PDMS/ceramic composite membrane synthesis and evaluation of ciprofloxacin removal efficiency

The present study employs an unexplored, one-step route for remediation of ciprofloxacin, an emerging contaminant, using hydrophobically modified ceramic membranes. Hydrophobic interaction between the membrane and the target contaminant, i.e., ciprofloxacin, is the governing factor responsible for its removal. The hydrophilic surface of hollow, single channel, macroporous clay-alumina membranes was made hydrophobic using cross-linked polydimethylsiloxane. The influencing parameters-concentration of polymer, cross-linking agent, catalyst and coating time-were optimized by Taguchi analysis to yield a membrane with enhanced ciprofloxacin rejection and high permeate flux. The synthesized membrane was characterized for its contact angle, clean water permeability, degree of swelling, degree of cross-linking, X-Ray diffraction, atomic fluorescence microscopy, field emission scanning electron microscopy. Effect of various operating parameters-cross flow velocity, transmembrane pressure, filtration time, solution pH-was investigated upon removal of ciprofloxacin in cross flow membrane filtration. Maximum rejection of 99.3% was obtained by the hydrophobic membrane having contact angle of 138.5 degrees for 5 mg/L feed solution. The stability of the membrane was judged in terms of change in ciprofloxacin rejection upon filtration for five consecutive cycles, each cycle being 180 min. The developed PDMS/ceramic composite membranes could have great prospect for long-term application in removal of emerging contaminants from water

Synthesis of bentonite clay based hydroxyapatite nanocomposites cross-linked by glutaraldehyde and optimization by response surface methodology for lead removal from aqueous solution

A novel nanocomposite (BT-HAp) was developed by chemical synthesis using hydroxyapatite nanoparticles and bentonite clay and was further applied for toxic lead (Pb) removal from aqueous solution. Three types of bentonite clay based nanocomposites were prepared by varying the pH of the solution (3, 7 and 10) with the addition of glutaraldehyde as a cross-linking agent. The formation and performance of the prepared BT-HAps are described herein. Clear and sharp XRD peaks suggested the presence of hydroxyapatite and bentonite clay compounds in the composite. The FTIR spectra confirmed the existence of the functional groups required to develop the nanocomposite. The Bt-HAp nanocomposites were also characterized in terms of BET, FESEM and TEM etc. to establish their formation. The nanocomposite synthesized at pH 7 showed a higher sorption capacity than those at pH 3 and 10. A mathematical and statistical optimizing technique (response surface methodology) was applied to verify the interactive effects of various parameters on the sorption capacity. The analysis of variance was discussed for the factors and response and confirmed the significance of the predicted model (R-2 = 0.9906). The Langmuir isotherm model best represented the phenomenon having a sorption capacity of 346 mg g(-1) at 30 degrees C. The sorption mechanism was well described by the pseudo 2nd order kinetic model indicating the coexistence of both physisorption and chemisorption. Moreover, a considerable amount of toxic Pb (similar to 99%) removal was observed for the synthesized nanocomposite via sorption

Ceramic membrane based microfiltration for treatment of highly contaminated tannery wastewater

The feasibility of treating tannery wastewater having high organic loads was studied using ceramic membrane based microfiltration process. The common effluent treatment plant (CETP) of a centralized leather complex was selected for the study which accommodates about 450 tanneries in the city, processing hides from raw to finished products. Effluent sample was collected from different locations of the CETP, i.e. untreated composite effluent, effluent from primary clarifier and from equalisation tank. The effluent had varying chemical oxygen demand (COD) and biochemical oxygen demand (BOD) values of 18,480-1500 mg/L and 5720-880 mg/L, respectively and turbidity of 2480-604 NTU. Prior to microfiltration study composite effluent was subjected to biological pretreatment using activated sludge collected from the common effluent treatment plant. The dried biomass was characterized by Fourier transform infrared spectroscopy (FT-IR). Crossflow microfiltration (CMF) study was conducted using indigenously developed porous ceramic membranes by the Central Glass and Ceramic Research Institute from cost effective composition of a-alumina and clay. COD and sulphide removal efficiency was observed with time for the direct microfiltration and microfiltration of pretreated effluent. The combined process was found highly effective for COD and sulphide removal. Depending on the initial loadings, about 67-92% removal of COD and 98-99% reduction of sulphide was obtained in the combined process whereas, in the single stage process, the removal was 48-68% and 60-65%, respectively. Membrane fouling was investigated using the linearized forms of cake formation equations obtained by Wiesener and Aptel

Tubular ultrafiltration ceramic membrane based on titania nanoparticles immobilized on macroporous clay-alumina support: Elaboration, characterization and application to dye removal

