腐植酸对氧化锌吸附Cu(Ⅱ)的影响

谢发之,谢志勇,李国莲,李海斌,汪雪春,岳先名,李振宇



腐植酸对氧化锌吸附Cu(Ⅱ)的影响

谢发之1,2*,谢志勇1,3,李国莲1,2,李海斌1,2,汪雪春1,3,岳先名1,3,李振宇1,3

(1.水污染控制与废水资源化安徽重点实验室,安徽合肥 230022；2.安徽建筑大学环境与能源工程学院,安徽合肥 230022；3.安徽建筑大学材料与化学工程学院,安徽合肥 230022)

为研究复杂三元体系中HA(Humic acid,腐殖酸)对氧化锌吸附Cu(Ⅱ)的影响,探究HA对重金属Cu(Ⅱ)在环境中迁移转化的作用机理,通过改变HA的添加顺序及添加量,系统研究了HA在不同环境条件下对氧化锌吸附Cu(Ⅱ)的影响作用.结果表明,添加HA能显著降低氧化锌对Cu(Ⅱ)的吸附量,在pH为5.05时添加50mg/L的 HA, Cu(Ⅱ)的最大吸附量降低了61.74%;离子强度增大会促进氧化锌对Cu(Ⅱ)的吸附,在NaNO3浓度为1.0mol/L时最大吸附量为21.79mg/g;pH值为5.05时吸附量达到最大值,升温有利于氧化锌对Cu(Ⅱ)吸附,氧化锌对Cu(Ⅱ)的吸附符合Freundlich模型.HA不同添加顺序对Cu(Ⅱ)的吸附量的影响表现为对照>后添加HA>同时添加HA>先添加HA.红外光谱特征表明,HA和Cu(Ⅱ)在氧化锌表面吸附位点形成竞争吸附,并且氧化锌表面的羟基在吸附HA和Cu(Ⅱ)的过程中产生重要作用.

腐植酸；氧化锌；Cu(Ⅱ)；吸附

腐殖酸(HA)是由动植物残体在微生物以及地球化学作用下分解和合成的一类有机大分子聚合物,其广泛存在于土壤和水体等环境介质中[1].由于HA含有丰富的羧基和酚基等官能团,HA在水体或水体沉积物中能与多价阳离子发生相互作用,从而对多价阳离子在环境中的迁移和吸附产生重要影响[[2-3].由于氧化锌在催化及电子工业等领域的广泛使用,氧化锌被不断释放到水环境系统中,严重危害水生生物及饮水安全[4].水环境系统中存在氧化锌不仅影响氮磷的迁移转化,而且影响金属阳离子的迁移转化[5-6].因此,研究HA与氧化锌之间的相互作用以及HA存在下氧化锌对重金属阳离子吸附行为的作用机制,对全面了解环境中氧化锌对重金属离子迁移转化行为的影响具有重要意义.

重金属Cu(Ⅱ)作为典型的水体污染物,其过量存在具有毒性和致癌性.沉积物中金属氧化物的吸附作用和水体中广泛存在的溶解有机质对Cu(Ⅱ)的络合作用,会对Cu(Ⅱ)在水体中的毒性及其迁移转化行为产生重要影响[7-8],溶解有机质存在下Cu(Ⅱ)与金属氧化物之间的作用机制尚不明确[9-10].已开展的研究主要集中在二元体系,如Bagheri等[11]研究了氧化锌薄膜吸附水溶液中的Cu(Ⅱ),氧化锌通过表面的羟基去质化络合Cu(Ⅱ),吸附等温线符合Azizian-Volkov模型.Yang等[12]从滇池沉积物中逐步分离获得4种HA,分别对Cu(Ⅱ)进行吸附实验,研究表明前期提取的HA因含有较多的羧基对Cu(Ⅱ)有较高的吸附容量.Bian等[13]研究了HA存在条件下,HA可以吸附在纳米氧化锌表面,从而纳米氧化锌在高离子强度的水溶液中的稳定性得到提高.基于HA-ZnO、HA-Cu(Ⅱ)发生相互作用二元体系,进一步研究揭示三元体系HA-ZnO-Cu(Ⅱ)相互作用规律有其必要性.

