Synthesis and analysis of cellulose based layered double hydroxide nanocomposite adsorbent for arsenic removal from water

Arsenic is a potential carcinogenic element and found in groundwater worldwide in concentration higher than the permissible limits for drinking. A low-cost solution for removal of arsenic from water was the objective of this study. A new adsorbent, that is, cotton linter cellulose (CLC) magnesium aluminum layered double hydroxide (LDH) bio-nanocomposite (CLC-Mg|Al LDH) was synthesized. The adsorbent and CLC were characterized using XRD and FTIR to identify difference in mixed phase of successful synthesis. Adsorbent was also characterized using BET, SEM, TEM and AFM techniques. XRD analysis showed that adsorbent was crystalline, TEM analysis showed that structure of adsorbent was sheet like having size range in nanometers. SEM analysis indicated that adsorbent had rough and porous surface while AFM results showed that adsorbent had good agglomeration of particles. After characterization optimization studies for various parameters was performed for arsenic removal. Optimum arsenic removal was achieved at pH, contact time, dose and temperature of 7, 25 min, 0.67 g/L and 25°C, respectively. Kinetic studies revealed adsorption followed pseudo-second-order model. Adsorption capacity of adsorbent was found to be 1.46 mg/g with 99.3% removal at 150 ppb initial arsenic concentration. Thermodynamic studies showed that adsorption process was spontaneous and exothermic. The cost of treatment came out to be USD 0.15/m3 of treated water.