Preparation of a new low-cost adsorbent based on peanut shell cellulose (PNS) and its adsorption performance for Pb(II) ions.

The treatment of heavy metal pollution is becoming more and more challenging. Peanut shell is a material containing a large amount of cellulose. In this paper, poly (methyl vinyl ether-alt-maleic anhydride) (PVM/MA) is used as a grafting bridge to introduce a large number of anhydride groups on the surface of peanut shell cellulose (PNS), and further react with hydroxy-terminated hyperbranched polyester (HBP-OH) to achieve a new polyhydroxyl peanut shell cellulose (PNS-OH) adsorbent with high efficiency in absorbing heavy metal ions. This is the first report of modifying PNS with both PVM/MA and HBP-OH. The structure of the adsorbent was characterized by FT-IR, SEM, XRD and BET. The adsorption experiment of the adsorbent on lead ions was carried out. The optimum adsorption conditions were studied from five aspects, such as pH, adsorption time, adsorbent dosage, initial concentration of adsorption solution and adsorption temperature. The kinetic, thermodynamic and isothermal adsorption laws of PNS-OH for lead ions were investigated. The results show that the adsorption performance of the adsorbent for lead ions is the optimal when pH is 6.0. The adsorption behavior conforms to the quasi-second-order kinetics and the Langmuir isothermal adsorption model. Furthermore, the adsorption process is spontaneous and endothermic. When the initial concentration of lead ions solution was 800 mg/L, the maximum adsorption capacity of lead ions by PNS-OH was 1286.300 mg/g, which is among the highest reported for cellulose-based adsorbents derived from agricultural waste. Furthermore, the adsorbent demonstrated excellent reusability, retaining over 90 % of its initial adsorption capacity after five regeneration cycles, highlighting its potential for long-term practical applications and cost-effectiveness.