1. K. Wang, G. Qiu, H. Cao, R. Jin, Removal of chromium (VI) from aqueous solutions using Fe3O4 magnetic polymer micro spheres functionalized with amino groups, Mater., 8 (2015) 8378–8391.
  2. D. Dutta, S. Thiyagarajan, D. Bahadur, SnO2 quantum dots decorated reduced graphene oxide nano composites for efficient water remediation, Chem. Eng. J., 297 (2016) 55–65.
  3. I.U. Salihi, S.R.M. Kutty, M.H. Isa, Adsorption of lead ions onto activated carbon derived from Sugarcane bagasse. In IOP Conference Ser.: Mater. Sci. Eng., 201(1) (2017) 012034. IOP Publishing.
  4. L.A. Giusto, F.L. Pissetti, T.S. Castro, F. Magalhães, Preparation of activated carbon from Sugarcane bagasse soot and methylene blue adsorption, Water Air Soil Pollut., 228 (2017) 249.
  5. S. Rajput, C.U. Pittman, D. Mohan, Magnetic magnetite (Fe3O4) nano particle synthesis and applications for lead (Pb2+) and chromium (Cr6+) removal from water, J. Colloid Interface Sci., 468 (2016) 334–346.
  6. J. Zhou, Y. Wang, J. Wang, W. Qiao, D. Long, L. Ling, Effective removal of hexavalent chromium from aqueous solutions by adsorption on mesoporous carbon micro spheres, J. Colloid Interface Sci., 462 (2016) 200–207.
  7. E. Petala, K. Dimos, A. Douvalis, T. Bakas, J. Tucek, R. Zbořil, M.A. Karakassides, Nanoscale zero-valent iron supported on mesoporous silica: Characterization and reactivity for Cr (VI) removal from aqueous solution, J. Hazard. Mater., 261 (2013) 295–306.
  8. Z. Yan, Z. Zhang, J. Chen, Biomass-based carbon dots: Synthesis and application in imatinib determination, Sens. Actuators, B., 225 (2016) 469–473.
  9. S. Li, L. Liu, Y. Yu, G. Wang, H. Zhang, A. Chen, Fe3O4 modified mesoporous carbon nano spheres: Magnetically separable adsorbent for hexavalent chromium, J. Alloys Compd., 698 (2017) 20–26.
  10. B. Qiu, H. Gu, X. Yan, J. Guo, Y. Wang, D. Sun, Q. Wang, M. Khan, X. Zhang, B.L. Weeks, D.P. Young, Cellulose derived magnetic mesoporous carbon nano composites with enhanced hexavalent chromium removal, J. Mater. Chem. A., 2(41) (2014) 17454–17462.
  11. G. Wang, S. Wang, W. Sun, Z. Sun, S. Zheng, Synthesis of a novel illite@ carbon nano composite adsorbent for removal of Cr (VI) from wastewater, J. Environ. Sci., 57 (2017) 62–71.
  12. Y. Du, L. Wang, J. Wang, G. Zheng, J. Wu, H. Dai, Flower, wire, and sheet-like MnO2-deposited diatomites: Highly efficient absorbents for the removal of Cr (VI), J. Environ. Sci., 29 (2015) 71–81.
  13. X. Sun, L. Yang, Q. Li, J. Zhao, X. Li, X. Wang, H. Liu, Amino-functionalized magnetic cellulose nano composite as adsorbent for removal of Cr (VI): synthesis and adsorption studies, Chem. Eng. J., 241 (2014) 175–183.
  14. Q. Chen, Z. Luo, C. Hills, G. Xue, M. Tyrer, Precipitation of heavy metals from wastewater using simulated flue gas: sequent additions of fly ash, lime and carbon dioxide, Water Res., 43(10) (2009) 2605–2614.
  15. A. Naeem, M.T. Saddique, S. Mustafa, Y. Kim, B. Dilara, Cation exchange removal of Pb from aqueous solution by sorption onto NiO, J. Hazard. Mater., 168(1) (2009) 364–368.
  16. X. Cheng, N. Li, M. Zhu, L. Zhang, Y. Deng, C. Deng, Positively charged microporous ceramic membrane for the removal of Titan Yellow through electrostatic adsorption, J. Environ. Sci., 44 (2016) 204–212.
  17. Y.X. Liu, D.X. Yuan, J.M. Yan, Q.L. Li, T. Ouyang, Electrochemical removal of chromium from aqueous solutions using electrodes of stainless steel nets coated with single wall carbon nanotubes, J. Hazard. Mater., 186(1) (2011) 473–480.
  18. M. Owlad, M.K. Aroua, W.A.W. Daud, S. Baroutian, Removal of hexavalent chromium-contaminated water and wastewater: a review, Water Air Soil Pollut., 200(1–4) (2009) 59–77.
