Influence of dissolved organic carbon nature on adsorption of ibuprofen, caffeine and diclofenac by powdered activated carbon from water

The impacts of structurally different dissolved organic carbon surrogates (DOC) on the adsorption of ibuprofen, caffeine and diclofenac (C0 2?3 ?g L-1) onto powdered activated carbon (PAC) were studied. The efficiency of PAC in a synthetic matrix (SM) was tested when low or high molecular weight DOC surrogates were added. Additionally, the impact of a potential natural coagulant was investigated. Different DOC surrogates differently affected the adsorption of tested organic micropollutants (OMPs). In the first 30 min, a positive impact of all types of surrogates on the adsorption of neutral and hydrophilic caffeine was observed, while for negatively charged ibuprofen and diclofenac, the impacts varied. The low molecular weight DOC (containing amino acids and resorcinol) positively impacted the adsorption of ibuprofen, while effects were not clear for diclofenac. The high molecular weight DOC decreased the degree of adsorption for both compounds. The mass transfer calculations showed that low molecular weight DOC accelerated the transport of OMPs. High molecular weight DOC slowed reaching equilibrium (within 48 h). Thermogravimetry confirmed that the DOC coating qualitatively changes during the adsorption, which also affects the OMPs removal. The addition of a natural coagulant affected ibuprofen and diclofenac adsorption. For neutral caffeine the effects were not clear.