Poly(N-isopropylmethacrylamide-acrylic acid) [pniM-Ac] microgel particles were synthesized by surfactant free radical precipitation polymerization method. Microgel particles were used as adsorbent for the removal of toxic dyes such as Congo red (CR) (anionic), methylene blue (MB) (cationic) and Rhodamine B (Rh-B) (cationic) from aqueous medium at ambient temperature. Due to presence of carboxylate groups inside the polymer chains of microgel particles, uptake of cationic dyes such as MB and Rh-B was high as compared to anionic dye CR at low temperature and high pH of the medium. But at high temperature, microgel particles were shrunken and their hydrophobicity was increased. Under such conditions, uptake of anionic dye CR was high due to increased hydrophobic interaction between polymer chains of microgel particles and dye molecules. Effect of dye concentration, adsorbent dose, pH of the medium and agitation time on the percentage removal of dyes was also investigated and their optimum values were determined. Langmuir isotherm model best explained the adsorption of CR, MB and Rh-B on microgel particles. Pseudo second order has well explained the kinetics of adsorption of all dyes on microgel system as compared to other kinetic models as reflected by the values of regression coefficients (R²). Mechanism of adsorption of all dyes on microgel particles was explained by intra-particle diffusion model. Microgel particles also showed high capacity to extract toxic dyes simultaneously from aqueous medium as compared to their individual adsorption. Pure and dye loaded microgel particles were analyzed by UV–visible (UV–vis) spectroscopy and Fourier transform infrared (FTIR) spectrometry. Size and morphology of microgel particles were investigated by transmission electron microscopy (TEM).

聚（N通过表面活性剂自由基沉淀聚合法合成了[-异丙基甲基丙烯酰胺-丙烯酸] [pniM-Ac]微凝胶颗粒。微凝胶颗粒用作吸附剂，用于在环境温度下从水性介质中去除有毒染料，例如刚果红（CR）（阴离子），亚甲基蓝（MB）（阳离子）和若丹明B（Rh-B）（阳离子）。由于在微凝胶颗粒的聚合物链内部存在羧酸根基团，因此在低温和介质的高pH下，与阴离子染料CR相比，阳离子染料（如MB和Rh-B）的吸收率较高。但是在高温下，微凝胶颗粒收缩并且疏水性增加。在这种条件下，由于微凝胶颗粒的聚合物链与染料分子之间的疏水相互作用增加，阴离子染料CR的吸收率很高。还研究了染料浓度，吸附剂剂量，介质的pH值和搅拌时间对染料去除率的影响，并确定了它们的最佳值。Langmuir等温线模型最好地解释了CR，MB和Rh-B在微凝胶颗粒上的吸附。伪二阶很好地解释了与其他动力学模型相比，所有染料在微凝胶体系上的吸附动力学，如回归系数（R²）。通过颗粒内扩散模型解释了所有染料在微凝胶颗粒上的吸附机理。与它们的单独吸附相比，微凝胶颗粒还显示出从水性介质中同时提取有毒染料的高能力。通过紫外-可见（UV-vis）光谱和傅里叶变换红外（FTIR）光谱分析了纯的和染料负载的微凝胶颗粒。通过透射电子显微镜（TEM）研究了微凝胶颗粒的尺寸和形态。