  19. M. Kaur, M. Singh, S.S. Mukhopadhyay, D. Singh, M. Gupta, Structural, magnetic and adsorptive properties of clay ferrite nano composite and its use for effective removal of Cr (VI) from water, J. Alloys Compd., 653 (2015) 202–211.
  20. N. Zaitseva, V. Zaitsev, A. Walcarius, Chromium (VI) removal via reduction–sorption on bi-functional silica adsorbents. J. Hazard. Mater., 250 (2013) 454–461.
  21. J.L. Lv, W. Zheng, Y. Fan, Z.M. Lei, S.R. Zhai, Multi functional hierarchical cabbage-like nZVI-Fe3O4/C composites for efficient chromium (VI) removal, J. Taiwan Inst. Chem. Eng., 65 (2016) 312–322.
  22. T. Yang, Y.K. Li, M.L. Chen, J.H. Wang, Supported carbon dots decorated with metallothione in for selective cadmium adsorption and removal, Chin. Chem. Lett., 26(12) (2015) 1496–1501.
  23. X.S. Wang, L. Zhu, H.J. Lu, Surface chemical properties and adsorption of Cu (II) on nano scale magnetite in aqueous solutions, Desalination, 276 (2011) 154–160.
  24. A. Uheida, G. Salazar-Alvarez, E. Björkman, Z. Yu, M. Muhammed, Fe3O4 and γ-Fe2O3 nano particles for the adsorption of Co2+ from aqueous solution, J. Colloid Interface Sci., 298(2) (2006) 501–507.
  25. J. Zhu, H. Gu, J. Guo, M. Chen, H. Wei, Z. Luo, H.A. Colorado, N. Yerra, D. Ding, T.C. Ho, N. Haldolaarachchige, Mesoporous magnetic carbon nano composite fabrics for highly efficient Cr (VI) removal, J. Mater. Chem. A., 2(7) (2014) 2256–2265.
  26. N.N. Nassar, Rapid removal and recovery of Pb(II) from wastewater by magnetic nano adsorbents, J. Hazard. Mater., 184(1) (2010) 538–546.
  27. P.Z.Z. Ngu, S.P.P. Chia, J.F.Y. Fong, S.M. Ng, Synthesis of carbon nano particles from waste rice husk used for the optical sensing of metal ions, New Carbon Mater., 31(2) (2016) 135–143.
  28. B. Das, P. Dadhich, P. Pal, P.K. Srivas, K. Bankoti, S. Dhara, Carbon nano dots from date molasses: new nano lights for the in vitro scavenging of reactive oxygen species, J. Mater. Chem. B., 2(39) (2014) 6839–6847.
  29. S. Sahu, B. Behera, T.K. Maiti, S. Mohapatra, Simple one-step synthesis of highly luminescent carbon dots from orange juice: application as excellent bio-imaging agents, Chem. Commun., 48 (2012) 8835–8837.
  30. M. Zhang, Q. Yao, C. Lu, Z. Li, W. Wang, Layered double hydroxide–carbon dot composite: high-performance adsorbent for removal of anionic organic dye, ACS Appl. Mater. Interfaces., 6(22) (2014) 20225–20233.
  31. R. Liu, J. Liu, W. Kong, H. Huang, X. Han, X. Zhang, Y. Liu, Z. Kang, Adsorption dominant catalytic activity of a carbon dots stabilized gold nano particles system, Dalton Trans., 43(28) (2014) 10920–10929.
  32. J. Wang, W. Zhang, X. Yue, Q. Yang, F. Liu, Y. Wang, D. Zhang, Z. Li, J. Wang, One-pot synthesis of multi functional magnetic ferrite-MOS2-carbon dot nano hybrid adsorbent for efficient Pb (II) removal, J. Mater. Chem. A., 4(10) (2016) 3893–3900.
  33. L. Wang, C. Cheng, S. Tapas, J. Lei, M. Matsuoka, J. Zhang, F. Zhang, Carbon dots modified mesoporous organo silica as an adsorbent for the removal of 2, 4-dichlorophenol and heavy metal ions, J. Mater. Chem. A., 3(25) (2015) 13357–13364.
  34. D. Dutta, D. Thakur, D. Bahadur, SnO2 quantum dots decorated silica nano particles for fast removal of cationic dye (methylene blue) from wastewater, Chem. Eng. J., 281 (2015) 482–490.
  35. W. Yao, X. Wang, Y. Liang, S. Yu, P. Gu, Y. Sun, C. Xu, J. Chen, T. Hayat, A. Alsaedi, X. Wang, Synthesis of novel flower-like layered double oxides/carbon dots nano composites for U(VI) and 241Am(III) efficient removal: Batch and EXAFS studies, Chem. Eng. J., 332 (2018) 775–786.
