22%（5次循环）	Zn(II) 18.10 Pb(II) 46.20	否
聚苯胺包被聚苯乙烯(PS/PANI)颗粒^[32]	330.0	96.00%（4次循环）	/	否
本研究	90.44	82.10%（5次循环）	见表5	是

图7 各单体(a)和PNIPAM/MSG/CS(b)几何优化后构型图；各单体(c)和PNIPAM/MSG/CS(d)的静电势分布图

Fig.7 Conformations of each monomer (a) and PNIPAM/MSG/CS (b) after geometry optimization；Electrostatic potential distribution of each monomer (c) and PNIPAM/MSG/CS (d)

图8 PNIPAM/MSG/CS的HOMO图和LUMO图

Fig.8 HOMO diagram and LUMO diagram for PNIPAM/MSG/CS

表7 PNIPAM/MSG/CS的HOMO和LUMO轨道参数

Table 7 HOMO and LUMO orbital parameters for PNIPAM/MSG/CS

	E_HOMO/eV	E_LUMO/eV	E_g/eV
PNIPAM-part	-5.785	-0.6941	5.091
MSG	-4.831	-1.609	3.222
CS-part	-5.456	0.1800	5.636
PNIPAM/MSG/CS-part	-4.689	-1.457	3.233

图9 PNIPAM/MSG/CS吸附Ag(I)的机理图

Fig.9 Mechanism diagram of Ag(I) adsorption by PNIPAM/MSG/CS

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