Sun Yonggang, Yao Qi, Zhang Xin, Yang Hongling, Li Na, Zhang Zhongshen, Hao Zhengping
Department of Environmental Nano-materials, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences Beijing 100085 P. R. China
National Engineering Laboratory for VOCs Pollution Control Material & Technology, University of Chinese Academy of Sciences Beijing 101408 P. R. China.
RSC Adv. 2018 May 29;8(35):19560-19569. doi: 10.1039/c8ra01721b. eCollection 2018 May 25.
Arsenic-rich non-ferrous smelter wastewater has the potential to cause harm to the environment and human health. The use of mineralizer modified and tailored scorodite crystals, a secondary As-bearing mineral, is considered to be the most promising strategy for arsenic stabilization. In this work, firstly, the mechanisms influencing the scorodite crystal characteristics for arsenic stabilization were investigated, and the results indicated that the scorodite stability was greatly influenced by the scorodite crystal shape and particle size. The crystal shape changes that the scorodite solids undergo during the aging period were observed, from a laminar structure to a polyhedron to a standard octahedral structure, and meanwhile, the As-concentration decreased from 10.2 mg L to 3.7 mg L, with the relative particle size value (RPS) increasing from 1.50 to 2.64. Secondly, the addition of a mineralizer to further improve the scorodite crystal stability was investigated. It was meaningful to observe that the lowest As-concentration of 0.39 mg L could be attained when trace NaF was employed, and it was of great significance to apply this strategy for the disposal of As and F-containing wastewater due to the electrostatic interaction between scorodite and sodium fluoride. However, the scorodite crystal stability was weakened when other mineralizers (NaSiO·9HO and Al(NO)·9HO) were added. This indicated that these mineralizers play different roles in influencing the crystal phase, shapes and sizes of the solid precipitate (mainly scorodite). Finally, the mechanisms of the scorodite crystal evolution and the arsenic leachability characteristics were analyzed. In conclusion, the addition of appropriate mineralizers is a potentially effective strategy for the control of crystal growth, and could be used in the disposal and stabilization of arsenic-rich non-ferrous effluents.
富含砷的有色金属冶炼废水有可能对环境和人类健康造成危害。使用矿化剂改性和定制的臭葱石晶体（一种含砷次生矿物）被认为是砷稳定化最具前景的策略。在这项工作中，首先，研究了影响臭葱石晶体特性以实现砷稳定化的机制，结果表明臭葱石的稳定性受其晶体形状和粒径的显著影响。观察到臭葱石固体在老化期间的晶体形状变化，从层状结构变为多面体再到标准八面体结构，同时，砷浓度从10.2 mg/L降至3.7 mg/L，相对粒径值（RPS）从1.50增加到2.64。其次，研究了添加矿化剂以进一步提高臭葱石晶体稳定性的情况。值得注意的是，当使用微量NaF时可达到最低砷浓度0.39 mg/L，由于臭葱石与氟化钠之间的静电相互作用，该策略对于含砷和氟废水的处理具有重要意义。然而，当添加其他矿化剂（Na₂SiO₃·9H₂O和Al(NO₃)₃·9H₂O）时，臭葱石晶体稳定性减弱。这表明这些矿化剂在影响固体沉淀物（主要是臭葱石）的晶相、形状和尺寸方面发挥着不同作用。最后，分析了臭葱石晶体演化机制和砷浸出特性。总之，添加合适的矿化剂是控制晶体生长的潜在有效策略，可用于处理和稳定富含砷的有色金属废水。