该研究通过改变HA和氧化锌添加至Cu(Ⅱ)溶液中的顺序,模拟不同环境条件下氧化锌对Cu(Ⅱ)的吸附,系统研究了离子强度、溶液初始pH、不同(HA)、吸附温度、初始〔Cu(Ⅱ)〕对氧化锌吸附Cu(Ⅱ)的影响,以期为重金属Cu(Ⅱ)在水体中的迁移转化及其污染防治技术提供科学依据.

1 材料与方法

1.1 实验材料

商品氧化锌由徐州试剂二厂生产,分子量为81.38.HA购自SIGMA-ALDRICH公司.盐酸、硝酸钠均购自国药集团上海化学试剂公司,分析纯.实验用水为超纯水.

1.2 实验方法

将不同0〔Cu(Ⅱ)〕溶液25mL加入50mL离心管中,背景溶液[以(NaNO3)计]为0.1mol/L,调节pH后,先后加入氧化锌0.02g和不同浓度的HA定容至50mL,(25±0.5) ℃置于振荡器中振荡吸附48h(根据吸附动力学试验表明,48h可达吸附平衡),离心后测定上清液中ρ[Cu(Ⅱ)].ρ[Cu(Ⅱ)]通过WFX-1E2型原子吸收光光度计(北京瑞利分析仪器公司)使用标准曲线法测定,仪器条件:波长为324.7nm,灯电流为2.0mA,光谱通带为0.4nm,空气流量为6.5L/min,乙炔流量为2.5L/min,燃烧高度为8mm.

HA与氧化锌添加顺序为:先添加HA(先加HA后添加氧化锌)、同时添加HA(HA与氧化锌同时添加)和后添加HA(先添加氧化锌至吸附平衡后添加HA),然后以不添加HA组(对照组)实验作为对比.氧化锌对Cu(Ⅱ)吸附量用(1)计算,并利用Langmuir模型(2)和Freundlich(3)模型拟合吸附过程[14-15].

式(1)中:e为平衡吸附量,mg/g;0、e为吸附前后〔Cu(Ⅱ)〕,mg/L;为溶液总体积,mL;为针铁矿的用量,mg.(2)中e为吸附平衡浓度mg/L;m为单分子层的最大吸附量,g/g;K为Langmuir吸附常数(L/mg).(3)中e为吸附平衡浓度(mg/L);F(mg1-1/nL1/ng-1)为符合Freundlich常数,为符合Freundlich的指数.

2 结果与讨论

2.1 氧化锌的表征

该研究中所用商品氧化锌的X射线衍射(XRD)图谱如图1所示,通过尖锐衍射峰及其他主要峰的2位置分析,其与标准图谱(PDF#36- 1451)能较好吻合,确定该氧化锌为六方红锌矿结构,晶格常数分别为a=3.249Å,c= 5.206Å.图2为该氧化锌的SEM图,该氧化锌团聚较为严重,颗粒大小不均匀,部分细小颗粒在60nm左右,其比表面积为24.6m2/g,表面Zeta电位为-19.8± 0.6mV.

