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C Rajagopal

Publications and source records attributed to C Rajagopal.

11 recordsLinked to original sources
PubMed2005

A pilot scale evaluation for adsorptive removal of lead (II) using treated granular activated carbon.

Wastewaters discharged from the defence serviceable industries pose a serious environmental hazard due to their heavy metal load. The present study focused on optimizing the operational variables viz, hydraulic loading rate, bed height and feed concentration through bench scale study and using that for assessing the efficiency of pilot scale system with sulphur loaded carbon (AC-S) as the adsorbent in the removal of Pb (II). Static mode adsorption studies were also carried out for Pb (II) removal using treated (AC-S) and untreated carbon (AC). AC-S shows about 35 percent increase in maximum adsorption capacity over that on AC. The maximum adsorption capacity in the column mode for Pb (II) at the optimized conditions: bed height of 0.4 m, hydraulic loading rate of 7.5 m3h(-1)m(-2) and the feed concentration of 6 mg l(-1) for achieving 50% breakthrough concentration was found to be 2.89 mg g(-1). Adsorption mechanism involved during Pb (1) in the column has also been explored. Bohart-Adams model was used for modeling the bench scale data and predicting the adsorption behavior at pilot scale level.

Adsorption↗
PubMed2004

Electrochemical removal of chromium from wastewater by using carbon aerogel electrodes.

A study has been carried out to determine the feasibility of electrochemical removal of chromium ions from industrial wastewater using carbon aerogel electrodes. In this work the effect of key variables including pH (2-7), concentration 2-8 (mg/l), and charge 0.3-1.3 (A h) was determined. The metal ion removal was significantly increased at reduced pH and high charge conditions. The metal concentration in the wastewater can be reduced by 98.5% under high charge (0.8A h) and acidic conditions (pH 2). The effect of the independent parameters--pH, effluent concentration and charge on the percentage removal was depicted by a quadratic equation obtained using Box-Behnken model. The regression analysis gave a R2 value of 0.9469 shows a close fit between the experimental results and the model predictions. The model was further used to optimise the parameters to maximise the percentage Cr-removal to more than 98%.

Carbon↗
PubMed2004

Mercury (II) removal from water by coconut shell based activated carbon: batch and column studies.

This study was undertaken to investigate adsorption behavior of Hg (II) from aqueous systems on activated carbon in static and dynamic mode by varying initial Hg (II) concentration, adsorbent dose and pH. Langmuir and Freundlich adsorption isotherm were applied to model the adsorption data. Removal of mercury obeyed the Langmuir and Freundlich adsorption isotherm models. The extent of removal of Hg (II) was found to be dependent on sorbent dose, pH and initial Hg (II) concentration. Mercury uptake increased from 72 to 100 percent with increasing pH from 2 to 10. A set of desorption studies was also performed for the metal ions with the aim of investigating the mechanism involved. Moreover, the competing effects of various ions like Pb (II) and Cu (II) is also described. The column capacity for a column diameter of 20 mm, bed height of 0.4 m, hydraulic loading rate of 7.5 m3 h(-1) m(-2) and a feed concentration of 3 mg l(-1) were found to be 3.02 mg g(-1). Breakthrough curves were plotted for the adsorption of mercury on the adsorbent using continuous-flow column operation by varying different operating parameters like hydraulic loading rate (3-10.5 m3 h(-1) m(-2)), bed height (0.3-0.5 m), and feed concentrations (2-6 mg l(-1)). The aim was to assess the effect of bed height, hydraulic loading rate and initial feed concentration on breakthrough time and adsorption capacity, which helped in ascertaining the practical applicability of the adsorbent. At the end an attempt has been made to develop empirical relationship from the data generated from column studies for designing the adsorption column, based on the Bohart-Adams model.

Adsorption↗
PubMed2001

Development of adsorptive removal process for treatment of explosives contaminated wastewater using activated carbon.

The adsorption characteristics of nitro-organics such as trinitro-toluene (TNT), dinitro-toluene (DNT) and nitrobenzene (NB) on granular activated carbon (GAC) were studied to understand their dynamic adsorption behaviour for dilute aqueous solutions. A model was developed to predict the dynamics of the adsorption process and the effect of various design and operating parameters on adsorption characteristics. The model predictions would provide inputs to design of bench scale and pilot plant scale experiments. Section 2 of the paper describes the assumptions, predictions, development of the model and its validation with experimental data generated during bench scale and pilot plant trials. Section 3 presents the breakthrough characteristics obtained by conducting experimental runs for GAC of different surface areas from 650 to 1500 m(2)/g, hydraulic loading rates (HLR) ranging between 12 and 24 m(3)/h/m(2), feed concentrations from 50 to 130 mg/l and bed heights between 300 and 1000 mm for TNT, DNT and NB solutions. The effect of these independent parameters on the breakthrough time, adsorption capacity and the minimum concentration achieved in the effluent was studied and the results obtained are presented in this paper. These indicate that the adsorption capacity goes though a maximum when studied as a function of HLR and feed concentration. The adsorption capacity per unit surface area also shows a maximum around 1000 m(2)/g. The minimum bed height required for meeting environmental effluent discharge limit of 1 ppm was experimentally found to be about 800 mm. These results compare well with the predictions based on the model developed for column adsorption process. Data from these experimental runs and the model predictions have been used to optimise various parameters for the design of a pilot plant unit with 200 l per hour capacity.

