具有pH自调节能力的陶粒在污水除铜中的应用

重金属污水对生态环境和人类健康构成了严重威胁,其中含铜污水因污染严重、回收价值高而受到重视。以造纸白泥和粉煤灰为主要原料,经高温固相反应制备具有pH自调节能力的陶粒,将其作为吸附剂用于含铜污水的处理。采用静态吸附法及单因素变量法,分析原料配比、Cu~(2+)初始质量浓度、吸附时间、初始pH对吸附效果的影响;结合XRD、SEM及EDS探究陶粒的除铜机制。结果表明:陶粒的主要矿物相为钙长石、钙铝黄长石和硅灰石;在水溶液中部分矿物相发生非全等水解,从而自主释放OH~-形成碱性氛围;在污水除铜时,Cu~(2+)形成氢氧化物沉淀并被陶粒吸附。当初始Cu~(2+)溶液为20 mg/L、陶粒投加量为4 g/200 mL时,含铜污水经静态吸附10 h后,剩余Cu~(2+)质量浓度为0.36 mg/L,Cu~(2+)去除率达98.2%,吸附容量达0.998 6 mg/g。除铜后污水符合《污水综合排放标准》(GB 8978—1996)中的一级标准0.5 mg/L。

Application of Ceramsites with pH Self-adjustment Ability as Adsorbent for Removal of Copper

Wastewater containing heavy metals has posed serious threat to the environment and human health. Because of its heavy pollution and recycling value, wastewater with copper has arousedgreat attention. Ceramsites with pH self-adjustment ability are used to adsorb copper from aqueous solution. The ceramsitesare prepared by high temperature solid state reaction method, with lime mud and fly ash as main raw materials. Variables such as initial concentration, contact time and initial pH are evaluated by static adsorption method. The removal mechanism is explored by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The crystalline phases of ceramsitesareanorthite, gehlenite and wollastonite. In aqueous solution, partial phases are heterogeneous hydrolyzed, which brought OH- releasing to form alkaline environment. In adsorption process, copper ions are formed hydroxide precipitation and subsequently adsorbed onto the surface of ceramsites. When the initial concentration and dosage are 20 mg/L and 4 g/200 mLrespectively, the removal process is equilibrated at 10 h with a removal rate of 98.2% and an adsorption capacity of 0.9986 mg/g. The result has met the primary standard of 0.5 mg/L in the integrated wastewater discharge standard (GB 8978-1996).