2.2(HA)的影响

如图3所示,在离子强度为0.1mol/L,0〔Cu(Ⅱ)〕为25mg/L,pH为5.05,温度为(25±0.5)℃时,Cu(Ⅱ)的吸附量随(HA)在0～75mg/L范围内增加而降低.HA含有丰富的羟基和羧基等官能团,大量的官能团通过静电作用、离子交换和络合作用增强对阳离子的吸附能力[16-17].氧化锌吸附Cu(Ⅱ)时,由于HA与Cu(Ⅱ)既能对氧化锌产生竞争吸附,同时由于HA能吸附Cu(Ⅱ),使得Cu(Ⅱ)在水溶液中部分被固定,因而被氧化锌吸附Cu(Ⅱ)的量会降低,因此随着HA浓度的增加,氧化锌对Cu(Ⅱ)的吸附量降低[18].由于HA和Cu(Ⅱ)均能被氧化锌吸附,HA与Cu(Ⅱ)竞争氧化锌表面的吸附位点,不添加HA时不存在竞争吸附,因而吸附量最大[11,19].添加HA时,后添加的HA将竞争氧化锌表面的吸附位点,已被吸附的Cu(Ⅱ)将会被部分替换下来,因而略比不添加HA时的吸附量低.而先添加HA时,HA先与Cu(Ⅱ)发生内层络合释放氢离子,抑制氧化锌表面的羟基去质子化(≡ZnOH+Cu2+Û≡ZnOCu+H+),氧化锌吸附产生的络合物及Cu(Ⅱ)被抑制,导致氧化锌对Cu(Ⅱ)的吸附量最小[11,20].同时添加HA,相当于腐植酸改性氧化锌吸附Cu(Ⅱ),Cu(Ⅱ)竞争氧化锌表面的HA,吸附量大小处在先添加HA与后添加HA的吸附量之间.因此,在该研究条件下HA的添加顺序对Cu(Ⅱ)吸附量的影响表现为对照(不添加HA)>后添加HA>同时添加HA>先添加HA.

2.3 离子强度的影响

如图4所示,在pH为5.05,(HA)为50mg/L,0〔Cu(Ⅱ)〕为25mg/L,温度为(25±0.5)℃,离子强度从0.1增至1.0mol/L时,对照组Cu(Ⅱ)的吸附量由14.12mg/g增至21.79mg/g.添加HA后,Cu(Ⅱ)的吸附量较对照组显著降低,同时Cu(Ⅱ)的吸附量也随离子强度增大而增大,在离子强度为1.0mol/L时达到相同吸附量21.79mg/g.未添加HA时,由于氧化锌在水溶液中与Cu(Ⅱ)形成内层络合,因而Cu(Ⅱ)的吸附量随离子强度增大而增大[21-22].由于氧化锌吸附HA的量随离子强度的增加而减小,则氧化锌吸附HA以外层络合为主[23].因外层络合比内层络合更易受到离子强度的影响,添加HA时,Na+依靠静电引力中和溶液中的负电荷,使HA因为失去部分水合分子而降低其稳定性,同时由于HA的负电性减弱易发生团聚,导致HA分子结构空间易阻碍与Cu(Ⅱ)络合,因而离子强度增大抑制HA吸附Cu(Ⅱ)的能力.当Na+大量存在时(即离子强度为1.0mol/L时),因为Na+能与HA中所能络合Cu(Ⅱ)的官能团COOH-和OH-反应,离子强度增加会使HA络合Cu(Ⅱ)的能力降低,在离子强度为1.0mol/L时HA络合Cu(Ⅱ)的能力降低至极限,因此在此离子强度下,不同添加顺序HA的吸附量与对照组相同[24-25].图5为氧化锌吸附Cu(Ⅱ)后在40℃条件下干燥获得的样品,根据图5可知3383cm-1处为羟基吸收峰,HA在该处存在酚羟基和醇羟基吸收峰,而在1113cm-1附近有明显的伸缩振动变化,即为氧化锌吸附Cu(Ⅱ)后形成络合物的峰,添加HA后该区域为脂肪族与羧酸等官能团中的C=O、C-N等键的伸缩振动峰,峰减弱表明了氧化锌吸附HA.HA不同添加顺序的红外光谱很相似,表明HA在氧化锌的表面以外层络合为主[26-27].

