Material Sample Pollutant Adsorption batch study pH Initial conc. Of adsorbate (mg/L) Contact time Adsorbent dosage Temp. Adsorption mechanism Max removal efficiency Ref. Oil palm frond (AC) Aqueous solution 2,4-Dichlorophenoxyacetic acid 200 mL 2,4-D solutions (30°C) shaken in water-bath at 120 rpm for 24 hr 2-12 50–300 5 min-30 hr 50-300 mg/L 30, 40, and 50°C Adsorption. 352.89 mg/g [42 ] Tea industry waste (AC) Aqueous solution Phenol 30 mg of TWAC, with a pH adjusted to 6.0, agitated at 400 rpm for 4 hr 2-10 100-1000 0-500 min 20-200 g/L 0-40 °C Film diffusion along with intraparticle diffusion 99.5% [46 ] Tea waste (magnetic particle-loaded tea waste) Aqueous solutions Seven different organic dyes 0.01 g MNLTW added to the 20 mL solution of different concentrations of dyes stirred for 35 min 2-9 20 5-50 min 0.01–0.05 g 25°C Physical and chemical adsorption. 126.58 mg/g, 87.72 mg/g, 82.64 mg/g, 129.87 mg/g, 119.05 mg/g, 113.64 mg/g, 128.21 mg/g for neutral red, reactive blue 19, Congo red, Janus green, crystal violet, and methylene blue, respectively. [118 ] Rice husk (AC) Synthetic water PAHs naphthalene (NA), phenanthrene (PH), pyrene (PY) Adsorption test conducted at 200 rpm ( ) 0.25-3.5 1 to 7 d 0.1–7 mg 25, 35, and 45°C Intraparticle diffusion 63.6 mg/g, 50.4 mg/g, 104.5 mg/g for NA, PH, and PY, respectively. [47 ] Nickel sulfide nanoparticles loaded on AC Synthetic water Methylene blue (MB) and safranin-O 0.005–0.025 g of adsorbent was added in 50 mL beakers on magnetic stirrer (750 rpm) 1-11 5–25 2–34 min 0.005-0.025 g 25°C Adsorption 99.9% [69 ] Tea waste (BC) Solution Sulfamethazine (SMT) Adsorbent dose of 1 g/L was added at 25°C in shaker (100 rpm) for 72 hr 3-9 0-50 — 1 g/L 25°C The π -π electron donor–acceptor interaction 33.81 mg/g [10 ] Tea waste (black tea and waste black or green tea) Stock solutions Methylene blue (MB) and eosin yellow (EY) Adsorbent mixed in 250 mL flask of dye solution and stirred at 100 rpm 3-11 200–400 0-360 min 1-3 g/L 303 K-313 K Electrostatic attraction 97.5% for MB 96.6% for EY [48 ] Date stones Stock solution L-Phenylalanine 50 mg mass of adsorbent mixed with adsorbate solution (200 mg/L) at 150 rpm for 300 min 2-9 50-1000 0-330 min 50 mg 20, 25, 35, and 40°C Hydrogen bonding formation, hydrophobic and electrostatic interactions 114 mg/g [49 ] Municipal sewage sludge and tea waste Aqueous solutions Methylene blue (MB) The solution was shaken at 180 rpm and 25°C for 1 day 2-11 100 24 h 2 -50 g/L 25, 35, and 45°C Electrostatic interaction, ion exchange, surface complexation, physical function 100% [60 ] Magnetic nanoparticle Aqueous solutions Cd2+ and acenaphthene Adsorbent was mixed with 20 mL of adsorbate solution (1 mg/L) and placed on shaker by using vials 4-10 0.5-50 0-6 hr 0.25-1.25 g/L 22-25°C Hydrophobic reactions for acenaphthene Complexation reaction for Cd2+ 2250 mg/kg and 1060 mg/kg for Cd2+ and acenaphthene, respectively [92 ] Tea waste and rice husk (BC) Aqueous solutions Carbofuran 1 g/L BC added into 50 mg/L solution of carbofuran and shaken at 100 rpm (30°C) 5 5-100 5-500 min 1 g/L 25, 35, and 45°C Pore diffusion, π -π interaction, H-bonding, van der Waals forces, and chemical bindings 22.3 and 6.9 mg/g on TWBC and RHBC, respectively [15 ] Cornstalk nZVI/BC Aqueous solutions Trichloroethylene (TCE) 30 mg/L TCE solution was treated with BC at 250 rpm 6.25, 7, and 8 30 — 100 mg 25°C Partition and adsorption. 99% [119 ] Cornstalk BC500 BC600 BC700 93.28%, 91.33%, and 91.74%, respectively Enteromorpha prolifera Aqueous solution Pyrene (PYR) and benzo(a)pyrene (BAP) 100 mL of PYR (50 μ g/L) and BAP (20 μ g/L) solutions with 0.05 g BC dosage were shaken at 150 rpm for 24 hr 2, 4, 7, 10, and 12 10-150 μ g/L for PYR 10-60 μ g/L for BAP 0-600 min 0.01-0.1 g 25°C Chemical adsorption 187.27 μ g/g and 80.00 μ g/g for PYR and BAP, respectively [62 ] Dewatered sewage sludge Stock solution Phosphate At 25°C, 0.12 g modified BC added in phenol solution (100 mL, 50 mg/L) at pH 4.5 and shaken for 3 hr 3-12 25, 50, 75, 100, 125, 150, and 175 10, 25, 40, 60, 90, 120, 150, and 180 min 1-2.6 g/L 25, 35, and 45°C Electrostatic attraction 96.8% [39 ] Tea waste Stock solutions Nitrate Adsorbate solution with TW adsorbent placed in vapor bath constant temperature vibrator at °C at 300 rpm for 120 min 1-12 25–1500 1–300 min 1–32 g/L °CElectrostatic attraction, ion exchange Max. ads. =132.26 mg/g, 89.2%, pH =3-10, dosage =8 g/L [108 ] Phosphate 1-12 50–800 1–300 min 0.4–3.6 g/L °CElectrostatic attraction, ion exchange 99.51 mg/g, 92.3%