6种矿物基填料的氨氮和磷吸附性能比较与作用机制

Comparison and mechanism of ammonia nitrogen and phosphorus adsorption properties of six mineral-based fillers

为高效去除污染水体中的氨氮(NH_(4)^(+)-N)和磷酸盐(PO_(4)^(3-)-P),筛选生态修复工程中吸附性能优异的矿物基填料,选取了3种天然填料(沸石、蛭石、火山岩)和3种加工型填料(陶粒、生物滤料、除磷滤料)开展NH_(4)^(+)-N、PO_(4)^(3-)-P的吸附动力学和等温线试验,结合X射线衍射、电子扫描显微镜等表征手段,对不同矿物基填料的吸附特性与作用机制进行对比和分析。结果表明:6种矿物基填料的NH_(4)^(+)-N和PO_(4)^(3-)-P吸附动力学过程均符合伪二级动力学方程,吸附速率主要受化学吸附过程控制。Langmuir和Freundlich方程都能很好地拟合不同矿物基填料的等温吸附曲线,NH_(4)^(+)-N的理论吸附容量排序为沸石(5.9416mg/g)>蛭石(3.6953 mg/g)>生物滤料(3.2500 mg/g)>除磷滤料(3.1389 mg/g)>火山岩(1.0000 mg/g)>陶粒(0.8571 mg/g),PO_(4)^(3-)-P的吸附容量大小为除磷滤料(4.2424 mg/g)>生物滤料(2.7917 mg/g)>蛭石(1.6250 mg/g)>陶粒(1.2105 mg/g)>火山岩(1.1579 mg/g)>沸石(0.5625 mg/g)。矿物基填料对NH_(4)^(+)-N和PO_(4)^(3-)-P的吸附特性与其比表面积、微孔结构、矿物组成和金属元素含量等因素相关,其中沸石的比表面积和阳离子交换量最大,对NH_(4)^(+)-N的吸附能力最强,生物滤料和除磷滤料中含有托贝莫来石、Ca、Fe等与磷结合能力较强的成分,对PO_(4)^(3-)-P的去除效果明显。综合来看,沸石和蛭石可用于NH_(4)^(+)-N污染水体的治理,生物滤料和除磷滤料可用于处理含磷污水,而治理同时含有NH_(4)^(+)-N和磷的污染水体时,可组合使用多种矿物基填料。对比其他填料,自主开发制备的生物滤料和除磷滤料在同步脱氮除磷方面具有明显优势,可作为氮、磷污染水体生态修复工程的优选基质。

In order to efficiently remove ammonia nitrogen(NH_(4)^(+)-N)and phosphates(PO_(4)^(3-)-P)from contaminated water and screen mineral-based fillers with excellent adsorption performance used in ecological restoration projects,three natural fillers(zeolite,vermiculite,volcanic rock)and three artificial fillers(ceramsite,biological filter,phosphorus removal filter)were selected to carry out experiments on the adsorption kinetics and isotherm of ammonia nitrogen and phosphorus.The adsorption properties and mechanisms of different mineral-based fillers were compared and analyzed by characterization methods such as X-ray diffraction and scanning electron microscopy.The results showed that the adsorption kinetics of complied with the pseudo-second-order kinetic equation,and the chemisorption process mainly controlled the adsorption rates.Both Langmuir and Freundlich equations could well describe the isothermal adsorption curves,and the theoretical adsorption capacity of NH_(4)^(+)-N was ranked as zeolite(5.9416 mg/g)>vermiculite(3.6953 mg/g)>biological filter(3.2500 mg/g)>phosphorus removal filter(3.1389 mg/g)>volcanic rock(1.0000 mg/g)>ceramsite(0.8571 mg/g).The adsorption capacity of PO_(4)^(3-)-P was as follows:phosphorus removal filter(4.2424mg/g)>biological filter(2.7917 mg/g)>vermiculite(1.6250 mg/g)>ceramsite(1.2105 mg/g)>volcanic rock(1.1579mg/g)>zeolite(0.5625 mg/g).The adsorption properties of different mineral-based fillers for NH_(4)^(+)-N and PO_(4)^(3-)-P were related to their specific surface area,micropore structure,mineral composition and metal element content,etc.Among them,zeolite had the largest specific surface area and cation exchange capacity,thus exhibiting the strongest adsorption capacity for NH_(4)^(+)-N.The biological filter and phosphorus removal filter contained tobermolite,calcium,iron and other components with strong phosphorus binding ability,which removed PO_(4)^(3-)-P from contaminated water obviously.On the whole,zeolite and vermiculite could be used for the treatment of ammonia nitrogen contaminated water,and biological filter and phosphorus removal filter could be chosen to remove phosphorus.When treating contaminated water containing both ammonia nitrogen and phosphorus,a variety of mineral-based fillers could be combined.Compared with other mineral fillers,the self-developed biological and phosphorus removal filters had obvious advantages in the simultaneous removal of nitrogen and phosphorus,and could be used as the optimal substrate fillers for ecological restoration projects of contaminated water.