Abstract

Many industries discharge wastewater from processing into surface and underground waterways, and then, these waste waters must therefore be treated in order to remove heavy metals. The most common treatment used is the activated carbon adsorption, a particularly competitive and effective process; however, the use of activated carbon is not suitable due to the high costs. Then, in order to minimize processing cost, recent investigations have been focused on the use of low-cost adsorbents as zeolites. In particular, clinoptilolite is known to have high selectivity for certain heavy metals. In this paper, the capability of clinoptilolite as a low-cost adsorbent for the removal of zinc and cadmium ions from wastewater was analyzed in a batch system. Preliminary characterization was performed on adsorbent material in order to evaluate the chemical-physical structure. Tests in batch for analyzing adsorbing capacity of clinoptilolite were carried out varying zinc and cadmium concentrations between 10 and 200 mg/L with different amounts of sorbent in the solution (10–60 g/L). For both zinc and cadmium ions, complete adsorption was reached when the concentration was equal to 10 mg/L and adsorption capacity decreased increasing metals amount. In particular, clinoptilolite permitted high Cd²⁺ abatement, probably due to its greater affinity with adsorbent in the single system. Binary system was then analyzed, and, contrary to previous tests, the adsorbent in the simultaneous presence of the two metals demonstrated a greater affinity toward zinc, showing a higher percentage of absorption, due to a different absorption mechanism in the presence of two ions.

中文翻译：

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以斜发沸石为吸附剂去除废水中的Zn 2+和Cd 2+

摘要

许多行业将处理过程中的废水排放到地表和地下水道中，因此，必须对这些废水进行处理，以去除重金属。最常用的处理方法是活性炭吸附，这是一种特别有竞争性和有效的过程。但是，由于成本高，不适合使用活性炭。然后，为了使加工成本最小化，最近的研究集中在使用低成本吸附剂作为沸石上。特别地，斜发沸石对于某些重金属具有高选择性。本文以分批方式分析了斜发沸石作为低成本吸附剂从废水中去除锌和镉离子的能力。对吸附剂材料进行了初步表征，以评估其化学物理结构。用于分析斜发沸石的吸附能力的分批测试是在10和200 mg / L之间改变锌和镉浓度，并在溶液中添加不同量的吸附剂（10–60 g / L）。对于锌和镉离子，当浓度等于10 mg / L时达到完全吸附，吸附能力降低，金属含量增加。特别是斜发沸石允许高Cd 当浓度等于10 mg / L时达到完全吸附，吸附能力降低，金属含量增加。特别是斜发沸石允许高Cd 当浓度等于10 mg / L时达到完全吸附，吸附能力降低，金属含量增加。特别是斜发沸石允许高Cd减少²⁺，可能是由于它与单一系统中的吸附剂具有更高的亲和力。然后分析二元系统，与先前的测试相反，在两种金属同时存在的情况下，吸附剂表现出对锌的更大亲和力，由于在两种离子存在下的吸收机理不同，因此显示出更高的吸收百分比。