Silver adsorption enhancement from aqueous and photographic waste solutions by mercerized coconut fiber

The mercerized coconut fiber (CF-NaOH) was prepared by treating the pristine coconut fiber (CF-Pure) with NaOH solution. The morphology and chemical composition of CF-Pure changed after mercerization process. The maximum Ag(I) adsorption capacity of the CF-Pure and CF-NaOH was 0.502 and 0.612 mmol/g, in which the equilibrium data fitted to the Freundlich and Langmuir isotherm models, respectively. The Ag(I) adsorption rate also increased by using CF-NaOH and the kinetic data of both CF-Pure and CF-NaOH obeyed the pseudo-second order kinetic model. The enhancement of Ag(I) adsorption selectivity from photographic waste solution was also observed for the CF-NaOH

Adsorptive removal of benzene from aqueous solution by surfactant modified banana trunk as adsorbents

The adsorptive removal of benzene from aqueous solution by four types of surfactant modified banana trunk (BT) adsorbents was investigated through batch adsorption experiments. The surface morphology and functional groups determination were conducted BT adsorbents indicating the significant changes were observed after modifications. The adsorption results indicated that the non-ionic surfactant (i.e. Triton-X 100) modified BT has the highest adsorption capacity (57.52 µmol/g) and its adsorption capacity significantly affected by the increase of temperatures, benzene concentrations and contact time

Removal of Elemental Mercury by Coconut Pith Char Adsorbents

AbstractCoconut pith (CP), which is abundantly available and cheap, has the potential of being used as low-cost adsorbents for elemental mercury removal. In this study, the preparation of chars was carried out through the carbonization of CP at three different environment conditions: (a) open reactor under nitrogen flow; (b) closed reactor under nitrogen environment; and (c) closed reactor under ambient environment; at the temperature of 700°C. The results show that the chemical, physical, morphological and spectral properties of the adsorbents greatly influenced by the environment of carbonization used. The highest Hgo adsorption capacity was observed for CCA700 (2395.98 μg/g), followed by CCN700 (2052.49 μg/g), and CFN700 (1416.92 μg/g). These results demonstrated that coconut pith derived chars could be potential as low-cost adsorbent alternatives for the removal of elemental mercury in gas streams

Characterization of natural zeolite for adsorptive removal of antibiotics from aqueous solution

The persistent existence of antibiotics in sewage wastewater treatment plants in recent years has emerged as a serious concern. In this study, natural zeolite (NZ02) obtained from China was employed as an adsorbent to remove tetracycline (TC) from aqueous solution. The characterization results show that the NZ02 consists of quartz, clinoptilolite-Na and heulandite having the CEC of 62.18cmol/kg and the surface area of 36.646m2/g. Adsorption results show that the maximum adsorption capacity of TC on NZ02 was 19.30mg/g and the equilibrium data followed theLangmuir adsorption isotherm model

Utilization of coconut milk processing waste as a low-cost mercury sorbent

Desiccated coconut waste sorbent (DCWS), a byproduct of coconut milk processing, was studied as a sorbent for Hg(II) sorption. Energy dispersive X-ray analysis indicated that the DCWS mainly contained C, N, and O, while the Fourier transform infrared measurements confirmed the existence of hydroxyl, carboxyl, and amine groups on the DCWS surface. The point of zero charge (pHpzc) and cation-exchange capacity (CEC) values were 6.05 and 2.02 meq/100g, respectively. The batch equilibrium data were fitted well by the Langmuir isotherm model with a maximum sorption capacity, qmax of 500 mg/g, while the kinetic sorption data were found to follow a pseudo-second-order kinetic model. A column sorption study showed that the sorption capacity increased and the breakthrough time decreased with the increase in the initial Hg(II) concentrations. The regeneration studies revealed that the DCWS could be regenerated and reused

Surface modifications of agrowaste biomass for Hg(II) and MeHg(II) removal from aqueous solution, oilfield produced water and natural gas condensate