The development of new membranes with improved separation properties, high mechanical and thermal stability using inexpensive and naturally abundant materials is of utmost importance for sustainable development and environmental applications. Ceramic materials due to their high chemical, mechanical and thermal stability in combination to their facile surface functionalization have inspired material scientists to design innovative low-cost ceramic-based membrane supports. This study focuses on the preparation and characterization of novel asymmetric ultrafiltration ceramic membrane coated with single separation layer made of TiO2 nanoparticles, and its application to removal of alizarin dye from aqueous solutions. The membrane was prepared by a simple and one-step deposition of micrometer-thick titania layer on the internal surface of the tubular-shape porous clay-alumina membrane support from an aqueous colloidal suspension of titanium oxide (TiO2) nanoparticles with size of 10 nm. The colloidal suspension was prepared in the presence of 0.2 wt.% of Dolapix, and 30 g of an aqueous solution of polyvinyl alcohol at 12 wt.% and 66 mL of H2O. Microfiltration tubular supports of 10 mm/7 mm (outer/inner diameter) were prepared through an extrusion method followed by a sintering process using China Clay Rajmahal grade and alumina, as mineral precursors. The composition of 25% of clay and 75% of alumina was selected in this work as it showed a lower sintering temperature (T-f = 1350 degrees C) which could ensure low cost elaboration process, an average water flux of 850 L h(-1) m(-2) bar(-1) as well as enhanced mechanical performance (approximate to 37 MPa) and large porosity (48%) with an average pore diameter of 0.75 mu m. SEM characterization showed that at the sintering temperature of 800 degrees C, the TiO2 nanoparticles coated densely and homogeneously the ceramic support forming a thin layer of about 4.2 mu m in thickness and leading to a clear reduction of the mean pore size (50 nm approximatively) while providing a water permeability of 117 L h(-1) m(-2) bar(-1). The so-designed ultrafiltration (UF) tubular ceramic membrane has proved efficient for alizarin red dye removal with a retention rate of 99% and a permeate flux of 70 L h(-1) m(-2) at pH 9 and a transmembrane pressure of 5 bar. (C) 2017 Elsevier B.V. All rights reserved

Surface Modification of Naturally Available Biomass for Enhancement of Heavy Metal Removal Efficiency, Upscaling Prospects, and Management Aspects of Spent Biosorbents: A Review

Heavy metal pollution in water emerges as a severe socio-environmental problem originating primarily from the discharge of industrial wastewater. In view of the toxic, non-biodegradable, and persistent nature of most of the heavy metal ions, remediation of such components becomes an absolute necessity. Biosorption is an emerging tool for bioremediation that has gained momentum for employing low-cost biological materials with effective metal binding capacities. Even though biological materials possess excellent metal adsorption abilities, they show poor mechanical strength and low rigidity. Other disadvantages include solid–liquid separation problems, possible biomass swelling, lower efficiency for regeneration or reuse, and frequent development of high pressure drop in the column mode that limits its applications under real conditions. To improve the biosorption efficiency, biomasses need to be modified with a simple technique for selective/multi-metal adsorption. This review is intended to cover discussion on biomass modification for enhanced biosorption efficiency, mechanism studies using various instrumental/analytical techniques, and future direction for research and development including the fate of spent biosorbent. In most of the previously published researches, difficulty of the process in scaling up has not been addressed. The current article outlines the application potential of biosorbents in the development of hybrid technology integrated with membrane processes for water and wastewater treatment in industrial scale

Energy efficient harvesting of Arthrospira sp using ceramic membranes: analyzing the effect of membrane pore size and incorporation of flocculant as fouling control strategy

BACKGROUND: Biomass harvesting is an important issue in commercialization of algal biofuel production. In the present study focus has been given to develop a robust ultrafiltration membrane on low cost ceramic substrate for efficient harvesting of Arthrospira sp. The effect of membrane pore size and flocculant addition as fouling reduction strategy was investigated. The study represents a comparative analysis in terms of flux, fouling, volume reduction factor (VRF) and energy consumption of different processes, viz. microfiltration (MF), ultrafiltration (UF), guar gum induced bioflocculation followed by MF and bioflocculation followed by UF, respectively. RESULTS: The MF process showed higher volume reduction factor (11.11) and concentration factor (12.5) with stabilized flux of 230 Lm(-2) h(-1) under optimized conditions. In terms of fouling, the UFmembraneswere less prone to fouling, with a flux recovery of about 93% during long-term operation. Incorporation of bioflocculant caused significant reduction in fouling of both the MF and UF membrane. Energy uptake in the MF process was lower (0.908 kWh m(-3)) than that of the UF process (2.625 kWh m(-3)). Among the various processes permeate from the UF showed the highest CO2 dissolution capacity (657 +/- 7mg L-1), hence could be reused for algal cultivation with negligible reduction in growth. CONCLUSION: The present study reveals that clay-alumina based ceramic MF and UF membrane can be effectively used in harvesting of algal biomass with suitable fouling control strategy based on the algal species and required biomass concentration. The processes developed exhibited less energy consumption compared with other existing processes. (C) 2017 Society of Chemical Industry

