膨润土/羧甲基纤维素钠水凝胶的制备及其应用

Preparation and application of bentonite/sodium carboxymethyl cellulose hydrogel

以HNO_(3)处理后的BT(NBT)、羧甲基纤维素钠(CMC)为原料,通过简单的化学交联制备了BT-g-CMC水凝胶,采用FTIR、XRD、TG、N_(2)吸附-脱附及SEM对其进行了表征。随后,将其用于废水中磷的回收,考察其对H_(2)PO_(4)^(-)的吸附性能、吸附动力学、吸附等温线及吸附机理。最后,将富含磷的BT-g-CMC1.0水凝胶(NBT/CMC质量比为1.00∶1)用作缓释肥料(SRFs),对其保水、缓释行为及盆栽实验进行了评价。结果表明,BT-g-CMC1.0水凝胶在298K下对H_(2)PO_(4)^(-)具有良好的亲和力,吸附量为18.78mg/g,吸附平衡时间为120 min。拟二级动力学模型和Freundlich等温线模型可以更好地描述H_(2)PO_(4)^(-)的吸附过程,化学吸附在吸附过程中起主导作用。SRFs具有优良的保水和缓释能力,对蔬菜生长具有促进作用。SRFs(用量为0.30 g)浸出3次时,对土壤中Cr(Ⅲ)的固定化率为82.9%。

BT-g-CMC hydrogels were prepared by simple chemical cross-linking between HNO_(3) treated BT(NBT)and sodium carboxymethyl cellulose(CMC),which were then characterized by FTIR,XRD,TG,N_(2) adsorption-desorption and SEM.Next,the hydrogels were used to recover phosphorus from wastewater,upon which their adsorption performance such as kinetics,isotherms and mechanism of H_(2)PO_(4)^(-)were investigated.Finally,BT-g-CMC1.0 hydrogel with a NBT/CMC mass ratio of 1.00∶1 rich in phosphorus was experimented as slow-release fertilizer(SRFs),and evaluations were conducted on its water retention ability,controlled-release behavior and fertilizing effects on pot plants.The results showed that the BT-g-CMC1.0 hydrogel had a good affinity for H_(2)PO_(4)^(-)at 298 K with an adsorption capacity of 18.78 mg/g,and equilibrium time of 120 min.It was also found that chemisorption played a leading role in the adsorption process that was better described by pseudo-second-order kinetic model and Freundlich isotherm model.Moreover,SRFs exhibited excellent performance in water retention,slow-release and plant growth promotion.When the amount of SRFs was 0.30 g and leaching for three times,the immobilization rate of Cr(Ⅲ)in soil was 82.9%.