Preparation of nitrogen-enriched pine sawdust-based activated carbons and their application for copper removal from the aquatic environment

Abstract

In this research study, compressed pellets of pine wood sawdust were carbonized at a temperature of 600 °C and then physically activated at 800 °C to obtain activated carbons (ACs). Then, some of the samples were enriched with nitrogen by reaction with urea at 300 °C. The AC samples prepared in this way were examined for the removal of Cu(II) in adsorption processes. Pine wood sawdust is waste resulting from processing in the wood industry and is a promising material to be reused for metal ions recovery. For this purpose, firstly, the AC was characterized using several analytical methods, including ash content, elemental composition, TGA, specific surface area and pore diameter (BET), pore size distribution (BJH), micropore volume, the content of surface acidic and basic functional groups, pH, FTIR and SEM morphology. Secondly, these materials before and after modification with nitrogen were used in experiments on the adsorptive removal of Cu(II) ions from aqueous solutions. The influence of parameters, such as initial pH, adsorbent dosage, initial Cu(II) concentration and contact time on the process, was investigated. Thirdly, adsorption kinetics and sorption isotherms were analyzed. According to the research results, it was reported that maximum sorption efficiency was equal to 99.9 and 99.8% at pH 5 for activated carbon AC (TK6AF1/2) and nitrogen-modified activated carbon NMAC (TK6MAF1/2), respectively. This proves that the examined waste materials exhibit satisfactory sorption properties in relation to Cu(II) ions and can be used as low-cost adsorbents in industrial wastewater treatment processes. These studies are in line with current global trends in sustainable and circular economy. Future research may focus on performing adsorption processes of copper and other metals at various temperatures as well as dynamic flow, studying metal ion competition, performing regeneration to reuse the adsorbents, carrying out realistic wastewater studies and cost estimation of entire processes on a laboratory and industrial scale.