Sara Heshmatian; Hooman Bakhshi; Shohreh Azizi; Itani Given Madiba
Abstract
This study presents a sustainable approach for converting waste sheep wool into high-performance activated carbon for Cr(VI) removal from aqueous solutions. Chemical (NaOH) and steam activation routes were evaluated, and steam activation at 900 °C for 3 h in a rotary furnace produced the optimal ...
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This study presents a sustainable approach for converting waste sheep wool into high-performance activated carbon for Cr(VI) removal from aqueous solutions. Chemical (NaOH) and steam activation routes were evaluated, and steam activation at 900 °C for 3 h in a rotary furnace produced the optimal material. The resulting carbon exhibited a high specific surface area (1807 m²/g), a pore volume of 1.002 cm³/g, and a well-developed micro-mesoporous structure. The optimized adsorbent achieved 99% removal of Cr(VI) from a 400 mg/L solution within 45 min. Physicochemical characterization (BET, SEM, XRD, Raman) and adsorption analysis (ICP-OES) confirmed the material’s suitability for adsorption processes. Equilibrium behavior was best described by the Freundlich isotherm (R² = 0.976), while the Langmuir model yielded a monolayer capacity of 147 mg/g. Kinetic data closely followed the pseudo-second-order model (R² = 0.999), suggesting adsorption dominated by electrostatic interactions and surface complexation under acidic conditions. These findings demonstrate that wool waste can be effectively valorized as a low-cost, scalable, and efficient adsorbent for Cr(VI) remediation.
Rozita Moradi; Majid Mohadesi
Abstract
The aim of this research was to separate mercury from gold refining wastewater using activated carbon (AC) from natural shells. To this end, walnut and coconut shells were used as the main source of AC. The characterizations of both ACs were compared by FTIR, BET, and SEM analyses. The FTIR results revealed ...
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The aim of this research was to separate mercury from gold refining wastewater using activated carbon (AC) from natural shells. To this end, walnut and coconut shells were used as the main source of AC. The characterizations of both ACs were compared by FTIR, BET, and SEM analyses. The FTIR results revealed interactions between the solute and the functional groups on the adsorbent surface. According to the BET results, the mean pore diameter (MPD) of AC from coconut shells (CSAC) was smaller than that derived from walnut shells (WSAC). The specific surface areas for CSAC and WSAC were 1069.1 and 119.6 m2/g, respectively. SEM results revealed that the porous texture of ACs emanates from their cellular structure. This research further studied the impact of operational parameters “adsorbent dose” (0.3-3.8 g/L), “pH” (2-9), and “residence time” (10-120 min) on mercury removal. Under optimal operational conditions, the mercury removal rate reached 97% (for WSAC) and 93% (for CSAC). Kinetic model assessments revealed the highest agreement between the experimental data and the pseudo-first-order (PFO) model. Both adsorbents were regenerable, with their performance (compared to fresh adsorbents) exceeding 90% after each regeneration.
Ahmad Sabzali; Fatemeh Mohammadi; Zeynab Sadeghzadeh; Mona Eghbali Gharehbelagh
Abstract
Treatment of pharmaceutical wastewaters, especially compounds resistant to biological degradation, is very important, and various methods have been introduced to treat such wastewaters on a laboratory and experimental scale. A new designed reactor consisting advanced oxidation and activated carbon adsorption ...
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Treatment of pharmaceutical wastewaters, especially compounds resistant to biological degradation, is very important, and various methods have been introduced to treat such wastewaters on a laboratory and experimental scale. A new designed reactor consisting advanced oxidation and activated carbon adsorption was undertaken for treating toxic pharmaceutical wastewater containing p-Nitrochlorobenzene (pNCB) in the pilot scale. During Paracetamol manufacturing some pNCB may be remained without any chemical changes depended on reaction condition. The effluent from reactor may have some concentration of the pNCB, which can cause a lot of problems if discharged directly into the environment. Organic substance and pNCB concentration of the influent and effluent of the reactor was investigated for 30 days in two phases. The first phase of operation included the achievement of stable conditions and the second phase included the survey of removal efficiency by changing the operational parameters. Raw wastewater was entered directly into the reactor through overhead distillation column in process of Paracetamol manufacturing. The wastewater flow ranged from 3.8 to 16 m3/day during two phases. The average efficiencies for the pNCB concentration removal were 99.4 % for the phase I and 98.0% for phase II. COD removal efficiency of 97.8% was achieved for the reactor. Although oxidation process is effective in removing pNCB, but the most effect was related to absorption process. This study demonstrates that application of Simultaneous ozonation and adsorption processes is effective for treating wastewater containing pNCB.