  36. J. Zhang, X. Zhang, S. Dong, X. Zhou, S. Dong, N-doped carbon quantum dots/TiO2 hybrid composites with enhanced visible light driven photo catalytic activity toward dye wastewater degradation and mechanism insight, J. Photochem. Photobiol. A., 325 (2016) 104–110.
  37. U. Baruah, A. Konwar, D. Chowdhury, A sulphonated carbon dot–chitosan hybrid hydrogel nano composite as an efficient ion-exchange film for Ca2+ and Mg2+ removal, Nano scale, 8(16) (2016) 8542–8546.
  38. Z. Wang, C. Xu, Y. Lu, F. Wu, G. Ye, G. Wei, T. Sun, J. Chen, Visualization of adsorption: luminescent mesoporous silica-carbon dots composite for rapid and selective removal of U (VI) and in situ monitoring the adsorption behavior, ACS Appl. Mater. Interfaces, 9(8) ( 2017) 7392–7398.
  39. J. Bai, C. Sun, X. Jiang, Carbon dots-decorated multi walled carbon nano tubes nano composites as a high-performance electrochemical sensor for detection of H2O2 in living cells, Anal. Bioanal. Chem., 408(17) (2016) 4705–4714.
  40. L.M. Ang, T.A. Hor, G.Q. Xu, C.H. Tung, S.P. Zhao, J.L. Wang, Decoration of activated carbon nanotubes with copper and nickel, Carbon, 38(3) (2000) 363–372.
  41. W. Cui, Q. Liu, N. Cheng, A.M. Asiri, X. Sun, Activated carbon nanotubes: a highly-active metal-free electrocatalyst for hydrogen evolution reaction, Chem. Commun., 50(66) (2014) 9340–9342.
  42. L. Dai, Y. Jiang, W. Meng, H. Zhou, L. Wang, Z. He, Improving the electrocatalytic performance of carbon nanotubes for VO2+/VO2+ redox reaction by KOH activation, Appl. Surf. Sci., 401 (2017) 106–113.
  43. C. Bouchelta, M.S. Medjram, O. Bertrand, J.P. Bellat, Preparation and characterization of activated carbon from date stones by physical activation with steam, J. Anal. Appl. Pyrolysis., 82(1) (2008) 70–77.
  44. S.K. Theydan, M.J. Ahmed, Adsorption of methylene blue onto biomass-based activated carbon by FeCl3 activation: equilibrium, kinetics, and thermodynamic studies, J. Anal. Appl. Pyrolysis., 97 (2012) 116–122.
  45. Y. Sun, Q. Yue, Y. Mao, B. Gao, Y. Gao, L. Huang, Enhanced adsorption of chromium onto activated carbon by microwave-assisted H3PO4 mixed with Fe/Al/Mn activation, J. Hazard. Mater., 265 (2014) 191–200.
  46. J. Xue, L. Huang, F. Jin, Q. Liu, G. Liu, M. Wang, G. Li, S. Zhou, Two novel and simple strategies for improvement of the traditional activation method for activated carbon preparation: nano-copper catalysis and Cu (II) doping, RSC Adv., 5(100) (2015) 81857–81865.
  47. A.L. Cazetta, O. Pezoti, K.C. Bedin, T.L. Silva, A. Paesano Junior, T. Asefa, V.C. Almeida, Magnetic activated carbon derived from biomass waste by concurrent synthesis: efficient adsorbent for toxic dyes, ACS Sustain. Chem. Eng., 4(3) (2016) 1058–1068.
  48. T. Budinova, E. Ekinci, F. Yardim, A. Grimm, E. Björnbom, V. Minkova, M. Goranova, Characterization and application of activated carbon produced by H3PO4 and water vapor activation, Fuel Process. Technol., 87(10) (2006) 899–905.
  49. E. Yagmur, M. Ozmak, Z. Aktas, A novel method for production of activated carbon from waste tea by chemical activation with microwave energy, Fuel, 87(15) (2008) 3278–3285.
  50. I.A.W. Tan, J.C. Chan, B.H. Hameed, L.L.P. Lim, Adsorption behavior of cadmium ions onto phosphoric acid-impregnated microwave-induced mesoporous activated carbon, J. Water Process Eng., 14 (2016) 60–70.
  51. I.A.W. Tan, J.C. Chan, B.H. Hameed, L.L.P. Lim, Adsorption behavior of cadmium ions onto phosphoric acid-impregnated microwave-induced mesoporous activated carbon, J. Water Process Eng., 14 (2016) 60–70.