2.4 pH的影响

如图6所示,在离子强度为0.1mol/L(HA)为50mg/L,0〔Cu(Ⅱ)〕为25mg/L,温度为(25±0.5)℃,对照组吸附量在pH值3.98~8.02范围内呈先增加后降低趋势,在pH值为5.05时达到最大吸附量14.12mg/g.添加HA的吸附量显著降低,其变化趋势与对照组基本相同,最大吸附量均出现在pH值5.05时,此pH值下对照组的吸附量比添加HA时在pH值的最低吸附量高80.08%.由于在水溶液中Cu(Ⅱ)存在不同形态,如图7所示.在pH为5.05时,Cu(Ⅱ)主要以Cu2+和Cu(OH)+形式存在,而氧化锌表面Zeta电位为-19.8±0.6mV,对带正电的阳离子吸附能力强,因此在pH为5.05时吸附量最大.随着pH值增加,Cu(Ⅱ)主要以不带电及带负电的离子存在,氧化锌静电吸引能力减弱导致吸附量降低[28].添加HA,随pH增加带负电荷的HA排斥带负电荷的水合Cu(Ⅱ)离子,HA及Cu(Ⅱ)均难以被氧化锌吸附,因此吸附量存在明显降低.同时,氧化锌在pH为5.05时,氧化锌表面主要发生(ZnO(s)+2H+(aq)ÛZn2+(aq)+ H2O)反应,如图8所示.此时有利于对Cu2+和Cu(OH)+形式的吸附,而再降低或升高pH时,因Cu(Ⅱ)离子形态及氧化表面形成带负电的离子均有对吸附量降低的影响[13,30].

2.5[Cu(Ⅱ)]的影响

如图9所示,在离子强度为0.1mol/L,HA)为50mg/L,pH为5.05,温度为(25±0.5)℃,0[Cu(Ⅱ)]在10~75mg/L范围内,对照组Cu(Ⅱ)的吸附量随0[Cu(Ⅱ)]的增加而增加,达到平衡时的吸附量为26.85mg/g.添加HA时,吸附量的变化趋势与对照组变化趋势相同,但吸附量较对照组显著降低,降低最显著的后添加HA组的平衡吸附量比对照组低61.74%.0[Cu(Ⅱ)]增加,氧化锌的吸附位点逐渐达到饱和,吸附量呈现先增加后保持不变的趋势.通过Langmuir和Freundlich方程拟合,结果如图10、11所示.pH为5.05的条件下,对照组氧化锌对Cu(Ⅱ)的吸附符合Langmuir模型,属于单层吸附;而添加HA, 氧化锌对Cu(Ⅱ)的吸附符合Freundlich模型,属于表面非均匀的多层吸附,可见HA影响氧化锌均匀性吸附Cu(Ⅱ)[30-31].同时添加HA最为符合Freundlich模型,相当于HA改性氧化锌导致氧化锌表面不均匀性最强[32].而后添加HA,即HA在干扰氧化锌吸附Cu(Ⅱ),影响氧化锌表面均匀性比同时添加HA弱.先添加HA,HA吸附了Cu(Ⅱ)后,氧化锌再对水溶液中Cu(Ⅱ)吸附,此时水溶液中Cu(Ⅱ)的组成比其他情况更为复杂,氧化锌线性相关系数拟合程度更为倾向于Freundlich模型.因此,通过Langmuir和Freundlich方程拟合能揭示HA影响氧化锌吸附Cu(Ⅱ)程度的强弱.

Fig.9 Effects of initial Cu(Ⅱ)concentration on the binding of Cu(Ⅱ)to Zinc Oxide

2.6 温度的影响

如图12所示,在离子强度为0.1mol/L,0[Cu(Ⅱ)]为25mg/L,pH为5.05,(HA)为50mg/L时,温度从25℃升至45℃,对照组的Cu(Ⅱ)吸附量增大了24.46%,后添加HA、先添加HA和同时添加HA分别增加了72.78%、69.89%和41.73%.HA由于静电库仑力作用在氧化锌表面缓慢形成有机薄膜,升温使溶液中的Cu(Ⅱ)克服氧化锌表面的液膜阻力增强,有利于Cu(Ⅱ)由微孔向内部扩散,因而氧化锌对Cu(Ⅱ)的吸附位点增多,有利于氧化锌对Cu(Ⅱ)的吸附[33].而升温会使得HA容易解离,减小HA对Cu(Ⅱ)的竞争吸附作用,因而升温有利于氧化锌对Cu(Ⅱ)吸附[34].对照组氧化锌对Cu(Ⅱ)的吸附符合Langmuir模型,意味着升温有利于吸附.添加HA,虽然吸附模型较为符合Freundlich模型,但升温依然有利于氧化锌对Cu(Ⅱ)吸附.添加HA,其吸附机理可能有氢键、偶极作用力、范德华力和化学键合等作用,吸附机理图如图13所示.

