运用涂铁砂粒进行分散式饮水除砷的效果

采用铁盐处理普通河砂研制成涂铁砂粒(IOCS),通过静态和动态吸附试验观察其分散式饮水除砷效果,并选取地砷病现场进行了验证.结果表明,IOCS性质较为稳定,扫描电镜下可见铁氧化物呈片状分散的覆盖在砂粒表层;IOCS无需活化处理,其对砷的最大吸附发生在30min～60min;pH5～9时,五价砷的去除率随着pH值的升高而下降,三价砷的去除率变化不明显.IOCS对砷的吸附符合朗格缪尔(Langmuir)吸附方程;5次滤柱循环中,75g(50ml)的IOCS分别处理含砷1.0mg·L^-1的水样408～426床(三价砷),390～412床(五价砷),用0.2 mol·L^-1NaOH进行再生处理,砷回收率均在94%以上.充填IOCS 3.0kg的家庭用模拟装置处理含1.0mg·L^-1的五价砷209L和198L,三价砷196L和185L,并在现场实验期间,连续处理含砷0.202～1.733mg·L^-1的水样200L,对水质亦无不良影响.无论是经济上还是技术上,IOCS均是适合于分散式饮水除砷的一种新型除砷剂.

Removal of Arsenic from Dispersed Drinking Water by Iron Oxide-coated Sand

The iron oxide-coated sand(IOCS) was developed by treating normal river sand with molysite and investigated by batch, column tests and autoptic experiment to evaluate it's ability of eliminating arsenic from dispersed drinking water. The results showed that IOCS was relatively stable and can be seen iron oxide distributedly patched the surface of sand by scan electron microscope. IOCS needn't any activation pretreatment. It reached the maximum adsorption within 30-60 min. The removal percentage of arsenate was decreased but the one of arsenite had little change when the pH varied from 5 to 9. And the arsenic adsorption matched the Langmuir isotherm. In 5 circles of runs, it treated 408-426 (arsenite) beds and 390-412(arsenate) beds volume of water with 75 g(50 ml) IOCS respectively when the influent arsenic concentration was 1.0 mg.L-1. And the arsenic percentage recovery was above 94% when regenerating the IOCS by 0.2 mol.L-1 NaOH. The home simulation unit contained IOCS 3.0 kg produced 209 L and 198 L, 196 L and 185 L of water when the influent arsenate or arsenite concentration was 1.0 mg.L-1, and 200 L arsenic free water with the influent arsenic 0.202-1.733 mg.L-1 during the field experimental period. The water quality was not affected by the adsorbent. With low-cost and simple operation, the IOCS should be a promising novel medium for arsenic removal in dispersed drinking water.