  52. L. Huang, Y. Sun, T. Yang, L. Li, Adsorption behavior of Ni (II) on lotus stalks derived active carbon by phosphoric acid activation, Desalination, 268(1) (2011) 12–19.
  53. L. Huang, Y. Sun, W. Wang, Q. Yue, T. Yang, Comparative study on characterization of activated carbons prepared by microwave and conventional heating methods and application in removal of oxytetracycline (OTC), Chem. Eng. J., 171(3) (2011) 1446–1453.
  54. M. Bhaumik, A. Maity, V.V. Srinivasu, M.S. Onyango, Removal of hexavalent chromium from aqueous solution using polypyrrole- polyaniline nanofibers, Chem. Eng. J., 181 (2012) 323– 333.
  55. H.P. Boehm, Surface oxides on carbon and their analysis: a critical assessment, Carbon, 40(2) (2002) 145–149.
  56. G.Z. Zhu, X.L. Deng, M. Hou, K. Sun, Y.P. Zhang, P. Li, F.M. Liang, Comparative study on characterization and adsorption properties of activated carbons by phosphoric acid activation from corncob and its acid and alkaline hydrolysis residues, Fuel Process. Technol., 144 (2016) 255–261.
  57. Z.A. ALOthman, A review: fundamental aspects of silicate mesoporous materials, Mater., 5(12) (2012) 2874–2902.
  58. M. Avila, T. Burks, F. Akhtar, M. Göthelid, P.C. Lansåker, M.S. Toprak, M. Muhammed, A. Uheida, Surface functionalized nanofibers for the removal of chromium (VI) from aqueous solutions, Chem. Eng. J., 245 (2014) 201–209.
  59. P.K. Pandey, S.K. Sharma, S.S. Sambi, Kinetics and equilibrium study of chromium adsorption on zeolite NaX, Int. J. Environ. Sci. Technol., 7(2) (2010) 395–404.
  60. I. Langmuir, The constitution and fundamental properties of solids and liquids. II. Liquids, J. Am. Chem. Soc., 39(9) (1917) 1848–1906.
  61. H.M.F. Freundlich, Over the adsorption in solution, J. Phys. Chem., 57 (1906) 1100–1107.
  62. S.A. Pathan, N.S. Pandita, Nanoporous carbon synthesized from grass for removal and recovery of hexavalent chromium, Carbon. Lett., 20(1) (2016) 10–18.
  63. M.S. Miao, Q. Liu, L. Shu, Z. Wang, Y.Z. Liu, Q. Kong, Removal of cephalexin from effluent by activated carbon prepared from alligator weed: Kinetics, isotherms, and thermodynamic analyses, Process Saf. Environ. Prot., 104 (2016) 481–489.
  64. S. Dubey, D. Gusain, Y.C. Sharma, Kinetic and isotherm parameter determination for the removal of chromium from aqueous solutions by nanoalumina, a nanoadsorbent, J. Mol. Liq., 219 (2016) 1–8.
  65. S. Yang, L. Li, Z. Pei, C. Li, J. Lv, J. Xie, B. Wen, S. Zhang, Adsorption kinetics, isotherms and thermodynamics of Cr (III) on graphene oxide, Colloids Surf., A, 457 (2014) 100–106.
  66. H. Mittal, N. Ballav, S.B. Mishra, Gum ghatti and Fe3O4 magnetic nanoparticles based nanocomposites for the effective adsorption of methylene blue from aqueous solution, J. Ind. Eng. Chem., 20(4) (2014) 2184–2192.
  67. J.N. Tiwari, K. Mahesh, N.H. Le, K.C. Kemp, R. Timilsina, R.N. Tiwari, K.S. Kim, Reduced graphene oxide-based hydrogels for the efficient capture of dye pollutants from aqueous solutions, Carbon, 56 (2013) 173–182.
  68. Y. Yao, S. Miao, S. Liu, L.P. Ma, H. Sun, S. Wang, Synthesis, characterization, and adsorption properties of magnetic Fe3O4@graphene nanocomposite, Chem. Eng. J., 184 (2012) 326–332.
  69. J. Zhang, T. Shang, X. Jin, J. Gao, Q. Zhao, Study of chromium (VI) removal from aqueous solution using nitrogen-enriched activated carbon based bamboo processing residues, RSC Adv., 5(1) (2015) 784–790.
  70. M.K. Rai, G. Shahi, V. Meena, R. Meena, S. Chakraborty, R.S. Singh, B.N. Rai, Removal of hexavalent chromium Cr (VI) using activated carbon prepared from mango kernel activated with H3PO4, Resour.-Effic. Technol., 2 (2016) S63–S70.