3 结论

3.10[Cu(Ⅱ)]在10~75mg/L范围内,氧化锌对Cu(Ⅱ)吸附随0[Cu(Ⅱ)]增加而增大,对照组最大平衡吸附量为26.85mg/g,添加HA显著降低了氧化锌对Cu(Ⅱ)的吸附量.对照组及不同HA添加顺序下,离子强度增大均促进氧化锌对Cu(Ⅱ)的吸附,在1.0mol/L时达到相同吸附量21.79mg/g.

3.2 pH值影响Cu(Ⅱ)吸附量变化,添加HA吸附量变化趋势与对照组基本相同,最大吸附量均在5.05时,此pH值时对照组吸附量比添加HA时在pH值的最低吸附量高80.08%,偏酸性条件有利于氧化锌对Cu(Ⅱ)吸附.HA与Cu(Ⅱ)竞争氧化锌表面的吸附位点,增加(HA)会降低氧化锌对Cu(Ⅱ)的吸附量,升温均有利于对照组和添加了HA体系中氧化锌对Cu(Ⅱ)的吸附.

3.3 HA的添加顺序对Cu(Ⅱ)吸附量的影响表现为对照组(不添加HA)>后添加HA>同时添加HA>先添加HA,水体中存在HA将降低了氧化锌吸附Cu(Ⅱ)的能力,因此不利于氧化锌在水体中固定Cu(Ⅱ)污染.

[1] Chen C S, Chen S. Adsorption of Pesticidal Compounds Bearing a Single Carboxyl Functional Group and Biogenic Amines by Humic Fraction-Immobilized Silica Gel [J]. Journal of agricultural and food chemistry, 2013,61(15):3600-3610.

[2] Guo X, Tu B, Ge J, et al. Sorption of tylosin and sulfamethazine on solid humic acid [J]. Journal of Environmental Sciences, 2016,43:208-215.

[3] Ji H, Wu G, Zi M, et al. Microsecond Molecular Dynamics Simulation of Methane Hydrate Formation in Humic-Acid- Amended Sodium Montmorillonite [J]. Energy & Fuels, 2016, 30(9):7206-7213.

[4] Hao L, Chen L, Hao J, et al. Bioaccumulation and sub-acute toxicity of zinc oxide nanoparticles in juvenile carp (Cyprinus carpio): a comparative study with its bulk counterparts [J]. Ecotoxicology and environmental safety, 2013,91:52-60.

[5] Sheela T, Nayaka Y A, Viswanatha R, et al. Kinetics and thermodynamics studies on the adsorption of Zn (II), Cd (II) and Hg (II) from aqueous solution using zinc oxide nanoparticles [J]. Powder Technology, 2012,217:163-170.

[6] Zheng X, Wu R, Chen Y G, et al. Effects of ZnO nanoparticles on wastewater biological nitrogen and phosphorous removal [J]. Environmental Science & Technology, 2011,45(7):2826-2832.

[7] 冯启言,张 彦,孟庆俊,煤矿区废水中溶解性有机质与铜的结合特性 [J]. 中国环境科学, 2013,33(8):1433-1441.

[8] 龙良俊,王里奥,余纯丽,等.改性污泥腐殖酸的表征及其对Cu2+的吸附特性 [J]. 中国环境科学,2017,37(3):1016-1023.

[9] Kim H, Jeong H, Byeon S H. Selective filter effect induced by Cu2+adsorption on the fluorescence of a GdVO4: Eu nanoprobe [J]. ACS applied materials & interfaces, 2016:15497-15505.

