Copper removal from aqueous solution using chemical precipitation and adsorption by Himalayan Pine Forest Residue as Biochar

Abstract

This research deals with the use of pine residue biochar as an adsorbent for the removal of copper from aqueous solution which is a major component of printed circuit boards from E-waste. Biochar was produced from pine residue such as bark, cone and needle through pyrolysis, and the effect of temperature on biochar properties was assessed. The biochar yield of about 33% and maximum surface area of 368 m2/g was obtained at pyrolysis temperature of 650°C. FTIR analysis revealed the existence of C-O, O-H and C = C functional groups on the surface of biochars. The point of zero charge of pine biochars were in the range 5.55 to 5.75. Batch adsorption studies revealed maximum copper adsorption capacity of 60–81 mg/g at near neutral pH. The batch adsorption data fitted well with Langmuir isotherm and followed the pseudo-second order kinetics. Adsorption of copper onto the biochar surface mainly followed physisorption which was reversable in nature. Desorption study revealed that pine biochar could be reused upto three cycles. Column adsorption data fitted well with Thomas model. These investigations revealed that the pine residue, which otherwise results in adverse environmental impacts, can be converted into useful resource like biochar as a heavy metal adsorbent.

Facilitation of interspecies electron transfer in anaerobic processes through pine needle biochar

“…The surface properties of PNB help in colonization and growth of microorganisms on the surface of biochar. PNB, when in contact with near neutral aqueous medium, acquires negative charge, since PNB has point of zero charge of 5.75 pH (Bashir et al 2022). During the entire span of 291 days of this investigation, the pH in the anaerobic reactors was in the range of 6.6-7.4.…”

“…Collection and preparation of pine needle residue PN forest residue was collected from the floor of the Himalayan pine forest, pre-treated and stored for biochar production according to the procedure presented elsewhere (Bashir et al 2022). The stored PN was analysed for its cellulose, hemicellulose and lignin content.…”

“…The stored PN was then converted into PNB through pyrolysis at 650 °C as per the procedure reported elsewhere (Bashir et al 2022). The PNB was ground with pestle and mortar and sieved to a particle size of 500-710 μm for use as support in continuously stirred tank reactor (CSTR) and to 1,000-1,200 μm for use in fixed bed reactor (FBR) in the subsequent experiments.…”

“…From this data it can be concluded that the PNB produced at 650 °C has superior properties as compared to other pyrolysis temperatures, such as higher carbon content, higher specific surface area and lower ash content. Biochar primarily consists of two predominant structural fractions, namely, stacked crystalline graphene sheets and randomly ordered amorphous aromatic structures (Bashir et al 2022). A variety of functional groups such as quinone (CO), phenol (OH) and carboxyl (COOH) etc.…”

“…A variety of functional groups such as quinone (CO), phenol (OH) and carboxyl (COOH) etc. (Figure S1) (Bashir et al 2022) are present on the surface of biochar, which are formed due to molecular rearrangement during pyrolysis (Azlina et al 2013;Mia et al 2016). Functional groups present on the biochar surface can accept or donate electrons due to the coexistence of basic to acidic and hydrophobic to hydrophilic properties of different functional groups (Uchimiya et al 2011;Ahmad et al 2014).…”