Enhanced adsorption of fluoride from aqueous solution using an iron-modified attapulgite adsorbent

Attapulgite modified with iron was used as an adsorbent for fluoride removal from aqueous solutions. The pristine attapulgite and the iron-modified attapulgite composite were characterized by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) techniques, and the pH point of zero charge measurement. The XRD analysis indicates the existence of iron oxide hydroxide (FeO[OH]) in the iron-modified attapulgite composite. The FT-IR spectra of the iron-modified attapulgite composite before and after adsorption indicate that the involvement of the hydroxide radical in the fluoride adsorption. The effects of pH, contact time, initial concentration, and temperature on fluoride adsorption by the adsorbent were studied in a batch system. Kinetics studies show that the fluoride adsorption kinetics over the adsorbent is well-described by the pseudo-second-order kinetic model. The fluoride adsorption isotherm is well-fitted by the Langmuir model. Desorption studies show that the iron-modified attapulgite adsorbent can be easily regenerated at pH 12.5. The adsorption mechanism is discussed in detail.

Reassessment of conservative management for stage T1N0M0 transitional cell carcinoma of the bladder

PURPOSE

We evaluated the outcome of stage T1 transitional cell carcinoma of the bladder treated with local tumor resection and intravesical therapies.

MATERIALS AND METHODS

Of 42 patients with stage T1 bladder cancer seen at our clinic during a 10-year period 38 were treated conservatively with local tumor resection, intravesical therapy and long-term followup. Bacillus Calmette-Guerin (BCG) was used as the primary intravesical agent since 1986.

RESULTS

Of the 38 patients 15 had initial grade 2 or 2 to 3 tumors, including 9 (60%) who had at least 1 or more local recurrences but without disease progression. The remaining 23 patients had grade 3 or grades 3 to 4 stage T1 tumors, with local recurrence in 17 (74%) and disease progression in 8 (35%). Furthermore, 5 patients (22%) died of the metastasis despite salvage therapies.

CONCLUSIONS

For patients with initial grade 2 or grades 2 to 3, stage T1 disease the risk of disease progression is low. Current management with local tumor resection and intravesical BCG is appropriate and should be continued. Patients with high grade, stage T1 disease are at particularly high risk for disease progression and BCG does not seem to decrease this risk effectively. Therefore, immediate cystectomy is appropriate and should be recommended.