[10] Zhu X, Shan Y, Xiong S, et al. Brianyoungite/Graphene Oxide Coordination Composites for High-Performance Cu2+Adsorption and Tunable Deep-Red Photoluminescence [J]. ACS applied materials & interfaces, 2016:15848-15854.

[11] Bagheri M, Azizian S, Jaleh B, et al. Adsorption of Cu (II) from aqueous solution by micro-structured ZnO thin films [J]. Journal of Industrial and Engineering Chemistry, 2014,20(4):2439-2446.

[12] Yang K, Miao G, Wu W, et al. Sorption of Cu2+on humic acids sequentially extracted from a sediment [J]. Chemosphere, 2015, 138:657-663.

[13] Bian S W, Mudunkotuwa I A, Rupasinghe T, et al. Aggregation and dissolution of 4nm ZnO nanoparticles in aqueous environments: influence of pH, ionic strength, size, and adsorption of humic acid [J]. Langmuir, 2011,27(10):6059-6068.

[14] Mittal H, Maity A, Sinha Ray S. The adsorption of Pb2+and Cu2+onto gum ghatti-grafted poly (acrylamide-co-acrylonitrile) biodegradable hydrogel: isotherms and kinetic models [J]. The Journal of Physical Chemistry B, 2015,119(5):2026-2039.

[15] Wang J, Li X. Ion-imprinted composite hydrogels with excellent mechanical strength for selective and fast removal of Cu2+[J]. Industrial & Engineering Chemistry Research, 2012,52(2):572- 577.

[16] Li Y, Yue Q, Gao B. Adsorption kinetics and desorption of Cu (II) and Zn (II) from aqueous solution onto humic acid [J]. Journal of hazardous materials, 2010,178(1):455-461.

[17] Lin D, Tian X, Li T, et al. Surface-bound humic acid increased Pb2+sorption on carbon nanotubes [J]. Environmental pollution, 2012,167:138-147.

[18] Sibanda H M, Young S D. Competitive adsorption of humic acids and phosphate on goethite, gibbsite and two tropical soils [J]. European Journal of Soil Science, 1986,37(2):197-204.

[19] Wang L, Han C, Nadagouda M N, et al. An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid [J]. Journal of hazardous materials, 2016,313:283-290.

[20] Karlsson T, Persson P, Skyllberg U. Complexation of copper (II) in organic soils and in dissolved organic matter-EXAFS evidence for chelate ring structures [J]. Environmental science & technology, 2006,40(8):2623-2628.

[21] Hayes K F, Papelis C, Leckie J O. Modeling ionic strength effects on anion adsorption at hydrous oxide/solution interfaces [J]. Journal of Colloid and Interface Science, 1988,125(2):717-726.

[22] Wang X, Cai W, Lin Y, et al. Mass production of micro/ nanostructured porous ZnO plates and their strong structurally enhanced and selective adsorption performance for environmental remediation [J]. Journal of Materials Chemistry, 2010,20(39): 8582-8590.

[23] Akhil K, Chandran P, Khan S S. Influence of humic acid on the stability and bacterial toxicity of zinc oxide nanoparticles in water [J]. Journal of Photochemistry and Photobiology B: Biology, 2015,153:289-295.

[24] Senesi N. Molecular and quantitative aspects of the chemistry of fulvic acid and its interactions with metal ions and organic chemicals: Part II. The fluorescence spectroscopy approach [J]. Analytica Chimica Acta, 1990,232:77-106.

[25] Klučáková M, Kalina M. Diffusivity of Cu (II) ions in humic gels–influence of reactive functional groups of humic acids [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015,483:162-170.

[26] Villaescusa I, Fiol N, Martinez M, et al. Removal of copper and nickel ions from aqueous solutions by grape stalk wastes [J]. Water Research, 2004,38(4):992-1002.

[27] Ballerini G, Ogle K, Barthés-Labrousse M G. The acid–base properties of the surface of native zinc oxide layers: an XPS study of adsorption of 1, 2-diaminoethane [J]. Applied surface science, 2007,253(16):6860-6867.

