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首页> 外文期刊>Journal of Environmental Science and Health. A, Toxic/Hazardous Substances & Environmental Engineering >The batch study of Sr~(2+) sorption by bone char
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The batch study of Sr~(2+) sorption by bone char

机译：骨炭吸附Sr〜（2+）的批次研究

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摘要

Considering the excellent sorption properties of synthetic calcium hydroxyapatite (HAP) towards many divalent cations, the potential application of bone char, the natural source of HAP, for sequestering Sr~(2+)ions from aqueous solutions has been studied in batch conditions. Contact time, initial solution pH and initial Sr~(2+) concentrations were varied to examine the effect of these process parameters on the amount of Sr~(2+) sorbed. The kinetics of Sr~(2+) sorption was found to be a 2-step process, with contact time of 24 h required for attaining equilibrium. The sorption isotherm was well fitted with Langmuir and DKR theoretical models. Sorption of Sr~(2+) on bone char was found to be a favorable, thermodynamically feasible and spontaneous process, with the maximum sorption capacity of 0.271 mmol/g and sorption energy of 11.09 kJ/mol. The sorption was pH-independent in the initial pH range 4-10, as a result of excellent buffering properties of bone char (constant final pH), while for pH > 10 sorbed amounts of Sr~(2+) increased due to attractive electrostatic forces between negatively charged sorbent surface and positively charged metal ions. On the basis of the amount of Ca~(2+) released and final pH decrease in respect to the point of zero charge of bone char (pHpzc), two possible mechanisms of Sr~(2+) sorption were identified: ion-exchange and the formation of complex compounds with HAP and carbon active surface sites. The amounts of Sr~(2+) leached from bone char increased with the increase of Ca~(2+) content and the decrease of solution pH. In comparison with synthetic HAP, bone char represents a cost-effective alternative for Sr~(2+) sequestering.
机译：考虑到合成的羟基磷灰石（HAP）对许多二价阳离子的优异吸附性能，已经研究了批处理条件下作为HAP天然来源的骨炭从水溶液中螯合Sr〜（2+）离子的潜在应用。改变接触时间，初始溶液的pH值和初始Sr〜（2+）浓度，以检查这些工艺参数对Sr〜（2+）吸附量的影响。发现Sr〜（2+）的吸附动力学是一个两步过程，需要24小时的接触时间才能达到平衡。吸附等温线非常适合Langmuir和DKR理论模型。发现Sr〜（2+）在骨炭上的吸附是一个有利的，热力学上可行的，自发的过程，最大吸附量为0.271 mmol / g，吸附能为11.09 kJ / mol。由于骨炭具有出色的缓冲性能（恒定的最终pH），因此在初始pH范围4-10内，吸附是独立于pH的，而在pH> 10时，由于静电吸引，Sr〜（2+）的吸附量增加带负电荷的吸附剂表面和带正电荷的金属离子之间的力。根据Ca〜（2+）释放量和最终pH相对于骨炭零电荷点（pHpzc）的降低，确定了Sr〜（2+）吸附的两种可能机理：离子交换并形成具有HAP和碳活性表面位点的复杂化合物。随着Ca〜（2+）含量的增加和溶液pH值的降低，从骨炭中浸出的Sr〜（2+）的量增加。与合成的HAP相比，骨炭代表了Sr〜（2+）隔离的一种经济有效的替代方法。

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