Heavy metal recovery from electroplating effluent using adsorption by jute waste-derived biochar for soil amendment and plant micro-fertilizer

Effluent from electroplating industries contains various toxic heavy metal ions such as chromium, nickel, lead, cadmium, copper and zinc. Recovery of the valuable heavy metals by environment friendly approach for recycling in various useful applications could be significant from the perspectives of clean process development with techno-economic viability. Zinc is an important component of electroplating effluent found in high concentration (80-750 mg/L). The present study investigates on recovery of zinc from electroplating effluent using an efficient biochar synthesized from jute industrial wastes. Biochar characteristics and metal removal mechanisms were established using BET surface area, zeta potential, FESEM-EDAX, elemental mapping, XRD, FTIR, XPS, XRF, Raman spectroscopy and roles played by functional groups. Optimum adsorption capacity of 526.32 mg g(-1) was obtained for Zn(II). Zn(II) binding was achieved by ion exchange, complexation with functional groups, electrostatic interactions, adsorption and micro-precipitation. The techno-economic analysis was performed for biochar prepared by chemical carbonization process and found competitive in comparison with other reported biochar obtained by slow pyrolysis process. Further, the disposal of the toxic metal-laden spent adsorbent is a critical issue that needs to be addressed. In the present study recycling potential of the exhausted Zn(II)-laden biochar was explored for the development of micro-fertilizer for plants and soil-fertility improvement. Application of the Zn(II)-laden biochar mixed with soil revealed a positive influence on Cicer arietinum seed germination, plant growth parameters, protein and chlorophyll a and b content. Significantly, there were no changes in the antioxidant enzymes activities, superoxide dismutase (SOD) and catalase (CAT) between the plants grown in control soil and different Zn(II)-laden biochar-mixed soil, suggesting that 15% of the Zn(II)-laden biochar could not be excess condition of zinc. The present study thus addresses an important aspect of solid waste management of jute industry considering significant volume of jute waste production of similar to 0.04 MT/day in India along with the remediation of electroplating and other metal-bearing industrial effluent. Further, micro-fertilizer application of the metal-laden sludge and soil productivity improvement at low cost, environmentally safe and fruitful manner makes the study significant from ecological as well as societal perspectives. GRAPHICS]

Treatment of textile dyehouse effluent using ceramic membrane based process in combination with chemical pretreatment

Treatment of highly concentrated dyebath effluent and comparatively dilute composite effluent having mixture of various reactive dyes collected from a cotton fabric dyeing unit was undertaken in the present study. Ceramic microfiltration membrane prepared from a cost effective composition of alumina and clay was used. Prior to microfiltration, a chemical pretreatment was carried out with aluminium sulphate in combination with a polymeric retention aid. An optimum dose of 100 mg/L of aluminium sulphate and 1 ml/L of a commercial flocculant Afilan RAMF was found effective for dye removal (> 98%) from the synthetic solutions of reactive dyes with initial concentration of 150 mg/L in both the single component and two component systems. In the microfiltration study, effect of operating pressure in the permeate flux was observed for both the pretreated and untreated effluents and permeate samples were analyzed for dye concentration, COD, turbidity, TSS, etc. during constant pressure filtration. About 98-99% removal of dyes was obtained in the combined process with COD reduction of 54-64%

Development of hydrophobic clay–alumina based capillary membrane for desalination of brine by membrane distillation

Clay–alumina compositions of 0, 20, 40 and 55 weight percent (wt%) clay and rest alumina were maintained in porous support preparation by extrusion followed by sintering at 1300 °C for 2.5 h to obtain 3 mm/2 mm (outer diameter/inner diameter) capillary. 1H,1H,2H,2H-perfluorodecyltriethoxysilane (97%) (C8) was used to modify the capillary surface of all compositions without any intermediate membrane layer to impart hydrophobic characteristics and compared in terms of contact angle produced by the capillaries with water and liquid entry pressure (LEPw). FTIR analysis showed that the hydrophilic surface of the capillary membranes was efficiently modified by the proposed grafting method. Capillary with 55 wt% clay produced a pore size of 1.43 micron and was considered as an ideal candidate for grafting with C8 polymer to impart surface hydrophobicity. The contact angle and LEPw value obtained for this modified membrane (C-55-M) were 145° and 1 bar, respectively. The modified capillary membrane was applied for desalination of brine by air gap membrane distillation (AGMD) at a feed pressure of 0.85 bar. Maximum flux obtained for C-55-M membrane was 98.66 L/m2 day at a temperature difference of 60 °C with salt rejection of 99.96%. Mass transfer coefficient of C-55-M was 16 × 10−3 mm/s at feed temperature of 70 °C