The removal process of Hg(II) and MeHg(II) from aqueous solution by surface modified agrowaste biomass (AWB) was studied. The surface modifications were carried out by methods of mercerization, oxidative delignification, acid treatment, and biological treatment using laccase. The modifications promoted disruption of AWB structural surfaces and thus changed their physical and chemical properties as well as Hg(II) and MeHg(II) adsorption performances. The adsorption efficiency of Hg(II) was higher than MeHg(II) for all AWB adsorbents. The adsorption capacity of Hg(II) and MeHg(II) for AWB-Pure was 0.97 and 0.17 mmol/g, respectively. The highest adsorption capacity of Hg(II) and MeHg(II) was respectively observed for the AWB-Laccase (0.98 ± 0.04 mmol/g) and AWB-NaOCl/NaOH (0.40 ± 0.07 mmol/g). The adsorption selectivity of modified AWB adsorbents towards Hg(II) and MeHg(II) studied using oilfield produced water and natural gas condensate samples was found to be lower as compared to AWB-Pure, but higher selectivity was observed for other metals. The renewability studies show that the pure and modified AWB adsorbents had similar adsorption performance characteristics. The high Hg(II) adsorption efficiency (η > 90 %) was observed up to the third adsorption cycle, while for the MeHg(II), it decreased after each adsorption–desorption cycle

Removal of Hg(II) and CH3Hg(I) using rasped pith sago residue biosorbent

Rasped pith sago residue (RPSR) was used as a biosorbent for inorganic (Hg(II)) and organic (CH3Hg(I)) mercury removal from aqueous solutions. In biosorbent preparation, the RPSR having particle size range of 0.06-0.10 was washed with deionized water repeatedly to eliminate impurities, dried in an oven at 50 degrees C for two days, followed with drying in a vacuum oven for 3h. The performance of RPSR as a novel biosorbent for removing mercury was evaluated in batch adsorption. The adsorption of mercury ions was found to highly dependent on the pH of the solutions. The Hg(II) adsorption was high at pH>4, while the CH3Hg(I) adsorption was found higher at pH<5. The higher adsorption capacity for Hg(II) and CH3Hg(I) was 0.288 and 0.213mmol/g, respectively. Both mercury adsorptions equilibrium and kinetics were fitted to the Langmuir isotherm model and pseudo-second-order kinetic model, respectively. These results indicate the RPSR has a potential to be a low-cost biosorbent for mercury removal process from aqueous solutions

Surface chemistry modifications of rice husk toward enhancement of Hg(II) adsorption from aqueous solution

The modified rice husks were characterized in terms of morphology (scanning electron microscopy), functional groups (Fourier transform infrared spectroscopy), surface charge (pH(pzc)), and elemental composition which indicate the treatments that led to significant changes to its surface chemistry. Batch adsorption studies showed that the highest adsorption capacity of Hg(II) was 89 and 118 mg/g obtained by sulfur-functionalized rice husk (RH-CS) and organosilane-grafted rice husk (RH-GM), respectively. The reusability of raw rice husk (RH-Raw) and alkali-treated rice husk (RH-NaOH) was superior to RH-CS and RH-GM; even though their adsorption capacities were slightly lower. However, their selectivity was comparable to that of the RH-CS and RH-GM. In addition, the results demonstrated the potential application of rice husk-based adsorbents for treating Hg(II) containing wastewaters such as produced water from oil and gas exploration activities

Adsorption equilibrium and kinetics of elemental mercury onto coconut pith

The experiment to discover the ability of Coconut Pith (CP) as an elemental mercury adsorbent was carried out using a conventional flow type packed-bed adsorber with N2 as a carrier gas, conducted at bed temperature of 50°C. The adsorbents were characterized through proximate analysis (moisture and ash content), CHNS elemental analysis, FTIR and Nitrogen Adsorption/Desorption (NAD) analysis. Adsorption results showed that the adsorption capacity increased with the increase of initial concentrations, from 0.25 to 1.04 µ g-1 for 100 and 500 µ m-3, respectively. Meanwhile, the kinetic results showed that the Hg° adsorption could be very well presented by the pseudo-second order model. Primary results suggested that the coconut pith with proper modification can be a very promising low-cost adsorbent material for Hgo removal from gas strea