Adsorption↗
PubMed1997

Interleukin-2-activated hematopoietic stem cell transplantation for breast cancer: investigation of dose level with clinical correlates.

Incubating hematopoietic stem cells with IL-2 in vitro for 24 h generates cytotoxic T cells. When infused into patients, these cells may stimulate a graft-versus-tumor (GVT) effect. This clinical trial was designed to assess the ability of IL-2 activated peripheral blood stem cells (PBSC) to reconstitute hematopoiesis, to investigate dose levels and dose-limiting toxicities of IL-2, and to evaluate clinical results and preliminary laboratory effects using a combination of IL-2-activated autologous PBSC followed by IL-2 after transplantation. Sixty-one women with stage II-IV breast cancer were treated. After the administration of carboplatin (200 mg/m2/day for 3 days) and cyclophosphamide (2 g/m2/day for 3 days), patients received autologous PBSC that were cultured in IL-2 for 24 h followed by parenteral administration of IL-2 beginning the day of transplantation. Three escalating doses of IL-2 were evaluated with increasing duration up to 4 weeks. Of the 57 patients receiving IL-2 after tranplantation, 19 patients (33.3%) were unable to complete the planned course of IL-2 therapy due to persistent fevers (n = 9), diarrhea (n = 2), pulmonary capillary leak syndrome (n = 3), development of a rash (n = 1), atrial fibrillation (n = 1), or patient's request (n = 3). One death occurred during hospitalization. Engraftment of neutrophils occurred on day 11.5 (mean; range 8-21 days) and platelets on day 11.7 (mean; range 7-33 days). The maximal tolerated dose of IL-2 was 6 x 10(5) IU/m2/day for 4 weeks. Disease-free survival rates for all stages were comparable to current reports in the literature. Preliminary laboratory evaluations include FACScan analysis of the IL-2 activated PBSC demonstrating an increased percentage of CD3+, CD25+, HLA-DR+ T cells. Phenotypically similar cells were present in peripheral blood samples of patients when tested 15 days after transplantation. This study demonstrates successful engraftment with IL-2-activated PBSC after high-dose chemotherapy for women with stage II-IV breast cancer. The regimen is feasible and, although toxicities are common, they are manageable and correlate with increasing dose and duration of IL-2.

Adult↗
PubMed1996

Hematopoietic potential of IL-2-cultured peripheral blood stem cells from breast cancer patients.

Patients receiving autologous transplants for various malignancies generally experience an increased incidence of relapse compared with patients receiving unmanipulated allogeneic transplants. We initiated a protocol for IL-2 activation of peripheral blood stem cells (PBSC) for induction of in vitro and in vivo autologous graft-versus-tumor (GVT) activity in patients with breast cancer. In this study we analyzed the effects of 24 h of IL-2 incubation on the hematopoietic potential of PBSC from these patients. Cells collected by leukapheresis were first cryopreserved and stored in liquid nitrogen, then thawed rapidly and incubated with IL-2 in a serum-free system for 24 h, with samples analyzed before and after incubation. Although there was a significant drop in mononuclear cells (MNC) (from 4.5 to 3.7 x 10(8)/kg) and CD34+ cells (from 12.3 to 7.5 x 10(6)/kg) after 24 h in culture, there was no significant change in colony-forming units (CFU) (from 12.5 to 11.5 x 10(5)/kg). Time to engraftment (neutrophils: < 0.5 x 10(9)/l; platelets: > 20 x 10(9)/l) was comparable to a cohort of similar patients receiving non-cultured PBSC transplants. These results indicate that mobilized frozen/thawed PBSC which have been cultured in IL-2 for 24 h retain adequate potential for hematopoietic reconsistution in this group of patients.

Breast Neoplasms↗
PubMed1984

A central apnoea extension alarm.

A central apnoea alarm designed to monitor the breathing of infants placed in four separate cubicles is described. It has been found to be effective and inexpensive, costing about 50 pounds.

Emergencies↗
PubMed1983

Plasma cholesterol and lipoprotein lowering effect of Anna Pavala Sindhooram.

Plasma lipid and lipoprotein lowering effect of Anna Pavala Sindhooram (APS), a Sidha medicinal preparation was investigated in normal rabbits, chicken and men, and in hypercholesterolemic rabbits. The drug exhibited a marked hypolipaemic and hypocholesterolemic action in the three species studied. In rabbits, marked reduction was observed in very low density lipoprotein cholesterol, while in chicks and in humans low density lipoprotein cholesterol was also reduced significantly when compared to the levels measured before the administration of the drug. The drug enhances faecal elimination of lipids and bile acids in atherosclerotic rabbits.

Adult↗