摘要
采用氧化Ti^(3+)方法得到水合Ti(OH)_(4)絮体沉淀物,研究了以新生成Ti(OH)_(4)絮体作为吸附剂吸附去除水中Mn^(2+)的效率,分析了吸附热力学、动力学及吸附前后Ti(OH)_(4)絮体的ζ电位变化,研究了pH值和几种常见离子对该吸附的影响。结果表明:Ti(OH)_(4)絮体对Mn2+的吸附可以较好地符合拟二级动力学模型;热力学结果显示,吉布斯自由能变化值ΔGΘ为负值,吸附反应可自发进行;吸附可以较好地用Langmuir等温式描述,pH值为7.0和8.5时,计算的Qmax分别为58.8 mg/g、92.6 mg/g,但pH值为8.5时不能排除Mn2+通过形成沉淀而去除的途径。在试验的条件下,吸附反应进行较快,吸附很快达到准平衡,而且平衡吸附容量与最大吸附容量在数值上较为接近,吸附性质属于单分子层化学吸附。吸附容量还与Ti(OH)4絮体表面的ζ电位值有一定的相关性,ζ电位值越低其对Mn^(2+)的吸附容量越大,并且吸附前后体系pH值的变化值(△pH)和Mn^(2+)的去除率(%)呈正向相关。水中NO_(3)^(-)、SO_(4)^(2-)、H_(2)PO_(4)^(2-)和HCO_(3)^(-)等离子可以促进Ti(OH)4对Mn2+的吸附,Ca^(2+)则表现出较强的抑制作用,而Na^(+)、K^(+)、Mg^(2+)、Cl^(-)等离子对吸附影响较小。Mn^(2+)的吸附机制实际上是静电吸引、表面配位、化学沉淀(高pH值时)的共同作用。
The adsorption efficiency of Mn^(2+) in water by newly generated Ti(OH)_(4) flocs as adsorbent which was prepared by Ti3+oxidation was studied. The thermodynamics and dynamics aspect of adsorption, the zeta potential changes of Ti(OH)_(4) flocs after adsorption, and the effects of pH value and several common ions on the adsorption were studied. The results show that the adsorption of Mn^(2+)ions by Ti(OH)_(4) flocs fit the pseudo-second-order kinetic model well. The thermodynamic results show that the change value of Gibbs free energy ΔGΘis negative, and the adsorption reaction can be spontaneous at different temperatures. The adsorption can be well described by Langmuir isotherm, and the calculated qmvalues are 58.8 mg/g and 92.6 mg/g at pH 7.0 and 8.5, respectively. However, when pH is 8.5, the removal of Mn^(2+) ions by precipitation cannot be excluded. Under the experimental conditions, the adsorption reaction proceeded rapidly and the adsorption reached quasi-equilibrium soon. In addition, the equilibrium adsorption capacity is close to the maximum adsorption capacity. The adsorption property belongs to monolayer chemisorption. There is a certain correlation between the adsorption capacity and zeta potential value on the surface of Ti(OH)_(4) flocs, that is, the lower the zeta potential is, the greater the adsorption capacity of Ti(OH)_(4) for Mn^(2+), and the change of pH before and after adsorption(△pH) and Mn^(2+) removal rate(%) are positively correlated. The common anions such as SO_(4)^(2-), NO_(3)^(-), H_(2)PO_(4)^(2-)and HCO_(3)^(-)can promote the adsorption of Mn^(2+)by Ti(OH)4flocs, while cation Ca^(2+) has a strong inhibition effect, while K^(+), Na^(+), Mg^(2+)and Cl^(-) have little effect on the absorption. The adsorption mechanism of Mn^(2+)is the combined action of electro static attraction, surface coordination reaction, and chemical co-precipitation(at high pH).
作者
薛莉娉
唐玉朝
黄显怀
伍昌年
梁恒
胡伟
唐小斌
李卫华
XUE Li-ping;TANG Yu-chao;HUANG Xian-huai;WU Chang-nian;LIANG Heng;HU Wei;TANG Xiao-bin;LI Wei-hua(Anhui Provincial Key Laboratory of Environmental Pollution Control and Resource Reuse,Anhui Jianzhu University,Hefei 230601,China;State Key Laboratory of Urban Water ResourcesandWater Environment,Harbin Institute of Technology,Harbin 150001,China;Hefei Changgang Capital Water Co.,Ltd.,Hefei 230601,China)
出处
《安全与环境学报》
CAS
CSCD
北大核心
2023年第2期530-537,共8页
Journal of Safety and Environment
基金
安徽省高校省级科学研究项目(KJ2019ZD54)
国家自然科学基金项目(51978003)。