[28] Degen A, Kosec M. Effect of pH and impurities on the surface charge of zinc oxide in aqueous solution [J]. Journal of the European Ceramic Society, 2000,20(6):667-673.

[29] Doyle F M, Liu Z. The effect of triethylenetetraamine (Trien) on the ion flotation of Cu2+and Ni2+[J]. Journal of colloid and interface science, 2003,258(2):396-403.

[30] Zhou Y T, Nie H L, Branford-White C, et al. Removal of Cu2+from aqueous solution by chitosan-coated magnetic nanoparticles modified with α-ketoglutaric acid [J]. Journal of Colloid and Interface Science, 2009,330(1):29-37.

[31] Lee S J, Chung S G, Kim D J, et al. New method for determination of equilibrium/kinetic sorption parameters [J]. Current Applied Physics, 2009,9(6):1323-1325.

[32] Lin J, Zhan Y, Zhu Z. Adsorption characteristics of copper (II) ions from aqueous solution onto humic acid-immobilized surfactant-modified zeolite [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2011,384(1):9-16.

[33] Kathy L, Godtredsen, Stone A T. Solubilization of manganese of manganese dioxide-bound copper by naturally occurring organic compounds [J]. Environmental Science & Technology, 1994,28: 1450-1458.

[34] Li J, Zhang S, Chen C, et al. Removal of Cu (II) and fulvic acid by graphene oxide nanosheets decorated with Fe3O4nanoparticles [J]. ACS applied materials & interfaces, 2012,4(9):4991-5000.

Effects of humic acid on the adsorption of copper(Ⅱ) onto zinc oxide.

XIE Fa-zhi1,2*, XIE Zhi-yong1,3, LI Guo-lian1,2, LI Hai-bin1,2, WANG Xue-chun1,3, YUE Xian-ming1,3, LI Zhen-yu1,3

(1.Anhui Key Laboratory of Water Pollution Control and Wastewater Resource, Hefei 230601, China；2.School of Environment and Energy Engineering, Anhui Jianzhu University, Hefei 230601, China；3.School of Materials and Chemical Engineering, Anhui Jianzhu University, Hefei 230601, China)., 2017,37(8)：2970~2977

To study the influence of humic acid on the adsorption of Cu (II) by zinc oxide, the adsorption of Cu (II) on zinc oxide in different environment conditions were investigated, by changing the order of addition and dosage of HA. The mechanism of fate and transport of Cu (II) in the water environment was also proposed. The results showed that the adsorption Cu(II) on zinc oxide could be significantly reduced by adding HA, and that the Cu (II) maximum adsorption decreased 61.74% by adding 50mg/L HA in the pH of 5.05. The Cu (II) adsorption increased by increasing the ionic strength, the maximum adsorption was 21.79mg/g when the concentration of NaNO3was 1.0mol/L. When the pH value was 5.05 the adsorption reached the maximum; and temperature was in favor of Cu (II) adsorption on zinc oxide. Cu (II) adsorption on zinc oxide fitted the Freundlich model well. The adding orders of HA influence the Cu (II) adsorption as the following: non-adding > adding after > adding simultaneously > adding ahead. The characteristics of infrared spectra showed that HA and Cu (II) form competitive adsorption on the surface adsorption and surface hydroxyl of zinc oxide play an important role in adsorption of HA and Cu (II).

humic acid；zinc oxide；copper (Ⅱ)；adsorption

X703.1

A

1000-6923(2017)08-2970-08

谢发之(1976-),男,安徽定远人,教授,博士,主要从事环境污染控制方面的研究.发表论文50余篇.

2017-02-02

安徽省自然科学基金项目(1608085MB43);国家自然基金项目(21107001);安徽省教育厅自然科学研究重点项目(KJ2016A154);安徽省2014年高校优秀青年人才支持计划项目

* 责任作者, 教授, fzxie@ahjzu.edu.cn