Improved Adsorption of 4-Nitrophenol onto a Novel Hyper-Cross-Linked Polymer

In the present study we prepared a hyper-cross-linked polymeric adsorbent (NDA-701) possessing a uniquely bimodal pore size distribution for 4-nitrophenol (4-NP) adsorption from water. A macroporous polymeric adsorbent Amberlite XAD-4 and a granular activated carbon GAC-1 were chosen for comparison. NDA-701 exhibited better mechanical strength and higher capacity of 4-NP than XAD-4, which possibly resulted from its hyper-cross-linking nature and micropore structure, respectively. 4-NP adsorption isotherm onto NDA-701 is well described by the Freundlich model, and its better kinetics performance than GAC-1 resulted from its macropore structure. After adsorption NDA-701 was amenable to an entire regeneration by using NaOH solution as regenerant, whereas only approximately 75% regeneration efficiency was observed for GAC-1. Results of continuous fixed-bed runs in pilot and industrial scale demonstrated that NDA-701 is capable of completely removing 4-NP from chemical effluent with no capacity loss, and 4-NP can be readily recovered by further treatment of the concentrated regenerant solution. It is attractive that the value of the recovered 4-NP from chemical wastewater will even engender a surplus after countervailing all the operation cost during field application.