بررسي پارامترهاي جذب و بازيابي كروم (۶+) از محلول آبي توسط جاذب پلي‌آنيلين ـ كربن فعال

Removal of Cr (VI) from Aqueous Solution by Adsorption on Polyaniline-Activated Carbon adsorbent

در اين مطالعه از يك پليمر رسانا به نام پلي‌آنيلين كه بر روي سطح كربن فعال سنتز شده است، به‌عنوان يك جاذب براي حذف كروم )?+( از محلول‌هاي آبي استفاده شده است. آزمايش‌ها در حالت ناپيوسته با متغيرهايي از قبيل: مقدار غلظت اوليه‌ي كروم )?+(، مقدار جاذب، زمان تعادل جذب، مقدار p‌H اوليه‌ي محلول، و دما انجام شده است. زمان تعادل جذب برابر ?? دقيقه به‌دست آمده است، ولي براي حصول اطمينان، زمان جذب در آزمايش‌ها ? ساعت منظور شده است. بيشينه‌ي جذب كروم )?+( براي رساندن محلول اوليه با غلظت (p‌p‌m) 15 به زير (p‌p‌m) 2 در دماي 40 درجه‌ي سانتي‌گراد، با p‌H اوليه محلول كوچك‌تر از 5 توسط (g/l‌i‌t) 10 جاذب پلي‌آنيلين?ـ كربن فعال حاصل شده است. عمليات بازيابي نيز توسط نيتريك اسيد و سود انجام شده است، كه از طريق نيتريك اسيد M 2، 83% بازيابي كروم 6+ به‌دست آمده است. با توجه به نتايج به‌دست‌آمده‌ي جاذب پلي‌آنيلين?ـ كربن فعال مي‌تواند به‌طور موثر براي حذف كروم از پساب مورد استفاده قرار گيرد.

Heavy metals, such as lead, chromium and nickel, are known to be major environmental pollutants and highly toxic to humans and other organisms, even at low concentrations. Chromium is widely used in many industries in various forms, but chromium (VI) is considered a definite carcinogen and, thus, should be almost completely removed from industrial wastewater to meet environmental laws and regulations. Many techniques are used to treat wastewater, containing Cr (VI), including; reduction followed by precipitation, Ion exchange, adsorption by clay or activated carbon and reverse osmosis. However, these processes often produce too much sludge, or are inefficient when large volumes of wastewater are involved or do not meet environmental standards. Adsorption is another effective method with very few disadvantages compared to others. In recent years, synthetic polymers have been considered as quality adsorbents for removal of Cr(VI) from wastewater. The aim of this study is to investigate the possibility of absorption of chromium from aqueous solutions by a new and innovative adsorbent produced from Polyaniline-activated carbon. The effect of various operative parameters on the adsorption of Cr (VI) was studied. Experiments were carried in batch mode and the effect of variables, such as the initial concentration of Cr (VI), amount of adsorbent, adsorption time, and initial pH value and temperature, were studied. The maximum adsorption of Cr (VI) was obtained at 40 ?C, with an initial concentration of 15 ppm, with an initial solution pH of less than 5 and addition of 10 g/lit Polyaniline-activated carbon. Recovery of the adsorbent was carried out by desorption with nitric acid, where 2 M nitric acid was used to recover 83% of Cr (VI). The results indicate that Polyaniline-Activated carbon can be effectively used in the treatment of wastewater containing Cr (VI). Kinetic studies on adsorption behavior closely followed the “Langmuir adsorption isotherm” model for a single layer.