Majid Baghdadi; Mohammad Javan; Tahere Taghizade Firozjaee; Nioushasadat Haji Seyed Javadi; Mahshid Mortazavi; Ali Torabian
Abstract
In this study, the effect of antibiotic wastewater containing 20 common pharmaceuticals (14 antibiotics and 6 non-steroidal anti-inflammatory drugs (NSAIDs)) individually as well as their combination was investigated on activatedsludge in batch reactors. The chemical oxygen demand (COD), the ammonium ...
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In this study, the effect of antibiotic wastewater containing 20 common pharmaceuticals (14 antibiotics and 6 non-steroidal anti-inflammatory drugs (NSAIDs)) individually as well as their combination was investigated on activatedsludge in batch reactors. The chemical oxygen demand (COD), the ammonium concentration, the inhibition rate and toxicity index of COD and ammonium were investigated in wastewater. The inhabitation for COD and ammonium removal was variable for each drug so that the pharmaceuticals are applied simultaneously had such a greater adverse effect on inhibition rate than individual compounds. The pretreatment of wastewaters containing drugs was performed by powdered activated carbon PAC to reduce the adverse effect of these drugs on activated sludge. The appropriate method for separation of PAC from wastewater before introducing to activated sludge process and the optimized adsorption and contact time during the pretreatment process were studied. The pretreatment of pharmaceuticals wastewater with activated carbon improved well COD and NH4+ removal to 71 % and 55 %, respectively, that demonstrate the activated carbon can be considered as a suitable pretreatment option for the activated sludge.
Nazanin Niknezhad; Neda Azimi; Shahin Ahmadi
Abstract
The purpose of this study was numerical and experimental investigations on the influence of ultrasound on Cr (VI) removal from aqueous solution by adsorption onto activated carbon nanoparticles. The effect of key factors on Cr (VI) elimination like media pH, absorbent mass, initial concentration of Cr ...
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The purpose of this study was numerical and experimental investigations on the influence of ultrasound on Cr (VI) removal from aqueous solution by adsorption onto activated carbon nanoparticles. The effect of key factors on Cr (VI) elimination like media pH, absorbent mass, initial concentration of Cr (VI) and the location of ultrasound transducers were considered. To perform CFD modeling of ultrasound propagation, the vibrations of 1.7 MHz piezoelectric transducers (PZTs) were defined based on the dynamic mesh model. The experimental results indicated that by pH raising from 2 to 8, Cr (VI) removal efficiency had a decreasing trend and at pH=8, it had the lowest value. The adsorption rate increased by augmentation in the adsorbent mass (AM) due to the enhancing its specific surface area. In comparison with using a shaker, ultrasound showed lower needed contact time for Cr (VI) elimination at identical conditions. In addition, CFD results depicted that the acoustic streams were induced in the direction of ultrasound propagation, which is caused to reach the better mixing and Cr (VI) removal efficiency. Finally, the experimental data were adopted with the Langmuir and Freundlich isotherms. The comparison of these models showed that both models were well suited to experimental findings and the data compatibility with Langmuir model was greater.
Danial Nayeri; Seyyed Alireza Mousavi; Azadeh Mehrabi
Abstract
In this study, oxytetracycline removal from aqueous solution by activated carbon prepared using corn stalks has been investigated. The adsorbent was characterized using Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope (SEM). The effects of main variables; adsorbent ...
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In this study, oxytetracycline removal from aqueous solution by activated carbon prepared using corn stalks has been investigated. The adsorbent was characterized using Fourier transform infrared spectrophotometer (FTIR) and scanning electron microscope (SEM). The effects of main variables; adsorbent dose, contact time, pH, and initial oxytetracycline concentration on the efficiency of adsorption efficiency were investigated. Results confirmed the effects of main variables and the maximum removal of antibiotic (99.9 %) achieved at initial concentration of 10 mg/L, pH of 9, and contact time of 60 min, when adsorbent dose was 1.5 g. The results of isotherm and kinetic studies showed that the oxytetracycline adsorption onto activated carbon prepared from corn stalks follows Freundlich isotherm (R2 = 0.98) and pseudo-second order kinetic model (R2 = 0.99). The maximum adsorption capacity of oxytetracycline was 522.6 mg/g. In brief, the activated carbon that has been prepared from corn stalks as low cost, non-toxic and environment friendly adsorbent shows a good ability for removal of oxytetracycline form water and wastewater.
