ABSTRACT

The main aim of this study was to remove hydrogen sulfide (H₂S) from biogas by adsorption using synthesized activated carbon prepared using locally available biomass. The effect of the type of precursors, impregnation reagent and bed height was studied in continuous reactors. Three types of biomass wastes (almond shells, eucalyptus and coffee grains) were collected, grinded, sieved, pyrolyzed at 500°C and impregnated with chemical reagents such as potassium hydroxide or zinc chloride. Adsorption tests were performed using a fixed bed filter filled with the produced activated carbon. The highest biochar yield of 36% was obtained eucalyptus followed by almond shells (28.5%) and coffee grains (24%), respectively. The highest adsorption capacity and removal efficiency were obtained with eucalyptus followed by almond shells and coffee grains, respectively. For instance, eucalyptus showed an adsorption capacity of ~690 (mg hydrogen sulfide/g adsorbent) followed by almond (230 mg hydrogen sulfide/g adsorbent) and coffee grains (22 mg hydrogen sulfide/g adsorbent). As an impregnation reagent, potassium hydroxide gave the highest adsorption efficiency and capacity than zinc chloride. Furthermore, the breakthrough time with KOH (180 min) was higher than ZnCl₂ (70 min). Increasing the bed height during continuous breakthrough tests increased the adsorption capacity and hydrogen sulfide removal efficiency. The results of this study showed that the adsorption efficiency of the synthesized activated carbon and consequently the hydrogen sulfide removal efficiency could be fine-tuned by selecting an appropriate biomass precursor and proper impregnation reagent.

摘要

本研究的主要目的是去除硫化氢（H ₂S）通过使用当地可用生物质制备的合成活性炭吸附从沼气中提取。在连续反应器中研究了前体类型、浸渍剂和床层高度的影响。三种类型的生物质废弃物（杏仁壳、桉树和咖啡粒）被收集、研磨、筛分、在 500°C 下热解，并用氢氧化钾或氯化锌等化学试剂浸渍。吸附测试是使用填充有生产的活性炭的固定床过滤器进行的。桉树的生物炭产量最高，为 36%，其次是杏仁壳 (28.5%) 和咖啡粒 (24%)。桉树的吸附能力和去除效率最高，其次是杏仁壳和咖啡粒。例如，桉树的吸附容量约为 690（毫克硫化氢/克吸附剂），其次是杏仁（230 毫克硫化氢/克吸附剂）和咖啡粒（22 毫克硫化氢/克吸附剂）。作为浸渍剂，氢氧化钾的吸附效率和吸附能力高于氯化锌。此外，KOH 的穿透时间（180 分钟）高于 ZnCl₂（70 分钟）。在连续突破测试期间增加床高度可增加吸附容量和硫化氢去除效率。该研究的结果表明，通过选择合适的生物质前体和合适的浸渍剂，可以微调合成活性炭的吸附效率和硫化氢去除效率。