The persistence of antibiotics in sewage wastewater treatment plants in recent years has emerged as a serious issue. This study therefore evaluated three types of natural zeolites (i.e., NZ01, NZ02, and NZ03) for the removal of selected antibiotics namely tetracycline (TC) and oxytetracycline (OTC) from aqueous solution. The physical and chemical properties of the natural zeolites were characterized using various analytical techniques and the antibiotic removal studies were carried out in a batch adsorption experiment evaluated at various experimental conditions. The highest adsorption capacity was 62.5 and 76.3 mmol/g for TC and OTC, respectively, observed for NZ02 at pH values between 7 and 8. The adsorption of TC and OTC followed the Langmuir and Temkin isotherm models, respectively, whereas the adsorption kinetic data obeyed the Elovich kinetic model. The regeneration study on NZ02 indicated that it can still remove TC and OTC after five adsorption/desorption cycles. The removal efficiency of TC and OTC also improved from approximately 5-39 and 28%, respectively, by addition of NZ02 during the coagulation/flocculation process. These results thus demonstrated the applicability of the natural zeolites, especially NZ02, for the removal of TC and OTC from aqueous solution; hence the potential for the application in sewage treatment process for removal of antibiotics through either conventional adsorption/desorption or adsorptive coagulation/flocculation (ACF) process.

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This study was conducted to investigate the potential application of oil palm empty fruit branches (OPEFB) as adsorbents to remove organic methylmercurry, MeHg(II), and inorganic Hg(II) from aqueous solution. The OPEFB was functionalized with amine containing ligand namely 3-ureidopropyltriethoxysilane (UPTES) aiming for better adsorption performance towards both mercury ions. The adsorption was found to be dependent on initial pH, initial concentraton, temperatures, and contact time. The maximum adsorption capacities (Q) of Hg(II) adsorption onto OPEFB and UPTES-OPEFB were 0.226 and 0.773 mmol/g, respectively. The Q of MeHg(II) onto OPEFB, however, was higher than UPTES-OPEFB. The adsorption kinetic data obeyed the Elovich model and the adsorption was controlled by the film-diffusion step. The calculated thermodynamic parameters indicate an endothermic adsorption process. Adsorption data analysis indicates that the adsorption mechanism may include ion-exchange, complexation, and physisorption interactions. The potential applications of adsorbents were demonstrated using oilfield produced water and natural gas condensate. The UPTES-OPEFB offered higher selectivity towards both mercury ions than OPEFB. The regenerability studies indicated that the adsorbent could be reused for multiple cycles.

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Immobilized nanoscale zero‐valent iron on natural zeolite (NI‐NZ) was synthesized for remediation of antibiotics‐contaminated wastewater. A series of characterization methods confirmed the success of preventing the agglomeration of nanoscale zero‐valent iron particles, using natural zeolite as supporting media. The equilibrium data fitted well with the Langmuir and Temkin models, whereas the pseudo‐second‐order and Elovich kinetic models were suitable to describe the kinetic data. The versatility of NI‐NZ was also tested in a coagulation‐flocculation process which increased the removal of tetracycline from 10 to 75 %.