Preparation and characteristics of three sorbents from wood chips screening reject (WCSR) modified by nitric acid, phosphoric acid, or sodium hydroxide

Abstract

Wood chips screening rejects (WCSR) are mainly composed of sawdust, bark specks, and wood pins generated from cutting and chipping processes, as well as solid waste from pulping processes. It can be modified so that it can better serve as effective sorbents for wastewater treatment. In this study, three WCSR based sorbents were prepared by nitric acid, phosphoric acid, and sodium hydroxide treatment, respectively. The purpose of the three treatments on WCSR was to increase the specific area of WCSR, which is very essential to a high sorbent performance. It was found that nitric acid, phosphoric acid, and sodium hydroxide can be efficient modifiers of WCSR according to the results from SEM and specific area analyses, compared with those of the controls. The FT-IR results also supported the findings stated above. Thermogravimetric (TGA) analysis and X-ray diffraction (XRD) analyses were also applied to characterize the prepared sorbents. WCSR sorbents modified by the three treatments exhibited higher methylene blue adsorption values compared with that of the control sample, and that the WCSR-HNO3 sorbent achieved the highest MB adsorption value among others, thanks to the strong acidic properties and high reactivity of HNO3 with WCSR. The study paves a potential way to convert WCSR into effective sorbents by acid and alkali treatment.